Variable-Angle Locking Plate (VA-LP) in Orthopedics

1. Definition and Concept

2. Design and Mechanisms of Locking

Fixed-Angle vs. Variable-Angle

Variable-Angle Locking Mechanisms (by manufacturer design)

1. Locking caps - a secondary cap is threaded over the screw head after placement to lock it at the selected angle
2. Over-compression screw heads - the screw head deforms slightly to grip the plate at the angle of insertion
3. Screws that cut threads into the plate - the locking screw itself machines threads into the plate hole at whatever angle it is inserted
4. Tabbed screw holes - flexible tabs in the plate hole deform around the screw head

"The specific design varies by manufacturer, and includes locking caps, over compression screw heads, screws that cut threads into the plate, and tabbed screw holes." - Rockwood & Green's Fractures in Adults, 10th ed., p. 492

3. Biomechanics

How Locking Plates Function

• Axial loads are converted to compressive stress at screw-bone interface (bone is stronger in compression than shear)
• Angular stability leads to uniform stress distribution across all screw-bone interfaces
• All screws must fail simultaneously for the construct to fail (vs. sequential failure in non-locking)
• Particularly beneficial in osteoporotic bone

Variable-Angle Specific Biomechanics

• Bending stability of a 4.5 mm locking plate is reduced to 63% at 5° deviation and 31% at 10° deviation of locking screw insertion vector
• Variable-angle systems provide greatest resistance when the screw is inserted perpendicular to the plate; resistance decreases almost linearly as off-axis angle increases
• Standard (fixed) locking systems provide greater resistance to rotational failure at the screw-plate interface than variable-angle systems

"Care should be taken when using variable angle locking plates because construct stability may be compromised as screw inclination is increased." - Rockwood & Green's, p. 493

"Tidwell et al. found that standard locking systems provided greater resistance to rotational failure at the screw-plate interface than variable-angle locking systems." - Rockwood & Green's, p. 2891

4. Clinical Indications

A. Periarticular Fractures

• Distal femur fractures: VA plates allow screws to be directed into specific articular fragments that would not be accessible at a fixed angle; especially useful in complex comminuted patterns
• Tibial plateau fractures: Screws can be directed toward depressed fragments at custom angles
• Distal radius fractures (volar plating): VA-LCP has a distinct mechanical advantage when fixing a smaller radial styloid fragment - fragment-specific fixation via customized screw placement is possible
• Clavicle fractures: Precontoured plates with VA holes are useful when the plate is not perfectly centered on the clavicle
• Distal humerus fractures: Available in precontoured locking plates for complex articular reconstruction

B. Periprosthetic Fractures

• Standard bicortical screws may be impossible to place (stem obstruction)
• Unicortical locked screws alone have insufficient torsional resistance
• VA locking technology allows surgeons to angle screws around the prosthetic stem to achieve bicortical purchase
• Modular plate systems (e.g., LOQTEQ VA Periprosthetic Plate) use hinged attachments that rotate up to 45° around the plate axis, with ±15° conical angulation

C. Osteoporotic Bone

• When bone quality is poor, the ability to direct screws into the strongest available bone stock (e.g., toward subchondral bone) is valuable
• Bicortical screw purchase is biomechanically superior to unicortical, and VA technology makes it achievable in more circumstances

D. Malreduction or Suboptimal Plate Position

• If the plate cannot be placed in the ideal position (e.g., anatomically precontoured plate slightly off-center), VA holes allow screw trajectories to compensate

5. Common VA-LCP Systems by Anatomical Region

6. Surgical Technique Considerations

1. Nonlocked screws first: All conventional (nonlocked) screws in the same segment must be placed BEFORE locking screws - mixing sequence improperly can lock a malreduction
2. Compression before locking: If compression is desired (stable simple fracture patterns), it must be achieved before locking screws are placed
3. Screw angle discipline: Even though VA plates allow angulation, deviating further than the design parameters will reduce construct stability
4. Working length: Leave empty holes over the fracture zone (bridges comminution) - the working length determines construct stiffness and micromotion for callus formation
5. Plate length: In comminuted/osteoporotic fractures, longer plates with spaced screws provide better stability than short plates with clustered screws

7. Advantages

• Accommodates individual patient anatomy and fracture geometry
• Critical for periprosthetic fractures where a stem obstructs standard trajectories
• Allows fragment-specific screw fixation in complex articular fractures
• Reduces risk of cross-threading (a major problem with fixed-angle locking plates if the surgeon's drill guide drifts)
• Useful when plate positioning is imperfect due to anatomical variation
• Dual functionality: can serve as compression plate or internal fixator/bridging plate depending on technique
• Materials available: stainless steel, titanium alloy, or CFR-PEEK (carbon fiber-reinforced polyether ether ketone)

8. Disadvantages and Limitations

• Lower bending and rotational strength at the screw-plate interface compared to fixed-angle locking plates, especially at high off-axis angles
• Technical complexity: more demanding to use correctly; requires understanding of biomechanical trade-offs
• Higher cost than conventional locking or nonlocking plates
• Clinical evidence remains limited: as stated in Rockwood & Green's, "the clinical effectiveness of variable angle locking technology remains unproven"
• Early mechanical failures have been reported - notably early reports of the Synthes VA locking distal femur plate (J Orthop Trauma, 2016)
• Risk of over-reliance on VA technology to compensate for suboptimal reduction

9. Comparison with Far-Cortical Locking (FCL) Screws

Summary

• Rockwood and Green's Fractures in Adults, 10th ed. (2025), pp. 476, 492-499
• Lenz M et al. "Concept of variable angle locking - evolution and mechanical principles." PMID: 25676391 (2015)
• Zdero R et al. "Biomechanical design optimization of distal femur locked plates." PMID: 37366552 (2023)

Vascularised Bone Grafts in Orthopedics

1. Definition and Basic Concept

"Although technically difficult to implant, [vascularised bone graft] allows more rapid union and cell preservation; best for irradiated tissues or large tissue defects." - Miller's Review of Orthopaedics, 9th ed.

2. Biological Basis

• Osteocytes survive - no mass cell death
• The bone can remodel and hypertrophy over time in response to mechanical load
• Osteogenesis, osteoinduction, and osteoconduction are all active
• The graft can bridge avascular zones because it brings its own blood supply
• Even if the vascular anastomosis fails, the graft can still function as a conventional cortical strut (one of the listed advantages)

3. Indications

1. Large segmental bone defects - the critical threshold is approximately 6 cm
   • Defects up to 6 cm: conventional techniques may suffice
   • Defects 6-10 cm: iliac crest or fibula may be appropriate
   • Defects >10 cm: free fibula is the graft of choice
2. Inadequate soft tissue coverage at the recipient site
3. Failed conventional bone grafting - persistent nonunion after standard treatment
4. Avascular necrosis (AVN) - femoral head AVN, scaphoid AVN
5. Congenital pseudarthrosis of the tibia - notoriously resistant to standard treatment
6. Infected nonunion / osteomyelitis - conventional grafts fare poorly in infected beds
7. Irradiated bone - post-radiotherapy tissue has severely compromised vascularity
8. Bone loss after tumour excision - fibrous dysplasia resection, bone tumour resection
9. Scaphoid nonunion with avascular proximal pole
10. Composite tissue loss - when both bone and soft tissue need reconstruction (flap with skin island)
11. Physeal transfer in children - where longitudinal bone growth is needed

"The transfer of a vascularized bone graft is indicated when traditional bone grafting techniques cannot be done, especially if soft-tissue coverage is inadequate." - Campbell's Operative Orthopaedics, 15th ed. (2026)

4. Donor Sites - The Three Main Sources

A. Free Fibula (Preferred for Long Bone Defects)

1. Supine position, hip and knee flexed, sandbag under ipsilateral buttock, pneumatic tourniquet applied
2. Lateral leg incision centred on fibula, from fibular neck toward ankle
3. Develop interval between peroneus longus anteriorly and soleus posteriorly
4. Peroneal vessels lie just deep to soleus, nearly in contact with the fibula
5. Dissect soleus origin off fibula to expose pedicle; retract peroneal muscles anteriorly in extraperiosteal fashion
6. Protect superficial peroneal nerve proximally and flexor hallucis longus posteriorly
7. Continue anteriorly, incise anterior intermuscular septum close to fibula
8. Harvest required length with osteotomes, maintaining 0.7-1.0 cm muscle cuff around the pedicle

B. Iliac Crest

C. Rib

D. Medial Femoral Condyle (MFC) - Newer Application

• Blood supply: descending medial genicular artery (branch of popliteal)
• Provides thin but highly osteogenic periosteal tissue
• Useful for: ulna, metacarpals, clavicle, tibia, humerus, mandible, scaphoid
• Can be transferred as a free flap with anastomosis end-to-side to radial artery

E. Distal Radius - Pedicled VBG for Scaphoid

• Donor site: dorsal distal radius
• Vascular pedicle: 1,2-intercompartmental supraretinacular artery (1,2-ICSRA) - a branch of the radial artery
• Indication: Scaphoid nonunion with avascular proximal pole, without humpback deformity
• Technique: Graft harvested as a dorsal pedicled flap and rotated into a prepared trough in the scaphoid

"Bone most commonly harvested from dorsal aspect of distal radius, based on 1,2 intercompartmental supraretinacular artery (1,2-ICSRA). For correction of both humpback deformity and avascular proximal pole: free transfer of medial femoral condyle bone graft, supplied by descending medial genicular, and connected end-to-side to radial artery." - Miller's Review of Orthopaedics, 9th ed.

5. Advantages and Disadvantages

Advantages (Campbell's Box 68.3)

1. One-stage procedure - reconstruction is complete in a single operation (vs. Masquelet two-stage technique)
2. Tubular bone is mechanically stronger than onlay cortical bone graft
3. Transfer of bleeding bone with both endosteal and periosteal circulation to the recipient site
4. Can be dowel grafted (intramedullary) into proximal and distal bone ends for stability during anastomosis
5. Fallback: can still function as a conventional cortical bone graft if the vascular anastomosis fails
6. Hypertrophies with weight-bearing over time - unlike conventional strut allografts which resorb
7. Suitable for composite reconstruction (bone + soft tissue + skin + nerve in one flap)
8. Functional joints, epiphyses, and skeletal muscle can be included in the composite graft

Disadvantages (Campbell's Box 68.3)

1. Long operating time - typically 4-8+ hours; limits use primarily to younger, fit patients
2. Elective procedure only - not suitable in emergency or staged settings
3. Donor site morbidity - particularly knee and ankle problems after fibula harvest
4. Major vessels sacrificed in both donor and recipient limbs
5. Difficult assessment of anastomosis patency postoperatively
6. Technically demanding - requires microsurgical expertise
7. Higher cost and need for specialised facilities
8. Risk of vascular thrombosis - if pedicle fails, graft reverts to conventional (slower) incorporation

6. Preoperative Planning

• Preoperative angiography of both donor and recipient limbs - to identify anomalous vascularity, previous vascular injury, or atherosclerotic disease
• For fibula: confirm the leg has three-vessel runoff (anterior tibial, posterior tibial, and peroneal) - peroneal artery can be sacrificed only if the other two are patent
• Select graft source based on defect size and recipient site requirements:
  • ≤6 cm: conventional grafting may suffice
  • 6-10 cm: iliac crest or fibula

  • 10 cm: fibula strongly preferred

7. Specific Clinical Applications

Long Bone Reconstruction (Post-Trauma / Tumour)

• Free fibula is the workhorse
• For tibial defects: the fibula can be intramedullary (dowel technique) or used as an onlay strut
• Over years, the fibula hypertrophies and remodels to resemble the reconstructed bone in cross-section
• Bone healing proceeds from both ends; union typically confirmed on serial radiographs

Congenital Pseudarthrosis of the Tibia

• Highly resistant to conventional grafting
• VBG (free fibula) used after resection of the pseudarthrotic segment

Femoral Head AVN

• Vascularised iliac crest pedicle flap (DCIA-based) used for core decompression + structural support
• Both pedicled iliac crest and free vascularised fibular graft (FVFG) are described

Scaphoid Nonunion with Avascular Proximal Pole

• Pedicled 1,2-ICSRA graft from distal radius: for nonunion without significant humpback deformity
• Free MFC graft: for nonunion with both humpback deformity AND AVN (corrects deformity and restores vascularity)
• Intraoperative punctate bleeding from the proximal pole is the best test of residual vascularity

Oncologic Reconstruction

• After tumour resection, VBG provides a biological alternative to megaprosthesis
• Systematic review (Ebad Ali et al., 2023, PMID: 37422827): VBG shows faster bone union than non-vascularised bone graft after tumour resection (p<0.001), with comparable MSTS functional scores and complication rates

8. Postoperative Monitoring

• Clinical monitoring: temperature, colour, capillary refill of any included skin paddle
• Selective angiography - confirms pedicle flow
• Serial imaging: radiographic monitoring of healing and graft hypertrophy over months
• Bone scintigraphy: can assess graft viability
• Thrombosis of the pedicle is the most feared early complication - results in graft acting as a non-vascularised strut at best, or complete failure at worst

9. Donor Site Complications

10. Comparison with Alternative Reconstruction Methods

Summary

• Campbell's Operative Orthopaedics, 15th ed. (2026), Chapter 68 (Free Tissue Transfer)
• Miller's Review of Orthopaedics, 9th ed., pp. 820-835
• Ebad Ali SM et al. "Outcomes Of Reconstruction With Vascularized Vs Non Vascularized Bone Graft After Resection Of Bone Tumours." PMID: 37422827 - Systematic Review & Meta-Analysis, 2023

Vascularised Fibular Graft (VFG) in Orthopedics

1. Introduction and Historical Background

"For most orthopaedic reconstructive procedures, the fibula is the preferred donor bone if its circulation has not been injured." - Campbell's Operative Orthopaedics, 15th ed. (2026)

2. Anatomy of the Fibular Graft

The Fibula as a Donor Bone

Vascular Pedicle

1. Nutrient (endosteal) artery - the dominant peroneal artery enters the fibula in its proximal third as the nutrient artery - this is why the proximal osteotomy must be within the proximal third
2. Periosteal vessels - branches of the peroneal artery supply the outer cortex through a 0.7-1.0 cm muscle cuff

Composite Flap Options

• Skin paddle (osteocutaneous flap): a skin perforator from the peroneal artery can be included - useful for mandibular reconstruction with soft tissue coverage
• Muscle: a small cuff of surrounding muscle (soleus/FHL) can be included for dead space filling
• Proximal articular surface and physis: in children, the proximal fibular epiphysis can be transferred as a vascularised epiphyseal graft to provide a growing joint surface

3. Indications

Absolute Indications (preferred over conventional methods)

1. Large segmental bone defects >6-8 cm - from:
   • High-energy trauma with bone loss
   • Tumour resection (primary bone tumours, soft tissue tumour resection)
   • Osteomyelitis with bone debridement
   • Irradiation necrosis
2. Defects in a compromised vascular bed - infected, irradiated, or avascular tissue
3. Failed conventional bone grafting - persistent nonunion after ≥2 standard attempts

Specific Clinical Scenarios

1. Avascular necrosis (AVN) of the femoral head - pre-collapse and early post-collapse stages
2. Congenital pseudarthrosis of the tibia (CPT) - a notoriously difficult condition
3. Tibial nonunion - especially with segmental defects or previous infection
4. Upper limb reconstruction - radius, ulna, humerus defects
5. Spine fusion - as a vascular strut in scoliosis or complex spinal reconstruction
6. Oncologic reconstruction (in combination with or without allograft - "allograft-prosthetic composite")
7. Paediatric bone loss - the physis-bearing graft uniquely allows for skeletal growth

Size-Based Decision Rule (Campbell's)

• Defect ≤6 cm: conventional bone grafting usually sufficient
• Defect 6-10 cm: iliac crest OR fibula
• Defect >10 cm: fibula strongly preferred

4. Preoperative Planning

1. Angiography (CT angiography or conventional) of both donor and recipient limbs
   • Confirm three-vessel runoff in the leg (anterior tibial, posterior tibial, peroneal) - the peroneal artery can only be sacrificed if the anterior and posterior tibial arteries are intact
   • Identify recipient vessels available for anastomosis
   • Rule out atherosclerosis or previous vascular injury
2. MRI of recipient site - assess bone quality, zone of injury, marrow involvement
3. Template planning - calculate defect size; plan osteotomy levels
4. 3D printing / Virtual Surgical Planning (VSP) - increasingly used for complex cases (especially mandible) to pre-plan osteotomy angles and graft contouring with patient-specific cutting guides

5. Surgical Technique - Fibular Harvest (Lateral Approach)

Patient Positioning

• Supine, donor extremity with hip and knee flexed, foot slightly internally rotated
• Sandbag under ipsilateral buttock
• Pneumatic tourniquet applied initially to maintain bloodless field

Step-by-Step Technique

Graft Fixation at Recipient Site

• Preferably dowel (intramedullary) technique: each end of the fibula is inserted into the medullary canal of the recipient bone - provides stability during anastomosis and maximises contact area
• Supplemental plates and screws (typically a long locking compression plate)
• Pedicle positioning must be planned before fixation - the pedicle must reach the recipient artery and vein without tension or kinking
• Arterial and venous microsurgical anastomoses are completed after fixation

6. FVFG for Specific Conditions

A. Long Bone Defects (Tibia, Femur, Humerus, Radius/Ulna)

• The fibula is doweled into both proximal and distal medullary canals for stability
• Over months to years, the fibula hypertrophies in response to mechanical loading - the cross-sectional area increases to match the recipient bone's demands
• Serial radiographs confirm progressive union and hypertrophy
• Supplemental conventional cancellous bone grafting at the graft-host junctions may accelerate union

• Union rate: 82% at 2 years, 97% at 5 years
• First union after index procedure: 70% at a mean of 10 months
• Overall union achieved in 91% of patients
• Smoking significantly increases risk of nonunion (p-value significant)
• Locking vs. traditional fixation made no difference to union rates

• Flap survival: 97% (147/151 cases)
• First union rate: 95%
• Second union rate (after revision): 97%
• Overall complication rate: 33%

B. Avascular Necrosis (AVN) of the Femoral Head

• The fibula is introduced through a core decompression track in the femoral neck into the necrotic segment of the femoral head
• The vascular pedicle is anastomosed to the lateral femoral circumflex vessels or terminal branches of the profunda femoris
• The living fibula provides both structural support (preventing femoral head collapse) and biological revascularisation of the necrotic zone
• Best results in Ficat/ARCO stages I-III (pre- and early post-collapse)
• Studies show lower conversion rates to total hip arthroplasty (THA) compared to core decompression alone in young patients (<50 years)

C. Congenital Pseudarthrosis of the Tibia (CPT)

• Vascular supply to a poorly-vascularised pathological tibial segment
• Structural cortical support
• In growing children, the proximal fibular physis can be included to provide continued longitudinal growth
• Important: in children with significant remaining growth, distal tibiofibular fusion (Technique 68.19) is recommended after fibula harvest to prevent progressive valgus ankle deformity - the remaining tibia tends to bow laterally without fibular support

D. Oncologic Reconstruction

• FVFG can be used alone or as a biological component in an allograft-fibula composite (allograft provides immediate bulk and structural support; FVFG provides biological healing at graft-host junctions)
• Can also be combined with megaprosthesis
• The fibula's capacity to hypertrophy makes it superior to inert allografts for long-term durability

7. Postoperative Care

8. Advantages

1. One-stage procedure - complete reconstruction in a single operation
2. Longest available vascularised bone - up to 26-30 cm, sufficient for even the largest long bone defects
3. Tubular cortical bone - mechanically stronger than onlay corticocancellous grafts from iliac crest
4. Hypertrophies with loading - the fibula gradually remodels to match the demands of the recipient site
5. Reliable pedicle anatomy - the peroneal artery is consistent in location and calibre
6. Straightforward dissection - compared to iliac crest, the technique is reproducible
7. Composite flap potential - skin paddle, muscle, physis all available
8. Fallback safety net - even if the vascular anastomosis fails, the graft still functions as a conventional cortical strut
9. Can bridge infected/irradiated beds - brings its own blood supply

9. Disadvantages and Limitations

1. Long operative time - typically 4-8+ hours, requiring two surgical teams working simultaneously
2. Major vascular sacrifice - the peroneal artery and its comitantes are permanently divided
3. Donor site morbidity - ankle and knee problems, wound complications
4. Small calibre mismatch - fibula diameter is smaller than most recipient long bones; requires hypertrophy period before full weight bearing
5. Technical demand - requires dedicated microsurgical expertise and infrastructure
6. Pedicle thrombosis risk - graft failure if anastomosis clots
7. Children with growth: risk of progressive ankle valgus deformity if distal tibiofibular fusion not performed
8. Assessment of patency is indirect and difficult

10. Donor Site Complications

11. Monitoring Graft Viability

12. Comparison with Other Reconstruction Methods

13. Outcomes Summary

• Union rates approach 97% at 5 years for long bone defects (Houdek et al.)
• Flap survival >97% in upper limb trauma (Liaw et al., PMID 35083566)
• Overall ~90% bony healing in large series
• FVFG delays THA conversion significantly in AVN of femoral head in young patients
• Smoking is the most important modifiable risk factor for nonunion
• Modern locking fixation has not been shown to improve union rates over traditional fixation

• Campbell's Operative Orthopaedics, 15th ed. (2026), Chapter 68 - Techniques 68.18, 68.19
• Miller's Review of Orthopaedics, 9th ed., pp. 820-834
• Liaw F et al. "Outcomes of free vascularised fibular graft reconstruction in upper limb trauma - a systematic review." Eur J Orthop Surg Traumatol. 2023. PMID: 35083566
• Houdek MT et al. "The outcome and complications of vascularised fibular grafts." Bone Joint J. 2017;99-B(1):134-138. Bone & Joint Journal
• Bumbasirevic M et al. "Free vascularised fibular bone grafts in orthopaedics." PMC 4037521 (2014)

Viscosupplementation in Orthopedics

1. Definition and Concept

2. Biology of Hyaluronan in Normal vs OA Joints

Normal Synovial Fluid

• Produced by type B synoviocytes (fibroblast-like cells) and chondrocytes
• A major component of synovial fluid and the extracellular matrix of articular cartilage
• Responsible for the viscoelastic properties of synovial fluid:
  • Viscous (resists flow) at slow movements - lubricates
  • Elastic (resists deformation) at rapid movements - absorbs shock

• Concentration: 2-4 mg/mL
• Molecular weight: 6-7 million Daltons

In Osteoarthritis

• HA concentration falls to ~1-2 mg/mL
• Molecular weight falls to ~1-3 million Daltons
• The synovial fluid becomes more watery, loses viscoelasticity
• Joint lubrication and shock absorption are impaired
• Chondrocyte function is adversely affected

Mechanisms of Action of Exogenous HA

3. HA Preparations Available

4. Indications

Primary Indication

• Knee osteoarthritis - the most evidence-based application; recommended for mild-to-moderate OA (Kellgren-Lawrence grades I-III) in patients who have failed first-line conservative therapies (analgesia, physiotherapy, weight loss)

Accepted Uses in Other Joints

Patient Selection - Who Responds Best

• Earlier-stage OA (KL grade I-III) - grade IV patients (bone-on-bone) respond poorly
• Younger patients with more preserved cartilage
• Patients not responding to NSAIDs/analgesia but not yet surgical candidates
• Patients with contraindications to surgery (comorbidities, anticoagulation)
• Patients wishing to delay arthroplasty
• Patients without significant effusion at the time of injection (effusion predicts poor response and increases risk of acute reaction)

5. Contraindications

6. Injection Technique

Knee Injection Approaches

1. Superolateral approach: Needle enters lateral to the superior pole of the patella, directed under the patella. Patient supine, knee extended. Most commonly used.
2. Anterolateral approach: Entry at the lateral joint line, 1 cm lateral to the patellar tendon, knee slightly flexed.
3. Anteromedial approach: Mirror image of anterolateral, medial infrapatellar point.
4. Medial infrapatellar (MIP): 1 cm medial and inferior to the inferior border of the patella, knee at 45° flexion.

• Obesity/difficult anatomy
• Significant osteophytes limit joint access
• Previous failed injections
• Hip, ankle, or small joint injections
• Studies show improved accuracy and potentially better outcomes with US guidance

Step-by-Step Technique (Knee)

1. Patient positioned supine, knee extended (or slightly flexed for anterolateral approach)
2. Identify landmarks - patellar borders, joint line
3. Aseptic skin preparation (povidone-iodine or chlorhexidine)
4. Optional: local anaesthetic raised at skin entry point
5. If significant effusion present: aspirate first (effusion dilutes HA and reduces efficacy)
6. Without changing needle position after aspiration, attach HA syringe and inject
7. Needle size: typically 21-22 gauge
8. Confirm intra-articular placement by absence of resistance to injection
9. Apply gentle pressure after needle withdrawal; ask patient to flex/extend knee to distribute HA

Post-Injection Care

• Avoid strenuous activity for 24-48 hours
• Ice pack if local discomfort
• Short-term rest recommended (though controversial)
• Next injection (if multiple course): 1 week later

7. Injection Schedule

8. Clinical Outcomes and Evidence

What the Evidence Shows

• 2025 Systematic Umbrella Review (Glinkowski & Tomaszewski, J Clin Med): moderate efficacy in pain relief and functional improvement, particularly in early-to-moderate OA
• EUROVISCO Consensus 2024 - 12 international OA experts using Delphi consensus: recommends HA for KL grades I-III who are insufficiently managed with first-line therapies
• LatinVisco Consensus 2026 (PMID: 41980630): 25 experts across Latin America confirmed HA reduces pain, improves function, and has a favourable safety profile in OA grades I-III
• Shoulder OA (Familiari et al. 2023, PMID: 37314198): HA superior to corticosteroids at longer follow-up in glenohumeral OA (effect size 4.43, p=0.00006 for HA+PT vs PT alone)
• Duration of benefit: typically 3-6 months per course; effects often outlast HA residence time in the joint

• Pereira et al. 2022 (BMJ) - 24 RCTs, ~9,000 patients: overall clinically irrelevant pain reduction vs. placebo for knee OA
• Pereira et al. 2024 (Osteoarthritis and Cartilage): HA associated with clinically irrelevant pain reduction and increased harms
• Post-arthroscopic HA injection (Mao et al. 2023, PMID: 36411508): HA after arthroscopic knee surgery showed no significant benefit in pain or function vs. control - not recommended
• HA vs PRP/PRGF (Migliorini et al. 2025, PMID: 39964439): PRGF may be associated with more favourable functional outcomes; no significant difference in WOMAC pain or stiffness

Guideline Positions (Summary)

The controversy reflects real biological heterogeneity - patients with early OA and preserved cartilage clearly respond better than those with end-stage disease. Many large negative meta-analyses include end-stage patients who would not be expected to benefit.

9. HA vs Other Intra-Articular Therapies

10. Adverse Effects and Complications

• Cross-linked (high-MW) products like Synvisc/Hylan GF-20
• Repeated injections (sensitisation)
• Active joint inflammation at time of injection

11. Special Considerations

In Patients on Anticoagulants

• Evidence supports safety of IA injections at therapeutic INR levels (warfarin)
• Also safe with direct oral anticoagulants (DOACs) at therapeutic levels
• Risk of haemarthrosis is small and generally manageable

Repeat Courses

• Supported by systematic review (Altman R et al., Semin Arthritis Rheum, 2018): repeated courses of HA are efficacious and safe
• Typically 1-2 courses per year; minimum 6-month interval between courses

Hip Viscosupplementation

• Must be ultrasound-guided (too deep for accurate blind injection)
• Evidence from 2025 systematic review (PMID: 40343507) supports benefit in hip OA
• Growing acceptance as a bridge to THA

Shoulder Viscosupplementation

• Systematic review 2023: IA HA in glenohumeral OA showed significant improvement vs. baseline and superiority to corticosteroids at longer-term follow-up
• Combined with physiotherapy appears most effective

12. Comparison with the Natural Disease Course

• Reverse cartilage damage
• Cure OA
• Replace surgical treatment in advanced disease

• Reduces pain for 3-6 months per course
• May improve function
• May delay need for surgery in appropriate patients
• Has a favourable safety profile compared to repeated corticosteroids (no cartilage toxicity at normal doses)

13. Summary

• Rheumatology, 2-Volume Set (2022, Elsevier), Chapter references for HA in OA
• Pfenninger and Fowler's Procedures for Primary Care, 3rd ed.
• Hamdan PC et al. "LatinVisco consensus on viscosupplementation for knee OA." Complement Ther Med. 2026. PMID: 41980630
• Familiari F et al. "Efficacy of IA HA injections in glenohumeral OA." J Orthop Res. 2023. PMID: 37314198
• Migliorini F et al. "HA vs PRGF for knee OA: meta-analysis of RCTs." Orthopadie. 2025. PMID: 39964439
• Mao B et al. "HA after arthroscopic knee surgery: systematic review and meta-analysis." Orthop Surg. 2023. PMID: 36411508

Recent Advances in Wound Management

1. Background - The Problem of Chronic Wounds

2. Wound Bed Preparation - The T.I.M.E. Framework (Updated)

• T - Tissue: Debridement of non-viable, infected, or hyperkeratotic tissue
• I - Infection/Inflammation: Biofilm control; appropriate antimicrobials
• M - Moisture balance: Neither too wet (maceration) nor too dry (desiccation)
• E - Edge of wound: Stimulating epithelial migration; addressing senescent wound edges

3. Advances in Debridement

A. Ultrasound-Assisted Wound Therapy (UAWT)

• Low-frequency ultrasound (20-40 kHz) delivered via mist or direct contact
• Disrupts biofilm mechanically via cavitation
• Stimulates growth factor release and fibroblast activity
• Shown to improve healing in chronic VLUs and DFUs
• Non-contact versions (e.g., MIST Therapy) allow treatment even in fragile tissue

B. Hydrosurgery (Versajet / Aquajet)

• High-pressure water jet system (Bernoulli effect) that selectively removes necrotic tissue while preserving viable tissue
• More precise than conventional surgical debridement
• Single-use disposable system reduces infection risk
• Used particularly in burn wounds and diabetic foot infections

C. Larval Therapy (Maggot Debridement Therapy - MDT)

• Sterile Lucilia sericata larvae applied to wounds
• Mechanisms: enzymatic digestion of necrotic tissue, antimicrobial secretions, growth factor production
• Particularly effective in infected sloughy wounds resistant to conventional debridement
• Systematic reviews confirm superiority to conventional methods for debriding necrotic tissue
• Licensed gel preparations (LarvE, BIOXODERM) allow application without direct larval contact - improving patient acceptance

D. Traditional Surgical Debridement - Updated Evidence

4. Negative Pressure Wound Therapy (NPWT)

Mechanism

• Removes excess exudate and inflammatory mediators
• Reduces oedema - decreases interstitial fluid
• Promotes granulation tissue formation and angiogenesis (macro- and microdeformation of wound edges)
• Decreases bacterial colonisation (debated)
• Draws wound edges together (macrodeformation)
• Increases local blood flow and vascularity

Current Evidence (2023-2025)

• The UK WOLLF trial (prospective RCT for open lower limb fractures): no significant difference in surgical site infections or quality of life between NPWT and standard sterile dressings
• A recent Cochrane review: remains uncertain whether NPWT is superior to standard dressings for wound infection, adverse events, or time to closure
• AAOS 2023 CPG (prevention of surgical site infection after major extremity trauma): NPWT received a strong recommendation in both open and closed fracture situations

"In situations where the wound cannot be closed primarily or there is concern for progression of soft tissue necrosis, negative-pressure wound therapy is recommended." - Sabiston Textbook of Surgery

Modern NPWT Innovations

5. Advanced Dressings

A. Antimicrobial Dressings - Beyond Silver

B. Antimicrobial Peptides (AMPs) in Dressings - 2025 Advance

• AMPs are short, cationic peptides (e.g. LL-37, defensins, magainins) with broad-spectrum antimicrobial activity via membrane disruption - fundamentally different from antibiotics
• Low propensity for resistance development - a critical advantage in the antibiotic-resistance era
• Incorporated into: hydrogels, electrospun nanofibre scaffolds, films, sponges, cryogels
• Hybrid systems combine AMPs with:
  • Metal nanoparticles (silver, zinc oxide, copper) for synergistic antimicrobial activity
  • Stimuli-responsive hydrogels (pH, temperature, glucose-triggered release)
  • Exosome carriers for improved delivery
• Additional effects: anti-biofilm activity, immunomodulation, pro-angiogenic, reduced scarring

C. Hydrogel Dressings

• Maintain moist wound environment; donate moisture to dry wounds
• Advanced formulations incorporate growth factors, stem cell-derived exosomes, or antimicrobial agents
• Machine learning-enabled visual monitoring hydrogels (2025): colour-changing dressings that signal infection or healing status to clinicians without removing the dressing

6. Bioengineered Skin Substitutes

Classification (Schwartz's Principles of Surgery)

Key Products in Detail

• Bilayer matrix: inner layer = cross-linked bovine collagen + shark-derived chondroitin-6-sulphate; outer layer = silicone
• The collagen matrix engrafts into the wound over 2-3 weeks as host fibroblasts and blood vessels infiltrate
• Silicone layer is then removed and replaced with thin autograft
• Advantages: closes full-thickness burns, may reduce future scarring, allows autograft harvest from a thinner donor site
• Disadvantages: two-stage procedure; no inherent antimicrobial activity

• Decellularised Atlantic cod or tilapia skin
• Rich in omega-3 fatty acids (anti-inflammatory)
• Promotes granulation tissue; resists bacterial infection
• Studies show comparable or superior outcomes to pig skin in some wound types
• Increasingly used for DFUs and partial-thickness burns

• Living bilayer skin equivalents containing fibroblasts and/or keratinocytes
• Provide continuous delivery of growth factors and cytokines
• FDA-approved for VLUs and DFUs
• Shown to significantly improve healing rates for 12+ week stagnant wounds

7. Cellular and Blood-Product Therapies

A. Platelet-Rich Plasma (PRP) and PRGF

• Autologous blood product concentrated in platelets (4-8x baseline) and growth factors (PDGF, TGF-β, VEGF, EGF)
• Several formulations: PRP, PRGF, PRF (platelet-rich fibrin), PRFM
• Evidence is mixed but growing - FDA-cleared for several wound indications
• Best evidence for: DFUs, chronic ulcers, post-surgical wounds, stimulating granulation in stalled wounds

B. Exosome Therapy (Emerging)

• Exosomes are cell-derived nanovesicles (30-150 nm) containing growth factors, miRNA, and signalling molecules
• Stem cell-derived exosomes (mesenchymal stem cells/adipose tissue) stimulate angiogenesis, fibroblast proliferation, and re-epithelialisation
• No immune reaction (unlike live cell therapy) - a major advantage
• Multiple in vitro and in vivo studies showing promise; early clinical trials under way (2024-2026)
• Incorporated into hydrogel scaffolds for sustained local delivery

C. Stem Cell Therapy

• Mesenchymal stem cells (MSCs) from bone marrow, adipose, or Wharton's jelly
• Promote angiogenesis, modulate inflammation, differentiate into fibroblasts
• Early clinical trials for diabetic wounds show promise
• Cost and regulatory hurdles remain barriers to widespread adoption

8. Wound Microbiome and Biofilm Management

The Biofilm Problem

• >50% of bacterial isolates in DFUs were biofilm producers
• Multidrug resistance exceeded 90% in several cohorts
• Fungi detected in 31% of ulcers by qPCR (but only 9% by culture - highlighting diagnostic gaps)
• Standard care (debridement, antiseptics, NPWT) remains the clinical basis for managing biofilm, but direct antibiofilm clinical evidence is limited

Emerging Antibiofilm Strategies

1. Accurate wound assessment (NERDS/STONEES criteria for local vs. spreading infection)
2. Targeted antimicrobial selection based on culture + sensitivity
3. Biofilm-focused strategies
4. Antimicrobial stewardship

9. Smart Dressings and Digital Wound Monitoring

Sensor-Embedded "Smart" Dressings

Electrically Active and Electrostimulation Dressings

• Galvanic microcurrents applied across wound bed
• Mimic the naturally occurring bioelectric signal of intact skin (disrupted by wounding)
• Stimulate fibroblast migration, keratinocyte proliferation, angiogenesis
• PROCELLERA (silver/zinc galvanic wound dressing) is FDA-cleared

Wireless and Telemedicine Integration

• Smart dressings transmit sensor data to smartphones or clinical servers in real time
• Remote wound monitoring platforms (e.g. Tissue Analytics, WoundRounds, Healogics)
• AI-powered wound measurement from smartphone photos - automated wound area, depth, and tissue composition analysis
• Clinical evidence: studies show 11-week faster healing times with bioengineered + monitoring-guided care vs. standard care

10. Growth Factor and Gene Therapy

Topical Growth Factors

Gene Therapy - Emerging Horizon

• Prademagene zamikeracel (Vyjuvek, Krystal Biotech): FDA-approved 2023 - first topical gene therapy for EB wounds, delivering functional COL7A1 gene via HSV vector directly to wound surface
• Proof-of-concept for gene therapy-enhanced wound healing
• Potential future applications: chronic wounds, impaired healing in diabetes, radiation damage

11. Emerging Technologies (2024-2026)

A. 3D Bioprinting of Skin

• Printing layers of keratinocytes, fibroblasts, and extracellular matrix at precise anatomical positions
• In situ bioprinting (printing directly into the wound) is under active development
• Companies like Organovo and Poietis are in early clinical stages
• Custom-geometry grafts: theoretically perfect-fit coverage of irregular wound shapes

B. Oxygen Therapy

• Topical oxygen therapy (TOT): delivers 100% humidified oxygen directly to wound surface via a sealed chamber or film
• Continuous diffusion of oxygen (CDO): electrochemical device generates dissolved oxygen locally
• Evidence for DFUs: accelerated closure vs. standard care in RCTs
• Hyperbaric oxygen therapy (HBO): systemic; supported evidence for DFUs, radiation necrosis, gas gangrene

C. Photobiomodulation (Low-Level Laser Therapy / LLLT)

• Low-energy laser or LED light (typically 630-1000 nm) applied to wound surface
• Stimulates mitochondrial cytochrome C oxidase → increased ATP production → fibroblast and keratinocyte proliferation
• Growing evidence in chronic wounds, diabetic ulcers, and post-surgical wounds
• Non-invasive; increasingly integrated with smart monitoring systems

D. Extracorporeal Shockwave Therapy (ESWT)

• Mechanical pressure waves applied around wound perimeter
• Stimulates angiogenesis (VEGF upregulation), growth factor release, and stem cell recruitment
• Used increasingly in DFUs, pressure injuries, and post-surgical wound complications

12. Wound Management by Wound Type - Summary

Summary

1. NPWT - portable, instillation-capable devices; strong evidence for open fractures despite mixed results in RCTs
2. Advanced debridement - ultrasound, hydrosurgery, larval therapy replacing blunt sharp debridement
3. Bioengineered skin substitutes - acellular matrices, living bilayer equivalents, fish skin xenografts
4. Biofilm management - antibiofilm dressings (PHMB, DACC, iodine), cold plasma, bacteriophage, AMP-loaded scaffolds
5. Smart dressings - pH, temperature, moisture, oxygen sensing with real-time remote monitoring
6. Cellular therapies - PRP, exosomes, MSCs providing growth factors and immunomodulation
7. Gene therapy - FDA-approved topical gene therapy (Vyjuvek) for EB as a proof-of-concept
8. 3D bioprinting, photobiomodulation, ESWT - emerging technologies approaching clinical translation

• Sabiston Textbook of Surgery, Biological Basis of Modern Surgical Practice, Chapters 9 & 10
• Schwartz's Principles of Surgery, 11th ed., Section on Bioengineered Skin Substitutes & Pressure Injuries
• Beraja GE et al. "What's New in Wound Healing: Treatment Advances and Microbial Insights." Am J Clin Dermatol. 2025. PMID: 40498297
• Zhu A et al. "Application of Antimicrobial Peptides in Wound Dressings." Drug Des Devel Ther. 2025. PMID: 41001070
• Theodorakopoulos G, Armstrong DG. "Biofilm in Diabetic Foot Ulcers: A Systematic Narrative Review." Int Wound J. 2025. PMID: 41339278
• Swanson T et al. "IWII Wound Infection in Clinical Practice consensus document: 2022 update." J Wound Care. 2022. PMID: 36475844

Wrist Triple Arthrodesis (Three-Corner Fusion)

1. Clarifying the Terminology

1. Three-Corner Fusion (3CF) - also called "capitolunate arthrodesis" with scaphoid and triquetrum excision: fuses only the capitate and lunate after excising both the scaphoid and triquetrum; effectively a two-bone fusion within the former four-corner complex
2. Scaphotrapeziotrapezoid (STT) arthrodesis (triscaphe fusion) - fuses scaphoid, trapezium, and trapezoid
3. Radioscapholunate (RSL) arthrodesis - fuses the radius, scaphoid, and lunate (a radiocarpal partial fusion)

2. Wrist Anatomy and Biomechanics Relevant to Arthrodesis

• Radiocarpal joint: distal radius articulates with the proximal carpal row (scaphoid, lunate, triquetrum)
• Midcarpal joint: proximal row articulates with the distal row (trapezium, trapezoid, capitate, hamate)
• Intercarpal joints: between individual carpal bones

Normal Carpal Kinematics

• Wrist flexion/extension: approximately 50% occurs at the radiocarpal joint, 50% at the midcarpal joint
• Radial/ulnar deviation: predominantly midcarpal
• The scaphoid acts as a mechanical link between proximal and distal carpal rows, transmitting forces from the distal row to the radius

3. Pathological Background - SLAC and SNAC Wrist

SLAC Wrist Staging (Watson and Ballet, 1984)

SNAC Wrist Staging

4. The Spectrum of Limited Wrist Arthrodesis

5. Four-Corner Arthrodesis (4CF) - The Gold Standard

Concept

Indications

• SLAC wrist stages II and III
• SNAC wrist stages II and III
• Failed proximal row carpectomy (in some cases)
• Younger, high-demand patients (preferred over PRC for grip strength)

Contraindications

• Radiolunate arthritis (Stage IV SLAC/SNAC) - indicates total wrist arthrodesis
• Active infection
• Inadequate bone stock
• Open distal radial physis (relative)

6. Three-Corner Arthrodesis (3CF) - The "Triple" Fusion

Concept

• Three-corner arthrodesis
• Capitolunate arthrodesis (with scaphoid and triquetrum excision)
• Bicolumn fusion (less common)
• "Triple fusion" when described as fusing across three remaining carpal bones

Rationale for Triquetrum Excision

• Easier lunate reduction (the triquetrum often tethers the lunate in a VISI position)
• Reduces fusion surface complexity - only two bones to fuse (capitate-lunate)
• Avoids subsequent pisotriquetral arthritis (a known complication of 4CF)
• Some studies show comparable or superior outcomes to 4CF

Indications

• SLAC/SNAC stages II-III (same as 4CF)
• Cases where pisotriquetral arthritis is pre-existing or anticipated
• Surgeon preference when lunate reduction is difficult in 4CF

7. Surgical Technique - 4CF/3CF

Patient Positioning

• Supine, arm on hand table, tourniquet at arm
• Image intensifier (C-arm) available throughout

Approach (Dorsal)

1. Incision: Longitudinal dorsal incision centred on the third metacarpal axis. Longitudinal preferred (allows future conversion to total wrist arthrodesis if needed)
2. Retinaculum: Incise extensor retinaculum in Z-fashion; preserve or transpose extensor pollicis longus (EPL) radially
3. Capsule: Longitudinal capsulotomy - two incisions (between ECU/EDC, and between EDC/ECRL intervals) or single "ligament-sparing" approach preserving dorsal radiocarpal ligaments
4. Expose carpus: Identify all carpal bones and assess joint surfaces

Scaphoid Excision

• Remove scaphoid piecemeal using osteotomes, rongeur, or burr
• Preserve radioscaphocapitate (volar) ligament to prevent carpal instability
• Preserve at least the proximal fibres to avoid ulnar translation of the carpus

Triquetrum Excision (for 3CF)

• Remove triquetrum similarly; preserve pisiform (sesamoid in FCU)
• Facilitates lunate reduction into neutral position

Cartilage Removal / Joint Preparation

• Denude all articular cartilage from the planned fusion surfaces using rongeur, curette, or motorised burr
• Create a flat, bleeding cancellous bone surface on each side
• Decortication extends to subchondral bone

Reduction and Alignment

• Critical step: Reduce the lunate into neutral (neither DISI nor VISI)
• The capitate-lunate axis must align with the longitudinal axis of the radius
• Use fluoroscopy to confirm normal carpal height and alignment
• Provisional K-wire fixation to hold reduction

Bone Grafting

• Cancellous bone graft from the excised scaphoid (± triquetrum) is packed into all fusion gaps
• Additional iliac crest, distal radius, or cancellous allograft if insufficient

Fixation Methods

• All fixation methods produce similar radiographic union rates - no significant difference between K-wire, screw, staple, non-locking plate, metal locking plate, and radiolucent locking plate
• Grip strength was significantly lower with metal locking plates (63.2%) vs K-wires (82.6%)
• No clinically relevant differences in range of motion between groups
• Conclusion: fixation method choice should be guided by surgeon experience and anatomical factors, not expected fusion rates

Closure

• Repair dorsal capsule
• Repair extensor retinaculum
• Skin closure; drain optional
• Volar or dorsal splint applied in neutral position

8. Arthroscopic Approach - Recent Advance

• Arthroscopic 4CF and 3CF are now established techniques
• Advantages over open: potentially reduced soft tissue trauma, less postoperative pain, faster rehabilitation, smaller scars
• Arthroscopic approaches may preserve more motion and grip strength in early follow-up
• Limitations: technically demanding; longer operative time; fluoroscopy-dependent; limited long-term comparative data vs. open
• Both compression screws and circular plates can be inserted arthroscopically or mini-open

9. STT (Scaphotrapeziotrapezoid) Arthrodesis

Concept

Indications

• Scapholunate dissociation (pre-arthritic, to stabilise the scaphoid)
• STT osteoarthritis (occurs in ~40% of wrist radiographs in the elderly)
• Rotatory subluxation of the scaphoid
• Kienbock disease (stage II-IIIa)

Biomechanical effect

• Stabilises the scaphoid in a slightly extended position relative to the lunate
• Reduces the SL gap
• Preserves more radiocarpal motion compared to 4CF (because the radiocarpal joint is untouched)

Limitations

• High nonunion rate in early series (corrected with modern fixation)
• Risk of radioscaphoid impingement if scaphoid is over-corrected
• Does not address established radioscaphoid arthritis

10. Radioscapholunate (RSL) Arthrodesis

Concept

Indications

• Radiocarpal arthritis (rheumatoid arthritis, post-traumatic)
• Distal radius malunion with radiocarpal arthritis
• Kienbock disease stage IV
• SLAC/SNAC with specific radiocarpal involvement

Key technical detail

• Distal scaphoid excision (DSE) with RSL fusion: improved postoperative wrist flexion (+8°) and radial deviation (+3°), reduced nonunion rates, and reduced secondary midcarpal OA
• Combined DSE + triquetrum excision (TE): best motion gains BUT highest rate of secondary midcarpal OA - likely due to increased laxity allowing abnormal loading
• Recommendation: DSE is beneficial; triquetrum excision requires careful selection

11. PRC vs 4CF/3CF - Comparative Decision Making

12. Expected Outcomes

Motion After 4CF/3CF

Patient-Reported Outcomes

• DASH scores: typically 19-25 post 4CF (good)
• VAS pain: significantly improved vs pre-op
• Patient satisfaction: ~85-90% satisfied at medium-term follow-up
• Return to work: most patients return to light-moderate work by 3-4 months

Union Rates (4CF)

• Overall: 85-95% depending on fixation and bone grafting
• Systematic review (Hayes et al. 2022): no significant difference in union rates between fixation methods

13. Complications

14. Postoperative Management

1. Immobilisation: Short arm cast or volar splint for 6-8 weeks minimum
2. K-wire removal: At 6-8 weeks if used (under X-ray control)
3. Cast duration: 8-12 weeks until radiographic fusion confirmed
4. Physiotherapy: Begins after cast removal - ROM exercises, grip strengthening
5. Weight bearing: No heavy lifting for minimum 12 weeks
6. Final review: CT scan at 3 months to confirm union if radiographs equivocal

15. Summary

• Campbell's Operative Orthopaedics, 15th ed. (2026), Chapters 74 & 38
• Rockwood & Green's Fractures in Adults, 10th ed. (2025), Chapter 44
• Miller's Review of Orthopaedics, 9th ed., pp. 2855-2912
• Hayes E et al. "Four-Corner Arthrodesis With Differing Methods of Osteosynthesis: A Systematic Review." J Hand Surg Am. 2022. PMID: 34253392
• Nie A et al. "Effect of Distal Scaphoid and Triquetrum Excision on RSL Fusion." J Hand Surg Am. 2026. PMID: 41498712
• Paul R, Persitz J. "Current Trends in 4-Corner and 3-Corner Fusions." Hand Clin. 2026. PMID: 41864627

Therapeutic Laser in Orthopaedics

1. Definition and Nomenclature

2. Physical Principles

2.1 Laser Properties

1. Monochromaticity - single wavelength
2. Coherence - waves in phase (spatial and temporal)
3. Collimation - minimal divergence; maintains intensity over distance

2.2 Wavelength and Tissue Penetration

• 632-670 nm (He-Ne, red diode): superficial soft tissue, wound healing
• 780-830 nm (GaAlAs diode): soft tissue, tendons, superficial joints
• 904-905 nm (GaAs pulsed): deep penetration, joint cartilage, bone - best evidence for knee OA
• 1064 nm (Nd:YAG): deepest penetration for HILT; muscle and deep joints

2.3 Dosimetry Parameters

3. Classification of Therapeutic Lasers

Class/Category System (IEC 60825-1)

LLLT vs HILT - Key Clinical Distinction

4. Mechanism of Action (Photobiomodulation)

Primary Photochemical Events

1. Photon absorption by cytochrome c oxidase (primary photoreceptor in red/NIR range)
   • Causes conformational changes in the enzyme
   • Reverses inhibition by nitric oxide (NO) - "photodissociation of NO"
   • Increases electron transport chain activity
2. Increased ATP production
   • Improved mitochondrial respiratory activity
   • More cellular energy available for repair processes
3. Reactive Oxygen Species (ROS) modulation
   • Low doses: transient ROS production acts as second messenger (hormesis)
   • Stimulates antioxidant enzyme upregulation (SOD, catalase)
4. Nitric Oxide (NO) release
   • Photodissociated NO diffuses from cytochrome c oxidase
   • Causes local vasodilation
   • Secondary messenger signalling for healing

Secondary Cellular Effects

The Arndt-Schulz Law (Hormesis)

5. Orthopaedic Applications and Evidence

5.1 Knee Osteoarthritis (Best Supported Indication)

LLLT for Knee OA

• Systematic review & meta-analysis (Oliveira et al. 2024, Physical Therapy, PMID: 38775202, 10 RCTs, 542 participants):
  • PBM significantly reduced pain at rest vs placebo: MD -0.7 (95% CI -1.1 to -0.2), moderate effect size
  • No significant benefit for Timed Up & Go Test
  • Significant within-group improvements in Lequesne Index and gait
  • Very low certainty of evidence - cannot recommend isolated use, but may complement other therapies
  • Conclusion: may be used as an adjunct, not standalone treatment

Optimal Wavelength for Knee OA

• Network meta-analysis (Fan et al. 2024, Aging Clin Exp Res, PMID: 39367994, 13 RCTs, 673 participants):
  • Overall LLLT superior to sham for pain (SMD = 0.96, p<0.05)
  • Not superior for function or stiffness
  • Best wavelength for pain: 904-905 nm (SUCRA 86.9%), followed by 785-850 nm
  • Evidence quality: low to very low

HILT for Knee OA

• Systematic review (Ahmad et al. 2022, Physiotherapy, PMID: 34654554):
  • Both LLLT+exercise and HILT+exercise effective vs exercise alone
  • HILT+exercise showed higher efficacy for reducing pain, stiffness, and improving function vs LLLT+exercise (indirect comparison)
  • Significant improvements in WOMAC, VAS, and functional tests with HILT

5.2 Tendinopathy

HILT for Tendinopathy

• Systematic review & meta-analysis (Hong et al. 2026, Lasers Med Sci, PMID: 41964853, 15 RCTs, 629 patients):
  • Conditions: lateral epicondylitis (53%), rotator cuff tendinopathy (27%), others (20%)
  • HILT significantly improved pain: MD -1.15 (95% CI -1.73 to -0.58) - exceeds MCID
  • HILT improved disability: SMD -1.00 (95% CI -1.77 to -0.22)
  • Site-specific effects: shoulder (rotator cuff) responded better (MD -2.54) than elbow (MD -0.91)
  • Treatment effects peaked at 16 weeks - cumulative benefit over time
  • Stress pain showed most substantial relief: MD -2.30

• Lateral epicondylitis (tennis elbow) - 830 nm or 1064 nm
• Rotator cuff tendinopathy - 830 nm, 904 nm
• Achilles tendinopathy - 780-830 nm
• Patellar tendinopathy - 780-830 nm
• De Quervain tenosynovitis - 630-780 nm

5.3 Neck Pain, Low Back Pain, and Frozen Shoulder

5.4 Fractures and Bone Healing

In Humans (Clinical)

• Systematic review & meta-analysis (Wang et al. 2026, Ann Med, PMID: 42080480, 12 studies, 9 meta-analysed):
  • PBM significantly reduces short-term (1-week) pain: MD -0.74 (95% CI -1.00 to -0.47, p<0.0001, I²=0%)
  • Significant improvement in grip strength at 4 weeks for upper limb fractures: MD 5.03 (95% CI 4.29-5.78)
  • No significant long-term benefits (4-26 weeks) for pain or function
  • No significant effect on bone healing clinically
  • No side effects reported in any study

In Animal Models

• Systematic review & meta-analysis (Hazrati et al. 2025, Lasers Med Sci, PMID: 40016554, 27 animal studies):
  • Most individual studies reported positive effects of PBMT on fracture healing
  • Meta-analysis: no significant effect on maximum fracture force or hydroxyapatite mineralisation (Raman peaks)
  • 780 nm, 808 nm, and 830 nm were most studied; 4 J/cm² most common dose
  • Most common sites: tibia > femur > mandible
• Systematic review on bone healing (Berni et al. 2023, Int J Mol Sci, PMID: 37108257):
  • In vitro and in vivo evidence for LLLT promoting angiogenesis, fracture healing, osteogenic differentiation of stem cells
  • Mechanisms: upregulation of BMP-2, alkaline phosphatase, RUNX2, VEGF, TGF-β
  • Dose-dependent effects; results vary by cell type and parameters
  • Clinical translation still limited

Current Position on Bone Healing

5.5 Other Musculoskeletal Applications

6. Devices Used in Orthopaedic Practice

LLLT Devices (Class 3B)

• Diode lasers: GaAlAs (780-870 nm), GaAs (904 nm) - most common
• He-Ne lasers: 632.8 nm - older, less portable
• LED clusters (LEDs, not strictly lasers but used as PBM): broad emission, lower coherence, cheaper
• Multi-probe arrays: multiple diode probes in one handpiece

HILT Devices (Class 4)

• Nd:YAG 1064 nm (e.g. BTL Super Inductive System, Gymna HIL, Diowave 810/980): most common in HILT; deep penetration
• Diode lasers at high power (5-25 W): used for deeper musculoskeletal conditions

Laser vs LED Distinction

7. Treatment Protocol in Orthopaedic Practice

Application Techniques

1. Point application (trigger point / grid method)
   • Probe placed in direct skin contact
   • Grid of points mapped over the treatment area
   • Each point treated for 30-60 seconds
   • Used for tendons, small joints, trigger points
2. Scanning technique
   • Probe moved continuously over treatment area
   • Used for HILT to distribute higher energy safely
   • Avoids focal heating at one point
3. Cluster probe / array
   • Multiple LEDs/laser diodes in a single applicator
   • Covers larger area; used for knee, shoulder, back
4. Intra-articular laser
   • Experimental; direct joint irradiation via optical fibre
   • Used in research settings for OA

General Protocol Template

8. Safety, Precautions, and Contraindications

Absolute Contraindications

• Malignancy in the treatment field (or suspected) - risk of stimulating tumour growth
• Pregnancy - direct irradiation over gravid uterus
• Over the thyroid gland (Class 4)
• Direct irradiation of eyes (retinal damage)
• Photosensitive conditions/medications (porphyria, certain drugs)
• Over haemorrhagic areas (active bleeding)

Relative Contraindications

• Epilepsy (flicker-sensitive; use non-pulsed mode)
• Active systemic infections
• Over growth plates in children (theoretical concern; low evidence)
• Over implanted electronic devices (pacemakers) - direct irradiation
• Dark/tattooed skin (higher absorption, focal heating risk)
• Corticosteroid injection within 48 hours (combined effect unknown)

Adverse Effects

• Rare and mild: transient erythema, flare of symptoms in first 24-48 hours (expected photobiological response - "post-treatment soreness")
• Skin burns (if Class 4 used incorrectly without scanning)
• Eye injury (if eye protection not used)
• No systemic adverse effects reported in any meta-analysis

9. Umbrella-Level Evidence Summary (2025)

• Knee OA disability: eSMD 0.65 (95% CI 0.14-1.15) ✓
• Fibromyalgia fatigue: eSMD 1.25 (95% CI 0.63-1.87) ✓
• Burning mouth syndrome pain: eSMD -0.92 ✓

10. Comparison with Other Physical Therapy Modalities

• Non-thermal (safe over implants, superficial nerves)
• Anti-inflammatory + anabolic (unique combined effect)
• Suitable over wounds and post-surgical scars
• Can be applied immediately post-injury
• No known drug interactions

11. Current Controversies and Limitations

1. Dosimetry heterogeneity: No universally accepted treatment protocol. Wavelength, power density, energy dose, and pulse frequency vary widely across studies, making comparison and pooling difficult.
2. Sham/placebo control difficulty: Blinding patients and operators is challenging; thermal sensation distinguishes active from sham in HILT trials.
3. Publication bias: Most meta-analyses identify likely positive publication bias; negative trials are less frequently published.
4. Lack of head-to-head comparisons: LLLT vs HILT vs sham vs other modalities rarely compared directly.
5. Optimal parameters unknown: Even for best-studied indication (knee OA), optimal wavelength/dose combination is not definitively established.
6. Short follow-up: Most trials follow up to 4-12 weeks; long-term benefits unclear.
7. Regulatory variation: FDA (USA) has cleared some LLLT devices for pain; CE-marked in Europe; listed as experimental by some payers (insurance).

12. Practical Summary for Orthopaedic Practice

• Therapeutic laser is safe with minimal side effects
• Best used as an adjunct to exercise and physiotherapy, not as a standalone treatment
• HILT > LLLT for deep musculoskeletal conditions (OA, LBP, frozen shoulder)
• 904-905 nm is the optimal wavelength for knee OA based on network meta-analysis
• Evidence quality remains low-moderate for most orthopaedic indications; further high-quality trials needed
• Eye protection is mandatory during all therapeutic laser applications

• Oliveira S et al. "Effectiveness of Photobiomodulation in Reducing Pain and Disability in Patients With Knee OA." Phys Ther. 2024. PMID: 38775202
• Fan T et al. "Optimal wavelength of LLLT in treating knee OA: network meta-analysis." Aging Clin Exp Res. 2024. PMID: 39367994
• Ahmad MA et al. "LLLT and HILT as adjuncts to rehabilitation in knee OA: systematic review." Physiotherapy. 2022. PMID: 34654554
• Hong R et al. "Effectiveness of HILT for tendinopathy: systematic review and meta-analysis." Lasers Med Sci. 2026. PMID: 41964853
• de la Barra Ortiz HA et al. "Quality appraisal of systematic reviews on HILT for musculoskeletal pain: umbrella review." Lasers Med Sci. 2024. PMID: 39652213
• Son Y et al. "Effects of photobiomodulation on multiple health outcomes: umbrella review of RCTs." Syst Rev. 2025. PMID: 40770824
• Wang W et al. "Effect of photobiomodulation on pain and function in fractures: systematic review and meta-analysis." Ann Med. 2026. PMID: 42080480
• Hazrati P et al. "Effect of PBMT on fracture healing: meta-analysis of animal studies." Lasers Med Sci. 2025. PMID: 40016554
• Berni M et al. "Role of LLLT in Bone Healing: Systematic Review." Int J Mol Sci. 2023. PMID: 37108257

Transcutaneous Electrical Nerve Stimulation (TENS) in Orthopaedics

1. Definition and Overview

• Non-invasive and non-pharmacological
• Portable and self-administered by patients at home
• Safe with a well-established adverse effect profile
• Used as an adjunct to exercise, physiotherapy, and pharmacological management - not as a standalone treatment

2. Historical Background

3. Physical Parameters and Device Technology

3.1 Key Electrical Parameters

3.2 Fibre Recruitment Hierarchy

• Sensory threshold: tingling/paresthesia without motor contraction (Aβ activation)
• Motor threshold: visible muscle twitch
• Pain threshold: uncomfortable but tolerable (used in certain protocols)

4. Types/Modes of TENS

4.1 Conventional TENS (High-Frequency TENS)

4.2 Acupuncture-Like TENS (Low-Frequency TENS / AL-TENS)

4.3 Burst-Mode TENS

4.4 Intense TENS

4.5 Hyperstimulation TENS (Electroacupuncture)

• Needle electrodes at acupuncture points (technically percutaneous/PENS)
• Produces strong stimulation at specific myofascial trigger or acupuncture points
• Not traditional TENS (surface electrodes) but often grouped together

5. Mechanism of Action

5.1 Gate Control Theory (Melzack and Wall, 1965)

• Large-diameter myelinated Aβ fibres (carrying non-noxious sensory input: touch, vibration) and small-diameter Aδ/C fibres (carrying pain signals) both synapse on transmission cells (T-cells) in the substantia gelatinosa (Laminae I and V) of the dorsal horn
• Aβ fibre activation activates interneurons (SG cells) which pre-synaptically inhibit the pain signal before it reaches T-cells
• High-frequency TENS activates Aβ fibres → "closes the gate" → reduces nociceptive transmission to the brain
• Simultaneously, Aβ activation inhibits C-fibre transmission in the dorsal horn

5.2 Endogenous Opioid Release (Low-Frequency TENS)

• Low-frequency TENS (1-10 Hz) activates delta-opioid receptors primarily
• High-frequency TENS (80-150 Hz) activates mu-opioid receptors
• Naloxone (opioid antagonist) blocks the analgesic effect of low-frequency TENS - direct evidence for opioid mechanism
• Endorphins released in spinal cord and brain (rostral ventromedial medulla, periaqueductal grey)

5.3 Descending Pain Inhibition

• TENS activates descending inhibitory pathways from the brain stem
• Periaqueductal grey (PAG) → rostral ventromedial medulla (RVM) → dorsal horn
• Serotonin (5-HT) and norepinephrine are key neurotransmitters in this pathway
• Mid-term effects on conditioned pain modulation (CPM) improve with TENS - evidence for central sensitisation reduction

5.4 Effects on Central and Peripheral Sensitisation

• Systematic review & meta-analysis (DeJesus et al. 2023, J Pain, PMID: 37030583, 58 studies, 35 meta-analysed):
  • Meta-analyses favoured TENS for reducing primary hyperalgesia (local; high evidence) and secondary hyperalgesia (remote; moderate evidence)
  • TENS reduces pain at rest and during movement in both chronic musculoskeletal pain and acute experimental pain
  • Moderate evidence for reduction of both central and peripheral sensitisation
  • Temporal summation and conditioned pain modulation were under-studied
• Systematic review (Rodriguez Lagos et al. 2023, Pain Med, PMID: 36130064, 24 RCTs):
  • Immediate effects on local pressure pain threshold (PPT): significant, moderate effect size (SMD 0.53, 95% CI 0.34-0.72)
  • Mid-term effects on local PPT: significant, large effect size (SMD 0.55)
  • Immediate effects on conditioned pain modulation: significant, large effect size (SMD 0.94)
  • Short-term effects were not sustained vs control
  • Suggests TENS modulates central pain mechanisms beyond pure peripheral gate-control

5.5 Other Mechanisms

• Peripheral vasodilatation: antidromic activation of sensory fibres releases vasoactive neuropeptides (substance P, CGRP) → local blood flow
• Muscle relaxation: reduces protective muscle spasm secondary to pain reduction
• Anti-inflammatory: some evidence for reduction of inflammatory markers in periarticular tissues
• Placebo effect: meaningful; must be accounted for in trial design

6. TENS vs PENS (Percutaneous Electrical Nerve Stimulation)

• PENS vs TENS: overall effect of PENS statistically but NOT clinically superior (MD = -1.0 cm; 95% CI: -1.5 to -0.4) with high heterogeneity (I²=76%)
• When only low risk-of-bias studies analysed: no clinically significant difference between TENS and PENS (MD -0.81 cm; 95% CI -1.6 to 0.02) - moderate GRADE evidence
• Conclusion: TENS can be recommended over PENS given equivalence in higher-quality studies plus non-invasive, self-administered advantages

7. Orthopaedic Indications and Evidence

7.1 Knee Osteoarthritis (Best-Studied Indication)

2022 Meta-Analysis

• Wu et al. 2022 (Clin Rehabil, PMID: 34971318, 14 RCTs, 1398 patients):
  • Active TENS > sham TENS for VAS pain reduction
  • TENS + other interventions > other interventions alone for VAS pain (short, medium, long term)
  • TENS combination superior for WOMAC pain subscale (medium and long term)
  • TENS combination superior for function (medium and long term)
  • TENS not effective for stiffness
  • TENS improved walking ability

2026 Meta-Analysis (Most Recent)

• Peng et al. 2026 (J Bodyw Mov Ther, PMID: 42264808, 21 RCTs, 20 meta-analysed):
  • TENS significantly improved pain: MD = -0.82 (95% CI: -1.01 to -0.62) ✓
  • TENS significantly improved total WOMAC score: MD = -4.76 (95% CI: -8.84 to -0.67) ✓
  • TENS significantly improved knee extension muscle strength: MD = 7.39 (95% CI: 0.91-13.88) ✓
  • TENS significantly improved knee flexion strength: MD = 4.72 (95% CI: 1.92-7.52) ✓
  • No significant effects on stiffness, ROM, or 6-minute walk test
  • Heterogeneity explained partly by TENS parameter variations
  • Conclusion: "TENS effectively reduces pain and improves muscle strength in KOA; promising as adjunctive multimodal strategy"

Noninvasive Electrical Stimulation Comparison (2026)

• Cano-Orihuela et al. 2026 (Front Med, PMID: 42040599, 15 RCTs, 1137 patients):
  • Compared tDCS, NMES, WB-EMS, TENS, CES, tVNS in knee OA
  • TENS: most variable results; best short-term analgesia but limited beyond short-term
  • tDCS: more consistent moderate analgesic effects
  • NMES: better for quadriceps strength, mobility, patient-reported outcomes
  • Conclusion: TENS useful for pain; NMES better for strength deficits

OARSI and ACR Position

• OARSI 2019 guidelines: TENS conditionally recommended for knee OA (evidence uncertain)
• ACR 2019 guidelines for hand/hip/knee OA: TENS conditionally recommended for knee OA

7.2 Chronic Low Back Pain

• WHO Systematic Review (Verville et al. 2023, J Occup Rehabil, PMID: 37991646, 17 RCTs, n=1027, informing WHO guideline):
  • TENS vs sham: marginal pain reduction in the immediate term (2 weeks): MD = -0.90 (95% CI: -1.54 to -0.26) - statistically significant but NOT clinically important
  • TENS reduced pain catastrophizing at 3 months (MD -11.20)
  • Little to no difference for function, disability, quality of life, or medication use
  • All evidence: very low certainty (GRADE)
  • WHO conclusion: benefit not established for chronic primary LBP
• NICE UK guidelines (2021): Do not offer TENS for low back pain with or without sciatica as an isolated treatment
• Clinical reality: TENS is widely used in LBP as adjunct despite weak isolated evidence; patient preference and safety justify continued adjunctive use

7.3 Neck Pain and Cervicogenic Pain

• Multiple RCTs show TENS reduces cervical pain VAS
• High-frequency (80-100 Hz) conventional TENS applied paravertebrally at C4-C6 level
• Used for cervical spondylosis, acute whiplash, cervicogenic headache
• Umbrella review evidence: HILT (not TENS) has largest effect size for neck pain; TENS evidence for neck pain remains limited

7.4 Postoperative Pain (Orthopaedic Surgery)

• Multiple RCTs support TENS for post-TKA pain management
• Reduces opioid consumption postoperatively
• Applied over the periincisional area; electrodes straddling the knee incision
• 2025 prospective RCT (Maeda et al., 3-arm: TENS vs MENS vs control post-TKA):
  • TENS and MENS groups showed superior pain relief during walking vs control
  • Administered from Day 3 post-op, 5×/week for 2 weeks

• Total hip arthroplasty
• Spinal surgery (postoperative)
• Shoulder arthroplasty / rotator cuff repair
• TENS reduces analgesic requirements, particularly opioids

7.5 Tendinopathy

• Lateral epicondylitis (tennis elbow): TENS applied over the lateral epicondyle; useful for acute/chronic pain
• Rotator cuff tendinopathy: paravertebral C5-C6 + local shoulder application
• Achilles/patellar tendinopathy: local electrode placement over tendon and muscle belly
• Evidence: mostly positive RCTs; moderate evidence; less robust than for OA

7.6 Fibromyalgia

• High-frequency TENS provides short-term pain relief in fibromyalgia
• Movement-evoked pain in fibromyalgia reduced by TENS applied during exercise
• Systematic review: TENS during physical activity reduces pain and improves exercise participation

7.7 TENS During Exercise ("Active TENS")

• Systematic review (de Espindula Brehm et al. 2024, Musculoskeletal Care, PMID: 39592440):
  • High-frequency TENS at sensory threshold applied simultaneously with exercise produces more significant analgesic effects than exercise alone
  • Enables patients to exercise with reduced pain, thus performing better rehabilitation
  • Key finding: TENS applied during functional activity (not just at rest) is clinically superior
  • Only 6 studies; methodology varies; more trials needed

7.8 Neuropathic Pain in Orthopaedic Practice

• Systematic review & meta-analysis (ElMeligie et al. 2025, Biomed Res Int, PMID: 41132422, 30 studies, 25 meta-analysed):
  • TENS slightly reduced neuropathic pain vs placebo: SMD = -0.35 (not clinically significant, p=0.13)
  • Spinal cord injury: TENS significantly superior to placebo for neuropathic pain (SMD = -1.14; 95% CI: -2.22 to -0.06, p=0.04)
  • Diabetic neuropathy: similar to placebo and other electrotherapies
  • Overall: small, clinically marginal effects for most neuropathic conditions

7.9 Other Orthopaedic Applications

8. Electrode Placement Principles

General Rules

1. Electrodes should be placed to direct the current through the painful area - the active electrode over the site of maximum pain, return electrode proximal or distal
2. Never cross the heart - both electrodes on the same limb/side or ipsilateral trunk
3. Electrodes should not touch each other - minimum 1-2 cm apart
4. Skin must be intact - clean, dry skin; avoid wounds, rashes, open areas

Common Orthopaedic Electrode Placement Patterns

9. Treatment Parameters by Mode

10. Equipment

Types of TENS Devices

Electrode Types

• Self-adhesive hydrogel pads: most common; reusable 5-10 times
• Carbon rubber electrodes with gel: reusable, better current distribution
• Stick-on patches: single-use; convenient for home
• Sizes: 5×5 cm (standard), 5×9 cm (large back), 2×2 cm (small joints)

11. Safety Profile, Contraindications, and Precautions

Absolute Contraindications

Relative Contraindications / Precautions

• Recent surgical incision (wait for wound closure)
• Dermatological conditions, rash, or broken skin
• Metal implants in treatment area (not an absolute CI; current flows around metal)
• Active infection (local)
• Known cardiac arrhythmia
• Children under 3 years (theoretical; limited evidence)

Adverse Effects

• Skin irritation / contact dermatitis - most common; from electrode gel or adhesive; usually self-limiting
• Burns - rare; only if defective equipment, very high intensity, or prolonged application on anaesthetic skin
• Hypersensitivity to electrode gel (allergy)
• Transient increase in pain - possible in first 1-2 sessions; resolves
• No systemic adverse effects documented at therapeutic intensities
• Tolerance/accommodation - analgesic effect diminishes with prolonged same-parameter use; managed by varying parameters

12. Comparison with Other Physical Therapy Modalities for Pain

Interferential Therapy (IFT) vs TENS

• Systematic review (Hussein et al. 2022, Am J Phys Med Rehabil, PMID: 34469914):
  • IFT significantly reduces pain in MSK conditions
  • IFT claimed to penetrate deeper than TENS (two kHz-range currents cross and beat at low frequency within tissue)
  • Both are commonly used as adjuncts in MSK practice
  • Direct head-to-head: mixed; IFT may be marginally better for deep structures (hip, lumbar spine)

13. Evidence-Based Summary by Orthopaedic Indication

14. Key Practical Points for Orthopaedic Practice

1. TENS should not be used in isolation - it is an adjunct to exercise, physiotherapy, and appropriate medications; studies show TENS + exercise consistently outperforms TENS alone
2. Activate TENS at sensory threshold (tingling, no pain, no muscle contraction) for conventional mode - patient should report comfortable, non-painful sensation
3. Vary parameters to prevent tolerance - switching between conventional and burst mode across sessions helps maintain efficacy
4. Simultaneous use during exercise may be superior to pre/post-exercise application alone (per 2024 systematic review)
5. Teach patients for home use - TENS is one of the few physiotherapy modalities that patients can safely self-administer; empowers self-management, reduces clinic visits
6. For postoperative pain: start from day 1-3 post-op; periincisional application effective; reduces opioid requirements and side effects
7. For knee OA: use 4-electrode configuration flanking the joint; high-frequency (80-100 Hz) conventional mode; 30-45 minutes per session; 5×/week
8. Electrode placement is critical: if the first placement is ineffective, reposition electrodes to bracket the pain site differently
9. Duration of treatment: minimum 4-week course; effects may take 2-4 weeks to become apparent (central mechanisms)
10. Document parameters: record frequency, pulse width, intensity, electrode placement, and patient response for reproducibility

15. Current Controversies

1. Lack of dosimetry standardisation: no universally agreed optimal frequency, pulse width, or intensity for any orthopaedic condition; this is the primary reason for heterogeneity across trials
2. Sham TENS design problems: some "sham" TENS devices still deliver sub-sensory current; adequate placebo blinding is difficult
3. Short trial durations: most trials are 2-8 weeks; long-term efficacy data are scarce
4. Industry-driven heterogeneity: different devices produce different waveforms marketed as "TENS" despite physical differences
5. Who responds to TENS?: emerging evidence suggests responders have different pain phenotypes (lower central sensitisation may respond better to conventional TENS; higher central sensitisation may need lower frequency/opioid pathway activation)
6. NICE 2021 LBP guideline: controversy in UK physiotherapy community around NICE removing TENS recommendation for LBP; many clinicians continue to use it as an adjunct given safety and patient benefit in individual cases

• Wu Y et al. "Effects of TENS in people with knee OA: systematic review and meta-analysis." Clin Rehabil. 2022. PMID: 34971318
• Peng Y et al. "Neuromodulation through TENS in knee OA: systematic review and meta-analysis." J Bodyw Mov Ther. 2026. PMID: 42264808
• Cano-Orihuela M et al. "Noninvasive electrical stimulation in knee OA: systematic review and meta-analysis." Front Med. 2026. PMID: 42040599
• Verville L et al. "WHO CPG systematic review: TENS for chronic primary LBP." J Occup Rehabil. 2023. PMID: 37991646
• Beltran-Alacreu H et al. "Percutaneous vs transcutaneous electrical nerve stimulation for MSK pain: systematic review and meta-analysis." Pain Med. 2022. PMID: 35167691
• Rodriguez Lagos L et al. "Effects of PENS and TENS on endogenous pain mechanisms: systematic review and meta-analysis." Pain Med. 2023. PMID: 36130064
• DeJesus BM et al. "Effect of TENS on pain-related quantitative sensory tests in chronic MSK and acute experimental pain: systematic review and meta-analysis." J Pain. 2023. PMID: 37030583
• de Espindula Brehm T et al. "Effects of TENS during functional activities or exercise: systematic review." Musculoskeletal Care. 2024. PMID: 39592440
• ElMeligie MM et al. "Neuropathic pain relief through TENS: systematic review and meta-analysis." Biomed Res Int. 2025. PMID: 41132422
• Hussein HM et al. "Interferential current for musculoskeletal pain: systematic review and meta-analysis." Am J Phys Med Rehabil. 2022. PMID: 34469914

Titanium Alloys in Orthopaedics

1. Introduction

2. Basic Properties of Titanium

Physical and Chemical Properties

Comparison with Other Orthopaedic Metals

3. Classification of Titanium Alloys

3.1 Alpha (α) Phase Alloys

• Pure titanium (CP-Ti, commercially pure) and alloys dominated by α-stabilisers (Al, O, N, C)
• Crystal structure: Hexagonal close-packed (HCP) at room temperature
• Properties: Good corrosion resistance, moderate strength, poor machinability
• Grades: CP-Ti Grades 1-4 (increasing oxygen content → increasing strength)
• Orthopaedic use: Dental implants, some bone screws; limited for high-load orthopaedic applications

3.2 Alpha-Beta (α+β) Alloys - THE CLINICAL WORKHORSE

• Contain both α-stabilisers (Al) and β-stabilisers (V, Mo, Nb, Zr)
• Most important alloy: Ti-6Al-4V (Grade 5)
• Dual-phase microstructure gives superior strength and machinability
• Used in the vast majority of orthopaedic metal implants worldwide

3.3 Beta (β) Phase Alloys - EMERGING GENERATION

• β-stabilisers predominate (Nb, Mo, Zr, Ta, Fe, Cr)
• Crystal structure: Body-centred cubic (BCC) - stable at room temperature with sufficient β-stabiliser
• Key advantage: Much lower elastic modulus (55-85 GPa) - closer to bone (15-25 GPa)
• Important alloys: Ti-13Nb-13Zr, Ti-15Mo, Ti-12Mo-6Zr-2Fe (TMZF), Ti-24Nb-4Zr-7.9Sn (TiNbZrSn), Ti-Nb-Ta-Zr
• Orthopaedic significance: Reduces stress shielding; the future direction of orthopaedic titanium development

4. The Workhorse: Ti-6Al-4V (Grade 5)

Composition

• Titanium: 89-91% (balance)
• Aluminium: 5.5-6.5% (α-stabiliser; increases strength)
• Vanadium: 3.5-4.5% (β-stabiliser; improves ductility and processability)
• Small amounts of oxygen, nitrogen, carbon, iron (controlled interstitials)

Role of Alloying Elements

Key Mechanical Properties (Ti-6Al-4V)

Ti-6Al-4V ELI (Extra Low Interstitials, Grade 23)

• Reduced oxygen (<0.13%), nitrogen, carbon, and iron content
• Enhanced ductility and fracture toughness
• Preferred for medical implants where fatigue loading is critical (femoral stems, intramedullary nails)
• Better cold workability

5. Biocompatibility Mechanisms

5.1 The Titanium Oxide Layer (TiO₂)

• Forms within milliseconds of surface exposure to oxygen or moisture
• Self-repairing: if scratched or disrupted, the oxide layer re-forms immediately
• Acts as a chemical barrier preventing direct metal-tissue contact
• Prevents ion release into surrounding tissue
• The TiO₂ surface has a negative charge at physiological pH - promotes protein adsorption and cell attachment
• TiO₂ is chemically inert - no toxic ion leaching under normal conditions

5.2 Protein Adsorption and Cellular Interactions

1. Protein adsorption (within seconds of implantation): fibronectin, vitronectin, and other extracellular matrix proteins adsorb onto the TiO₂ surface
2. Cell attachment: osteoblasts, fibroblasts, and endothelial cells recognise adsorbed proteins via integrin receptors
3. Osteoblast activity: titanium surfaces promote osteoblast proliferation, differentiation, and mineralisation
4. Macrophage response: titanium elicits a mild, manageable foreign body response compared to other metals

5.3 Osseointegration

• Unique to titanium among common metallic biomaterials - cobalt-chrome is biologically inert and does not osseointegrate directly
• The TiO₂ layer allows bone to grow into direct contact with the metal surface
• Calcium and phosphate ions from body fluids deposit on TiO₂, forming a calcium titanate and calcium phosphate interlayer that chemically bonds to bone
• Porous and roughened surfaces dramatically enhance osseointegration by increasing surface area and providing scaffold for bone ingrowth

6. The Critical Issue: Stress Shielding

Definition

The Modulus Mismatch Problem

Solutions to Stress Shielding

1. Use β-type Ti alloys (lower modulus: 55-85 GPa)
2. Porous/lattice structures - reduce effective modulus to match bone
3. Additive manufacturing - engineered porous geometry with controlled porosity
4. Tapered implant design - gradual load transfer
5. Flexible intramedullary nail designs - slotted, thinner cross-sections

7. Orthopaedic Applications

7.1 Fracture Fixation

Intramedullary Nails

• Virtually all modern intramedullary nails are Ti-6Al-4V
• Advantages over stainless steel nails:
  • ~50% lower elastic modulus → reduced stress concentration at nail tip
  • Lighter weight
  • MRI compatibility (post-op imaging possible)
  • Better corrosion resistance at nail-bone interface
• Tapered nail tip and rounded distal geometry reduce stress risers
• Examples: Synthes Expert Nail, Stryker T2, Smith & Nephew Trigen

Plates and Screws

• Titanium alloy plates (Ti-6Al-4V or CP-Ti) for periarticular, distal radius, foot and ankle fixation
• Lower stiffness than stainless steel → reduced stress at plate ends → lower risk of refracture
• Screws: Ti-6Al-4V cortical, cancellous, locking screws
• Limitation: titanium is softer than cobalt-chrome and stainless steel → more susceptible to galling (thread damage); avoid mixing titanium and stainless steel hardware (galvanic corrosion)

External Fixators

• Pins and rings in titanium for MRI-compatible circular fixators (especially Ilizarov rings)
• Carbon fibre external fixator bodies with titanium pins

7.2 Total Joint Arthroplasty

Total Hip Arthroplasty (THA)

• Cementless titanium stems rely on osseointegration for fixation
• Porous coating (sintered beads, plasma spray, electron beam melting trabecular metal) provides scaffold for bone ingrowth
• Modulus closer to cortical bone than cobalt-chrome → less proximal stress shielding
• Survival: ~94% at 15 years for cementless titanium stems

• Hemispherical press-fit cups with porous outer surface
• Screw holes for supplementary fixation
• Bears polyethylene, ceramic, or metal bearing liners

Total Knee Arthroplasty (TKA)

• Tibial trays: titanium alloy (Ti-6Al-4V); excellent for cementless fixation
• Femoral components: Cobalt-chrome (preferred for the articulating bearing surface due to higher hardness)
• Patellar component: polyethylene (all-poly) or titanium-backed
• Hybrid TKA: titanium tibial tray + cobalt-chrome femoral component is the standard combination

7.3 Spinal Implants

Pedicle Screws and Rods

• Ti-6Al-4V pedicle screws: standard across most systems
• Titanium rods: available alongside cobalt-chrome; slightly more flexible
• MRI advantage: titanium produces markedly less artefact than cobalt-chrome or stainless steel - critical for post-op neurological assessment

Interbody Cages (IBF)

• Ti-6Al-4V or porous titanium interbody cages (TLIF, PLIF, ALIF, XLIF)
• Porous titanium cages allow bone ingrowth through the implant
• 3D-printed trabecular titanium cages (e.g. Stryker TRITANIUM®, DePuy Actis) achieve 70% porosity with gyroid or diamond lattice structures

Dynamic Stabilisation Rods

• Titanium rods with engineered flexibility for dynamic stabilisation
• Balance between mobility preservation and mechanical stability

7.4 Shoulder and Upper Extremity

• Shoulder arthroplasty: titanium glenoid baseplate (reverse shoulder); titanium humeral stems
• Distal radius plates: low-profile titanium locking plates (Ti-6Al-4V)
• Proximal humerus: titanium PHILOS plates, nail-plate devices
• Elbow, wrist, hand: titanium mini-plates and screws

7.5 Foot and Ankle Surgery

• Titanium hindfoot fusion nails, ankle plates
• Metatarsal and midfoot screws
• Titanium staples for arthrodesis

7.6 Trauma - Specific Examples

• Proximal femur: Cephalomedullary nails (Ti-6Al-4V): Gamma nail, PFNA, TFN
• Tibial nail: Ti-6Al-4V
• Humeral nail: Ti-6Al-4V
• Distal femur plate: Ti-6Al-4V LISS plate
• Calcaneal plate: Ti-6Al-4V

8. Porous Titanium - Mimicking Cancellous Bone

8.1 Rationale

8.2 Types of Porous Titanium Surfaces