Arthroscopic (Endoscopic) Carpal Tunnel Release

Orthopaedics Postgraduate Examination Essay

Introduction

Surgical Indications

• Conservative measures (nocturnal splinting, corticosteroid injection) have failed after 3-6 months
• Neurophysiological evidence of moderate-to-severe CTS (prolonged distal motor latency, reduced SNAP amplitude, absent sensory action potential)
• Thenar wasting or progressive motor weakness
• Severe symptoms causing significant functional impairment
• Rapidly progressive or severe disease at presentation

Relevant Surgical Anatomy

• Median nerve: The most palmar structure. Its thenar (recurrent) branch arises at the distal TCL edge - it may take an extraligamentous (46%), subligamentous (31%), or transligamentous (23%) course, the last two being at risk with incomplete visualisation.
• Ulnar nerve and artery: Lie just medial (ulnar) to the TCL within Guyon's canal. The safe corridor during endoscopic dissection hugs the ulnar aspect of the TCL, medial to the median nerve, lateral to the ulnar neurovascular bundle.
• Superficial palmar arch: Located 5-8 mm distal to the distal margin of the TCL; at risk if the ligament is cut beyond its distal boundary.
• Flexor tendons: Nine tendons occupy the tunnel deep to the nerve; inadvertent division is a recognised but rare complication of ECTR.
• Palmar cutaneous branch of the median nerve: Arises 5 cm proximal to the wrist crease and runs radial to the palmaris longus; at risk in extended open but not in standard endoscopic incisions.

Endoscopic Techniques

1. Single-Portal Technique (Agee System)

1. General or regional anaesthesia; local anaesthesia feasible but may compromise visualisation due to tissue oedema.
2. Exsanguinate the limb; inflate tourniquet over adequate padding.
3. A transverse or longitudinal incision is made at the proximal wrist flexion crease between palmaris longus and flexor carpi ulnaris.
4. Blunt longitudinal dissection protects subcutaneous nerves and exposes the forearm fascia.
5. A U-shaped, distally based flap of forearm fascia is incised and elevated palmarly to create a "mouth" at the proximal end of the carpal tunnel.
6. A synovium elevator scrapes the TCL's deep surface, optimising the endoscopic view.
7. The blade assembly is inserted aligned with the ring finger, hugging the hook of the hamate on the ulnar side, pressed snugly against the deep surface of the TCL.
8. The distal TCL edge is identified by video picture, ballottement, and transillumination. The blade is elevated and the ligament divided in proximal-to-distal passes.
9. To avoid fat obscuring the lens: the distal one-half to two-thirds of the ligament is released first.
10. Complete division is confirmed by: (a) a trapezoidal defect through which palmar fascia fibres and fat protrude, (b) the ligament edges "flopping" into the window on blade rotation, and (c) palpable motion between the divided TCL and overlying skin.
11. Forearm fascia is released with tenotomy scissors under direct vision using right-angle retractors.
12. Skin closure with subcuticular or simple sutures; well-padded volar splint applied.

2. Dual-Portal Technique (Chow System)

Postoperative Management

• Sutures removed at 10-14 days.
• Active finger motion encouraged from day 1.
• Light activities of daily living permitted at 1-2 weeks.
• Forceful wrist flexion avoided for 3-4 weeks to allow soft-tissue healing.
• Strenuous activities gradually resumed over 3-4 weeks postoperatively.
• Formal hand therapy prescribed for pillar pain, grip weakness, or scar sensitivity.

Advantages of ECTR Over OCTR

Disadvantages and Complications

General Complications

• Incomplete TCL release: The most common cause of recurrent symptoms; more likely early in the learning curve. Reported at a higher rate with ECTR than OCTR.
• Transient nerve injury: ECTR carries a significantly higher incidence of transient postoperative neuropraxia (median or ulnar) compared to OCTR, though permanent nerve injury rates are equivalent. (Koong et al., Hand 2023, PMID 35179060)
• Vascular injury: Injury to the superficial palmar arch or ulnar artery is a rare but serious complication.
• Flexor tendon injury: Inadvertent laceration during tunnelling.
• Infection: Lower rate than OCTR due to smaller incisions.
• Pillar pain: Pain over the thenar/hypothenar eminences, less common than with OCTR.
• Reflex sympathetic dystrophy (CRPS): Rare.
• Higher revision rate: ECTR has a higher risk of needing repeat surgery at 1 year compared with OCTR.

Cost and Resource Implications

Outcomes and Evidence Summary

"High-level evidence suggests that outcomes are similar at 6 months except that patients with endoscopic release are at greater risk of nerve injury... The surgical technique for median nerve decompression should be tailored by the surgeon's expertise."

1. El Masri et al. (2024) - Umbrella review and meta-analysis of 9 meta-analyses: ECTR associated with better pinch strength at 3 and 6 months and shorter time to return to work. No significant difference in hand function, symptom severity, grip strength, pain, or total complications. Differences in nerve injury rate were statistically unclear. (PMID 38768022)
2. MacDonald & Rea (2022) - Systematic review of 23 RCTs: ECTR showed greater short-term improvement in grip strength and symptom severity, and faster return to work. The open group had more severe irreversible complications (prolonged pain, wound infection). The endoscopic group had a higher risk of repeat surgery. No significantly superior technique in long-term outcomes. (PMID 35146621)
3. Koong et al. (2023) - Meta-analysis of 23 RCTs comparing single-portal vs. dual-portal vs. open: Significantly higher transient postoperative nerve injury with ECTR (both portal types) vs. OCTR, though overall complication and re-operation rates were equivalent. Scar tenderness was significantly less with the dual-portal technique. Pillar pain, symptom relief, and patient satisfaction did not differ between groups. (PMID 35179060)

• Diabetic patients: Similar short-term benefit but worse 10-year outcomes (symptom severity and functional status) compared to non-diabetics.
• Workers' compensation patients: Three times the complications, nearly twice the rate of persistent pain, 5 weeks longer to return to work, 16% less likely to return to previous vocation.
• Severe electrophysiological disease: Considerable improvement expected but recovery is prolonged and may be incomplete at 1 year.
• Paediatric CTS (rare, usually idiopathic): Treatment generally successful.

Comparison Summary: ECTR vs. OCTR

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 82)
• El Masri J et al. Endoscopic Versus Open Carpal Tunnel Release: An Umbrella Review and a Meta-analysis. Ann Plast Surg. 2024. PMID 38768022
• MacDonald E, Rea PM. A Systematic Review of RCTs Evaluating Open and Endoscopic Carpal Tunnel Release. Adv Exp Med Biol. 2022. PMID 35146621
• Koong DP et al. Open versus Single- or Dual-Portal Endoscopic CTR: A Meta-Analysis of RCTs. Hand (NY). 2023. PMID 35179060

Medial Collateral Ligament (UCL) Reconstruction of the Elbow

Orthopaedics Postgraduate Examination Essay

Introduction

Relevant Anatomy

1. Anterior Bundle of the UCL

• Anterior band: taut at 0-60 degrees of elbow flexion
• Posterior band: taut at 60-120 degrees of elbow flexion

2. Posterior Bundle

3. Transverse Ligament (Cooper's Ligament)

Dynamic Stabilisers

• Flexor carpi ulnaris (FCU): primary dynamic stabiliser
• Flexor digitorum superficialis (FDS): secondary dynamic stabiliser
• Surrounding muscle mass can mask clinical valgus instability in up to 50% of cases.

Ulnar Nerve

Mechanism of Injury and Pathomechanics

• Repetitive valgus overload during the acceleration phase of throwing
• During late cocking and early acceleration, up to 64 N·m of valgus torque is applied at the elbow - near the ligament's tensile failure point
• Pitcher fatigue, poor biomechanics, or high pitch count results in progressive fibre failure, partial tearing, then complete disruption

• Direct valgus stress (football tackling, gymnastics)
• Elbow dislocation (disruption progresses from lateral to medial per O'Driscoll's instability circle)
• Javelin throwing

• Capitellar chondromalacia (radiocapitellar compression)
• Posteromedial olecranon osteophyte formation
• Loose body formation
• Ulnar neuritis

Clinical Presentation

• Overhead throwing athlete (typically pitcher, javelin thrower, tennis player, racket sports)
• Medial elbow pain during the acceleration phase of throwing
• Decreased ball velocity and accuracy
• Acute "pop" with immediate pain (complete acute tears)
• Associated paresthesiae/weakness in the ulnar two digits (ulnar neuritis)

• Valgus stress test: medial elbow pain/instability at 20-30 degrees of flexion (unlocks olecranon from fossa)
• Moving valgus stress test (O'Driscoll): valgus stress applied through arc of 70-120 degrees - medial pain at 70-90 degrees is sensitive (100%) and specific (75%) for UCL tear
• Milking manoeuvre: valgus stress with elbow flexed >90 degrees and thumb pulled
• Tenderness directly over the UCL, 2 cm distal to the medial epicondyle (at the sublime tubercle insertion)
• Ulnar nerve percussion sign (Tinel at cubital tunnel)
• Thenar/hypothenar wasting if chronic nerve involvement

Investigations

• AP and lateral: usually normal in chronic insufficiency
• May show calcification within the UCL (stress response or degeneration)
• Medial joint space widening on valgus stress views
• Posteromedial olecranon osteophytes (valgus overload)

• Gold standard investigation
• MRA superior to plain MRI for partial undersurface tears
• T-sign on MRA: leakage of contrast at undersurface insertion at sublime tubercle - diagnostic of partial undersurface tear
• Evaluates: UCL integrity, flexor-pronator mass, adjacent bone, concomitant pathology
• Guides differentiation of complete vs. partial tear and location (proximal vs. distal)

• Dynamic assessment of UCL laxity under valgus stress
• Operator dependent; useful in experienced hands

• Indicated if ulnar neuritis suspected

• Medial instability confirmed by valgus stress under anaesthesia: opening >1-2 mm between ulna and trochlea using anterolateral portal at 70-90 degrees of flexion
• Identifies concomitant pathology (osteochondral defects, loose bodies, synovitis)
• High-resolution MRA has largely replaced routine pre-reconstruction arthroscopy

Non-operative Treatment

• Rest from throwing for 6-12 weeks
• Physical therapy: maintain elbow motion, strengthening of FCU and flexor-pronator mass
• Graduated return-to-throwing programme
• Platelet-rich plasma (PRP) injections (primarily for grade 1-2 injuries)
• Brace support

• Overall return to sport (RTS) rate: 79.7%
• Return to previous level of play: 77.7%
• Proximal tears: RTS 89.7% vs. distal tears: RTS 41.2% (P<0.0001)
• Grade 1 and 2 injuries have excellent outcomes with conservative management
• No significant difference in RTS between PRP and physical therapy alone

Surgical Indications

• Non-operative management fails after 3-6 months
• Complete UCL tear in a competitive overhead athlete wishing to return to sport
• Acute complete tear in a high-level athlete with clearly reconstructible anatomy
• Progressive valgus instability affecting sports performance
• Recurrent instability after primary repair

• Significant concomitant elbow arthrosis
• Non-competitive athlete content with activity modification
• Medical comorbidities precluding anaesthesia

Graft Choices

Surgical Techniques

1. Modified Jobe (Figure-of-Eight) Technique

1. Pneumatic tourniquet; arm on arm board, rolled towel beneath elbow.
2. 10-cm incision over the medial epicondyle.
3. Muscle-splitting approach: the FCU is split longitudinally (rather than detached) - this avoids FPM detachment and reduces morbidity.
4. Ulnar nerve identified, dissected from cubital tunnel, and protected on a vessel loop throughout (but not transposed unless symptomatic).
5. The native UCL is exposed by elevating the flexor digitorum profundus from its anterior surface. The ligament is split longitudinally to inspect the articular surface and confirm pathology.
6. Ulnar tunnels: 3.6-mm drill at posterior edge of sublime tubercle (aiming anterior and parallel to joint line) and at anterior border 1 cm distal to joint line; tunnels connected with curved curette. The sublime tubercle bridge must not be violated.
7. Humeral tunnels: Y-shaped configuration - first hole at humeral UCL origin aiming proximal-lateral to exit posterosuperior border of medial epicondyle; second hole from medial prominence toward UCL insertion. Adequate bone bridges maintained.
8. Graft passed through ulnar tunnel (equal lengths on each side); each limb threaded through arms of Y-shaped humeral tunnel.
9. Figure-of-eight configuration: the two graft limbs are crossed and sutured between the ulnar and humeral tunnels to recreate native UCL biomechanics.
10. Calcification in the ligament must be removed before tunnel placement.
11. Tourniquet released; wound irrigated; FCU fascia approximated; subcuticular closure.
12. Plaster splint at 60 degrees of flexion.

2. Docking Technique (Altchek/Paletta)

1. Muscle-splitting approach through FCU, ulnar nerve protected.
2. Ulnar tunnels: two drill holes on either side of sublime tubercle connected by curved curette, with a 2-cm bridge maintained between them.
3. Humeral tunnel: single 15-mm longitudinal tunnel in the anterior half of medial epicondyle at the UCL's native insertion; two small exit tunnels at top of epicondyle using a dental drill.
4. Graft passed through ulnar tunnel anterior-to-posterior.
5. One limb pre-sutured (Krackow) and docked into humeral tunnel; elbow reduced with forearm supination and gentle varus stress, elbow cycled to prevent graft creep.
6. Final graft length estimated; second limb similarly docked.
7. Sutures tied over bony bridge on humeral condyle.
8. Splint at 60 degrees.

3. DANE TJ (Dines et al.)

4. UCL Repair with Internal Brace (Dugas et al.)

• The native UCL is repaired with a collagen-coated fibre tape (internal brace) between suture anchors at the medial epicondyle and sublime tubercle, augmenting primary repair
• Biomechanical studies show augmented repair is as strong as reconstruction at time zero with more resistance to gapping
• 102/111 patients returned to play at the same or higher level by 6.7 months (vs. ~12-18 months after reconstruction)
• KJOC overhead athlete scores averaged 88 in professional pitchers
• Not appropriate for degenerative/attritional UCL tears - reserved for acute avulsions with healthy ligament

Ulnar Nerve Management

• Ulnar neuritis occurs in up to 40% of athletes with UCL insufficiency
• Nerve is always identified and protected on a vessel loop during surgery
• Routine submuscular transposition is no longer recommended - evidence shows it increases complications without improving outcomes
• Transposition reserved for: preoperative ulnar neuritis unresponsive to conservative measures, nerve subluxation, or intraoperative nerve tethering
• The meta-analysis by Looney et al. (2021) demonstrated that outcomes of docking vs. modified Jobe are equivalent when FPM is preserved and routine submuscular transposition is not performed

Postoperative Rehabilitation

• Sutures removed at 1 week
• Hinged elbow brace: motion 45-90 degrees initially; gradually advanced to full motion over 3 weeks
• Wrist and hand exercises from day 1

• Formal physiotherapy begins at 6 weeks
• Gradual forearm and shoulder strengthening
• Valgus stress across elbow strictly avoided during this phase
• Light bench pressing permitted at 12 weeks

• Progressive strengthening programme
• Interval throwing programme begins at 4 months for throwing athletes

• Return to competitive throwing: 12-18 months
• High school/collegiate athletes (internal brace repair): ~6-7 months
• Pitchers typically require a full season before returning to competitive play

Outcomes

• Approximately 75-80% of patients return to sport at the same level or better by 1 year after reconstruction (Miller's Review of Orthopaedics, 9th Ed)
• RTS rates between 66% and 98% have been reported across studies - the wide range reflects variability in patient selection, technique, definition of success, and sport level

• When FPM is preserved and routine submuscular transposition is not performed: no significant difference in proportion of excellent outcomes (P=0.139) or time to return to sport (P=0.729)
• When controlling for FPM detachment: docking technique historically appeared superior due to reduced morbidity of the approach, not the fixation method itself

• Routine diagnostic arthroscopy at the time of UCL reconstruction does not significantly reduce the need for future valgus extension overload-related surgeries (P=0.584)
• Trend away from routine arthroscopy unless specifically indicated is justified

• Older age, higher level of professional play, postoperative workload, and limited professional experience
• Ulnar neuritis, non-dominant arm injury, psychiatric comorbidity
• Marked inconsistency in reported risk factors across studies

Complications

Comparison of Techniques

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 52, Techniques 52.13-52.16)
• Miller's Review of Orthopaedics, 9th Ed (Ch. 7)
• Looney AM et al. Modified Jobe Versus Docking Technique for Elbow UCL Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2021. PMID 32598852
• Gopinatth V et al. Return to Sport After Nonoperative Management of Elbow UCL Injuries: A Systematic Review and Meta-analysis. Am J Sports Med. 2023. PMID 36876746
• Looney AM et al. Routine diagnostic arthroscopy with elbow UCL reconstruction does not reduce future VEOS-related surgeries. J Shoulder Elbow Surg. 2022. PMID 34478864
• Berk AN et al. Inconsistencies in reporting risk factors for UCL reconstruction failure: a systematic review. J Shoulder Elbow Surg. 2023. PMID 37003424

Medial Patellofemoral Ligament (MPFL) Reconstruction

Orthopaedics Postgraduate Examination Essay

Introduction

Anatomy

MPFL

• The MPFL's femoral attachment is adjacent to the adductor tubercle, medial epicondyle, and the distal femoral physis (relevant in skeletally immature patients)
• The medial quadriceps tendon-femoral ligament (MQTFL) runs more proximally and is an anatomic variant in some individuals; it can be used as an alternative reconstruction target
• At the patella, the MPFL blends with the medial retinaculum and the VMO expansion
• The saphenous nerve and its infrapatellar branch are at risk during medial dissection

Patellofemoral Stabilisers

• MPFL (primary - 50-60% medial restraint at 0-30°)
• Medial patellomeniscal ligament
• Medial patellotibial ligament
• Bony architecture of the trochlear groove

• Vastus medialis obliquus (VMO) - primary dynamic medial stabiliser
• Rectus femoris, IT band
• Hip abductors (indirect effect on Q-angle)

Pathoanatomic Risk Factors for Instability

• Type A: Shallow groove (crossing sign only)
• Type B: Flat or convex trochlea with supratrochlear spur
• Type C: Asymmetric facets (lateral facet convex, medial facet absent)
• Type D: Asymmetric + cliff pattern with trochlear bump

Clinical Presentation

• Typically adolescent/young adult female (2:1 female predominance)
• Acute twisting injury with feeling/sight of patella dislocating laterally and spontaneous reduction on knee extension
• "Pop" followed by haemarthrosis, diffuse peripatellar swelling
• In chronic cases: repeated episodes of dislocation or subluxation with minor activity or in certain knee positions
• Associated pain, giving way, and anterior knee pain

• Patellar apprehension test: lateral displacement of patella with knee in slight flexion - apprehension or guarding indicates instability (most sensitive test)
• Patellar glide test: assess lateral/medial displacement in quadrants at 30° flexion; >3 quadrants lateral glide suggests instability
• J-sign: lateral patellar tracking in terminal extension (patella tracks laterally as knee extends)
• Medial peripatellar tenderness (at MPFL patellar insertion)
• Haemarthrosis in acute injury
• VMO hypoplasia in chronic cases

Investigations

• Anteroposterior: assess alignment, trochlear morphology
• Lateral at 30° flexion: patellar height (Blumensaat line, Insall-Salvati, CDI), trochlear depth, crossing sign, trochlear bump, double contour (DeJour classification)
• Merchant/Skyline view (30-45° flexion): patellar tilt (sulcus angle, congruence angle, patellofemoral angle), lateral subluxation

• Gold standard for TT-TG measurement (superimposed axial cuts at trochlear groove and tibial tubercle level)
• Normal TT-TG: 9-13 mm
• TT-TG >20 mm indicates significant lateral malalignment requiring distal realignment
• Patellar tilt measurement at 20° flexion

• MPFL injury: most commonly disrupted at patellar insertion (>70%); less commonly at femoral origin or mid-substance
• Bone bruise pattern: lateral femoral condyle + medial patellar facet (pathognomonic of acute dislocation)
• "T-sign": partial undersurface MPFL tear
• Identifies concomitant osteochondral injury (medial patellar facet is the most common donor site)
• Provides TT-TG estimate (tends to underestimate vs. CT)
• Assesses trochlear dysplasia and cartilage status

Non-operative Treatment

• Short period of immobilisation (1-3 weeks) in extension or a hinged brace
• Patellar stabilising brace during return to activity
• Physiotherapy: VMO strengthening, hip abductor strengthening, proprioception
• Cryotherapy and analgesia
• Graduated return to sport at 6-12 weeks

• Operative treatment resulted in a significantly lower rate of recurrent instability vs. non-operative management (10.69% vs. 29.93%; RR 2.49; 95% CI 1.34-4.61; P=0.004)
• No significant difference in Kujala scores between groups
• Trial Sequential Analysis showed current evidence insufficient to draw definitive conclusions
• Operative treatment (both repair and reconstruction) had significantly lower re-dislocation rates vs. non-operative management

Surgical Indications

• Recurrent lateral patellar dislocation (≥2 dislocations)
• First-time dislocation with large osteochondral fragment requiring fixation
• Failed conservative management (persistent instability, apprehension)
• Symptomatic subluxation refractory to non-operative management
• High-risk first-time dislocation with trochlear dysplasia, patella alta, or elevated TT-TG (relative)

• TT-TG <20 mm (or <15 mm without dysplasia)
• CDI <1.3 (no significant patella alta)
• Trochlear dysplasia DeJour A or low-grade B (no trochlear bump/cliff)

• TT-TG >20 mm
• Significant patella alta (CDI >1.2-1.3)
• Concomitant distal patellar chondral disease (anterior-medialisation/Fulkerson osteotomy)

• Severe trochlear dysplasia (DeJour B/D) with trochlear bump causing mechanical block

Surgical Decision Framework

Graft Choices for MPFL Reconstruction

• Gracilis, semitendinosus, tibialis anterior
• Outcomes review (Colasanti et al., 2023, PMID 37979146): allograft MPFL reconstruction demonstrates satisfactory outcomes with low re-dislocation rates; appropriate alternative when autograft harvest is contraindicated

Surgical Techniques

Medial Quadriceps Tendon-Femoral Ligament (MQTFL) Reconstruction - Phillips Technique

1. Supine; tourniquet on upper thigh; lateral post for arthroscopic assessment.
2. Diagnostic arthroscopy through standard medial and lateral portals: assess patellar tracking, evaluate for intraarticular damage (osteochondral lesions, loose bodies).
3. 3-cm incision 3 cm medial to inferior patellar tuberosity; harvest gracilis or semitendinosus in standard fashion; double/fold the graft; place #0 Vicryl Krackow suture in each tail.
4. Two 2-cm incisions: first just medial to superior patellar border; second from adductor tubercle to just distal to medial epicondyle.
5. Subcutaneous dissection to expose the patellofemoral ligament at both incisions.
6. A passage is created under the medial retinaculum between the two incisions (in the layer of the MPFL).
7. Patellar fixation: A transverse tunnel (typically 4.5-mm) is created at the superomedial patella; the looped end of the graft is secured here with a bioabsorbable interference screw or anchor.
8. Femoral fixation: The graft is routed through the subcutaneous passage to the femoral incision and secured at the anatomic MPFL femoral origin (between adductor tubercle and medial epicondyle, just proximal to physis) using an anchor or tunnel and screw.
9. Critical - graft tensioning: The graft is tensioned with the knee at 30 degrees of flexion. Overtightening must be avoided as this overloads the medial facet cartilage.
10. Intraoperative fluoroscopy assists with anatomically accurate femoral origin identification.
11. Patellar tracking reassessed throughout fixation.
12. Wound closure in layers.

MPFL Reconstruction - Standard Technique (Schöttle Point)

• Posterior cortex line of the femur
• Posterior cortical line of the Blumensaat line
• Distal to the posterior femoral condyle

1. Graft secured at patella first (transverse patellar tunnel or dual anchors at superomedial patella)
2. Femoral isometric point confirmed with fluoroscopy using the Schöttle method
3. Femoral tunnel drilled (typically 7-8 mm diameter for looped hamstring graft)
4. Graft tensioned at 20-30° of knee flexion with the patella centred in the trochlea
5. Fixation with interference screw or suture anchors
6. Free patellar movement (should translate 1-2 quadrants medially without excessive resistance)
7. Neither lax nor overtight - a key principle

Hardware-Free Techniques

• Knotted graft passed through bone tunnels and tied over a cortical bridge
• Eliminates implant-related complications, reduces cost, facilitates physis preservation
• Systematic review (Marín Fermín et al., J Orthop Surg Res 2022, PMID 35193641): hardware-free MPFL reconstruction is safe and effective; Kujala score improvement +13.2 to +54/100; re-dislocation rate 8.33%; advantages include physis preservation and lower cost

Important Technical Principles

1. Femoral tunnel positioning is the most critical step: errors here are the leading cause of MPFL reconstruction failure
   • Too proximal: graft tightens in flexion → medial facet overload and cartilage damage
   • Too anterior: graft tightens in flexion
   • Too distal: graft too lax in flexion
2. Do not overtighten: the MPFL should function as a check-rein, not an active restraint; target 1-2 quadrants of lateral patellar glide post-fixation
3. Patellar tunnel position: must be at native MPFL insertion (superomedial patella, upper two-thirds of medial border)
4. Address all pathoanatomy: isolated MPFL reconstruction in the presence of uncorrected high TT-TG or significant patella alta risks failure
5. Distal femoral physis: in skeletally immature patients, the femoral attachment must be placed distal to the physis (typically using anchors at the anterior aspect of the medial epicondyle) or a physis-sparing technique must be used

Postoperative Rehabilitation

• Hinged brace locked in extension for ambulation; non-weight bearing
• Cryotherapy, elevation; wound care

• Progressive weight bearing with hinged brace
• Controlled range of motion (0-90° initially)
• Quadriceps activation, straight-leg raises, patellar mobilisation

• Full weight bearing without brace
• Progressive quadriceps and hip strengthening; cycling, pool walking
• Functional rehabilitation focus on neuromuscular control

• Running programme
• Sport-specific training
• Proprioception and agility drills

• Mean return to sport: 6.7 months (range 3-6.4 months)
• Most athletes return to or surpass preoperative activity by 12 months

Outcomes

• Return to sport rate: 92.8% (95% CI 86.4-97.6)
• Return to preoperative activity level: 71.3% (95% CI 63.7-78.4)
• Mean return to sport: 6.7 months
• Overall complication rate: 8.8%
• Recurrence of instability: 1.9% (95% CI 0.4-4.0)
• Kujala score improved from 60.3 preoperatively to 90.0 postoperatively
• Adding osteotomy did not significantly change return-to-sport rate (95.4% vs 86.9%; P=0.22)

• Mean age 24.5 years; 67% female; follow-up 47.3 months
• Significant improvements in Kujala, IKDC, Lysholm, and Tegner scores
• Pooled complication rate: 8%
• Mean TT-TG 15.3 mm; mean CDI 1.11 (confirming isolated reconstruction is used in appropriately selected patients)

• No significant difference in Kujala or Lysholm scores between groups
• MPFL + TTT significantly decreased CDI (corrects patella alta); isolated MPFL did not
• Complication rate was significantly higher with MPFL + TTT (RR 2.472; P<0.001)
• Isolated MPFL sufficient when TT-TG ≤20 mm and no significant patella alta

Risk Factors for Failure After Isolated MPFL Reconstruction

• CDI >1.3 (patella alta): OR 2.72 for recurrent instability (P=0.02)
• DeJour type B or D trochlear dysplasia (trochlear bump): OR 3.28 (P<0.001)
• Age, sex, and TT-TG distance (within currently studied ranges) did not significantly predict failure

Complications

Comparison of Techniques

Special Considerations

• Risk of distal femoral physeal injury with femoral tunnel crossing the physis
• Femoral fixation should be placed distal to the physis (anterior medial epicondyle region)
• Hardware-free techniques and physis-sparing anchors preferred
• Good results reported with appropriate technique (Campbell's 2026)

• When TTT is added, staged rehabilitation is extended; weight bearing restricted for 4-6 weeks
• Most athletes return to unrestricted sport at 6-9 months after combined MPFL + TTT

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 52, Technique 52.1; Tables 52.2-52.3)
• Miller's Review of Orthopaedics, 9th Ed (Ch. 4)
• Platt BN et al. Return to Sport After MPFL Reconstruction: A Systematic Review and Meta-analysis. Am J Sports Med. 2022. PMID 33720789
• Castagno C et al. Isolated MPFL Reconstruction Outcomes: A Systematic Review and Meta-analysis. Knee. 2023. PMID 37531844
• Xu T et al. MPFL Reconstruction with and without Tibial Tubercle Transfer: A Systematic Review and Meta-analysis. Orthop Surg. 2023. PMID 37688429
• Dandu N et al. Trochlear Bump and Patella Alta Predict Recurrent Instability After Isolated MPFL Reconstruction. Am J Sports Med. 2025. PMID 39763469
• Patel S et al. Operative Versus Nonoperative Treatment of MPFL Injuries: Systematic Review and Meta-analysis of RCTs. Am J Sports Med. 2026. PMID 41496495
• Marín Fermín T et al. Hardware-free MPFL Reconstruction in Recurrent Patellofemoral Instability. J Orthop Surg Res. 2022. PMID 35193641

Medial Patellotibial Ligament (MPTL) Reconstruction

Orthopaedics Postgraduate Examination Essay

Introduction

Anatomy of the Medial Patellar Stabilisers

• MPFL (medial patellofemoral ligament): runs from the proximal two-thirds of the medial patellar border to the medial femoral epicondyle. The primary static restraint to lateral patellar translation (accounts for ~50% of passive medial restraining force at 0-30° of knee flexion).
• MQTFL (medial quadriceps tendon-femoral ligament): proximal MPFL fibres that attach to the quadriceps tendon at the superomedial patella rather than the patella itself.

• MPTL (medial patellotibial ligament): the focus of this essay.
• MPML (medial patellomeniscal ligament): runs from the inferomedial patellar border to the anterior horn of the medial meniscus.

MPTL Anatomy in Detail

• Patellar attachment: inferomedial border of the patella (lower one-third of medial patellar border, at or near the inferior pole)
• Tibial attachment: anteroinferior aspect of the proximal tibia (medial surface, below the joint line and medial to the patellar tendon insertion), typically at the level of the tibial plateau or just below
• Course: runs obliquely from the inferomedial patella to the anteromedial proximal tibia
• Length: approximately 30-40 mm (shorter than the MPFL)
• Layering: lies within the second layer of the medial retinaculum (same layer as the superficial MCL anteriorly and the posterior oblique ligament posteriorly per Warren and Marshall's three-layer description)
• Relationship: Deep to the crural/deep fascia (layer I); superficial to the knee joint capsule (layer III)
• Relation to MCL: Lies anterior to the medial collateral ligament and proximal to the pes anserinus insertion

Imaging of the MPTL

• MRI: The MPTL is visualised on axial and coronal fat-suppressed proton density sequences at the level of the inferior patella and patellar tendon/femorotibial joint margin. Individual layers of the medial retinaculum are typically fused on MRI and the individual ligamentous components (MPTL, MPML) may not always be distinguishable as separate structures from the retinacular condensations. The ligament extends from the medial patellar margin to the medial proximal tibia and is best seen on low axial cuts through the inferior patella.

Biomechanics

• The MPFL and MQTFL collectively account for approximately 50% of the total restraint to lateral patellar displacement; the remaining 50% is shared by MPTL, MPML, bony architecture, and dynamic stabilisers
• The MPTL functions primarily in greater degrees of knee flexion, in contrast to the MPFL which is the dominant restraint near full extension
• The MPTL has a primary role in controlling patellar rotation and tilt rather than lateral shift (Felli et al., 2021)
• In patella alta, the MPTL becomes especially relevant because the patella engages the trochlear groove later in flexion, meaning its distal (tibial) tethering from the MPTL is important for restraint during the pre-engagement phase
• The tibial attachment means the MPTL functions as a distal check-rein, limiting superior migration of the patella in terminal extension as well as tilt during early flexion

Pathology and Clinical Relevance

When Does MPTL Insufficiency Matter?

1. Chronic recurrent patellar instability where isolated MPFL reconstruction has failed or is predicted to be insufficient
2. Patella alta - where the patella sits proximal to the trochlear groove, the distal tethering provided by the MPTL is particularly important; patella alta is a recognised risk factor for failure of isolated MPFL reconstruction (CDI >1.3 carries OR 2.72 for recurrence)
3. Generalised ligamentous laxity / hypermobility syndromes - where multiple stabilisers are attenuated
4. Persistent patellar tilt despite MPFL reconstruction (the MPTL being the primary anti-tilt restraint)
5. Skeletally immature patients where tibial tubercle osteotomy is contraindicated and the MPTL may provide an adjunct stabilisation without bony procedures
6. Complex multidirectional instability involving tilt, rotation, and shift

Relationship to MPFL

Indications for MPTL Reconstruction

• Historically limited data; rarely performed in isolation in the modern era
• Appropriate in select patients with isolated distal retinacular insufficiency manifesting primarily as tilt or rotational instability

• Recurrent patellar instability with features of tilt/rotation as well as shift
• Patella alta (CDI >1.2-1.3) where the MPTL provides distal tethering that cannot be corrected by MPFL alone
• Failure of isolated MPFL reconstruction with persisting instability
• Complex instability where multiple stabilisers are deficient
• Skeletally immature patients where tibial tuberosity osteotomy is contraindicated and bony procedures must be deferred
• TT-TG distance in the borderline range (15-20 mm) where distal realignment is not clearly indicated but augmentation of distal soft-tissue restraints is desirable

• Significant patellofemoral osteoarthritis (relative)
• Uncorrected severe bony malalignment with TT-TG >20 mm (distal realignment preferred or added)
• DeJour type B/D trochlear dysplasia with trochlear bump - trochleoplasty considerations take priority

Graft Selection

Surgical Techniques

Principle

1. Restore normal length-tension relationship through the arc of flexion
2. Avoid overtightening (risks medial patellar impingement and articular cartilage damage)
3. Be compatible with concomitant MPFL reconstruction if performed together
4. Respect the distal femoral physis in skeletally immature patients (tibial fixation is generally physis-safe, but the patellar and tibial growth centres must be respected in younger children)

Technique 1: Hamstring Tenodesis / Semitendinosus Loop Technique (Historical)

Technique 2: Combined MPFL + MPTL Reconstruction with Gracilis Graft (Modern Anatomic Technique)

• Supine; tourniquet on upper thigh
• Ipsilateral knee prepared; contralateral leg for graft harvest if needed (or ipsilateral gracilis)
• Diagnostic arthroscopy first: assess patellar tracking, chondral status, intraarticular pathology

• Gracilis (and/or semitendinosus) harvested from the ipsilateral knee via a 2-cm transverse incision at the pes anserinus
• Graft prepared: tubularised, whipstitched with No. 0 or No. 1 absorbable braided suture at each end; sized for appropriate tunnel diameter (typically 5-6 mm)
• A bifurcated technique may be used: one gracilis looped to provide both a superior limb (MPFL) and an inferior limb (MPTL)

• Two small incisions: one at the superomedial patellar border (MPFL insertion) and one at the inferomedial patellar border/inferior pole (MPTL insertion)
• Subcutaneous dissection in the layer of the retinaculum, taking care to protect the saphenous nerve and its infrapatellar branch
• The MPTL attachment is identified at the inferomedial corner of the patella, just medial to the patellar tendon
• Either a transosseous tunnel through the inferior-to-medial patella or a suture anchor at the MPTL footprint is used for patellar fixation

• A separate small incision is made at the anteromedial proximal tibia, 1-2 cm below the joint line and medial to the patellar tendon
• The tibial MPTL attachment is identified and a tibial tunnel (typically 5-6 mm) is drilled at this site, directed posteromedially
• Alternatively, a suture anchor can be used in the proximal tibia at the native MPTL footprint
• The graft is routed from the patellar fixation through the subcutaneous plane to the tibial anchor

• The MPFL limb is routed subcutaneously to the femoral attachment point (Schöttle point: between adductor tubercle and medial epicondyle, confirmed with fluoroscopy)
• A 7-8 mm femoral tunnel is drilled and the graft fixed with an interference screw

• Critical step: The MPTL component is tensioned with the knee at 60-90 degrees of flexion (the angle at which the MPTL is most functionally relevant), maintaining patellar centring
• The MPFL component is tensioned at 30 degrees of flexion
• Both components must allow free patellar translation (1-2 quadrants medially) and must not be overtightened
• Intraoperative patellar tracking assessed through full range of motion

• Standard layered wound closure; retinaculum approximated over the reconstruction
• Hinged brace applied; splint optional

Technique 3: Medial Patellar Tendon Transfer (Roux-Goldthwait Variant)

Postoperative Rehabilitation

• 0-2 weeks: Hinged brace locked in extension; weight bearing as tolerated; cryotherapy
• 2-6 weeks: Progressive range of motion (0-90°); quadriceps activation; straight-leg raises
• 6-12 weeks: Full weight bearing; progressive strengthening; cycling; pool therapy
• 3-6 months: Running; sport-specific training; proprioception and plyometric progression
• Return to sport: Typically 6-9 months after combined MPFL + MPTL reconstruction; earlier with isolated soft-tissue procedures if additional bony work not performed

Outcomes

Isolated and Combined MPTL Reconstruction

• Good and excellent outcomes achieved in >75% of cohorts in most studies
• Re-dislocation rate: <10% across most series with or without associated MPFL reconstruction
• One outlier study reported an 82% failure rate (likely representing a technically flawed or overly selected population)
• Techniques included: hamstring tenodesis, medial patellar tendon transfer, and MPTL reconstruction combined with MPFL
• Results were consistent across different techniques
• Median Coleman Methodology Score: 66/100 (moderate quality)
• Conclusion: MPTL reconstruction leads to favourable clinical outcomes and is a valid patellar stabilisation procedure

• Good and excellent outcomes overall
• Low recurrence rates
• Procedures included: hamstring grafting, medial patellar and quadriceps tendon transfer, with or without bony procedures
• Median modified CMS: 70.6 ± 14.4 (range 38-84)
• Conclusion: Combined MPFL + MPTL reconstruction leads to favourable outcomes and is a valid surgical procedure for patellar stabilisation

• Pooled effects positive and incremental for Kujala score at 12 and 24 months
• Pain reduction trend sustained over time
• Conclusion: Combined reconstruction provides good knee function and maintains patellofemoral balance; patient pain decreases progressively, making it a valid surgical method for patellar stabilisation

• 86-88% excellent subjective outcomes at 12 and 24 months
• IKDC improved from 51.9 ± 13.8 to 85 ± 13.9 at 24 months (P<0.05)
• Kujala improved from 55.1 ± 15.2 to 89.5 ± 10.2 at 24 months (P<0.05)
• VAS pain improved from 58 ± 11 to 11 ± 4 at 24 months (P<0.05)
• Patellar tilt, patellar shift, CDI, Insall-Salvati ratio, and TT-TG all decreased significantly
• Concluded that combined MPFL + MPTL reconstruction is an effective treatment for patellar instability with patella alta, emphasising the combined effect over MPFL alone

MPTL vs. MPFL: Functional Comparison

Complications

Special Considerations

Patella Alta

• It does not engage the trochlear groove until 20-30° or more of flexion
• During the pre-engagement phase, only soft-tissue restraints (including the MPTL) prevent lateral escape
• The MPTL's tibial attachment naturally limits superior patellar migration and lateral tilt during this vulnerable phase
• Combined MPFL + MPTL reconstruction corrects both shift and tilt/rotation, effectively reducing the functional effect of patella alta without requiring a tibial tubercle distalisaton in selected cases (Yang & Zhang, 2019)

Skeletally Immature Patients

• Tibial tubercle transfer is contraindicated with open proximal tibial physes
• The MPTL tibial insertion site is typically distal to the proximal tibial physis and can often be used safely
• Caution is still required in very young patients with wide-open physes
• Combined MPFL + MPTL reconstruction avoids femoral/tibial physis injury when suture anchors at the medial epicondyle and proximal tibia are used appropriately
• Hardware-free suture techniques further reduce implant-related physis risks

Role of Arthroscopy

• Assessment of patellar tracking and tilt
• Identification of chondral lesions (medial patellar facet most commonly involved)
• Removal of loose bodies
• Confirmation of MPTL/MPML deficiency under dynamic assessment

Summary: Place of MPTL Reconstruction in the Surgical Algorithm

RECURRENT LATERAL PATELLAR INSTABILITY
          │
          ├── TT-TG >20 mm?  → Add Tibial Tubercle Transfer (Elmslie-Trillat / Fulkerson)
          │
          ├── CDI >1.3 (Patella Alta)?  → Consider MPFL + MPTL (distal tether without osteotomy)
          │                                or Add Tibial Tubercle Distalisaton
          │
          ├── DeJour B/D Trochlear Dysplasia?  → Consider Trochleoplasty addition
          │
          ├── Tilt/rotation predominant?  → Add MPTL Reconstruction
          │
          ├── Open physes (skeletally immature)?  → MPFL + MPTL (physis-sparing)
          │
          └── Standard recurrent instability  → Isolated MPFL Reconstruction

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 52; extraarticular ligamentous structures)
• Baumann CA et al. Reconstruction of the MPTL results in favorable clinical outcomes: a systematic review. KSSTA. 2018. PMID 29344696
• Felli L et al. Anatomy and biomechanics of the medial patellotibial ligament: A systematic review. Surgeon. 2021. PMID 33121878
• Aicale R, Maffulli N. Combined MPFL and MPTL reconstruction for patellar instability: a PRISMA systematic review. J Orthop Surg Res. 2020. PMID 33183310
• Hinckel BB et al. MPTL and MPML: anatomy, imaging, biomechanics, and clinical review. KSSTA. 2018. PMID 28289819
• Tanaka MJ et al. Recognition of evolving medial patellofemoral anatomy provides insight for reconstruction. KSSTA. 2019. PMID 30370440
• Yang Y, Zhang Q. Reconstruction of MPFL and reinforcement of MPTL is effective for patellofemoral instability with patella alta. KSSTA. 2019. PMID 30421164
• Abbaszadeh A et al. Combined MPFL and MPTL reconstruction in recurrent patellar instability: A systematic review and meta-analysis. World J Clin Cases. 2023. PMID 37469731

Oblique Lumbar Interbody Fusion (OLIF)

Orthopaedics Postgraduate Examination Essay

Introduction

Historical Development

• 1997: Anterior retroperitoneal approach described (Mayer)
• 2006: XLIF (extreme lateral interbody fusion via transpsoas corridor) popularised by Ozgur et al.
• 2012: OLIF technique described by Silvestre et al. as "mini-open anterior retroperitoneal lumbar interbody fusion"
• 2014 onwards: Rapid adoption; evidence base growing substantially
• Current: OLIF is now one of the most commonly performed minimally invasive lumbar fusion techniques worldwide

Relevant Anatomy

The OLIF Corridor

• Anteriorly/medially: Aorta (left side) or inferior vena cava/right common iliac vein
• Posterolaterally: Anterior border of the psoas muscle
• Superficially: Peritoneal sac (reflected anteriorly)

Level-Specific Anatomy

Structures at Risk

1. Genitofemoral nerve (GFN): Runs on the anterior surface of the psoas muscle in a medial-to-lateral direction; at risk from retraction. Causes anterior thigh numbness/dysaesthesia. Most common neurological complication of OLIF.
2. Sympathetic chain: Lies anterior to the vertebral bodies in the prevertebral space; at risk from anterior retraction. Injury causes sympathetically-mediated leg temperature changes, Horner syndrome (if high), or (in males) retrograde ejaculation if the superior hypogastric plexus is disrupted at L4-L5 or L5-S1.
3. Lumbosacral plexus and exiting nerve roots: Lie within the psoas muscle; less directly at risk than in XLIF (which splits the psoas) but may be affected by aggressive posterior retraction.
4. Left common iliac vein / iliac artery: At L4-L5 and L5-S1; thin-walled and easily torn. Most serious vascular complication.
5. Lumbar segmental vessels: Cross at the mid-vertebral body level; division required at some levels to improve corridor access.
6. Ureter: Lies in the retroperitoneal fat swept anteriorly with the peritoneum; injury is rare but serious.
7. Peritoneum and bowel: Inadvertent entry during retroperitoneal dissection.

The Surgical Corridor Zones (Zones of Approach)

• Zone 1 (ALIF): Anterior to vessels
• Zone 3 (LLIF/XLIF): Trans-psoas, lateral
• Zone 4 (PLIF/TLIF): Posterior, transforaminal

Indications

• Degenerative disc disease with axial/radicular pain failing conservative management
• Degenerative lumbar spondylolisthesis (Grade I-II; low-grade slip)
• Degenerative lumbar scoliosis - coronal and sagittal deformity correction; suitable for multilevel fusion (L1-L5)
• Adjacent segment disease after prior posterior fusion
• Foraminal stenosis without significant central canal stenosis (indirect decompression by disc height restoration)
• Isthmic spondylolisthesis (low grade)
• Revision surgery where posterior scarring makes repeat posterior access difficult

• Moderate central canal stenosis (with supplementary posterior decompression)
• Hypertrophic facet arthropathy causing foraminal stenosis

Contraindications

• Prior retroperitoneal surgery with extensive adhesions (relative)
• Abdominal aortic aneurysm in the operative field
• Retroperitoneal fibrosis
• Severe osteoporosis (greatly increased cage subsidence risk)
• High-grade spondylolisthesis (Grade III-IV)

• Central canal stenosis requiring direct decompression (OLIF alone insufficient; requires posterior stage)
• L5-S1 pathology (technically more demanding; consider ALIF)
• Obesity (retroperitoneal fat obscures corridor)
• Prior abdominal/pelvic surgery with retroperitoneal adhesions
• Inflammatory arthropathy requiring biopsy/synovectomy

Advantages Over Competing Techniques

Surgical Technique

Patient Positioning

1. Patient placed in right lateral decubitus position (left side up) tilted slightly backward (10-20° posterior tilt) to open the corridor between the psoas and anterior vessels at the target level.
2. The operating table may be flexed at the level of the iliac crest to open the flank and expand the working corridor.
3. The table should be absolutely flat without lateral roll artefact to ensure accurate fluoroscopic assessment.
4. Intraoperative fluoroscopy (C-arm) positioned for AP and lateral views.
5. Neurophysiological monitoring (EMG, neuromonitoring) is optional for OLIF (unlike XLIF where it is mandatory) but may be used as an adjunct.

Approach and Corridor Development

1. Under fluoroscopy, mark the centre of the target disc on the skin.
2. A 4-cm skin incision is made centred over the projection of the target disc, parallel to the external oblique muscle fibres.
3. The external oblique, internal oblique, and transversus abdominis muscles are split along the direction of fibres using a blunt muscle-splitting technique (not cut transversely).
4. The retroperitoneal space is accessed by blunt dissection through the retroperitoneal fat; the peritoneal sac is mobilised and retracted anteriorly.
5. The anterior longitudinal ligament is used as the medial landmark; the anterior border of the psoas muscle is used as the lateral landmark.
6. The genitofemoral nerve on the psoas surface is carefully identified and protected; it runs from medial to lateral and should not be stretched.
7. The sympathetic chain in the anterior third of the vertebral body is mobilised anteriorly if necessary.
8. For multilevel fusions: the incision may be enlarged to 6 cm, or a "sliding window" technique (4-cm incision repositioned sequentially) exploits the mobility of the abdominal wall.
9. Self-retaining retractors (Langenbeck hooks or purpose-designed OLIF retractors with blade lighting) are placed to maintain exposure. The anterior blade retracts the vessels medially; the posterior blade retracts the psoas laterally.
10. Fluoroscopic confirmation of the correct level before discectomy.

Disc Preparation and Cage Insertion

1. Annulotomy is made in the left anterolateral disc.
2. Thorough discectomy using curettes, shavers, and Kerrison rongeurs; endplate preparation to bleeding subchondral bone.
3. Endplate integrity must be preserved - violation increases subsidence risk (the most common OLIF-specific complication).
4. Sequential dilatation and sizing of the disc space.
5. A large-footprint OLIF cage (typically 18-22 mm wide, 45-60 mm long, 8-18 mm height) is inserted. The larger cage:
   • Provides greater disc height restoration and foraminal decompression
   • Spans the ring apophysis (strongest part of the endplate) on both sides, reducing subsidence risk
   • Allows application of more graft material
6. Cage fill with autograft (local bone from reamings or iliac crest) ± BMP-2 ± DBM.
7. Final fluoroscopic confirmation of cage position (AP and lateral).

L5-S1 Extension

• Operating table tilted to near-supine position to allow infra-aortic access below the iliac bifurcation
• Confirm on lateral pelvic radiograph that a line parallel to the L5-S1 disc passes above the pubic symphysis
• Left common iliac vessels identified and gently mobilised
• L5-S1 disc exposed below the bifurcation of the iliac vessels; exposure confirmed with guide pin and C-arm

Supplemental Fixation

• L4-L5 (most mobile level)
• High-grade instability
• Multilevel constructs
• Osteoporosis

• Percutaneous posterior pedicle screws (most common): placed in same anaesthetic, same or prone positioning ("single-position" or staged)
• Lateral plate fixation: applied directly to the vertebral bodies through the OLIF corridor
• Stand-alone OLIF with integrated fixation cage: some modern cage designs include integrated fixation screws into the vertebral bodies (controversial)
• Combined with TLIF/PLIF for cases requiring direct posterior decompression

Postoperative Management

• Early mobilisation: ambulation permitted day 1-2 postoperatively
• Short hospital stay: typically 2-3 days (major advantage vs. open posterior approaches)
• Lumbar brace/orthosis for 6-8 weeks in most protocols
• Physiotherapy: core strengthening and graduated activity from 4-6 weeks
• Return to sedentary work: 4-6 weeks; heavy labour: 3-6 months
• Radiological follow-up: plain radiographs at 6 weeks, 3 months, 6 months, 12 months; CT at 6-12 months to confirm fusion

Outcomes

OLIF vs. MIS-TLIF

• Blood loss: Significantly less with OLIF (95% CI -121 to -55 mL; P<0.05)
• Hospital stay: Shorter with OLIF (95% CI -1.98 to -0.85 days; P<0.05)
• Fusion rate: Higher with OLIF (OR 1.04-3.60; P<0.05)
• Disc height restoration: Greater with OLIF (95% CI 0.50-3.63; P<0.05)
• Foraminal height: Greater with OLIF (95% CI 0.96-4.13; P<0.05)
• Complication rates: Significantly lower with MIS-TLIF (OR 1.01-2.06; P<0.05)
• No significant differences in operative time, patient satisfaction, or functional scores

• OLIF superior in: blood loss, hospital stay, VAS-leg pain, ODI, disc height, foraminal height, segmental lordosis, cage height
• No significant difference in: operative time, complications, fusion rate, VAS-back pain

• OLIF: shorter operative time, less blood loss, shorter hospital stay, better disc height, better VAS leg, better ODI, better segmental and lumbar lordosis angle
• No significant difference in: JOA scores, fusion rates, complication rates, or patient satisfaction

OLIF vs. ALIF

• No significant difference in disc height, segmental lordosis, lumbar lordosis, VAS, ODI
• Comparable operative time, blood loss, and hospital stay
• Both achieved >90% fusion rate
• OLIF had a significantly higher complication rate: 18.83% vs. ALIF 7.32%, with cage subsidence being the most notable OLIF complication
• ALIF requires vascular surgeon involvement; higher cost

OLIF vs. LLIF/XLIF

• No significant differences in blood loss, surgical duration, VAS-back, VAS-leg, ODI, or fusion rates at >2 years follow-up
• OLIF: significantly higher rates of abdominal complications, system failure, and vascular injuries
• LLIF: significantly higher rates of postoperative neurological symptoms and psoas weakness
• Both effective; complication profiles differ by technique

OLIF for Spondylolisthesis

• OLIF superior in: operative time (shorter), blood loss (less), hospital stay (shorter), VAS improvement, ODI improvement, disc height restoration, lumbar lordosis correction
• No significant difference in: complication incidence, fusion rate

Summary of Key Outcomes Data

• Study of 812 patients: 4% intraoperative/in-hospital complication rate; no abdominal or urologic injuries; 3 vascular and 3 neurological injuries
• Woods et al. (137 patients, L1-L5, L5-S1 or both): 12% overall complication rate; most common complications: subsidence (4.4%), postoperative ileus (2.9%), vascular injury (2.9%); fusion rate 98%

Complications

Approach-Related (OLIF-Specific)

Procedure-Related

Risk Factors for Cage Subsidence

• Osteoporosis (low BMD/T-score <-2.5)
• Endplate violation during preparation
• Undersized cage
• Cage not spanning apophyseal ring
• Excessive disc height distraction
• Single-level without posterior fixation

OLIF vs. Other Interbody Techniques: Summary Comparison

Special Applications

OLIF for Adult Degenerative Scoliosis

• A single incision can access L1-L5 through a "sliding window" or extended approach
• Large cages enable coronal and sagittal deformity correction at multiple levels
• Less blood loss and shorter operative time than open approaches
• Typically combined with posterior pedicle screw fixation in same anaesthetic (single-position surgery)

Single-Position OLIF Surgery (Lateral-to-Prone)

OLIF at L5-S1

• Table repositioning to near-supine or additional tilt
• Mobilisation of the iliac bifurcation
• More technically demanding; many surgeons prefer ALIF at L5-S1 and restrict OLIF to L1-L5

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 44, Technique 44.21; Lumbar Interbody Treatment Algorithm Fig. 44.32)
• Wang YL et al. OLIF versus MIS-TLIF for lumbar degenerative disease: systematic review and meta-analysis. Neurosurg Rev. 2023. PMID 37119422
• Li XY et al. Efficacy of OLIF versus TLIF in lumbar degenerative diseases: systematic review and meta-analysis. Arch Orthop Trauma Surg. 2023. PMID 37079105
• Sun D et al. OLIF versus ALIF for degenerative lumbar disease: systematic review. Eur Spine J. 2023. PMID 36587140
• Ricciardi L et al. Lumbar interbody fusion using OLIF and LLIF: meta-analysis of comparative studies. Eur J Orthop Surg Traumatol. 2023. PMID 34825987
• Shi J et al. Meta-analysis of OLIF and TLIF in degenerative lumbar spondylolisthesis. J Orthop Surg Res. 2024. PMID 38622724
• Liu D et al. Meta-analysis of MIS-TLIF versus OLIF for lumbar degenerative diseases. J Orthop Surg Res. 2024. PMID 39736715

Role of Bone Marrow Injections (BMAC) in Orthopaedics

Orthopaedics Postgraduate Examination Essay

Introduction

Biology and Composition of BMAC

Bone Marrow Aspirate (BMA)

• Red blood cells and granulocytes
• Haematopoietic stem cells and progenitor cells
• Mesenchymal stem cells (MSCs) - the regenerative core
• Platelets
• Growth factors in moderate concentrations

Bone Marrow Aspirate Concentrate (BMAC)

• Mesenchymal stem cells (MSCs): multipotent progenitors capable of differentiating into osteoblasts, chondrocytes, tenocytes, adipocytes, and myocytes
• Haematopoietic stem cells: multipotent and immunomodulatory
• Growth factors: PDGF (platelet-derived growth factor), TGF-β (transforming growth factor-beta), BMP-2, BMP-7 (bone morphogenetic proteins), VEGF (vascular endothelial growth factor), IGF-1 (insulin-like growth factor)
• Cytokines: IL-1 receptor antagonist (IL-1ra) - directly anti-inflammatory; important in OA
• Platelets (at varying concentrations depending on processing)

• Haematopoietic stem cells are pluripotent and able to differentiate
• The number of pluripotent cells is decreased in patients who smoke, drink alcohol, or use steroids - relevant for patient selection
• Centrifugation concentrates pluripotent cells in the buffy coat layer
• Success is dependent on the concentration of viable stem cells available for injection
• BMA harvested in small (<5 mL) aliquots per aspiration site to maximise MSC yield (larger volumes per site aspirate more blood and dilute MSC concentration)

MSC Mechanism of Action (Rockwood & Green, 10th Ed 2025)

• Paracrine signalling: secretion of growth factors and cytokines that stimulate endogenous repair
• Immunomodulation: suppression of pro-inflammatory cytokines (TNF-α, IL-1, IL-6); promotion of anti-inflammatory macrophage phenotype
• Angiogenesis stimulation: via VEGF secretion
• Recruitment of resident progenitor cells to the repair site
• Chondroprotection: attenuation of chondrocyte apoptosis; reduction of matrix metalloproteinase activity

Procurement Technique

Donor Sites

• Posterior iliac crest (most common; highest MSC density)
• Anterior iliac crest (patient supine; easier access)
• Greater trochanter / proximal femur
• Proximal tibia (convenient for intraoperative harvest in knee procedures)
• Calcaneus
• Vertebral body (intraoperative)

Harvest Technique (Campbell's, Technique 64.9 - Connolly et al./Brinker et al.)

1. General or regional anaesthesia; patient prone (posterior ICBG) or supine (anterior ICBG)
2. Small 2-3 mm incision over the iliac crest
3. An 11-16 gauge marrow aspiration needle inserted into multiple areas of the iliac crest
4. A minimum of 40 mL up to 150 mL of marrow aspirated; harvested in small aliquots of <5 mL per aspiration to avoid blood dilution of the MSC-rich marrow
5. Heparinised syringes used to prevent clotting
6. Marrow processed by centrifugation (BMAC) or used unprocessed (BMA)
7. BMAC concentrated to typically 3-7× the MSC density of native aspirate (varies by centrifuge system)

Injection Technique for Non-union

1. Under image intensification, an 18-gauge needle inserted to localise the non-union site
2. Microtrauma created at the non-union site first with the needle to stimulate local biology
3. Marrow injected directly into the non-union site and adjacent bone-muscle junction (well-vascularised area)

Clinical Applications

1. Fracture Non-union and Delayed Union

• Percutaneous bone marrow grafting has been shown to be as effective as open bone grafting techniques for selected non-unions
• Most effective for delayed union (before established non-union)
• Advantages over open iliac crest bone grafting (ICBG): decreased donor site morbidity, decreased cost, minimally invasive
• Brinker et al.: 9 of 11 healed with unprocessed (non-concentrated) BMA grafting for distal tibial metadiaphyseal delayed unions after plate fixation
• The role of concentrating the marrow (BMAC vs. BMA) is still not completely defined; concentration adds expense; no large randomised trials currently evaluate BMA vs. BMAC

• 25 studies included; aseptic non-union: union rates with BMA 79-100%, BMAC 50-100%
• Septic non-union: BMA 73-100%, BMAC 83-100%
• 18/24 studies reported union rates >80%
• One study: significant reduction in autograft reinfection rate when combined with BMAC (P=0.009)
• Major adverse events: 2 deep infections at injection site, 1 case of heterotopic ossification; most only had transient donor site discomfort
• Literature is highly heterogeneous; additional Level I data needed

• 15 RCTs, 1,286 patients with delayed union/non-union
• PRP+BMAC ranked optimal for improving healing rates (SUCRA 91.6%) and reducing adverse events (SUCRA 99.8%)
• PRP+ACB (autologous cancellous bone) ranked optimal for shortening healing time (SUCRA 93.6%)
• BMP and PRP both significantly shortened healing time vs. standard treatment alone

• Best results in biologically active (oligotrophic/hypertrophic) non-unions with adequate mechanical stability
• Poor results in avascular or atrophic non-union with large gaps (may need open bone grafting)
• Percutaneous technique suitable for accessible non-unions with intact fixation
• Combined with bone grafting (allograft + BMAC) as a graft extender when autograft volume is limited

2. Knee Osteoarthritis

• 8 studies, 299 knees, mean follow-up 12.9 months
• 94.4% of patient-reported outcomes showed significant improvement from baseline (P<0.05)
• Pain (VAS, NRS) significantly improved in all 5 studies reporting numerical pain scores
• BMAC did not demonstrate superiority over other biologic therapies (PRP, microfragmented adipose tissue) or over placebo in 3 comparative studies
• High cost limits utility despite demonstrable benefit

• 48 studies, 9,338 knees
• SUCRA rankings at minimum 6 months:
  • PRP: 91.54 (highest likelihood of improvement in pain and function)
  • BMAC: 76.46 (second)
  • HA: 53.12
  • CS: 15.18
  • Placebo: 13.70
• PRP, BMAC, and HA all led to significant functional improvement vs. placebo
• Conclusion: PRP, BMAC, and HA outperform corticosteroids at ≥6 months

• 27 Level I studies; BMAC (226 patients) vs. HA (1,128 patients) vs. PRP (1,042 patients)
• Network meta-analysis: BMAC significantly better than HA for postinjection WOMAC (P<0.001), VAS (P=0.03), and subjective IKDC (P<0.001)
• No significant difference between PRP and BMAC
• Conclusion: Patients receiving PRP or BMAC can expect better outcomes than HA

• BMAC is a valuable source of MSCs; evidence supports attenuation of inflammatory pathways in knee OA
• Effective in improving functional outcomes in clinical trials
• Superiority of BMAC over other orthobiological treatments cannot be established due to conflicting results
• Best results in mild-to-moderate OA (Kellgren-Lawrence II-III); limited benefit in severe OA

• Kellgren-Lawrence grade II-III (moderate OA)
• Young to middle-aged active patient
• BMI <30 preferred
• Failed viscosupplementation and corticosteroid injections
• Not a bone-on-bone joint (KL grade IV)
• Non-smoker, no chronic alcohol use, no chronic steroid therapy (reduces MSC number)

3. Cartilage Defects and Osteochondral Lesions

• Focal chondral defects (Grade III-IV ICRS): adjunct to microfracture, autologous chondrocyte implantation (ACI), or matrix-induced repair
• Osteochondral lesions of the talus (OLT): combined with juvenile articular cartilage allograft or scaffold
• Osteochondritis dissecans

• Meta-analysis (Chahla et al.): BMAC-laden scaffold material in focal chondral defects - all 8 clinical trials reported good-to-excellent functional outcomes and significant pain reduction up to 24 months
• Three independent clinical trials: BMAC intra-articular injection significantly reduced knee pain and improved function in OA; superior results in KL II-III (mild-to-moderate OA)

• Micronised allogenic cartilage ECM combined with BMAC showed satisfactory patient-reported outcomes and superior MRI results compared to microfracture alone
• BMAC augmentation of cartilage repair procedures improves biological environment for fibrocartilage and hyaline cartilage repair

• MSCs differentiate into chondrocytes in the scaffold environment
• Paracrine effects reduce chondrocyte apoptosis
• BMP-2/7 and TGF-β stimulate proteoglycan and type II collagen synthesis
• IL-1ra reduces catabolic metalloproteinase activity

4. Bone Grafting Adjunct and Graft Extender

• Allograft bone alone has limited osteogenic properties; mixing with BMA/BMAC improves biological activity (Campbell's, 15th Ed 2026)
• High-quality evidence comparing autograft vs. allograft + BMAC is still lacking
• Used in spinal fusion, limb reconstruction, and tumour surgery reconstruction
• Reamer-irrigator-aspirator (RIA) harvest from the femur/tibia intramedullary canal can be combined with BMAC as a biological supplement

5. Tendinopathy and Rotator Cuff

• Chronic Achilles tendinopathy: BMAC or BMA injected into the tendon body or peritendinous region; early case series show pain reduction and functional improvement but no high-level comparative evidence
• Rotator cuff tears / augmentation of repair: BMAC applied at the tendon-bone interface during rotator cuff repair; biomechanical and early clinical data suggest improved healing
• Patellar tendinopathy / lateral epicondylitis: small case series; improvement in pain scores at short-term follow-up

6. Avascular Necrosis (AVN)

• BMA/BMAC injected into the decompression tract after drilling
• Aims to repopulate ischaemic bone with osteogenic progenitors and stimulate angiogenesis via VEGF
• Best results in Ficat/Steinberg stage I-II (pre-collapse)
• Several case series report halting progression and reducing need for THA
• No large RCTs; evidence level III-IV

7. Stress Fractures and High-Risk Fractures

• BMAC uses the patient's own MSCs to assist in bone healing without much of the morbidity of autologous bone grafting
• Some studies have shown benefits in high-risk fractures, non-unions, and bone defects
• The process is difficult to standardise and needs more rigorous research before definitive recommendation

BMAC vs. Other Orthobiological Therapies

Practical Considerations and Limitations

Processing Variability

• No standardised centrifugation protocol; different systems yield vastly different MSC concentrations
• MSC viability after processing is not uniformly measured
• The concentration of MSCs in the final BMAC product is difficult to quantify without flow cytometry

Patient-Specific Factors Reducing Efficacy

• Smoking: reduces pluripotent cell number
• Alcohol use: reduces MSC viability
• Chronic steroid therapy: diminishes MSC pool
• Advancing age: MSC number and differentiation capacity decline
• Obesity: altered MSC function; inflammatory adipokine environment
• Severe osteoporosis: altered marrow cellularity

Cost-Effectiveness

• BMAC is significantly more expensive than PRP or HA due to:
  • Specialised centrifuge equipment
  • Theatre/procedure room for harvest
  • Anaesthesia or sedation for iliac crest aspiration
  • Higher volume of procedure time
• Cost-effectiveness not yet established relative to alternatives with comparable efficacy

Regulatory and Ethical Status

• In many countries, BMAC derived and used in the same operative session is classified as a "minimal manipulation" autologous tissue and does not require separate regulatory approval
• Expanded/cultured MSCs from bone marrow constitute a cellular therapy product and are subject to strict regulatory oversight (e.g. EMA, FDA phase III trials required)
• The distinction between BMAC (point-of-care, same session) and cultured MSC therapy is important clinically and legally

Summary of Evidence by Application

Future Directions

1. Standardised processing protocols: uniformity in centrifugation speed, time, and final concentration
2. MSC enumeration: point-of-care cell counting to quantify injected cells
3. Biomarker-guided selection: identifying patients most likely to benefit (based on marrow cellularity, inflammatory profile)
4. Combination therapies: PRP+BMAC (highest SUCRA for healing; Wang 2025) shows particular promise for non-union management
5. Large RCTs: especially for non-union, cartilage repair, and AVN applications
6. Comparison with isolated MSC therapies: role of non-cellular growth factor components vs. the MSC themselves
7. Scaffold optimisation: defining the ideal carrier (hydrogel, collagen matrix, PRP membrane) to retain BMAC at the target site

Conclusion

• Campbell's Operative Orthopaedics, 15th Ed 2026 (Ch. 64, Technique 64.9; Ch. 55)
• Rockwood & Green's Fractures in Adults, 10th Ed 2025
• Rheumatology, 2-Volume Set, Elsevier 2022
• Keeling LE et al. BMAC for Treatment of Knee Osteoarthritis: A Systematic Review. Am J Sports Med. 2022. PMID 34236913
• Belk JW et al. PRP or BMAC Injections Have Better Outcomes Than HA: Systematic Review and Meta-analysis. Arthroscopy. 2023. PMID 36913992
• Jawanda H et al. PRP, BMAC, and HA Outperform Corticosteroids: Systematic Review and Network Meta-analysis. Arthroscopy. 2024. PMID 38331363
• Migliorini F et al. Management of Knee Osteoarthritis Using BMAC: A Systematic Review. Br Med Bull. 2025. PMID 39506910
• Moyal AJ et al. BMA and BMAC in Long-Bone Nonunion: Systematic Review. Eur J Orthop Surg Traumatol. 2024. PMID 39060552
• Wang X, Zhang Y. BMP, PRP, and BMAC in Bone Delayed Union/Nonunion: Network Meta-analysis of RCTs. Eur J Med Res. 2025. PMID 41316346