DIABETIC FOOT

MS Orthopaedics - 20 Marks Answer

DEFINITION / INTRODUCTION

PATHOPHYSIOLOGY / ETIOPATHOGENESIS

1. Peripheral Neuropathy (MOST IMPORTANT)

• Sensory neuropathy: Polyneuropathic loss of sensation in a "stocking distribution," progressing proximally. Loss of protective sensation is the most common cause of plantar foot ulcers. Diagnosed by inability to perceive the 5.07 Semmes-Weinstein monofilament (10 g pressure). Patients with this finding have a 30% risk of developing a foot ulcer.
• Autonomic neuropathy: Abnormal sweating mechanism leads to a dry foot. This creates fissuring cracks, which become portals for infection.
• Motor neuropathy: Most commonly involves the common peroneal nerve, causing foot drop and loss of tibialis anterior function. Small intrinsic muscles are also affected, resulting in claw toes with toe-tip ulcerations due to excessive pressure.

2. Hypomobility Syndrome

3. Peripheral Vascular Disease

4. Immune System Impairment

5. Metabolic Deficiency

6. Structural/Biomechanical Factors

CLINICAL FEATURES

History

• Long-standing diabetes (usually >10 years)
• Peripheral neuropathy symptoms: numbness, tingling, paresthesias
• Claudication (suggests PVD)
• Prior ulcers, amputations, vision problems, renal disease
• Patients frequently deny trauma due to sensory loss

Physical Examination

• Shiny, hairless, taut skin - suggests peripheral arterial disease
• Dry, scaly, fissured skin - suggests autonomic neuropathy
• Erythema, swelling, warmth - may indicate infection or Charcot neuroarthropathy (distinguish by elevation: Charcot subsides; infection does not)
• Claw toes, hammer toes, midfoot collapse ("rocker bottom" deformity)

Probe-to-bone test: 57% positive predictive value and 96% negative predictive value for osteomyelitis (Campbell's Operative Orthopaedics 15e)

• Palpate dorsalis pedis and posterior tibial pulses
• Doppler examination if pulses absent
• Ankle-Brachial Index (ABI): Normal = 1.0; Minimum for healing = 0.45; Value >1.3 indicates vessel calcification (non-compressible)
• Absolute toe pressures: Minimum for healing = 40 mmHg; TcPO₂ >40 mmHg predictive of healing

• 10-g monofilament testing at 10 sites on foot
• Vibration sense (128 Hz tuning fork), proprioception
• Silfverskiöld test: assesses gastrocnemius vs. Achilles contracture

CLASSIFICATION OF DIABETIC FOOT ULCERS

Wagner-Meggitt Classification (Most Widely Used)

University of Texas (Depth-Ischemia) Classification (Modification)

INVESTIGATIONS

MICROBIOLOGY

• Superficial/mild infections: Gram-positive cocci - S. aureus (including MRSA), Streptococci
• Severe/deep infections: Polymicrobial - aerobic Gram-negatives, Pseudomonas (over-represented), Anaerobes
• Empirical therapy for severe infections must cover Pseudomonas; add metronidazole for abscess/devitalised tissue
• Superficial swabs are unreliable for determining deep infection organisms - bone biopsy is preferred

CHARCOT NEUROARTHROPATHY (Charcot Joint)

• Occurs in 1-1.5% of diabetics; 7.5% of diabetic patients with neuropathy
• Two pathophysiologic theories: neurotraumatic (repeated microtrauma with no pain response) and neurovascular (autonomic dysfunction causes hyperemia and bone resorption)
• Presents as swollen, warm, erythematous foot - often confused with infection or gout
• Classic radiographic appearance: "bag of bones" pattern - fragmentation, dislocation, dense new bone
• Most commonly affects tarsometatarsal joints (Lisfranc) → "rocker bottom" deformity

• Stage 0 (Prodromal): Warmth, swelling, normal X-ray
• Stage I (Fragmentation/Development): Bone fragmentation, joint dislocation
• Stage II (Coalescence): New bone formation, fusion begins
• Stage III (Reconstruction): Consolidation, deformity fixed

MANAGEMENT

Principles: Multidisciplinary Team

A. Medical / Conservative Management

1. Glycemic control - HbA1c optimization (cornerstone of all treatment)
2. Nutritional optimization - Delay surgery if albumin <2.5 g/dL or total protein <6 g/dL
3. Antibiotics:
   • Mild-moderate infection: Oral agent active against Gram-positive cocci (MRSA-active if risk factors)
   • Severe infection: IV broad-spectrum (cover Gram-negatives, Pseudomonas, anaerobes)
   • Duration guided by tissue vs. bone involvement (soft tissue: 2 weeks; osteomyelitis: 4-6 weeks)
4. Wound care:
   • Regular debridement of callus and necrotic tissue
   • Moist wound dressings
   • Negative-pressure wound therapy (NPWT/VAC dressing) for large wounds
   • Biological dressings (collagen, growth factor-containing)
5. Offloading (MOST IMPORTANT for ulcer healing):
   • Total Contact Cast (TCC): Gold standard for plantar neuropathic ulcers - distributes pressure over entire plantar surface
   • Removable cast walkers (RCW) / Scotchcast boots
   • Extra-depth therapeutic shoes with custom insoles (Plastazote - closed-cell cross-linked polyethylene)
   • Crutches/wheelchair

B. Vascular Intervention

• Full vascular assessment mandatory in patients with poor pulses
• Percutaneous transluminal angioplasty (PTA) for suitable lesions
• Bypass surgery (femoropopliteal/tibial) for long occlusions
• Improving vascularity is essential before foot salvage surgery

C. Surgical Management

• All necrotic tissue, slough, and infected bone must be removed
• Leave wound open; secondary closure or skin grafting once healthy granulation bed established

• Claw toes / dorsal toe ulcers: Flexor tenotomy or proximal interphalangeal joint resection
• Plantar hallux IP joint ulcers: Keller arthroplasty (if TCC failed)
• Achilles lengthening: For recurrent forefoot/midfoot ulcers with equinus contracture - offloads forefoot pressure
• Midfoot collapse (Charcot): Osteotomy of bony prominence (if stable deformity) OR midfoot fusion (if instability present)
• Charcot active phase: Total Contact Cast immobilization until Stage III; surgical reconstruction (superconstructs) for unstable deformity

In extensive peripheral neuropathy, a below-knee amputation in a zone with better sensation may be more appropriate than a foot-level procedure (Bailey & Love 28e).

Skin closure must be tension-free; excess bone may need resection to allow this.

PREVENTION (Highly Examinable)

1. Optimal glycemic control - target HbA1c <7%
2. Daily foot inspection (use mirror if needed; arrange assistance if retinopathy)
3. Proper footwear - well-fitting shoes; avoid walking barefoot
4. Regular chiropody/podiatry review
5. Monofilament screening at every diabetes clinic visit
6. Patient education on foot hygiene, nail care, avoidance of extremes of temperature
7. Smoking cessation - worsens peripheral vascular disease
8. Diabetic therapeutic shoe bill (USA) allows for extra-depth shoes + 3 custom insoles/year for at-risk patients

PROGNOSIS

• Infected diabetic foot ulcer must be regarded with urgency - can quickly progress to render the limb non-salvageable
• Five-year mortality of diabetic foot complications (30.5%) is comparable to that of many cancers
• Major amputation 5-year mortality: ~50-70%
• Goal of treatment: Ulcer-free, functional, plantigrade foot that fits within a brace or shoe

SUMMARY BOX (Bailey & Love 28e Key Points)

• Most important risk factor for osteomyelitis is presence of a foot ulcer
• Superficial swabs are unreliable for identifying deep pathogens
• In severe disease, surgical debridement is mandatory followed by culture-guided antibiotics
• Probe-to-bone test + elevated CRP + abnormal plain X-ray = confirmed osteomyelitis
• Full vascular assessment is mandatory in all diabetic foot infections
• Amputation wound healing is problematic; always plan for tension-free closure

PEARSON FLEXION ATTACHMENT (PEARSON KNEE-FLEXION PIECE)

MS Orthopaedics - 20 Marks Answer

INTRODUCTION / DEFINITION

HISTORICAL BACKGROUND

• Hugh Owen Thomas (1834-1891) designed the Thomas splint originally as a knee splint for tuberculosis, but it was later adapted for femoral shaft fractures
• The Pearson attachment was subsequently developed specifically to overcome knee stiffness by allowing controlled flexion while traction is maintained
• The combination of Thomas splint + Pearson attachment with skeletal traction became the standard non-operative treatment for femoral shaft fractures before the era of intramedullary nailing
• By the 1970s-1980s, intramedullary nailing gradually superseded this method in developed countries, but it remains in use where operative facilities are limited

ANATOMY OF THE APPARATUS

A. Thomas Splint (The Base Frame)

1. Ring (proximal end) - oval padded ring that sits in the groin against the ischial tuberosity; provides counter-traction in static mode
2. Two parallel side bars - medial and lateral; extend distally beyond the foot
3. Distal crossbar - connects the two side bars at the foot end

• Ring circumference = circumference of thigh at groin level
• Length = length of good limb (crotch to heel) + 15-25 cm

• One under the thigh
• One under the knee
• One just above the tendo calcaneus

B. Pearson Attachment (Knee-Flexion Piece)

1. Two short side bars (thigh piece) that clamp onto the side bars of the Thomas splint at the level of the knee joint
2. A hinge joint at the level of the knee axis - allows controlled flexion/extension
3. Leg piece bars - support the leg distal to the knee
4. Slings supporting the leg between the bars
5. Adjustable cord - limits the degree of knee flexion (can be progressively lengthened to increase ROM)
6. Patient-assist cord - allows the patient to actively assist knee extension

CLINICAL PHOTOGRAPHS AND DIAGRAMS

Thomas Splint applied with skin traction (Pye's Surgical Handicraft 22e)

Thomas splint with Pearson knee attachment and skeletal traction (Pye's Surgical Handicraft 22e)

Pearson knee-flexion piece in use - showing key numbered components:

Six methods of skeletal traction (A = Thomas splint + Pearson attachment) - Rockwood & Green 10e

Clinical setup - Thomas leg splint with Pearson attachment on a hospital bed:

TYPES OF TRACTION WITH THOMAS SPLINT

1. Fixed (Static) Traction

• The traction cord from the tibial pin or skin extensions is tied directly to the distal end of the Thomas splint using a Spanish windlass
• The force and counterforce are contained within the closed system
• Counterforce = ring pressing on ischial tuberosity
• Used for: initial immobilization, transport of patient, pre-hospital/emergency phase
• Advantage: portable, no weights needed

2. Balanced (Sliding/Dynamic) Traction

• The splint is suspended by overhead slings and pulleys
• A separate weight is attached to the traction pin cord via a pulley at the foot of the bed
• Counterforce = patient's own body weight (foot of bed elevated)
• Allows some patient movement in bed
• Used for: definitive non-operative management in hospital

INDICATIONS FOR THOMAS SPLINT + PEARSON ATTACHMENT

1. Fractures of the femoral shaft (diaphyseal fractures) - primary indication
2. As a temporary measure for comfort and transport prior to operative fixation
3. Where intramedullary nailing or operative fixation is unavailable (resource-limited settings)
4. Pediatric femoral shaft fractures in older children (after 2 years)
5. Pathological fractures where surgery is contraindicated
6. Open fractures with significant soft tissue compromise where immediate IMN is deferred

PROCEDURE / TECHNIQUE OF APPLICATION

Step 1: Traction Pin Insertion (Steinmann/Denham Pin)

• Preferred site: proximal tibia - just below and behind the tibial tubercle, 2 cm behind the anterior border
• Alternative sites: distal tibia (4-5 cm above medial malleolus), or calcaneum
• Pin inserted from the lateral side to avoid neurovascular structures
• Pin driven at right angles to the limb in the coronal plane
• Denham threaded pins preferred - prevent rotation and loosening
• Traction stirrup must move freely on the pin (if it binds, pin rotates → infection)
• Pin sites dressed with benzoin tincture-soaked pads

Step 2: Skin Extension Application

• Elastoplast strapping (7.5-10 cm wide) applied directly to shaved skin on both sides
• Outer strip placed slightly posteriorly; inner strip slightly anteriorly - to counteract external rotation tendency
• Extensions held with circumferential crepe bandages ending above the malleoli
• Orthopaedic felt pads protect the malleoli

Step 3: Thomas Splint Application

• Splint sized and prepared with three slings
• Passed over the foot and up the thigh to sit in the groin
• Tapes of skin extensions passed: outer tape over lateral bar; inner tape under medial bar (counteracts rotation)
• Tapes tied over distal end of splint; wooden bar used as windlass if needed
• Padding placed:
  • Behind fracture site - acts as fulcrum for correction
  • Behind knee - maintains 15° flexion
  • Along shin - prevents pressure sores

Step 4: Balanced Suspension Setup (Once in Hospital Bed)

• Overhead Balkan beam frame with pulleys set up
• Splint suspended by slings attached to overhead frame
• Separate traction cord from tibial pin passed over pulley at foot of bed and loaded with weights (typically 4-7 kg initially)
• Foot of bed elevated on blocks for countertraction
• X-ray taken to check alignment; pads adjusted as needed
• A posterior pad under the distal femur is almost always required to correct posterior sag

Step 5: Pearson Attachment Application (after 4-6 weeks)

1. Traction cord transferred from the Thomas splint end to the Pearson attachment
2. The Pearson piece is clamped to the side bars of the Thomas splint at the level of the knee axis
3. End of the Thomas splint is raised and supported
4. Adjustable cord (cord 5) limits initial flexion to a small arc (20-30°)
5. Patient-assist cord (cord 8) allows active knee extension exercises
6. Flexion range is progressively increased over subsequent weeks as callus matures

TIMING

ADVANTAGES OF THE PEARSON ATTACHMENT

1. Prevents knee stiffness - major advantage over rigid Thomas splint alone
2. Maintains traction while allowing knee movement simultaneously
3. Prevents quadriceps wasting by allowing active and passive knee exercises
4. Psychological benefit - patient can partially mobilize the knee
5. Graduated - flexion range can be controlled and progressively increased
6. Patient can actively assist knee extension using the assist cord

COMPLICATIONS

General Traction Complications:

Specific to Pearson Attachment:

• If applied too early (before stabilizing callus): angulation at fracture site
• Hinge misalignment with knee axis: uneven joint loading, cartilage stress
• Excessive or rapid flexion increase: pain and fracture instability

NURSING CARE / MONITORING

1. Inspect ring area (groin/ischial tuberosity) for pressure sores every 4 hours; apply olive oil
2. Check peroneal nerve function daily (dorsiflexion, sensation first web space)
3. Pin site care: clean with antiseptic, inspect for erythema/discharge
4. Check traction cords and pulleys - cords must not touch bed or pulleys
5. Check traction weights are hanging freely (not resting on floor)
6. Ensure foot of bed is elevated (countertraction)
7. Regular quadriceps exercises even before Pearson attachment
8. Foot/ankle exercises to prevent DVT
9. Regular chest physiotherapy

COMPARISON: THOMAS SPLINT + PEARSON vs. INTRAMEDULLARY NAIL

CURRENT STATUS

• Resource-limited settings
• Where operative fixation is unavailable or contraindicated
• As a bridge to surgery

SUMMARY BOX (Examination Points)

• Pearson attachment is a hinged frame added to the Thomas splint at the knee axis
• Applied after 4-6 weeks when stabilizing callus appears
• Transfers the traction cord from the Thomas splint distal end to the Pearson piece
• Allows progressive knee flexion while maintaining femoral traction
• Thomas splint: invented by Hugh Owen Thomas, counter-traction on ischial tuberosity
• Skeletal traction preferred in adults (Steinmann/Denham pin in proximal tibia)
• Skin traction used in children and elderly
• Static traction = closed system (splint + windlass); Balanced traction = weights and pulleys
• Commonest complication: Pressure sore + common peroneal nerve palsy

PEARSON FLEXION ATTACHMENT (PEARSON KNEE-FLEXION PIECE)

MS Orthopaedics - 20 Marks Answer

INTRODUCTION / DEFINITION

HISTORICAL BACKGROUND

• Hugh Owen Thomas (1834-1891) designed the Thomas splint originally as a knee splint for tuberculosis, later adapted for femoral shaft fractures
• The Pearson attachment was subsequently developed to overcome knee stiffness by allowing controlled flexion while traction is maintained
• Thomas splint + Pearson attachment + skeletal traction became the standard non-operative treatment for femoral shaft fractures before the intramedullary nail era
• By the 1970s-1980s, intramedullary nailing superseded this method in developed countries, but it remains relevant where operative facilities are limited (Rockwood & Green 10e)

ANATOMY OF THE APPARATUS

A. Thomas Splint (The Base Frame)

1. Ring (proximal) - oval padded ring seated in the groin against the ischial tuberosity; provides counter-traction in static mode
2. Two parallel side bars - medial and lateral, extending distally beyond the foot
3. Distal crossbar - connects side bars at the foot end
4. Three slings of non-stretch bandage:
   • One under the thigh
   • One under the knee
   • One just above the tendo calcaneus

• Ring size = circumference of thigh at groin
• Length = length of good limb (crotch to heel) + 15-25 cm

B. Pearson Attachment (Knee-Flexion Piece)

1. Short thigh side bars - clamp onto the Thomas splint bars at knee level
2. Hinge joint at the knee axis - allows controlled flexion/extension
3. Leg piece bars - support the leg distal to the knee
4. Slings supporting the leg between the bars
5. Adjustable cord - limits and controls degree of knee flexion (progressively lengthened)
6. Patient-assist cord - allows active knee extension by the patient

DIAGRAMS AND PICTURES

TYPES OF TRACTION

1. Fixed (Static) Traction

• Traction cord tied directly to the distal end of Thomas splint via a Spanish windlass
• Force and counterforce contained within a closed system
• Counterforce = ring pressing on ischial tuberosity
• Use: Emergency, transport, pre-hospital phase

2. Balanced (Sliding/Dynamic) Traction

• Splint suspended by slings and overhead pulleys; weights applied via pulley at foot of bed
• Counterforce = patient's own body weight (foot of bed elevated)
• Allows some patient movement in bed
• Use: Definitive in-hospital management

INDICATIONS

1. Fractures of the femoral shaft (diaphyseal) - primary indication
2. Temporary measure for transport/comfort before operative fixation
3. Where IM nailing is unavailable (resource-limited settings)
4. Pediatric femoral fractures in older children
5. Pathological fractures where surgery is contraindicated
6. Open fractures where immediate IMN is deferred

TECHNIQUE OF APPLICATION

Step 1: Skeletal Pin Insertion (Steinmann/Denham Pin)

• Preferred site: upper tibia - just below and behind the tibial tubercle, 2 cm behind the anterior border
• Alternative sites: distal tibia (4-5 cm above medial malleolus), calcaneum
• Inserted from the lateral side to protect neurovascular structures
• Inserted at right angles to the limb in the coronal plane
• Denham threaded pins preferred - prevent pin rotation and loosening
• Traction stirrup must move freely on pin (if it binds → rotation → sepsis)
• Pin sites covered with benzoin tincture-soaked pads

Step 2: Skin Extensions

• Elastoplast 7.5-10 cm wide, applied to shaved skin bilaterally
• Outer strip posteriorly; inner strip anteriorly - counteracts external rotation tendency
• Held with circumferential crepe bandages above the malleoli
• Orthopaedic felt pads protect the malleoli

Step 3: Thomas Splint Application

• Splint passed over foot and up thigh with ring seated in groin
• Tapes: outer tape over lateral bar; inner tape under medial bar (counteracts rotation)
• Tapes tied to distal end with windlass if needed
• Padding:
  • Behind fracture site - acts as corrective fulcrum
  • Behind knee - maintains 15° flexion
  • Along shin - prevents pressure sores

Step 4: Balanced Suspension (In-Hospital)

• Balkan beam overhead frame set up with pulleys
• Splint suspended by slings; traction weights (4-7 kg) applied via proximal tibial pin
• Foot of bed elevated on blocks
• X-ray taken; posterior pad under distal femur almost always needed to correct posterior sag (Rockwood & Green 10e)
• Fracture position checked and adjusted with pads

Step 5: Pearson Attachment Application (at 4-6 weeks)

1. Traction cord transferred from Thomas splint end to Pearson attachment
2. Pearson piece clamped to side bars at the knee axis level
3. End of Thomas splint raised and supported
4. Adjustable cord set to allow initial small arc of flexion (20-30°)
5. Flexion progressively increased over weeks as callus matures
6. Patient uses assist cord for active knee extension exercises

TIMING GUIDE

ADVANTAGES OF PEARSON ATTACHMENT

1. Prevents knee stiffness - most important advantage over rigid splint alone
2. Maintains traction while simultaneously allowing knee flexion/extension
3. Reduces quadriceps wasting - active and passive knee exercises possible
4. Gradual and controlled - adjustable cord allows incremental increase in ROM
5. Patient can actively assist knee extension - psychological benefit and muscle activation
6. Simple, cheap, no anaesthesia required for application

COMPLICATIONS

General Traction Complications

Specific to Pearson Attachment

• Applied too early (before callus): angulation at fracture site
• Hinge misalignment with knee axis: uneven joint loading
• Rapid flexion increase: pain and fracture instability

NURSING CARE (Key for Examination)

1. Inspect ring/groin area for pressure sores every 4 hours; apply olive oil to ring
2. Daily peroneal nerve check - dorsiflexion power, sensation in first web space
3. Pin site care - antiseptic dressing, inspect for erythema/discharge
4. Traction cords must not touch bed; weights must hang freely
5. Foot of bed elevated for countertraction
6. Quadriceps exercises from day one
7. Foot/ankle exercises to prevent DVT
8. Regular chest physiotherapy
9. Ensure patient can plantarflex and dorsiflex the foot

COMPARISON: THOMAS SPLINT + PEARSON vs. INTRAMEDULLARY NAIL

CURRENT ROLE / STATUS

• Emergency splinting and patient transport device
• Pre-operative temporary immobilization

• Operative fixation unavailable or contraindicated
• Patient unfit for surgery
• Bridge to delayed definitive surgery

EXAMINATION SUMMARY BOX

• Pearson = hinged frame added to Thomas splint at knee axis
• Applied after 4-6 weeks when stabilizing callus appears
• Traction cord transferred from Thomas splint to Pearson piece
• Allows progressive knee flexion while maintaining femoral traction
• Thomas splint: counter-traction on ischial tuberosity
• Static traction = closed system (windlass); Balanced = weights + pulleys
• Steinmann pin in proximal tibia is the anchor point for skeletal traction
• Denham threaded pins prevent rotation and loosening
• Most important complication to monitor: common peroneal nerve palsy (foot drop)
• Key nursing check every 4 hours: peroneal nerve function + pressure areas