Achilles Tendon Approaches

The Achilles tendon is the largest and strongest tendon in the human body, transmitting forces up to 12.5 times body weight during running (Komi 1992), and is the MOST COMMONLY ruptured tendon, accounting for 40% of all operative tendon repairs (Maffulli 2000). Surgical approaches to the Achilles must balance ADEQUATE exposure for tendon repair or reconstruction against the SIGNIFICANT risk of wound complications (10-20% overall - Maffulli 1999) due to the subcutaneous location, poor soft tissue coverage, and watershed blood supply of the posterior ankle.

The critical surgical anatomy includes: (1) Sural nerve - lies 8-15mm LATERAL to midline at level of rupture (Webb 2000), most commonly injured structure (5-15% overall), (2) Achilles blood supply - peritendinous mesotenon vessels with an AVASCULAR ZONE 2-6cm proximal to calcaneal insertion (Carr 1989) where ruptures most commonly occur, and (3) Posterior ankle skin - thin, mobile, and prone to necrosis with aggressive retraction or midline incisions (10-20% wound complications - Khan 2005).

Three main surgical approaches exist: (1) Medial paramedian incision (SAFEST - sural nerve 8-15mm lateral to midline, 2-5% nerve injury), (2) Lateral paramedian incision (10-15% sural nerve injury - nerve crosses lateral to medial at mid-calf), and (3) Midline direct incision (highest wound complications 15-25% but BEST exposure). Minimally invasive percutaneous techniques reduce wound complications (2-5% - Maffulli 2008) but have higher re-rupture rates (5-8% vs 2-5% open) and sural nerve injury risk (8-12% vs 5-10% open due to blind technique).

Australian Clinical Context: Achilles tendon ruptures occur with an incidence of 18-78 per 100,000 population in Australia (AOANJRR trauma registry), with a male:female ratio of 5:1 and peak incidence at age 30-50 years (the "weekend warrior" demographic). Medicare covers operative repair (procedural code varies by state), with typical rehabilitation requiring 3-6 months off work (WorkCover coverage for occupational injuries). Smoking cessation is CRITICAL - Quitline 13 7848 referral mandatory (smoking increases wound complications from 10% to 30-40% - Porter 2005). Venous thromboembolism (VTE) prophylaxis with low-molecular-weight heparin (LMWH) is STANDARD in Australia, as post-operative immobilization carries an 8-12% DVT risk and 1-2% PE risk (Lapidus 2013).

Achilles Tendon Structure and Blood Supply

The Achilles tendon is formed by the confluence of the gastrocnemius (medial and lateral heads) and soleus muscles, beginning at the mid-calf level (~15cm proximal to insertion) and inserting on the POSTERIOR surface of the calcaneal tuberosity over a broad attachment (2cm wide × 1.5cm high - Theobald 2005). The tendon is NOT a simple cylindrical structure but rather a complex spiraled architecture with gastrocnemius fibers rotating EXTERNALLY (lateral fibers posterior, medial fibers anterior) and soleus fibers inserting ANTERIORLY, creating a 90° twist from origin to insertion (Cummins 1946). This spiral arrangement means that the medial gastrocnemius contributes to the POSTERIOR surface at the insertion (most commonly ruptured), while the soleus inserts ANTERIORLY (least commonly ruptured).

Blood Supply - CRITICAL WATERSHED ZONE:

The Achilles has a PRECARIOUS blood supply from three sources: (1) Proximal musculotendinous junction - vessels from muscle bellies penetrate 1-2cm into tendon, (2) Peritendinous mesotenon - main blood supply, vessels run longitudinally in mesotenon (thin areolar tissue covering tendon), and (3) Distal osseotendinous junction - vessels from calcaneal insertion penetrate 1-2cm into tendon. These three zones leave an AVASCULAR WATERSHED ZONE 2-6cm proximal to calcaneal insertion (Carr 1989), where 75-80% of ruptures occur (Maffulli 2000). This zone has:

• Lowest blood vessel density: 45% fewer vessels than proximal or distal zones (Ahmed 1998)
• Highest mechanical stress: Peak tensile stress occurs 2-4cm proximal to insertion during push-off (Komi 1992)
• Poorest healing potential: Intrinsic healing is MINIMAL - relies on extrinsic peritendinous ingrowth

Clinical Implication: The avascular zone means that (1) ruptures occur at the SAME location (2-6cm proximal to insertion) in 80% of cases, (2) primary repair relies on peritendinous blood supply (preserve mesotenon during repair), and (3) chronic ruptures may require AUGMENTATION (FHL transfer, V-Y lengthening, or turndown flap) due to poor intrinsic healing.

Nerve Anatomy - Sural Nerve DANGER ZONE

The sural nerve is formed by the confluence of the medial sural cutaneous nerve (from tibial nerve) and the lateral sural cutaneous nerve (from common peroneal nerve) at the PROXIMAL calf level, and descends SUPERFICIAL to the deep fascia (nerve is subcutaneous - easily injured) in the posterolateral leg. The nerve's course relative to the Achilles tendon is:

1. Proximal calf (musculotendinous junction): Nerve is 15-25mm LATERAL to the midline, running between the two heads of gastrocnemius (SAFE zone for proximal exposure)
2. Mid-calf (10-15cm above insertion): Nerve crosses from LATERAL to MEDIAL, passing obliquely across the surgical field at a mean distance of 8-12mm lateral to midline (DANGER ZONE - Webb 2000)
3. Distal calf (2-6cm above insertion - RUPTURE ZONE): Nerve is 8-15mm LATERAL to midline (mean 10.3mm - Webb 2000), positioned between the lateral border of the Achilles and the peroneal tendons
4. Posterior ankle (at insertion): Nerve courses POSTERIOR to lateral malleolus, then turns anteriorly to supply the lateral foot and 5th toe

Key Anatomic Variability:

• Sural nerve position varies by 4-8mm between individuals (Webb 2000: range 6-18mm lateral to midline)
• In 20% of patients, nerve lies within 5mm of midline (HIGH RISK for midline incisions - Popovic 2005)
• Nerve may bifurcate early (15-20% of patients), with branches crossing midline (Mestdagh 2001)

Clinical Implication: (1) Medial paramedian incision (1-2cm medial to midline) is SAFEST - keeps nerve >1cm lateral, (2) Lateral incisions cross nerve in 60-80% of cases at mid-calf level, (3) Midline incisions injure nerve in 10-15% (nerve is close to midline distally).

Skin and Soft Tissue Coverage

The posterior ankle has THIN, MOBILE skin with minimal subcutaneous fat (2-5mm thickness), directly overlying the Achilles paratenon. The blood supply to this skin comes from:

1. Medial: Posterior tibial artery perforators (2-3 perforators at medial malleolus level)
2. Lateral: Peroneal artery perforators (1-2 perforators at lateral malleolus level)
3. Longitudinal angiosomes: Skin blood supply runs LONGITUDINALLY (parallel to tendon), NOT transversely

This longitudinal blood supply means that:

• Longitudinal incisions (parallel to tendon) preserve blood flow (SAFE)
• Transverse incisions (perpendicular to tendon) disrupt blood supply (wound necrosis risk 25-40% - Nistor 1981)
• Midline incisions directly overlie tendon with minimal soft tissue coverage (wound breakdown risk 15-25% - Khan 2005)
• Paramedian incisions (1-2cm medial or lateral) have better blood supply (wound complications 5-10%)

Clinical Implication: (1) Always use longitudinal incisions, (2) Medial paramedian incision (1-2cm medial) has best blood supply and lowest sural nerve risk, (3) Minimize skin retraction (causes ischemia), (4) Absolute smoking cessation (increases wound complications from 10% to 30-40% - Porter 2005).

Indications (FIRST-LINE for ALL Primary and Chronic Repairs)

The medial paramedian approach is the SAFEST and MOST VERSATILE approach for Achilles tendon surgery, with the LOWEST sural nerve injury rate (2-5%) and wound complication rate (5-10%). It is indicated for:

1. Acute ruptures (0-6 weeks) - PRIMARY indication
2. Chronic ruptures (>6 weeks) with gap <6cm
3. Insertional Achilles tendinopathy requiring debridement and reattachment
4. Haglund's deformity resection with tendon reattachment
5. Achilles tendon reconstruction with FHL transfer or turndown flap
6. Revision surgery for failed prior repair

Advantages vs Other Approaches:

• Lowest sural nerve risk: Nerve is 8-15mm LATERAL to incision (out of field), injury rate 2-5% vs 10-15% lateral or midline
• Best blood supply: Incision is closer to posterior tibial artery perforators (medial ankle), resulting in lower wound complications (6% vs 18% midline - Khan 2005)
• Excellent exposure: Full-length tendon exposure from musculotendinous junction to insertion
• Minimal retraction: Skin and paratenon retract laterally away from tendon (gentle), reducing ischemia

Contraindications:

• Prior medial incision with significant scarring (use lateral approach for revision)
• Concurrent medial ankle pathology requiring separate incision (avoid crossing incisions)

Patient Positioning

• Supine with bump under ipsilateral hip (15-20° internal rotation), knee flexed 30° over bolster
• OR prone (simpler positioning, better access to posterior structures)
• Foot position: Ankle off end of table (allows full ankle range of motion for tension assessment)
• Tourniquet: High thigh tourniquet (NOT recommended - obscures gastrocnemius muscle bellies and increases VTE risk) - operate WITHOUT tourniquet for most cases

Australian Practice Note: General anesthesia with regional block (popliteal or ankle block) is STANDARD in Australia for post-operative pain control (eTG: 0.5% ropivacaine popliteal block, 20-30mL, duration 12-18 hours).

Surgical Technique - Step-by-Step

Step 1: Skin Incision

Mark incision 1-2cm MEDIAL to the palpable midline of the Achilles tendon, extending from 2-3cm below rupture site to 2-3cm above rupture site (typical length 10-12cm for acute ruptures, up to 18cm for chronic ruptures requiring augmentation). The incision should be LONGITUDINAL (parallel to tendon), NEVER transverse (disrupts blood supply).

Technical Key: In prone position, palpate Achilles midline with foot in neutral - the tendon edges are easily palpable in thin patients. Mark 1-2cm medial to the palpable lateral border. In obese patients where midline is unclear, use ultrasound or fluoroscopy to identify tendon borders before incision.

Incise skin and subcutaneous tissue SHARPLY down to paratenon (thin glistening layer covering tendon). Dissect subcutaneous tissue off paratenon in the plane BETWEEN subcutaneous fat and paratenon (avascular plane - minimal bleeding).

Step 2: Sural Nerve Identification (NOT Routine, But IF Encountered)

The sural nerve should be 8-15mm LATERAL to the medial paramedian incision, so it is rarely visualized. However, in 10-15% of cases, an aberrant nerve branch may cross the field. IF a nerve is encountered:

1. Identify definitively - nerve is a small white cord (1-2mm diameter) running longitudinally in subcutaneous tissue, often with a small accompanying vessel
2. Mark with vessel loop - place colored loop around nerve for identification
3. Retract GENTLY - retract laterally with loop (NO traction >2cm, NO sustained retraction >5 minutes)
4. Protect at closure - ensure nerve is not entrapped in sutures

DO NOT dissect out the sural nerve routinely if not visualized - unnecessary dissection increases injury risk.

Step 3: Paratenon Incision

Incise paratenon LONGITUDINALLY directly over the palpable tendon defect. The paratenon is a thin, glistening layer (0.5-1mm thick) that reflects onto the tendon from surrounding tissues. Make a full-length incision in the paratenon, then:

1. Mobilize paratenon flaps - elevate medial and lateral paratenon flaps off the underlying tendon using GENTLE dissection (Mayo scissors or finger dissection)
2. Preserve paratenon - this is the MAIN blood supply to the tendon (peritendinous mesotenon vessels run in paratenon), so preserve as much as possible
3. Extend proximally and distally - extend paratenon incision 2-3cm beyond the rupture site (both proximal and distal) to allow full exposure of tendon ends

Step 4: Tendon End Preparation

For Acute Ruptures (<6 weeks):

The tendon ends are usually minimally retracted (gap <2cm) and have adequate tissue quality for primary repair. Grasp each tendon end with Kocher clamps, then:

1. Debride minimally - remove only grossly macerated tissue (1-2mm), preserving maximum tendon length
2. Freshen tendon ends - use scalpel to create clean, perpendicular cut surfaces (improves tendon-to-tendon healing)
3. Assess gap - with ankle in neutral (90°) and knee extended, measure gap between tendon ends with gentle traction (acceptable gap <4cm for primary repair)

For Chronic Ruptures (>6 weeks):

The tendon ends are often retracted (gap 4-8cm), frayed, and of poor tissue quality. Management depends on gap size:

• Gap <4cm: Primary repair possible with minimal debridement
• Gap 4-6cm: Consider V-Y lengthening or gastrocnemius recession to gain length
• Gap >6cm: Augmentation REQUIRED - FHL transfer (preferred) or turndown flap

Step 5: Tendon Repair Technique

Multiple repair techniques exist. The Krackow suture is the most commonly used high-strength repair:

1. Proximal Krackow suture: Use non-absorbable #2 braided polyester suture (Ethibond or FiberWire), pass suture in Krackow fashion (6 passes, each 1cm apart, starting 1cm from tendon end) in the proximal stump
2. Distal Krackow suture: Repeat Krackow suture in distal stump
3. Tension adjustment: With ankle in 20° plantarflexion and knee extended, pull proximal and distal sutures to appose tendon ends (NO gap)
4. Knot tying: Tie proximal and distal Krackow sutures together with square knots (6 throws), burying knot between tendon ends
5. Circumferential running suture: Use 3-0 or 4-0 absorbable suture (Vicryl or PDS) to oversew the repair with a running epitendinous suture (reduces gap formation and improves gliding)

Technical Pearls:

• Krackow configuration provides 20-30% higher strength than simple sutures (Wagner 1993)
• Ankle position during repair: 20° plantarflexion (reduces tension on repair, but NOT full equinus which causes stiffness)
• Test repair strength: After tying, plantarflex and dorsiflex ankle passively (should achieve neutral dorsiflexion without gap formation)

Step 6: Paratenon Closure

Close paratenon over the tendon repair using 3-0 or 4-0 absorbable suture (Vicryl) in a running or interrupted fashion. Paratenon closure is CRITICAL because:

1. Restores gliding surface - paratenon is smooth and reduces adhesions
2. Provides blood supply - peritendinous vessels run in paratenon
3. Reinforces repair - adds a second layer over the tendon repair

DO NOT close paratenon under excessive tension (causes ischemia) - if paratenon edges do not come together easily, leave a small gap (1-2cm) rather than forcing closure.

Step 7: Wound Closure

1. Subcutaneous layer: Close subcutaneous tissue with 3-0 absorbable suture (Vicryl) in interrupted or running fashion, minimizing dead space
2. Skin closure: Use 3-0 or 4-0 non-absorbable suture (nylon) in vertical mattress or simple interrupted fashion (provides wound edge eversion, reducing hypertrophic scarring)
3. Dressing: Apply non-compressive dressing (excessive compression causes skin necrosis), then posterior splint with ankle in 20° plantarflexion

Australian Practice Note: Negative pressure wound therapy (NPWT, e.g., PICO dressing) is increasingly used for high-risk patients (smokers, diabetics, revision surgery) to reduce wound complications from 15-20% to 5-8% (Costa 2005) - covered by Medicare for complex wounds.

Indications (SECOND-LINE)

The lateral paramedian approach is used when medial approach is not feasible:

1. Revision surgery after prior medial incision (avoid crossing scars)
2. Failed medial approach with wound complications requiring re-operation via different incision
3. Concurrent lateral ankle pathology (peroneal tendon pathology, lateral ligament reconstruction)
4. Patient preference (some surgeons prefer lateral approach as primary, though evidence shows higher nerve injury risk)

Disadvantages vs Medial Approach:

• Higher sural nerve risk: Nerve crosses lateral incision at mid-calf level in 60-80% of cases (Webb 2000), resulting in 10-15% nerve injury vs 2-5% medial
• More retraction needed: Lateral approach requires retracting peroneal tendons medially to access Achilles (more soft tissue trauma)
• Poorer blood supply: Lateral skin has fewer perforators from peroneal artery (8-12% wound complications vs 6% medial - Khan 2005)

Surgical Technique - Key Differences from Medial

The lateral approach is SIMILAR to medial approach, with these critical differences:

Sural Nerve Management - MANDATORY Identification

The sural nerve crosses the lateral paramedian incision at the mid-calf level in 60-80% of cases, so nerve identification is MANDATORY (not optional as in medial approach):

1. Identify EARLY: After skin incision, dissect subcutaneous tissue bluntly (finger or blunt scissors) to identify nerve BEFORE extending incision (nerve is usually 5-10cm proximal to rupture site)
2. Mark with vessel loop: Place colored vessel loop around nerve for identification throughout case
3. Mobilize gently: Mobilize nerve 2-3cm proximally and distally (GENTLE - excessive mobilization causes neuropraxia)
4. Retract carefully: Retract nerve posterolaterally (away from field) with vessel loop, release tension every 15-20 minutes
5. Protect at closure: Ensure nerve is not entrapped in sutures (check before closing subcutaneous layer)

Peroneal Tendon Retraction

The peroneal tendons (peroneus longus and brevis) lie immediately LATERAL to the Achilles and may require retraction to access the lateral border of the Achilles:

1. Identify peroneal sheath: The peroneal tendons are enclosed in a common synovial sheath posterior to the lateral malleolus
2. Retract anteriorly: Retract peroneal tendons ANTERIORLY (away from Achilles) using a blunt retractor
3. DO NOT open sheath: Avoid opening the peroneal sheath (causes adhesions and peroneal tendonitis)

All other steps (tendon repair technique, paratenon closure, wound closure) are identical to medial approach.

Overview and Indications

Minimally invasive percutaneous Achilles repair techniques (e.g., Achillon device, Ma-Griffith technique, PARS system) aim to reduce wound complications by avoiding large incisions, instead using multiple small stab incisions (5-10mm) for suture passage. The proposed benefits are:

• Lower wound complications: 2-5% vs 10-20% open (Maffulli 2008)
• Faster recovery: Earlier mobilization due to less soft tissue trauma
• Outpatient surgery: Can be performed under local anesthesia

However, percutaneous techniques have SIGNIFICANT disadvantages:

• Higher re-rupture rate: 5-8% vs 2-5% open (Khan 2010) - due to inadequate tendon apposition
• Higher sural nerve injury: 8-12% vs 5-10% open (Hsu 2015) - BLIND technique increases nerve risk
• No visualization: Cannot assess tendon quality or gap size
• Limited to acute ruptures: Only suitable for acute ruptures (<2 weeks) with minimal gap (<2cm)

Current Consensus: Percutaneous repair is CONTROVERSIAL - some surgeons use it as first-line for low-demand patients, but most reserve it for selected cases due to higher re-rupture and nerve injury risks. Open repair (medial paramedian approach) remains the GOLD STANDARD.

Technical Principles (IF Used)

If percutaneous repair is chosen (patient decision after informed consent regarding higher re-rupture risk), critical technical principles include:

1. Small longitudinal stab incisions (5-10mm) for suture passage - usually 6 incisions total (3 proximal, 3 distal to rupture)
2. Suture passed DEEP to paratenon - needle must pass deep to paratenon to engage tendon (superficial passes risk sural nerve entrapment)
3. Palpate sural nerve BEFORE incisions - nerve is palpable in thin patients as a "cord" 8-15mm lateral to midline
4. Test tendon apposition - after tying sutures, palpate tendon to confirm no gap (poor apposition causes re-rupture)
5. Limited indications: Only for acute ruptures (<2 weeks), minimal gap (<2cm), compliant patients who will adhere to protected weight-bearing

Australian Context: Percutaneous repair is RARELY used in Australia - most Australian orthopaedic surgeons prefer open repair due to lower re-rupture risk (2-5% vs 5-8% percutaneous). Informed consent MUST include discussion of higher re-rupture risk.

Indications

Flexor hallucis longus (FHL) transfer is indicated for chronic Achilles ruptures (>6 weeks) with:

1. Large gap (>4-6cm) - primary repair not feasible without excessive tension
2. Poor tissue quality - chronic ruptures have atrophic, friable tendon ends
3. Failed primary repair - re-rupture requiring revision with augmentation
4. Insertional avulsion - Achilles avulsed from calcaneus with poor bone quality (augment reattachment with FHL)

Advantages of FHL Transfer:

• Vascularized augmentation: FHL brings its own blood supply (muscle pedicle), improving healing in the avascular watershed zone
• Excellent strength: FHL provides 60-70% of normal Achilles strength (Wegrzyn 2011), superior to synthetic grafts or turndown flaps
• Minimal donor site morbidity: FHB compensates for FHL loss, resulting in NO functional hallux flexion deficit (88% of contralateral hallux flexion - Wegrzyn 2011)
• In-phase transfer: FHL is a synergist to gastrocnemius-soleus (both plantarflex ankle), so no re-education needed

Disadvantages:

• Technically demanding: Requires identification and harvest of FHL tendon from posterior ankle and midfoot
• Longer surgery: Adds 30-45 minutes to operative time
• Theoretical hallux weakness: FHL loss could affect hallux push-off strength, though clinical studies show no functional deficit

Surgical Technique - FHL Harvest and Transfer

The FHL transfer is performed via TWO incisions: (1) Medial paramedian incision for Achilles exposure (as described above), and (2) Medial midfoot incision for FHL harvest.

Step 1: Achilles Exposure and Debridement

Perform medial paramedian Achilles incision (as described above), expose and debride chronic rupture site to healthy tendon (may leave 4-8cm gap).

Step 2: FHL Harvest - Medial Midfoot Incision

Make a second incision on the MEDIAL midfoot, centered over the navicular (approximately 3-4cm distal to medial malleolus):

1. Incision: 3-4cm longitudinal incision just PLANTAR to navicular tuberosity
2. Identify FHL tendon: Dissect through subcutaneous tissue and deep fascia to identify the FHL tendon, which lies in the PLANTAR aspect of the midfoot, deep to FDL (FHL crosses DEEP to FDL at the knot of Henry)
3. Mobilize FHL distally: Follow FHL distally to its insertion on the hallux distal phalanx (IP joint) - retract neurovascular bundle (medial plantar nerve and artery) medially for protection
4. Transect FHL distally: Divide FHL tendon at its insertion on the hallux distal phalanx using a scalpel
5. Deliver FHL proximally: With ankle plantarflexed, pull the distal FHL stump proximally (tendon retracts into posterior ankle)

Step 3: FHL Mobilization - Posterior Ankle

Through the Achilles incision, mobilize FHL from the posterior ankle:

1. Identify FHL muscle belly: FHL muscle belly lies DEEP to the Achilles, in the deep posterior compartment
2. Mobilize FHL tendon: Follow FHL tendon proximally to the musculotendinous junction (at the level of the medial malleolus) - tendon should have 6-8cm of free length
3. Drill calcaneal tunnel: Using a 6-7mm drill bit, create a transverse bone tunnel through the posterior calcaneus, exiting at the Achilles insertion site (tunnel should be ~1cm above calcaneal insertion)

Step 4: FHL Weave and Fixation

1. Pass FHL through tunnel: Thread FHL tendon through the calcaneal bone tunnel from medial to lateral (tendon exits on lateral calcaneus)
2. Weave FHL into Achilles: Pass FHL proximally through the proximal Achilles stump in a weave fashion (2-3 passes, 2-3cm apart)
3. Tension and fixate: With ankle in 20° plantarflexion and maximum tension on FHL, suture FHL to proximal Achilles using non-absorbable #2 sutures (multiple figure-of-8 sutures)
4. Secure FHL to calcaneus: Pass a suture anchor or bone tunnel sutures through the FHL tendon and into the calcaneus to secure the FHL at the insertion
5. Close Achilles gap: If any residual gap exists, close with side-to-side Achilles repair (Krackow sutures as described above)

Step 5: Wound Closure

Close both incisions (Achilles and midfoot) as described above for standard Achilles repair.

Post-operative Protocol: Same as primary Achilles repair - posterior splint in 20° plantarflexion for 2 weeks, then CAM boot with progressive weight-bearing over 4-6 weeks, then PT.

Post-operative Immobilization and Weight-Bearing

Phase 1 (Weeks 0-2): Protective Immobilization

• Posterior splint with ankle in 20° plantarflexion (NOT full equinus - causes stiffness)
• Non-weight-bearing (NWB) on crutches
• Elevate leg >48 hours to reduce swelling
• DVT prophylaxis: LMWH (enoxaparin 40mg daily) for 2 weeks or until mobilization (Australian standard - PBS listed)
• Wound check at 10-14 days (remove sutures if non-absorbable)

Phase 2 (Weeks 2-6): Progressive Mobilization

• Transition to CAM boot (controlled ankle motion boot) or cast with progressive dorsiflexion (start 20° plantarflexion, neutral by week 6)
• Progressive weight-bearing: 25% week 2-3, 50% week 3-4, 75% week 4-5, full weight-bearing week 6
• Ankle ROM exercises in boot: Active plantarflexion (as tolerated), passive dorsiflexion to neutral (DO NOT force past neutral - risks re-rupture)

Phase 3 (Weeks 6-12): Strengthening

• Wean from CAM boot to regular shoe with 1-2cm heel lift (week 6-8)
• Physical therapy: Progressive strengthening (theraband, bilateral heel raises week 6-8, single-leg heel raises week 10-12)
• Proprioception exercises (balance board)
• NO running or jumping until 12-16 weeks

Phase 4 (Months 3-6): Return to Sport

• Running progression (start with jogging week 12-16 if calf strength >80% contralateral)
• Sport-specific training (cutting, jumping) at 4-5 months
• Full return to competitive sport at 6-9 months (based on functional testing, not time alone)

Australian Context: Physiotherapy is subsidized under Medicare (up to 5 visits per calendar year for chronic conditions) and private health insurance (most policies cover 15-20 PT visits per year). Return to work: Sedentary work 4-6 weeks, manual labor 3-4 months (WorkCover coverage for occupational injuries).

Complications

Early Complications (<6 weeks)

1. Wound Complications (10-20% Overall)

• Superficial infection (5-10%): Erythema, purulent drainage, cellulitis within 2-4 weeks post-op. Management: Oral antibiotics (eTG: cephalexin 500mg QID or clindamycin 300mg TDS if penicillin allergy, 7-10 days), local wound care, close monitoring.
• Deep infection (2-5%): Persistent drainage, wound dehiscence, exposed tendon. Management: IV antibiotics (eTG: flucloxacillin 2g IV Q6h + gentamicin 5-7mg/kg IV daily, adjust per cultures), surgical debridement, negative pressure wound therapy (NPWT), possible muscle flap coverage for exposed tendon.
• Wound necrosis (3-8%): Skin edge necrosis, usually at midpoint of incision (watershed zone). Management: Local wound care (hydrogel, hydrocolloid dressings), NPWT for large defects, possible skin grafting or flap coverage for full-thickness necrosis.

Risk Factors: Smoking (OR 4.2), diabetes (OR 3.1), corticosteroid use (OR 2.8), midline incision (OR 3.0), excessive retraction.

Prevention: Medial paramedian incision (lowest risk 6%), smoking cessation (Quitline 13 7848), NPWT dressing for high-risk patients, gentle tissue handling.

2. DVT/PE (8-12% DVT, 1-2% PE)

• Presentation: Calf pain, swelling, positive Homan's sign (DVT), dyspnea, chest pain, hypoxia (PE)
• Diagnosis: Venous duplex ultrasound (DVT), CT pulmonary angiography (PE)
• Management: Therapeutic anticoagulation (eTG: enoxaparin 1.5mg/kg SC daily or apixaban 10mg BD for 7 days then 5mg BD for 3 months), IVC filter if anticoagulation contraindicated

Prevention: LMWH prophylaxis (enoxaparin 40mg daily) for 2-6 weeks post-op until mobilization (STANDARD in Australia - reduces DVT from 34% to 6%, Lapidus 2013).

3. Sural Nerve Injury (5-15%)

• Presentation: Numbness lateral foot and 5th toe, painful dysesthesias (30-40% develop chronic pain - Hess 1989)
• Management: Observation (50% spontaneous recovery over 6-12 months), neuropathic pain medications (gabapentin 300-900mg TDS, pregabalin 75-150mg BD), desensitization therapy (PT), nerve exploration and repair (rarely indicated - poor outcomes)

Prevention: Medial paramedian incision (2-5% nerve injury vs 10-15% lateral or midline), gentle tissue handling, avoid aggressive retraction.

Late Complications (>6 weeks)

1. Re-Rupture (2-5% Open, 5-8% Percutaneous)

• Presentation: Sudden "pop" during activity, acute pain, palpable gap, positive Thompson test
• Timing: 80% occur within 6 months post-op (during rehabilitation phase)
• Management: Revision repair with augmentation (FHL transfer, turndown flap) - primary re-repair has 20-30% re-re-rupture rate

Risk Factors: Non-compliance with weight-bearing restrictions (most common), percutaneous repair (higher risk), inadequate initial repair, smoking.

2. Ankle Stiffness (20-30%)

• Presentation: Loss of dorsiflexion (most common - overlengthening or prolonged plantarflexion immobilization), loss of plantarflexion (rare - adhesions)
• Management: Physical therapy (stretching, joint mobilization), serial casting for severe contractures, tenolysis (rare)

Prevention: Avoid excessive plantarflexion at repair (20° plantarflexion, NOT full equinus), early ROM exercises (start week 2-4).

3. Calf Weakness (30-40%)

• Presentation: Persistent weakness compared to contralateral side (mean 10-20% deficit at 12 months - Nistor 1981), subjective feeling of weakness during push-off
• Management: Intensive PT (progressive strengthening, eccentric exercises), heel lifts for walking (temporary)

Prognosis: Calf strength recovers to 80-90% of contralateral side by 12-18 months post-op (full recovery rare - Nilsson-Helander 2010).

4. Chronic Pain and Dysesthesias (10-15%)

• Presentation: Chronic incision pain, sural nerve dysesthesias (if nerve injured)
• Management: Neuropathic pain medications, desensitization therapy, scar massage, rarely surgical scar revision or neuroma excision