Operative Management of Neglected Achilles Tendon Ruptures: Direct Repair and Tendon Transfer Techniques

INTRODUCTION AND PATHOMECHANICS

Neglected (or chronic) ruptures of the Achilles tendon are typically defined as those presenting more than four to six weeks after the initial injury. Unlike acute ruptures, which can often be managed non-operatively or with primary end-to-end repair, neglected ruptures present a unique and formidable reconstructive challenge. The delay in diagnosis or treatment leads to proximal retraction of the gastrocnemius-soleus complex, atrophy of the calf musculature, and the formation of a non-functional, disorganized fibrovascular scar tissue (the "pseudotendon") bridging the defect.

Because the pseudotendon lacks the organized type I collagen structure and tensile strength of a native tendon, patients experience profound weakness in plantarflexion, an inability to perform a single-leg heel raise, and an altered, energy-inefficient gait pattern. The primary surgical objective is to restore the resting length and tension of the musculotendinous unit, thereby re-establishing the biomechanical advantage of the triceps surae.

💡 Clinical Pearl

The critical determinant of the surgical approach in neglected ruptures is the size of the tendon defect after the excision of the pseudotendon and maximal mobilization of the proximal muscle belly. Preoperative MRI measurements often underestimate the true intraoperative gap once healthy tendon ends are debrided.

PREOPERATIVE EVALUATION AND IMAGING

A meticulous clinical examination is paramount. Patients typically present with a palpable gap (though this may be obscured by the pseudotendon or localized edema), a positive Thompson test, and significantly reduced plantarflexion power.

Imaging Modalities

• Plain Radiographs: Weight-bearing anteroposterior and lateral views of the ankle are necessary to rule out avulsion fractures of the calcaneal tuberosity and to assess for Haglund's deformity or intratendinous calcifications.
• Magnetic Resonance Imaging (MRI): The gold standard for evaluating neglected ruptures. MRI accurately delineates the extent of tendon retraction, the length of the pseudotendon, and the degree of fatty infiltration or atrophy within the gastrocnemius and soleus muscle bellies.
• Ultrasound: A dynamic and cost-effective alternative that can assess the gap size during passive dorsiflexion and plantarflexion, though it is highly operator-dependent.

ALGORITHMIC APPROACH TO GAP MANAGEMENT

The surgical strategy is dictated by the intraoperative gap measured with the ankle in neutral dorsiflexion (0 degrees) after thorough debridement of the scar tissue:
* Gap < 2 to 3 cm: Direct repair with extensive proximal mobilization of the gastrocnemius-soleus complex.
* Gap 3 to 6 cm: V-Y tendinous advancement, turndown flaps, or local tendon transfers (e.g., Peroneus Brevis or Flexor Hallucis Longus).
* Gap > 6 cm: Local tendon transfers, often augmented with free tissue grafts (e.g., hamstring autograft) or synthetic mesh, occasionally requiring gastrocnemius recession.

DIRECT REPAIR OF NEGLECTED RUPTURES

When the defect is relatively small (typically under 3 cm after debridement), direct end-to-end repair can be achieved through aggressive proximal mobilization. This technique relies on releasing the myofascial adhesions that tether the retracted muscle.

Patient Positioning and Anesthesia

The patient is placed in the prone position under general or regional anesthesia. A thigh tourniquet is applied. The bilateral lower extremities should be prepped and draped to allow intraoperative comparison of resting equinus tension with the contralateral, uninjured limb.

Surgical Approach and Dissection

1. Incision: Make a curvilinear, posteromedial incision. The incision must extend proximally as far as necessary to allow adequate mobilization of the tendon and muscle belly. A posteromedial approach minimizes the risk of injury to the sural nerve, which crosses the lateral border of the Achilles tendon approximately 10 cm proximal to the calcaneal insertion.
2. Paratenon Preservation: Deepen the incision through the subcutaneous tissue. Meticulously incise and preserve the paratenon, as it contains the critical vascular supply necessary for tendon healing.
3. Scar Resection: Identify the pseudotendon bridging the gap. Resect the majority of this disorganized scar tissue until healthy, parallel collagen fibers are identified at both the proximal and distal tendon stumps.

⚠️ Surgical Warning

Failure to resect the pseudotendon back to healthy, viable tissue will result in a high risk of re-rupture. Healthy tendon will appear pearly white with distinct longitudinal striations, whereas scar tissue appears dull, grey, and amorphous.

Proximal Mobilization

To bridge the gap without excessive tension:
* Free the gastrocnemius and soleus muscles individually in the proximal leg.
* Utilize a combination of sharp and blunt dissection to release the fascial attachments between the soleus and the deep posterior compartment.
* If necessary, perform a fractional lengthening of the gastrocnemius aponeurosis to gain an additional 1 to 2 cm of length.

Tendon Repair and Augmentation

1. Suture Placement: Proceed with the repair using heavy, nonabsorbable, multi-strand sutures (e.g., #2 or #5 FiberWire or Ethibond). Utilize a locking stitch configuration, such as the Krackow or Giftbox technique, to ensure secure purchase in the tendon stumps.
2. Tensioning: Keep the knee flexed at 30 to 45 degrees and the foot in equinus (plantarflexion) during the repair to relieve tension. Tie the sutures, ensuring the resting tension matches the contralateral limb.
3. Plantaris Reinforcement: If the plantaris tendon is intact, harvest it using a tendon stripper. Fan it out and weave it across the repair site to provide biological augmentation and structural reinforcement.

PERONEUS BREVIS TRANSFER (WHITE AND KRAYNICK; TEUFFER MODIFICATION)

For significant tendon defects (typically 3 to 6 cm) in active patients where direct repair is impossible without excessive tension, a local tendon transfer is indicated. The modification described by White and Kraynick, and later Teuffer, utilizes the peroneus brevis tendon.

The peroneus brevis is an excellent transfer option because it is a strong plantarflexor, its harvest does not significantly compromise hindfoot eversion (as the peroneus longus is preserved), and it provides robust, vascularized tissue to bridge the Achilles defect.

Surgical Technique: Step-by-Step

1. Exposure and Preparation

• Incision: Expose the Achilles tendon and the tuberosity of the calcaneus through a posterolateral incision. This approach allows simultaneous access to the Achilles defect and the peroneal compartment.
• Nerve Protection: Carefully identify and retract the sural nerve in the proximal part of the wound. The nerve is highly vulnerable during the posterolateral approach.
• Debridement: Make an incision through the sheath of the Achilles tendon to expose the ruptured ends. Resect the scarred pseudotendon and dissect proximally to free the gastrocnemius-soleus complex, maximizing native length.

2. Harvest of the Peroneus Brevis

• Distal Detachment: Through a small secondary incision over the lateral border of the foot, identify the insertion of the peroneus brevis at the base of the fifth metatarsal. Detach the tendon sharply from its insertion.
• Tendon Routing: Incise the lateral intermuscular septum. Draw the detached peroneus brevis tendon proximally into the primary posterolateral incision. Ensure there are no fascial bands tethering the tendon, which could limit its excursion.

3. Calcaneal Fixation (Dynamic Loop Creation)

• Tunnel Preparation: Drill a transverse hole through the calcaneal tuberosity, positioned anterior to the native Achilles insertion to avoid posterior cortical blowout.
• Tendon Passage: Pass the peroneus brevis tendon from lateral to medial through the calcaneal drill hole.
• Loop Fixation: Route the tendon proximally and suture it directly to the proximal stump of the Achilles tendon (and to itself) using multiple interrupted nonabsorbable sutures. This creates a "dynamic loop" that acts as a robust, vascularized bridge across the defect, transferring the contractile force of the peroneal muscle directly to the calcaneus.

🔪 Pitfall

When drilling the calcaneal tunnel, ensure the trajectory is strictly transverse and adequately sized (usually 5.5 to 7.0 mm depending on tendon diameter). A tunnel that is too small will cause friction and damage the graft, while a tunnel placed too posteriorly risks calcaneal fracture.

PLANTARIS TENDON AUGMENTATION (TECHNIQUE 48-15)

To further reinforce the peroneus brevis transfer or a tenuous direct repair, the plantaris tendon can be utilized as a biological weave. This technique enhances the structural integrity of the construct and provides a scaffold for cellular ingrowth.

Surgical Steps for Plantaris Weave

1. Identification and Harvest: Identify the plantaris tendon medially, between the gastrocnemius and soleus muscle bellies. Release it proximally with a closed tendon stripper, leaving its distal insertion on the calcaneus intact.
2. Figure-of-Eight Weave: Place the harvested proximal end of the plantaris tendon on a large fascial needle. Pass it in a figure-of-eight manner from posterior to anterior through the ruptured ends of the Achilles tendon and the transferred peroneus brevis.
3. Fanning and Closure: Leave enough of the plantaris tendon to be fanned out over the distal part of the repair. Tack it down over the repair site with fine absorbable sutures (e.g., 3-0 Vicryl) to create a smoother contour and facilitate closure of the paratenon over the tendon graft.
4. Layered Closure: Close the tendon sheath (paratenon) meticulously with fine absorbable sutures. This layer is critical to prevent skin adhesions and ensure gliding. Close the subcutaneous tissues and skin in a standard fashion.

POSTOPERATIVE CARE AND REHABILITATION

The postoperative protocol for neglected ruptures is generally more conservative than that for acute ruptures, given the complexity of the reconstruction and the reliance on tendon transfers or extensive mobilization.

Phase I: Maximum Protection (Weeks 0–4)

• Immobilization: Immediately postoperatively, apply a sterile dressing and a short-leg cast (or rigid splint) with the foot in gravity equinus (approximately 20 to 30 degrees of plantarflexion) to eliminate tension on the repair.
• Weight-Bearing: Strict non-weight-bearing (NWB) with crutches or a knee scooter.
• Edema Control: Strict elevation of the limb above heart level to mitigate swelling and protect the delicate soft-tissue envelope.

Phase II: Controlled Mobilization (Weeks 4–8)

• Transition: Remove the cast and transition the patient to a Controlled Ankle Motion (CAM) boot fitted with heel wedges (usually three wedges, totaling ~30 degrees of equinus).
• Weight-Bearing: Initiate progressive partial weight-bearing (PWB), advancing to full weight-bearing (FWB) in the boot as tolerated.
• Range of Motion: Begin active plantarflexion and gentle, gravity-assisted dorsiflexion to neutral. Passive dorsiflexion stretching is strictly contraindicated at this stage.
• Wedge Removal: Remove one heel wedge every 10 to 14 days, gradually bringing the foot to a neutral position.

Phase III: Strengthening and Proprioception (Weeks 8–16)

• Boot Weaning: Discontinue the CAM boot and transition to normal footwear, often utilizing a small silicone heel cup for an additional 2 to 4 weeks.
• Physical Therapy: Focus on concentric and eccentric strengthening of the gastrocnemius-soleus complex. Incorporate proprioceptive training (e.g., BAPS board, single-leg stance).
• Tendon Transfer Re-education: If a peroneus brevis transfer was performed, specific biofeedback and neuromuscular re-education are required to train the peroneal muscle to fire during the push-off phase of the gait cycle.

Phase IV: Return to Activity (Months 4–6+)

• Advance to plyometrics, jogging, and sport-specific drills.
• Return to high-impact sports is generally delayed until 6 to 9 months postoperatively, contingent upon the patient demonstrating at least 85% to 90% strength and functional symmetry compared to the uninjured limb.

COMPLICATIONS AND MANAGEMENT

Reconstruction of neglected Achilles ruptures carries a higher complication rate than acute repairs. Surgeons must be vigilant in both preoperative planning and postoperative surveillance.

• Wound Dehiscence and Infection: The posteromedial and posterolateral approaches traverse areas with tenuous vascularity. Meticulous soft-tissue handling and preservation of the paratenon are essential. Superficial infections are managed with oral antibiotics, while deep infections may require surgical debridement and negative pressure wound therapy.
• Sural Nerve Injury: The sural nerve is at high risk during posterolateral incisions and percutaneous suturing. Injury can result in painful neuromas or lateral foot numbness. Careful blunt dissection and direct visualization are mandatory.
• Re-rupture: While less common with robust tendon transfers, re-rupture can occur due to non-compliance with the postoperative protocol or failure to resect the pseudotendon adequately. Management typically requires revision surgery with allograft augmentation.
• Deep Vein Thrombosis (DVT): Prolonged immobilization places patients at risk for VTE. Chemical prophylaxis (e.g., LMWH or direct oral anticoagulants) should be considered based on individual patient risk stratification (e.g., Caprini score).