Operative Management of Foot and Ankle Tendon Disorders

Introduction to Foot and Ankle Tendinopathy

The operative management of tendon disorders in the foot and ankle represents a complex intersection of soft-tissue reconstruction and biomechanical realignment. Foundational literature by pioneers such as Johnson, Myerson, Mann, and Sobel has established that isolated soft-tissue procedures are rarely sufficient for chronic tendinopathies associated with structural deformity. Successful outcomes dictate a comprehensive approach: addressing the primary tendon pathology while simultaneously correcting underlying osseous malalignment to protect the reconstruction.

This masterclass provides an exhaustive, evidence-based framework for the surgical management of the four major tendon groups of the foot and ankle: the Posterior Tibial Tendon (PTT), the Peroneal Tendons, the Flexor Hallucis Longus (FHL), and the Anterior Tibialis Tendon (ATT).

Posterior Tibial Tendon Dysfunction (PTTD) and Adult Acquired Flatfoot Deformity

Posterior tibial tendon dysfunction (PTTD) is the leading cause of adult acquired flatfoot deformity (AAFD). The PTT is the primary dynamic stabilizer of the medial longitudinal arch. Its failure leads to a predictable cascade of ligamentous attenuation (spring ligament, talonavicular capsule, deltoid ligament) and progressive osseous deformity (hindfoot valgus, forefoot abduction, and midfoot supination).

Clinical Staging and Surgical Indications

The Johnson and Strom classification, later modified by Myerson, dictates the surgical algorithm:

• Stage I: Tenosynovitis without deformity. Treatment: Nonoperative (immobilization, orthotics). Surgical tenosynovectomy is reserved for refractory cases.
• Stage II: Flexible flatfoot deformity. Treatment: Joint-sparing osteotomies combined with tendon transfer (e.g., Flexor Digitorum Longus [FDL] transfer + Medializing Calcaneal Osteotomy [MDCO] +/- Lateral Column Lengthening).
• Stage III: Rigid, non-reducible flatfoot deformity. Treatment: Subtalar or Triple Arthrodesis.
• Stage IV: Deltoid ligament compromise with talar tilt in the ankle mortise. Treatment: Tibiotalocalcaneal (TTC) arthrodesis or deltoid reconstruction with joint-sparing hindfoot correction.

Surgical Technique: Stage II PTTD Reconstruction

The gold standard for Stage II PTTD is the FDL tendon transfer combined with a medializing calcaneal osteotomy (MDCO).

1. Patient Positioning and Preparation

The patient is placed supine with a bump under the ipsilateral hip to internally rotate the leg, bringing the medial malleolus directly anterior. A thigh tourniquet is applied.

2. Medializing Calcaneal Osteotomy (MDCO)

Correcting the hindfoot valgus is critical to decrease the excursion and mechanical demand on the transferred FDL tendon.

• Approach: An oblique incision is made over the lateral calcaneus, avoiding the sural nerve and peroneal tendons.
• Osteotomy: An oscillating saw is used to perform an oblique osteotomy posterior to the posterior facet of the subtalar joint, angled at 45 degrees to the plantar surface.
• Displacement: The posterior tuberosity is translated medially by 10 to 15 mm.
• Fixation: The osteotomy is provisionally pinned and then rigidly fixed with one or two large-fragment (6.5 mm or 7.0 mm) cannulated headless compression screws placed from the posterior heel into the anterior calcaneal body.

Surgical Pitfall: Failure to adequately medialize the calcaneal tuberosity will leave residual hindfoot valgus, placing excessive eccentric load on the FDL transfer, leading to early clinical failure.

3. FDL Harvest and Transfer

• Approach: A medial incision is made from the distal medial malleolus extending to the navicular tuberosity.
• Tendon Inspection: The PTT sheath is opened. The diseased PTT is inspected. If severely degenerated, it is excised, leaving a small distal stump.
• FDL Harvest: The FDL is identified plantar to the navicular. It is traced distally to the Knot of Henry. The FDL is transected as distally as possible, and the distal stump is sutured to the Flexor Hallucis Longus (FHL) to prevent lesser toe clawing.
• Navicular Tunnel: A drill hole (typically 4.5 to 5.5 mm) is created dorsal-to-plantar through the navicular.
• Tensioning: The FDL is passed through the navicular tunnel from plantar to dorsal.

Clinical Pearl: Tension the FDL transfer with the foot held in maximal equinovarus and the ankle in slight plantarflexion. The tendon is sutured to itself and the periosteum using non-absorbable braided suture.

4. Spring Ligament Repair

The superomedial calcaneonavicular (spring) ligament is routinely inspected. If attenuated, it is imbricated and repaired using suture anchors placed into the sustentaculum tali to restore the static medial arch support.

Disorders of the Peroneal Tendons

The peroneus longus (PL) and peroneus brevis (PB) are the primary evertors of the foot and dynamic stabilizers of the lateral ankle. Pathology ranges from tenosynovitis and split tears to frank rupture and recurrent subluxation.

Pathoanatomy and Biomechanics

The PB tendon lies anterior and medial to the PL tendon within the retromalleolar groove. The superior peroneal retinaculum (SPR) is the primary restraint to subluxation. Longitudinal split tears of the PB are common and typically occur due to mechanical attrition against the sharp posterior edge of the fibula during forced dorsiflexion and inversion.

Surgical Technique: Peroneal Tendon Repair and Tubularization

1. Approach and Exploration

• Positioning: Lateral decubitus or supine with a large bump under the ipsilateral hip.
• Incision: A longitudinal incision is made along the posterior border of the fibula, extending distally to the base of the fifth metatarsal.
• Retinacular Release: The SPR is incised longitudinally, leaving a 2-3 mm cuff on the fibula for later repair.

2. Tendon Debridement and Tubularization

• The tendons are delivered from the wound. The PB is inspected for the classic longitudinal split tear.
• < 50% Degeneration: The degenerative edges of the split are excised. The tendon is then tubularized using a running locked 4-0 non-absorbable suture.
• > 50% Degeneration: If the PB is non-viable, the diseased segment is excised, and a side-to-side tenodesis of the proximal and distal PB stumps to the intact PL tendon is performed.

Clinical Pearl: Always inspect the retromalleolar groove. A flat or convex fibular groove is a primary risk factor for peroneal pathology. If present, a fibular groove deepening procedure must be performed concurrently.

3. Fibular Groove Deepening and SPR Reconstruction

• A cortical flap is created on the posterior fibula using a sharp osteotome.
• Cancellous bone is curetted from beneath the flap to deepen the sulcus.
• The cortical flap is tamped down into the newly created recess.
• The tendons are reduced, and the SPR is repaired tightly over the tendons using drill holes or suture anchors in the posterolateral fibula.

Flexor Hallucis Longus (FHL) Pathology

FHL tendinopathy, often termed "Dancer's Tendinitis," frequently occurs at the fibro-osseous tunnel posterior to the medial malleolus or at the Knot of Henry. It is a common cause of posterior ankle impingement in ballet dancers and athletes requiring extreme plantarflexion.

Clinical Presentation

Patients present with posteromedial ankle pain, triggering of the hallux, and pain with resisted hallux plantarflexion. The "FHL stretch test" (pain with passive ankle and hallux dorsiflexion) is pathognomonic.

Surgical Technique: FHL Release

Open Posteromedial Approach

• An incision is made posterior to the medial malleolus, taking care to protect the posterior tibial neurovascular bundle.
• The FHL is identified by its low-lying muscle belly.
• The fibro-osseous sheath is released completely from the posterior talus down to the sustentaculum tali.
• The tendon is delivered and inspected. Any nodular thickening or low-lying muscle belly causing impingement is debrided.

Endoscopic Posterior Release

For isolated posterior impingement, a two-portal posterior endoscopic approach (van Dijk technique) offers excellent visualization with lower morbidity.
* Portals are placed medial and lateral to the Achilles tendon at the level of the joint line.
* The flexor retinaculum over the FHL is released endoscopically, and any associated os trigonum is excised.

Surgical Pitfall: During endoscopic FHL release, the neurovascular bundle lies immediately medial to the FHL tendon. The surgeon must keep the camera lateral to the FHL and direct all cutting instruments laterally to avoid catastrophic neurovascular injury.

Anterior Tibialis Tendon (ATT) Ruptures

ATT ruptures are relatively rare and often present late. They typically occur in males over 50 years old following an eccentric load to a plantarflexed foot.

Diagnosis and Indications

Patients present with a "foot drop" or a slapping gait. The classic triad includes:
1. Loss of normal ATT contour at the anterior ankle.
2. Weakness in dorsiflexion.
3. A palpable defect.

Operative repair is indicated for active patients to restore gait mechanics and prevent secondary equinus contracture.

Surgical Technique: ATT Reconstruction

1. Primary Repair (Acute Ruptures)

• An anterior longitudinal incision is made over the ankle joint.
• The extensor retinaculum is incised in a step-cut fashion to allow for anatomic repair and prevent bowstringing.
• The tendon ends are debrided. A Krackow suture technique using heavy non-absorbable suture (e.g., #2 FiberWire) is used to reapproximate the tendon.
• The repair is performed with the ankle in 10-15 degrees of dorsiflexion.

2. Tendon Transfer (Chronic/Neglected Ruptures)

In chronic cases with a gap exceeding 3-4 cm, primary repair is impossible.
* Extensor Hallucis Longus (EHL) Transfer: The EHL is harvested distally, routed through the ATT sheath, and fixed into the medial cuneiform or navicular using a biotenodesis screw.
* The distal EHL stump is tenodesed to the Extensor Digitorum Longus (EDL) to maintain hallux extension.
* Alternatively, an intercalary allograft (e.g., semitendinosus) can be utilized to bridge the ATT defect.

Postoperative Rehabilitation Protocols

Successful tendon surgery relies heavily on strict adherence to postoperative rehabilitation. While protocols vary based on the specific procedure and patient factors, general guidelines apply:

Phase I: Maximum Protection (Weeks 0-6)

• Immobilization: The patient is placed in a well-padded short leg cast or rigid fracture boot.
• Weight-Bearing: Strictly non-weight-bearing (NWB) for 4 to 6 weeks.
• Positioning: For PTTD/FDL transfers, the foot is casted in slight equinovarus. For peroneal repairs, the foot is casted in slight eversion. For ATT repairs, the foot is casted in dorsiflexion.

Phase II: Progressive Loading (Weeks 6-12)

• Transition: Transition to a controlled ankle motion (CAM) boot.
• Weight-Bearing: Progressive partial weight-bearing advancing to full weight-bearing by week 8-10.
• Physical Therapy: Initiation of active range of motion (AROM). Passive stretching of the antagonist muscles (e.g., Achilles stretching for PTTD patients).

Phase III: Strengthening and Return to Activity (Weeks 12+)

• Footwear: Transition to supportive athletic shoes, often with custom orthotics (e.g., medial posting for PTTD).
• Therapy: Isotonic and isokinetic strengthening. Proprioceptive training (BAPS board).
• Milestones: Return to high-impact sports or heavy labor is typically restricted until 6 to 9 months postoperatively, contingent upon the restoration of >80% symmetric strength and pain-free dynamic loading.

Conclusion

The surgical management of foot and ankle tendon disorders demands meticulous preoperative planning, a deep understanding of biomechanics, and precise surgical execution. Whether addressing the complex multi-planar deformity of PTTD, the mechanical attrition of peroneal tears, or the functional deficits of ATT ruptures, the orthopedic surgeon must look beyond the isolated tendon. By combining robust soft-tissue repairs with appropriate osseous realignments, surgeons can reliably restore function, alleviate pain, and prevent the progression of degenerative joint disease.