Approach to the Subtalar Joint - Sinus Tarsi Approach

What it exposes. The sinus tarsi (Ollier) approach gives direct lateral access to the subtalar (talocalcaneal) joint, particularly the posterior facet, the sinus tarsi and the middle/anterior facets, without violating the peroneal tendon sheath. It is the workhorse exposure for subtalar arthrodesis, tarsal coalition resection and selected calcaneal fracture ORIF. Why this approach is chosen. It provides excellent visualisation of the posterior facet for joint-surface preparation in arthrodesis and access to the sinus tarsi contents for coalition excision or osteochondral lesion work, while minimising soft-tissue disruption compared with the extensile lateral approach. For displaced intra-articular calcaneal fractures it achieves comparable reduction quality for most Sanders II/III patterns with a significantly lower wound-complication rate. Primary indications: - Subtalar arthrodesis (isolated talocalcaneal fusion)

• Tarsal coalition resection (calcaneonavicular or talocalcaneal bars)
• Calcaneal fracture ORIF (selected Sanders II/III via sinus tarsi or extensile lateral)
• Osteochondral lesions of the talar posterior facet or subtalar joint
• Subtalar joint debridement or loose-body removal
• Triple arthrodesis (combined with a medial approach) Contraindications: - Active infection over the lateral hindfoot
• Severe scarring from previous lateral incisions (consider an alternative)
• Isolated medial pathology requiring a medial approach only
• Patient factors precluding non-weight-bearing (compliance issues) Alternative approaches. A medial approach is used for isolated middle-facet coalition or medial talocalcaneal pathology; a posterior approach gives posterior subtalar access in selected cases; arthroscopic subtalar arthrodesis is a minimally invasive option with limited visualisation; and the extensile lateral approach provides broad exposure for complex calcaneal fractures. Approach variants.

Position & landmarks. Supine with a sandbag or bump under the ipsilateral hip to internally rotate the foot, the knee slightly flexed over a bolster to relax the gastrocnemius, and the foot plantigrade or slightly plantarflexed. Apply a thigh tourniquet (250–300 mmHg after exsanguination) and confirm fluoroscopy for lateral, Broden and axial heel views. Palpate and mark the tip of the lateral malleolus, the sinus tarsi depression (anteroinferior to the malleolus), the anterior process of the calcaneus, the base of the fourth metatarsal and the peroneal tubercle; mark the peroneal tendon course and the sural nerve.

Work down through the layers along the oblique Ollier line — protecting the sural nerve, then developing the interval between the peroneal tendons and EDB to reach the posterior facet of the subtalar joint.

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Structures at risk, by layer

Sural nerve injury management. - Intra-operative clean transection: primary repair; if the proximal end cannot be saved, bury it in muscle to prevent neuroma.

• Suspected neurapraxia: observe, document and follow up closely.
• Established painful neuroma: desensitisation and local steroid injection; if refractory, surgical excision with proximal-stump burial. Extensile options. - Proximal extension along the posterior border of the fibula reaches the lateral ankle and peroneal tendons; the sural nerve becomes more superficial proximally, increasing risk.
• Distal extension toward the fourth-metatarsal base or a dorsal limb reaches the talonavicular joint for triple arthrodesis, and may need a separate medial incision.
• Extensile lateral (L-shaped) adds a vertical limb along the posterior calcaneal border for broad calcaneal exposure in Sanders II–IV fractures; the corner must be handled carefully to avoid wound-edge necrosis, the sural nerve is mobilised with the posterior flap, and the peroneals are exposed and protected throughout.
• Combined medial approach for triple arthrodesis exposes the talonavicular joint, middle facet and sustentaculum while protecting the posterior tibial tendon and neurovascular bundle, allowing complete preparation of all three joints. Closure. Irrigate and achieve haemostasis; let the EDB fall back or loosely approximate it, close the fascia where possible, approximate subcutaneous tissue and close skin with interrupted nylon or staples without tension. Apply a sterile dressing and a posterior splint or short-leg cast.

Post-operative care. Check and document lateral foot sensation (sural nerve function) and inspect the wound; apply a posterior splint or short-leg cast with the ankle neutral and elevate the limb above heart level for 48–72 hours, with DVT prophylaxis per protocol. Keep the patient non-weight-bearing for 6–12 weeks depending on the procedure (arthrodesis versus ORIF), progressing on radiographic healing. Follow up at 2 weeks (wound check, suture removal), 6 weeks (lateral, Broden and axial radiographs), 12 weeks (confirm union, progress weight-bearing) and 6–12 months for functional review.

• Subtalar arthrodesis — isolated talocalcaneal fusion; fix with 2–3 large cannulated screws (6.5 or 7.3 mm) from the posterior calcaneus into the talar body.
• Triple arthrodesis — combined with a medial approach to the talonavicular and calcaneocuboid joints.
• Tarsal coalition resection — calcaneonavicular or talocalcaneal bars, with fat or muscle interposition to prevent recurrence.
• Calcaneal fracture ORIF — sinus tarsi or extensile lateral technique depending on fracture pattern.
• Osteochondral lesion treatment or loose-body removal, and subtalar joint debridement or synovectomy.