Sinus Tarsi Approach to Calcaneus

What it exposes. The sinus tarsi approach gives a small, direct window onto the anterolateral posterior facet of the calcaneus and the lateral wall, through the cone-shaped sinus tarsi (the anterolateral opening between the talus and calcaneus). It is a minimally invasive alternative to the lateral extensile (L-shaped) approach for displaced intra-articular calcaneal fractures, paired with percutaneous indirect reduction and fluoroscopy-guided fixation. Why it exists — wound safety. Wound breakdown (infection, dehiscence, full-thickness flap necrosis) is one of the largest barriers to successful extensile-lateral ORIF: even an anatomic reduction fails if the wound exposes the hardware. In a large extensile-lateral series the overall wound-complication rate was 17.8%, with smoking (OR 5.79), diabetes (OR 6.23) and higher Sanders grade (OR 5.44) the strongest independent predictors (Ding 2013). The sinus tarsi approach minimises the soft-tissue envelope — a 3-4 cm incision, no full-thickness flap, no extensive periosteal stripping, and a shorter operation — which is exactly why it is most valuable in high wound-risk patients. The trade-off — limited exposure. The approach does NOT give complete exposure. Only the anterolateral 30-40 percent of the posterior facet is seen directly; the posteromedial facet, the sustentaculum region and the tuberosity are assessed by fluoroscopy only. Reduction is therefore indirect — percutaneous Essex-Lopresti maneuver, plantar bone tamps and extensive fluoroscopy — so patient selection is critical. Ideal indications. Sanders II-III fractures with limited comminution (2-3 large fragments), primary fracture lines in the coronal plane (amenable to lateral manipulation), an intact sustentaculum tali (the medial reduction reference), and a displaced fracture (articular step-off greater than 2 mm or Böhler angle less than 20 degrees). It is especially attractive in high wound-risk patients — smokers, diabetics, the elderly with thin skin, the obese, and the previously scarred lateral hindfoot — and for one side of a bilateral injury. Contraindications (use lateral extensile). Sanders IV (severe comminution, 4+ fragments — cannot be reduced indirectly), central depression with small comminuted fragments, significant tuberosity varus/valgus (no access through the sinus tarsi), and medial-wall comminution or sustentaculum fracture (loss of the reduction reference). Relative contraindications are severe peripheral vascular disease (ABI less than 0.7) and fracture age greater than 3 weeks (early callus defeats indirect reduction).

Position. Lateral decubitus, injured side up, ankle neutral — the same position as the extensile approach. Bean-bag or lateral positioners for stability; bolsters support the leg so the anterolateral foot is accessible. Tourniquet optional — many prefer it down given the shorter, minimally invasive procedure and the reduced ischaemia-time concern.

Work from skin to posterior facet through the sinus tarsi window, then reduce the fracture indirectly with the Essex-Lopresti maneuver and a plantar bone tamp, confirming everything by fluoroscopy before fixation.

View larger

Structures at risk, by layer

Complications - Inadequate reduction (most common intraoperative issue). Persistent step-off greater than 2 mm or Böhler angle not restored to 25-40 degrees. Repeat the percutaneous maneuvers; if still inadequate after 2-3 attempts, convert to lateral extensile rather than accept malreduction.

• Intra-articular hardware (3-5%). Screw penetration into the subtalar joint — prevent with guide wires and Broden-view confirmation before final tightening; recognized post-op, return for removal/revision.
• Wound complications (3-5% — the primary advantage over extensile lateral at 10-25%). Superficial dehiscence 2-3%, superficial infection 1-2%, deep infection rare (less than 1%); manage as for the extensile approach (local care, oral/IV antibiotics, debridement if deep).
• Loss of reduction (5-8%). Usually early, from inadequate fixation, early weight-bearing, or severe osteoporosis; revise if under 3 weeks, otherwise observe and plan subtalar fusion if symptomatic arthritis develops.
• Subtalar arthritis (40-50% long-term — same as extensile lateral). Driven principally by the initial injury (articular impaction, Sanders grade, residual step-off) rather than the exposure; pooled comparisons show no significant radiographic difference between approaches (Lv 2020, Attenasio 2024). Anatomic restoration (step-off less than 2 mm) is the modifiable factor most associated with delaying secondary fusion.
• Hardware irritation (5-10%). Lower than the extensile approach; remove after union (12-18 months) if symptomatic. Extensile options. If the fracture is more complex than pre-op imaging suggested, convert to the lateral extensile approach by extending the sinus tarsi incision into the full L-shaped incision. For severe lateral wall collapse, add a small 2-3 cm lateral incision to push the wall fragments medially (total 5-7 cm, still lower wound risk than 12-15 cm extensile). A laminar spreader in the sinus tarsi (subtalar distraction) widens the window and improves visualization; bone graft may be packed through the sinus tarsi into a large metaphyseal void. Closure. Remove the temporary K-wires, replace the EDB over the sinus tarsi, close the subcutaneous layer loosely with absorbable suture and the skin with interrupted or subcuticular sutures, and apply a bulky dressing with a posterior splint.

• ORIF of displaced intra-articular calcaneal fractures (Sanders II-III) — the principal operation done through this exposure.
• Subtalar arthrodesis — for post-traumatic arthritis or as salvage after calcaneal fracture.
• Triple arthrodesis — when subtalar, talonavicular and calcaneocuboid joints are all arthritic.
• Access to the calcaneocuboid joint and anterior process fractures, and as the working portal for subtalar arthroscopy.