Sonographically guided posterior subtalar joint injections: anatomic study and validation of 3 approaches.

OBJECTIVE: To describe and validate 3 different approaches to perform sonographically guided posterior subtalar joint (PSTJ) injections.

DESIGN: Sonographically guided procedures performed on cadaveric specimens.

SETTING: Procedural skills lab at a tertiary medical facility.

METHODS: Three ultrasound-guided approaches to inject the PSTJ: anterolateral, posteromedial, and posterolateral were derived based on anatomic review, published fluoroscopic and computed tomography (CT) techniques, and clinical experience. Three separate unembalmed cadaveric ankle-foot specimens were injected by a single, experienced operator using a 25-gauge, 38-mm stainless steel needle. A different approach was used on each specimen. The needles were left in place and each specimen was subsequently dissected by co-investigators to confirm accurate needle placement and determine the proximity of each needle to local tendons and neurovascular structures.

MAIN OUTCOME MEASUREMENTS: Direct assessment of needle placement within posterior subtalar joint.

RESULTS: All 3 approaches provided accurate needle placement into the posterior subtalar joint while avoiding nearby tendinous and neurovascular structures.

CONCLUSIONS: Sonographically guided PSTJ injections are technically feasible. All 3 approaches provide accurate needle placement while minimizing the risk of needle entry into adjacent soft tissue structures not visualized by other modalities such as fluoroscopy or CT.