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.