Accuracy of sonographically guided posterior subtalar joint injections: Comparison of 3 techniques

Objective. The primary purpose of this investigation was to determine the accuracy of 3 different sonographically guided posterior subtalar joint (PSTJ) injection techniques in an unembalmed cadaveric model. Methods. A single experienced examiner injected the PSTJs of 12 unembalmed cadaveric ankle-foot specimens using the anterolateral, posterolateral, and posteromedial approaches. The injection order for each specimen was randomized, and each technique was completed with a different-color diluted latex solution. Coinvestigators blinded to the injection technique dissected each specimen and graded the colored latex location as accurate (in the PSTJ), accurate with overflow (within the PSTJ but also in other regions), or inaccurate (no latex in the joint). Results. All 3 sonographically guided PSTJ injection approaches accurately placed latex into the PSTJ (100% accuracy). Latex was also found in adjacent regions in 19.4% (7 of 36) of injections: 8.3% (3 of 36) within the tibiotalar joint, 8.3% (3 of 36) in the peroneal (fibularis) tendon sheath, and 2.8% (1 of 36) in the flexor hallucis longus tendon sheath. The anterolateral approach placed latex outside the PSTJ 25% of the time (3 of 12 injections: 1 tibiotalar and 2 peroneal [fibularis] sheath), the posterolateral approach 25% of the time (3 of 12 injections: 1 tibiotalar, 1 peroneal [fibularis] sheath, and 1 flexor hallucis longus tendon sheath), and the posteromedial approach 8.3% of the time (1 tibiotalar). Conclusions. This cadaveric investigation suggests that all 3 sonographically guided PSTJ techniques may be used to access the PSTJ with a high degree of accuracy. Clinicians should consider sonographically guided PSTJ injections as a favorable alternative to fluoroscopy and computed tomographic guidance when diagnostic or therapeutic image-guided PSTJ injections are indicated.