Arthroscopic visualization of the posterior subtalar joint in the prone position: A cadaver study

Purpose: Subtalar arthroscopy in the prone position is thought to allow broader access to the posterior aspect of the joint than in the standard supine or lateral position. This study is aimed to assess if using the posteromedial (PM) portal in the prone position can increase the working area available through the dorsal and ventral posterolateral (PL) portals commonly used in the standard techniques. Type of Study: In vitro cadaver study. Methods: Six below-knee cadaver specimens were subjected to experimental arthroscopy on the posterior subtalar joint in a simulated prone position. On both the talar and calcaneal surfaces, the working areas (the maximal extent available to a working instrument while preserving Surrounding cartilage) for the PL portals and the PM portal were identified. The combined area was compared with the area available from the PL portals alone, to assess the area extended with the PM portal. Results: The talar working areas provided by the PL portals and PM portal were 31% +/- 13% and 26% +/- 8% of the total articular surface, respectively. The combined working area (43% +/- 13%) was greater than the PL working area alone; use of the PM portal increased the working area by a factor of 1.45. The calcaneal working areas from the PL and PM portals were 25% +/- 11% and 20 +/- 7%, respectively. The combined working area (35% +/- 14%) was similarly increased by a factor of 1.46 using the PM portal compared with PL portals alone (P <.05). Conclusions: In prone subtalar arthroscopy, significant extension of the working area was found by adding the PM portal to the standard PL portals, on both the talar and calcaneal surfaces. Clinical Relevance: The PM portal that can be used in the prone position has a potential to increase the arthroscopic working area in the posterior subtalar joint.