Arthroscopic Posterior Ankle Ligament Anatomy

BACKGROUND: The purpose of this article is to document the normal arthroscopic appearance of the posterior ankle capsular and ligamentous structures, and variations in their anatomical relationships. METHODS: 102 ankle arthroscopy videotapes were evaluated retrospectively for the configuration of the posterior capsuloligamentous structures. Based on these observations, the variations in the appearance and position of the posterior tibiofibular ligament (PTFL) and transverse (tibiofibular) ligament (TTFL) were documented. In addition, differences in the appearance of the flexor hallucis longus (FHL) were also noted. RESULTS: All patients had evidence of both a PTFL and TTFL, which formed a labrum or meniscus-like addition to the posterior distal tibia. No patients demonstrated disruption of the PTFL; 3 had tears of the TTFL. We noted 4 distinct patterns of the PTFL and the TTFL. Thirty-four patients (33%) had a gap of ≥2 mm between the 2 ligamentous structures. Thirty-three (32.4%) had a gap <2 mm between the PTFL and TTFL. Twenty-six (25.5%) had a confluence of the 2 ligaments without a gap. Nine (9%) demonstrated a sizable gap between the 2 ligaments, and the TTFL appeared as a “cord-like” structure. CONCLUSION: To our knowledge, this is the first article to describe the variations in the arthroscopic normal posterior capsuloligamentous structures and FHL of the ankle. LEVEL OF EVIDENCE: Level IV, case series.