Access to the talar articular surface without osteotomy to treat osteochondral lesions of the talus using autologous membrane induced chondrogenesis (AMIC) and autologous bone graft

M. Farndon, J. Sharpe

Introduction: Recent cadaveric studies appear to provide conflicting opinions regarding possible access to some zones of the talar articular surface without the use of an osteotomy and / or ligament release in the approach. We report a series of cases involving AMIC treatment of larger osteochondral lesions of the talus (OLT) without use of osteotomy or release in talar zones potentially considered inaccesible (zone 4 medially and zone 6 laterally).

Methods: 18 consecutive cases involving potentially inaccessible talar zones were retrospectively identified. All had undergone open treatment of OLT via mini arthrotomy with subsequent autologous bone grafting & AMIC. No osteotomies or ligament releases were performed. Extra-articular distraction was used in all anterior approaches, though no posterior approaches. Pre-op MR scans imaging were reviewed by a single experienced MSK radiologist; zonal involvement, area, volume and AMADEUS (Area Measurement Depth & Underlying Structures) score was recorded in each case.

Results: There were 8 female and 10 male patients with a mean age of 45 years (range 16 to 84). 13/18 (72%) OLT were medial (zone 4) and 5/18 (28%) were lateral (zone 6). The mean AMADEUS score was 46 (range 10 to 65). The mean area was 189mm² (range 91 to 345) and the mean volume of cystic defects was 423mm³ (range 180 to 728). All 18 OLT were accessed without osteotomy or ligament release to allow thorough curettage / debridement / nanofracture / autologous bone grafting and AMIC treatment. The approaches utilised were posteromedial 3/18, anteromedial 10/18 and anterolateral 5/18 respectively. None have required further intervention at mean FU 3.2 years from index scan (range 0.4 to 5.2).

Conclusion: Larger OLT in zones 4 and 6, including those with a significant cystic component, can be accessed safely and treated without the need for malleolar osteomy or ligament release.