Transmalleolar vs Portal-Based Minimally Invasive Tibiotalar Joint Preparation: A Cadaveric Study

Background: Successful ankle arthrodesis depends on thorough preparation of the tibiotalar joint. Open, arthroscopic, and minimally invasive (MIS) techniques exist. MIS burr preparation under fluoroscopy enables smaller incisions and preserves the osteogenic bone slurry. Traditional anteromedial and anterolateral portal-based MIS approaches may leave posterior “blind spots” and limit deformity correction. A transmalleolar MIS technique has been proposed to improve joint access while facilitating apposition and deformity correction. The purpose of this study was to compare the proportion of tibiotalar joint prepared and safety profiles between the transmalleolar and portal-based MIS techniques. Methods: Fourteen fresh frozen cadaveric lower extremities (7 matched pairs) were randomized to transmalleolar or portal-based MIS tibiotalar joint preparation (n = 7 each). A single fellowship-trained surgeon performed all procedures using standardized burr instrumentation and fluoroscopy. Specimens were disarticulated, photographed with calibration markers, and analyzed using ImageJ to quantify percent preparation of the tibial plafond, talar dome, and combined surfaces. Two independent reviewers (1 masked) performed measurements. Distances to the posterior tibial tendon, posterior tibial artery, and tibial nerve were measured; <5 mm was considered at risk. Paired t tests, Fisher exact test, and ICC were used ( P < .05). Results: Transmalleolar MIS achieved greater tibial plafond preparation (94.7% vs 76.8%, P = .009) than the portal technique. Talar dome (67.5% vs 73.5%, P = .534) and combined preparation (83.6% vs 75.5%, P = .248) were similar. Posterior talar zones remained incompletely prepared in most specimens (5/7 vs 6/7). Reliability was excellent (intraclass correlation coefficients >0.90). No neurovascular injuries occurred. Fewer transmalleolar specimens were at risk (28.6% vs 57.1%, P = .592), although not statistically significant. Conclusion: Compared with traditional portal-based MIS tibiotalar joint preparation, the transmalleolar MIS technique provided a statistically increased area of tibial plafond preparation without increasing the neurovascular risk. Overall preparation and talar debridement were similar, with comparable safety profiles. Level of Evidence: Level V, cadaveric / basic science study.