Lateral Column Pressures Following Combined Subtalar/Talonavicular Fusion with and without Calcaneocuboid Fusion

Category: Hindfoot; Other Introduction/Purpose: There are few comparative studies between the traditional triple arthrodesis and the commonly performed modified procedure in which the calcaneocuboid joint is spared. Earlier investigations proposed that stiffening the lateral column of the hindfoot can increase lateral plantar pressures, potentially precipitating lateral column pain. We used a cadaver model to quantify the potential for reduced lateral column overload achieved by sparing the calcaneocuboid joint in a cadaveric model of triple arthrodesis simulating standing on both a neutral and sloping surface. Methods: Nine fresh-frozen, thawed cadaver legs were tested in 2 positions of the loaded surface: neutral and 10 degrees of eversion. Tendon loading and axial pressure was applied according to standard cadaveric models. Medial and lateral forefoot pressures were recorded using a pressure-sensitive plate (F-scan). The data were normalized as a percentage of the native state. Results: In neutral loading, the mean contact pressures under the fifth metatarsal head increased dramatically compared to the native state in both the standard (76.3%, p<.005) and calcaneocuboid-sparing (103.5%, p<.007) procedures. Pressure was reduced underneath the first metatarsal head medially in both standard (-52.8%, p< 0.017) and calcaneocuboid-sparing (-57.2%, p< 0.008). Loading on an everted surface yielded larger overall pressures laterally, but the further increases compared to the native state following both standard (39.0%, p < 0.04) and calcaneocuboid-sparing (57.9%, p< 0.03) procedures were smaller than in the neutrally loaded foot. No statistically significant difference was observed between the arthrodesis groups when loaded either on a neutral or sloped surface. Conclusion: In our cadaveric model, both traditional triple arthrodesis and the calcaneocuboid-sparing procedure resulted in significant elevation of lateral forefoot plantar pressures compared to the native state, but there was no identifiable protective effect from sparing the calcaneocuboid joint even in the provocative condition of loading on a sloping surface. Clinical Relevance: While other factors may guide the choice to spare the calcaneocuboid joint when performing hindfoot fusion, there is no evidence that preserving its motion significantly reduces the risk of lateral column overload.