Medial and Lateral Column Load Distribution After In Situ Subtalar/Talonavicular Fusion With and Without Calcaneocuboid Fusion: A Cadaveric Study.

BACKGROUND

Previous investigations have speculated that stiffening the lateral column of the hindfoot in triple arthrodesis can increase lateral plantar pressure with resulting lateral column pain. It is unclear whether sparing of the calcaneocuboid joint in hindfoot arthrodesis yields lower lateral column plantar forefoot pressures vs triple arthrodesis including the calcaneocuboid joint.

METHODS

Tendon loading and axial pressure were applied to 9 cadaveric legs according to standard cadaveric models. Medial and lateral forefoot pressures were recorded using a pressure-sensitive plate. Specimens were tested in native state, after sequential subtalar and talonavicular fixation, and after added calcaneocuboid fixation. All fixation was performed in situ in a neutral foot position. Testing was performed both on a neutral sensor plate and on a plate with 10 degrees of lateral slope.

RESULTS

In neutral position, pressure under the fifth metatarsal increased significantly from 31.0 ± 22.4 kPa in the native state to 63.1 ± 33.0 kPa (P = .018) after CC-sparing fusion and to 54.7 ± 27.9 kPa (P = .023) after triple arthrodesis. In the everted position, there was no significant difference in pressure under the fifth metatarsal from 56.8 ± 31.8 kPa in the native state to 89.7 ± 55.4 kPa (P = .134) after CC-sparing fusion and to 78.9 ± 42.9 kPa (P = .111) after triple fusion. No statistically significant pressure differences under the fifth metatarsal were found between the arthrodesis groups with loading on a neutral (P = .687) or sloped (P = .393) surface.

CONCLUSION

In our in situ fusion cadaveric model, both traditional triple arthrodesis and the calcaneocuboid-sparing procedure resulted in significantly higher lateral forefoot plantar pressure compared with the native state, but there was no significant difference in lateral pressure between the procedures on both a flat and a laterally inclined surface. These findings should be interpreted in light of limitations including small sample size, static loading conditions, intact cartilage, and lack of formal radiographic assessment of hindfoot alignment.

CLINICAL RELEVANCE: Although other considerations may warrant sparing the calcaneocuboid joint during hindfoot fusion, its preservation did not reduce lateral column overload in this model.