Effects of Calcaneal Osteotomies on Gait Kinematics in Simulated Progressive Collapsing Foot Deformity: A Cadaveric Study

Background: Calcaneal osteotomies are often used to correct hindfoot valgus and forefoot abduction in patients with PCFD. Calcaneal osteotomies are commonly performed to address hindfoot valgus and forefoot abduction present with PCFD. This study compared the dynamic effects of medializing calcaneal osteotomy (MCO) and lateral column lengthening (LCL), after simulated PCFD (sPCFD), on joint kinematics and plantar pressure during simulated gait. Methods: Twelve cadaveric mid-tibia specimens were loaded on a 6-degree-of-freedom robotic gait simulator. Gait was simulated first in the intact and sPCFD conditions. After sPCFD testing, surgical reconstruction and testing was performed in stages with MCO and LCL (6- and 8-mm grafts). Ankle, subtalar, and talonavicular joint kinematics and plantar pressures were collected, and differences compared between the intact, sPCFD, and surgically corrected conditions. Results: The isolated MCO partially corrected foot kinematics, and notably increased talar dorsiflexion throughout the stance. The isolated LCL restored ankle kinematics, but subtalar eversion and talonavicular abduction were still uncorrected during stance. However, LCL and MCO together were able to restore talonavicular kinematics throughout stance to normal levels. Larger LCL graft size further improved foot kinematics, but resulted in overcorrection in the subtalar and ankle joints during portions of stance. All procedure combinations increased lateral plantar pressure relative to the sPCFD condition. Conclusion: Isolated MCO and LCL, and a combination of both, all partially restored ankle and hindfoot joint kinematics. However, overcorrection in certain planes of motion and increased lateral plantar pressure suggest a risk of lateral column overload as LCL graft size increases. Clinical Relevance: The synergistic effect of MCO and LCL may be effective at restoring kinematics, but surgeons should be cautious in increasing osteotomy size at the lateral column to avoid overload. Gait simulation may help us learn how to titrate combinations of corrections that best restore kinematics—and ultimately, improve clinical outcomes.