The impact of a medial displacement calcaneal osteotomy and posterior tibial tendon repair on multi-segment foot kinematics and kinetics in patients suffering from posterior tibial tendon dysfunction.

Posterior tibial tendon dysfunction (PTTD) now renamed progressive collapsing foot deformity, is the most common cause of adult acquired flatfoot deformity. When conservative approaches are unsuccessful, a medial displacement calcaneal osteotomy (MDCO) is commonly paired with tendon repair or reinforcement. This study aimed to elucidate the mechanical function of the foot and ankle joints in 15 patients undergoing combined MDCO, for which the restoration of joint mechanics and energetics remains poorly understood. A control group of 32 healthy volunteers was included for comparison. Foot joint kinematics and kinetics during the stance phase of walking were quantified using a four-segment foot model. Validated patient-reported outcome measures (Visual Analogue Scale, Foot Function Index 5PT, 36-Item Short Form Survey) and radiographic measurements were collected pre- and postoperatively. Statistical analyses included zero-dimensional and one-dimensional tests comparing preoperative, postoperative, and control data. Results demonstrate that combined MDCO surgery increased ankle inversion, enhanced Chopart joint adduction, and improved ankle power during push-off. Although the procedure produced significant improvements in pain, functional outcomes, and radiographic alignment, residual kinetic deficits and deviations from normative gait patterns persisted postoperatively. Overall, MDCO and tibialis posterior repair produced clinically meaningful improvements in subjective and objective outcomes. These results highlight the importance of tailoring surgical strategies to individual patient goals and indicate that additional research is warranted to evaluate long-term biomechanical outcomes.