Three-dimensional gait analysis following surgical correction of proximal femoral type IV fibrous dysplasia with varus deformity.

This study aimed to analyse postoperative gait characteristics in patients with fibrous dysplasia (FD) of the proximal femur with varus deformity and to comprehensively assess limb function. We retrospectively reviewed patients who underwent surgical correction between January 2013 and October 2017. Limb length discrepancy and mechanical axis alignment were evaluated at follow-up. Gait parameters of both lower limbs were assessed using a three-dimensional (3D) gait analysis system, and the affected side was compared with the contralateral limb. Limb alignment and length were largely restored, with residual discrepancies of ≤ 2 cm in most patients. Functional outcomes were excellent, with high Musculoskeletal Tumour Society (MSTS) and Harris Hip Score results. However, gait asymmetries persisted postoperatively. Compared with the contralateral limb, the affected limb demonstrated significantly lower gait speed (0.98 ± 0.13 vs. 1.15 ± 0.15 m/s) and cadence (99.07 ± 5.97 vs. 110.32 ± 7.21 steps/min). Single-limb support time was shorter (33.47 ± 2.63 vs. 39.59 ± 3.69%) and double-limb support time was prolonged (16.20 ± 2.67 vs. 11.85 ± 3.49%). Both peaks of vertical ground reaction force were lower on the affected side. Hip extension and total hip range of motion were significantly reduced on the affected side, whereas knee and ankle joint parameters showed no significant differences between limbs. Despite correction of deformity and satisfactory clinical scores, residual gait abnormalities persisted after surgery. Three-dimensional gait analysis provides an objective means of functional evaluation and can complement traditional functional assessment tools in guiding targeted postoperative rehabilitation.