Lower limb deformity and gait deviations of osteogenesis imperfecta

Background: Osteogenesis imperfecta is a rare genetic disorder characterized by complex lower limb deformities, resulting in various gait limitations. This study aimed to (1) investigate the incidence and association between radiographic changes and gait impairment; (2) propose a lower limb deformity index to quantify deformity severity as well as gait performance. Methods: Bilateral X-ray images and 3D gait analysis results were assessed retrospectively from 48 patients with osteogenesis imperfecta. Multivariate linear regression was used to investigate the contribution of each deformity to gait performance. Eight scoring approaches of the proposed index, calculated from radiographic changes, were evaluated by their linear relationship to gait deviation. Results: Patients with osteogenesis imperfecta had high incidence of anterolateral bowing of femur, and anteromedial bowing of tibia, along with abducted hip, varus knee, hip flexion and ankle dorsiflexion deformities. Their maximum joint kinematics and kinetics were less than healthy controls, which was consistent with their major deformities. However, multivariate linear regression indicated a limited contribution from each deformity to gait deviation (only mechanical axis deviation out of 14 radiographic measures showed significance). Remarkably, our proposed index presented a significant linear correlation to gait deviation (Correlation coefficient: -0.650; R square: 0.423; F value: 33.719, p < 0.001). Conclusions: This study preliminary demonstrated the association between lower limb deformities and gait deviations of patients with osteogenesis imperfecta and proposed a lower limb deformity index to quantify the deformity severity that reflects gait performance.