Balance and biomechanics: exploring lower extremity biomechanics in Parkinson’s disease

Background: Postural instability (PI) is a symptom seen in 16% of Parkinson Disease (PD) patients and has limited response to dopaminergic therapy. Understanding the factors contributing to PI, such as biomechanical changes, is important for the development of non-pharmacological treatment. Aims: To investigate the relationship between lower extremity biomechanics and balance parameters in PD patients. Methods: A total of 18 participants (n = 9 female) were enrolled in the study. Lower extremity biomechanics were evaluated using a combination of measurements, including femoral anteversion angle, Q angle, leg length, navicular drop test (NDT), gastrocnemius shortness, range of motion (ROM) assessments, and the Foot Posture Index (FPI). Balance was assessed through the Postural Stability Test, Fall Risk Index (FRI), and the Mini-BESTest. Results: A significant correlation was observed between FRI and femoral anteversion (r = 0.58, p = 0.011) as well as hip flexion ROM (r = 0.67, p = 0.002) and lateral malleoli curvature (r = 0.48, p = 0.04). Overall Stability Index (OSI) was significantly associated with NDT (r = 0.53, p = 0.024) and forefoot abduction/adduction (r = 0.67, p = 0.002). The Anteroposterior Stability Index (APSI) correlated with NDT (r = 0.47, p = 0.048), knee flexion ROM (r = 0.47, p = 0.045), and forefoot abduction/adduction (r = 0.65, p = 0.004). Moreover, Mini-BESTest scores were associated with hip abduction (r = 0.55, p = 0.017), ankle plantar flexion (r = 0.63, p = 0.005), and knee flexion ROM (r = 0.47, p = 0.048). Conclusions: This study demonstrated that lower extremity biomechanical features, including alignment and joint mobility, are significantly linked to balance and fall risk in individuals with PD. Incorporating biomechanical assessments into clinical evaluations may aid in developing individualized treatment strategies for balance disorders in PD.