Biomechanical Gait Analysis in Patients with Osteonecrosis of the Femoral Head.

Although osteonecrosis of the femoral head is a prevalent condition, its effects on gait parameters have not been thoroughly studied and are not well-established in the current literature. The primary aim of the present study is to describe gait in patients with a diagnosis of osteonecrosis.  This is a cross-sectional study. Nine patients diagnosed with osteonecrosis of the femoral head who were regularly followed-up at an outpatient clinic were selected for the present study and underwent gait analysis using Vicon Motion Capture Systems. Spatiotemporal data was obtained, and joint angles were calculated using an Euler angle coordinate system. Distal coordinate systems were used to calculate joint moments and force plates to obtain ground reaction forces.  Patients with osteonecrosis presented with slower velocity (0.54 m/s ± 0.19) and smaller cadence (83.01 steps/min ± 13.23) than healthy patients. The pelvic obliquity range of motion was of 10.12° ± 3.03 and rotation was of 18.23° ± 9.17. The mean hip flexion was of 9.48° ± 3.40. Ground reaction forces showed reduced braking and propelling forces. Joint moments were reduced for flexion and adduction (0.42 Nm/kg ± 0.2 and 0.30 Nm/kg ± 0.11, respectively) but the abduction moment was increased (0.42 Nm/kg ± 0.18).  The present study showed that osteonecrosis of the femoral head presents compensatory gait mechanisms, with increased pelvic motion and decreased knee flexion to protect the hip joint. Decreased moments for hip flexion and adduction were also identified and muscle weakness for those groups may be correlated to the disease.