Study design: This study prospectively analyzed gait in 21 patients with flatback and reviewed radiographs and charts.
Objective: To analyze the effect of sagittal imbalance on gait and hip and knee joints.
Summary of background data: Loss of lumbar lordosis causes anterior displacement of the center of gravity, which creates instability and increases the work of gait. Several compensatory changes occur in response. The long-term effect of these changes on extra-axial joints has not been reported, nor have many studies analyzed the gait deviations in patients with flatback. Over time, as patients' ability to compensate is limited, increased gait deviations result.
Methods: A total of 21 of 44 patients who had gait analysis as part of the preoperative workup were selected based on outlined criteria. Kinetics and kinematics data were analyzed along with radiographic and chart review. Normal healthy individuals served as controls.
Results: Gait deviations were present in gait kinetics and kinematics, including decreased stride length and velocity, to almost 60% of controls. Stance duration was prolonged with increased hip and knee flexion during stance. Hip and knee extensor moments were decreased with vertical ground reaction force showing slower rate of loading, reduced peak values, and flattening of normal loading response.
Conclusion: Patients with flatback develop several compensatory mechanisms. The goal of the compensation is to maintain an efficient gait and decrease joint damage, but these safeguards fail over time. Flatback not only causes backache, abnormal posture, and abnormal body mechanics but also compromises the stability of gait and taxes the knee and hip joints adversely.