Dynamic Changes of Pelvis and Lower Extremities after Operation in Lumbar Degenerative Kyphosis

ABSTRACT

OBJECTIVE: Gait pattern in patients with lumbar degenerative kyphosis (LDK) is disturbed because trunk bends forward due to decreased lumbar lordosis. Surgical therapy in LDK is required when conservative management fails. We investigated kinematic and kinetic changes of the pelvis, hip, and knee joints on the sagittal plane in patients with LDK before and after operation. METHOD: Fifteen patients underwent operations between March 1999 and September 2003. Gait analysis was performed for all patients. RESULTS: Total lumbar lordotic angle increased from 10.50 degrees +/-11.22 degrees to 26.71 degrees +/-8.80 degrees postoperation. In gait analysis, anterior pelvic tilting angle increased from maximum 7.86 degrees +/-9.69 degrees, minimum 4.40 degrees +/-9.82 degrees to maximum 12.61 degrees +/-5.36 degrees, minimum 9.68 degrees +/-5.63 degrees (p<0.05). Maximum hip flexion angle changed from 31.39 degrees +/-11.71 degrees to 35.83 degrees +/-5.84 degrees (p<0.05). Maximum knee flexion angle in terminal stance phase decreased from 13.32 degrees +/-7.34 degrees to 8.30 degrees +/-6.38 degrees (p<0.05). CONCLUSION: After corrective operation, an increase of lumbar spine lordosis and anterior pelvic tilt with decrease of knee flexion were observed. However, an increase of maximum hip flexion secondary to increased anterior pelvic tilting influenced ambulation negatively. Therefore, stretching of the hip flexor and strengthening of the hip extensor are required before and after operation.