Static and Dynamic Parameters in Patients With Degenerative Flat Back and Change After Corrective Fusion Surgery

OBJECTIVE To evaluate characteristics of static and dynamic parameters in patients with degenerative flat back (DFB) and to compare degree of their improvement between successful and unsuccessful surgical outcome groups. METHODS Forty-seven patients with DFB were included who took whole spine X-ray and three-dimensional motion analysis before and 6 months after corrective surgery. Forty-four subjects were selected as a control group. As static parameters, thoracic kyphosis (TK), thoracolumbar junction (TLJ), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were measured. As dynamic parameters, maximal and minimal angle of pelvic tilt, lower limb joints, and thoracic and lumbar vertebrae column (dynamic TK and LL) in sagittal plane were obtained. RESULTS The DFB group showed smaller TK and larger LL, pelvic posterior tilt, hip flexion, knee flexion, and ankle dorsiflexion than the control group. Most of these parameters were significantly corrected by fusion surgery. Dynamic spinal parameters correlated with static spinal parameters. The successful group obtained significant improvement in maximal and minimal dynamic LL than the unsuccessful group. CONCLUSION The DFB group showed characteristic lower limb and spinal angles in dynamic and static parameters. Correlation between static and dynamic parameters was found in spinal segment. Dynamic LL was good predictor of successful surgical outcomes.