Successful detection of postoperative improvement of dynamic sagittal balance with a newly developed three-dimensional gait motion analysis system in a patient with iatrogenic flatback syndrome: A case report.

A 75-year-old Japanese woman with Parkinson's disease complained of lower back pain and gait disturbance because of iatrogenic flatback syndrome. The preoperative global spinal parameters were as follows: C7SVA, 168 mm; TK, 52°; LL, -0.8°; PI, 57°; PT, 55°; TPA, 60°. We performed 3D gait analysis using a VICON System and calculated the dynamic SVA. Preoperatively, her flexion deformity gradually progressed during walking. The dynamic parameters gradually increased as follows: thoracic SVA, 216-241 mm; lumbar SVA, 53-69 mm; spinal SVA, 270-311 mm. We performed two-stage corrective surgery. Her lower back pain and gait disturbance significantly improved. The postoperative global spinal parameters were as follows: C7SVA, 1 mm; TK, 47°; LL, 61°; PI, 52°; PT, 20°; TPA, 13°. Dynamic SVA detected by our 3D gait analysis using VICON were as follows: thoracic SVA, 128 mm; lumbar SVA, 4.9 mm; and spinal SVA, 133 mm. The postoperative dynamic SVA did not change during walking. This is the first report of a patient with iatrogenic flatback syndrome whose postoperative improvement of dynamic spinal sagittal alignment was successfully detected with a newly developed 3D gait analysis system that enabled us to analyze a dynamic change of SVA based on the patient's actual walking with a continuous long-distance gait. Our 3D gait analysis has potential usefulness for evaluating postoperative sagittal balance for iatrogenic flatback syndrome.