Locomotor biomechanics after total sacrectomy: a case report.

STUDY DESIGN: Biomechanical analysis of locomotion after total sacrectomy in a single patient case.

OBJECTIVE: To describe the biomechanics of locomotion after successful total sacrectomy and spinopelvic reconstruction.

SUMMARY OF BACKGROUND DATA: Total sacrectomy is a complex surgery that has significant consequences for mobility after surgery due to loss of lower lumbar and sacral innervation to the lower extremities, and the anatomic dissociation of the spine from the pelvis. There is no existing literature quantifying locomotor biomechanics after total sacrectomy.

METHODS: A 22-year-old female with a sacral osteosarcoma underwent an en bloc sacrectomy with L3 to pelvis instrumented fusion. Neuromuscular function was tested 1 year after surgery using monopolar needle electromyography. Three-dimensional motion capture and surface electromyography were used to quantify spatiotemporal characteristics of locomotion and lower extremity kinematics, kinetics, and muscle function during locomotion at 6 months and 1 year after surgery.

RESULTS: Electrodiagnostic testing suggested partial preservation and reinnervation of S1 nerve root function on the right, resulting in greater than expected activity in the hamstrings, gluteus maximus, and triceps surae postsurgically. Unexpectedly on the left, there was residual activity in the hamstrings, despite the loss of sacral innervation and the sciatic nerve. At 1 year after surgery, the patient was able to walk independently. Kinematic and kinetic impairments and compensations were most evident in the sagittal and coronal planes.

CONCLUSION: Excellent locomotor outcomes are possible after total sacrectomy.