LAUSR

OBJECTIVE The mechanical alteration in the adolescent/pediatric cervical spine after spinal fusion remains unknown. The purpose of this study was to investigate morphologic changes in the cervical spine in adolescent/pediatric patients who underwent spinal fusion. METHODS Ten adolescent/pediatric patients (9-18 years) who underwent cervical spinal fusion were included. The anteroposterior diameter (AP-D) of the vertebral body was evaluated using lateral radiographs. The AP-D ratio was defined as the ratio of the AP-D at final follow-up to the postoperative value. The kyphosis angles at the fused level and cervical spine (C2-C7) also were measured. RESULTS The mean follow-up period was 20.0 years (range, 12-40 years). The AP-D was reduced in 4 patients and increased or remained unchanged in 6 patients. The AP-D reduction was usually seen at the middle of the fused levels and was remarkable in patients who underwent kyphosis correction using posterior instrumentation combined with anterior fusion. The AP-D ratio was significantly correlated to segments of anterior fusion (P = 0.029) and the kyphosis angle of the fused levels (P = 0.016). CONCLUSIONS Cervical kyphosis correction using posterior instrumentation combined with endplate destruction by anterior bone grafting is a risk factor for atrophic morphologic changes in the vertebral body in adolescent/pediatric patients. Endplate destruction and instrumentation-induced stress shielding could alter bone remodeling.