Shengrong Lin1, Feifei Zhou1, Yu Sun2, Zhongqiang Chen1, Fengshan Zhang1, Shengfa Pan1. 1. Department of Orthopedics, Peking University Third Hospital, Beijing 100191, China. 2. Department of Orthopedics, Peking University Third Hospital, Beijing 100191, China. Email: sunyuor@vip.sina.com.
Abstract
OBJECTIVE: To explore the changes of sagittal balance of cervical spine after open-door expansive laminoplasty. METHODS: The clinical and radiological data were analyzed retrospectively for 90 patients undergoing open-door expansive laminoplasty due to cervical spondylotic myelopathy. The Japanese Orthopedic Association (JOA) score and 3 cervical sagittal parameters including C2-C7 SVA, C0-2 Cobb angle and T1-Slope on lateral view radiographs were recorded before operation and at the final follow-up. RESULTS: The average follow-up period was 16.7 (3-40) months. The post-operative JOA score rose to 14.6 ± 0.2 from pre-operative 12.2 ± 0.3 with 43.5% ± 4.2% recovery rate. The post-operative values of C2-C7 SVA, C0-2 Cobb angle and T1-Slope were significantly different from pre-operative ones (P = 0.022, P < 0.001, P = 0.002) . C2-C7 SVA increased to (23.0 ± 1.2) mm from pre-operative (20.7 ± 1.1) mm. C0-2 Cobb angle increased (23.1 ± 0.8) ° from pre-operative (19.9 ± 0.8)°; T1-Slope increased to (26.2 ± 0.7)° from pre-operative (25.1 ± 0.7)°. The changes of C0-2 Cobb angle and T1-Slope were correlated with that of C2-C7 SVA respectively (Pearson = 0.469, P < 0.001) (Pearson = 0.303, P = 0.004) . Patients with higher preoperative T1-Slope had less JOA improvement (31.5% vs 53.7%, P = 0.019) than those with lower preoperative T1-Slope after laminoplasty. CONCLUSION: The sagittal balance of cervical spine significantly changes after open-door expansive laminoplasty with forward tilting of cervical vertebra. And compensation occurs by excessive high-strength contraction of posterior muscles to maintain lordosis in upper cervical spine. A higher pre-OP T1-Slope affects the outcomes of open-door expansive laminoplasty.
OBJECTIVE: To explore the changes of sagittal balance of cervical spine after open-door expansive laminoplasty. METHODS: The clinical and radiological data were analyzed retrospectively for 90 patients undergoing open-door expansive laminoplasty due to cervical spondylotic myelopathy. The Japanese Orthopedic Association (JOA) score and 3 cervical sagittal parameters including C2-C7 SVA, C0-2 Cobb angle and T1-Slope on lateral view radiographs were recorded before operation and at the final follow-up. RESULTS: The average follow-up period was 16.7 (3-40) months. The post-operative JOA score rose to 14.6 ± 0.2 from pre-operative 12.2 ± 0.3 with 43.5% ± 4.2% recovery rate. The post-operative values of C2-C7 SVA, C0-2 Cobb angle and T1-Slope were significantly different from pre-operative ones (P = 0.022, P < 0.001, P = 0.002) . C2-C7 SVA increased to (23.0 ± 1.2) mm from pre-operative (20.7 ± 1.1) mm. C0-2 Cobb angle increased (23.1 ± 0.8) ° from pre-operative (19.9 ± 0.8)°; T1-Slope increased to (26.2 ± 0.7)° from pre-operative (25.1 ± 0.7)°. The changes of C0-2 Cobb angle and T1-Slope were correlated with that of C2-C7 SVA respectively (Pearson = 0.469, P < 0.001) (Pearson = 0.303, P = 0.004) . Patients with higher preoperative T1-Slope had less JOA improvement (31.5% vs 53.7%, P = 0.019) than those with lower preoperative T1-Slope after laminoplasty. CONCLUSION: The sagittal balance of cervical spine significantly changes after open-door expansive laminoplasty with forward tilting of cervical vertebra. And compensation occurs by excessive high-strength contraction of posterior muscles to maintain lordosis in upper cervical spine. A higher pre-OP T1-Slope affects the outcomes of open-door expansive laminoplasty.