ObjectiveTo explore a better segment of fixation and fusion for high-grade spondylolisthesis. MethodsA total of 21 patients with high-grade spondylolisthesis who had undergone reduction and posterior instrumented fusion between July 2007 and March 2012, were retrospectively reviewed. All cases underwent posterior spinal canal decompression, Schanz screws fixation and reduction, and intervertebral and posterolateral fusion. The concept of "unstable zone" and the feature of spinal deformity helped us to identify the most appropriate segment to fuse. The pre/post-operative differences on slip percentage, pelvic incidence (PI) and lumbosacral angle were compared and analyzed. The nerve function was evaluated by physical examination and neurological Frankel grade. The Visual Analogue Scale (VAS) and Oswestry Disability Index were used to assess clinical and functional outcomes of lower limbs. Bone fusion was assessed using CT reconstruction. ResultsAll patients were followed up between 12 and 48 months. The clinical and radiological outcomes such as VAS scores and PI angle were all improved compared with that of preoperative, and the differences were all statistically significant (P<0.05). ConclusionFor children with severe spondylolisthesis, if not combined with structural scoliosis, the fixation and fusion level should be up to the upper vertebra which PI angle>60°, and try to protect the posterior longitudinal ligament complex in case adjacent segments become instability or even slip. For adults with severe spondylolisthesis, if not combined with other spinal disorders such as severe osteoporosis, only mono-segmental fusion is recommended after reduction. If the slipped vertebrae could not be reduced to Meyerding gradeⅠ, two or more segments would need to be fixed and fused.
ObjectiveTo explore the effect on sagittal spine-pelvis balance of different fusion segments in anterior cervical discectomy and fusion (ACDF).MethodsThe clinical data of 326 patients with cervical spondylotic myelopathy, treated by ACDF between January 2010 and December 2016, was retrospectively analysed. There were 175 males and 151 females with an average age of 56 years (range, 34-81 years). Fusion segments included single segment in 69 cases, double segments in 85 cases, three segments in 90 cases, and four segments in 82 cases. Full spine anterolateral X-ray films were performed before operationand at 12 months after operation. The spine-pelvis parameters of fusion segments were measured and compared. The parameters included C0-2 Cobb angle, C2-7 Cobb angle, C2-7 sagittal vertical axis (C2-7 SVA), T1 slope (T1S), thoracic inlet angle (TIA), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), C7 sagittal vertical axis (C7 SVA), T1 pelvic angle (TPA). The Japanese Orthopaedic Association (JOA) score of cervical spine and visual analogue scale (VAS) scores of pain of cervical spine and upper extremity were compared before operation and at 12 months after operation. Pearson correlation analysis was performed on LL, PI, SS, C7 SVA, and TPA before and after operation to evaluate the changes of spine-pelvis fitting relationship after ACDF.ResultsAll 326 patients were followed up 12-32 months (mean, 18.5 months). During the follow-up period, internal fixator was in place, and no spinal cord nerve or peripheral soft tissue injury was found. JOA scores and cervical VAS scores improved significantly at 12 months after operation (P<0.05), no significant difference was found in VAS scores of upper extremity when compared with preoperative scores (P>0.05). The preoperative cervical VAS scores and the postoperative JOA scores at 12 months had significant differences between groups (P<0.05). At 12 months after operation, there was no significant difference in sagittal spine-pelvis parameters in the single segment group compared with preoperative ones (P>0.05); but the C0-2 Cobb angle, C2-7 Cobb angle, C2-7 SVA, T1S, TIA, C7 SVA, and TPA in the double segments, three segments, and four segments groups were significant larger than preoperative ones (P<0.05). The C0-2 Cobb angle, C2-7 Cobb angle, T1S, C7 SVA, and TPA among 4 groups had significant differences before operation and at 12 months after operation (P<0.05). At 12 months after operation, the changes of C7 SVA and TPA in the double segments, three segments, and four segments groups were significantly larger than those in the single segment group (P<0.05). PI had positive correlations with LL and SS before and after operation in 4 groups (P<0.05).ConclusionNormal fitting relationship between lumbar spine and pelvis in physiological state also exists in patients with cervical spondylotic myelopathy, and ACDF can not change this specific relationship. In patients with cervical spondylotic myelopathy, the sagittal spine-pelvis sequence do not change after ACDF single-level fusion, while the sagittal spine-pelvis balance change after double-level and multi-level fusion.