Association of long-term outcome of long cervical fusion with sagittal balance: the significance of T1 slope minus cervical lordosis.

Introduction: Retrospective study to assess correlation between the sagittal alignment of the cervical spine and the long-term outcomes of long cervical fusion due to cervical spondylotic myelopathy (CSM), with the emphasis on T1 slope minus cervical lordosis (T1S-CL).

Summary Of Background Data: Growing evidence shows that the sagittal profile can play a major role in the outcomes of treatment, but the role of its correction is yet to be established.

Material And Methods: We conducted a retrospective analysis of 54 patients treated for CSM from 2006 to 2012. The neck pain-related disability was measured using NDI, the myelopathy was measured with the mJOA and Nurick scales. Six years after the surgery, standardised X-ray measurements were obtained, including C2-C7 lordosis (CL), C2-C7 sagittal vertical alignment (SVAC2-C7), T1 slope (T1S), and T1S minus CL (T1S-CL). The patients were divided based on the T1S-CL into two groups, using the threshold value of 16.5 degrees.

Results: A statistically significant improvement was noted in the mean NDI, mJOA, and median Nurick scale during the initial two years in both groups. The better aligned group had a better outcome measured with NDI at all follow-ups. The mJOA was significantly better in the better aligned group, but only preoperatively; at all follow-ups, the difference was not significant. T1S-CL had the strongest correlation with the NDI at the final follow-up.

Conclusions: T1S-CL is an effective prognostic factor of the long term outcome after long cervical fusion in CSM treatment.