Fixed Neck Position in Multilevel Cervical Posterior Decompression and Fusion to Reduce Postoperative Disturbances of Cervical Spine Function

INTRODUCTION: Difficulties with neck mobility often interfere with patients' activities of daily living (ADL) after cervical posterior spine surgery. The range of motion of the cervical spine decreases markedly after multilevel cervical posterior decompression and fusion (PDF). However, details regarding the limitations of cervical spine function due to postoperative reduced neck mobility after multilevel PDF are as yet unclarified. The present study aimed to clarify the quality of life and its related factors after PDF, and the optimal fixed neck position in multilevel PDF that minimizes the limitations of ADL accompanying markedly reduced postoperative neck mobility. METHODS: Limitations of ADL involving neck extension, rotation, and flexion were investigated in 32 consecutive patients who underwent C2-T1 PDF using the responses to the cervical spine function domain of the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ). The EuroQol 5 Dimension, Japanese Orthopedic Association score, and five domains of the JOACMEQ were also investigated. We investigated the risk factors regarding the fixed neck position in PDF for the impossibility to perform ADL involving each of three movements using cut-off values obtained from receiver-operating characteristic curves. RESULTS: Postoperative comprehensive quality of life was significantly related to neurological improvements and to poor outcomes of cervical spine function after PDF. The significant risk factors for impossibility to perform ADL involving neck rotation were a C2-C7 lordotic angle ≥ 6° (P = 0.0057) or a proportion coefficient of C2-T1 tilt angle/C2-C7 lordotic angle ≤ 1.8 (P = 0.0024). There were no significant risk factors for impossibility to perform ADL involving neck extension or flexion. CONCLUSIONS: The optimal fixed neck position in C2-T1 PDF to reduce postoperative limitations of ADL involving neck mobility is a C2-C7 lordotic angle of less than 6°, or a C2-T1 tilt angle (°) of greater than 1.8 × the C2-C7 lordotic angle (°).