Relationship Between C2 Semispinalis Cervicis Preservation and C2 Spinous Process Morphology During Cervical Laminoplasty Involving C3

STUDY DESIGN: Retrospective study OBJECTIVES: Due to anatomical variations in the semispinalis cervicis insertion in the C2 spinous process, complete preservation is not always possible when the C3 level is included in a cervical laminoplasty. Three-dimensional computed tomography was used to evaluate the relationship between the incidence of semispinalis cervicis injury and the C2 inter-spinous angle. METHODS: We included 95 patients who underwent a cervical laminoplasty that included a C3 laminectomy for cervical myelopathy. Patients with a C2 inter-spinous angle above and below 60° were classified into wide- and narrow-angled groups, respectively (n = 48 and n = 47). Whether the C2 semispinalis cervicis insertion was preserved, or detached and reattached was reviewed from surgical records. The pre and postoperative C2-C7 lordosis and range of motion (ROM) were measured, and clinical outcomes were obtained from the patient charts. RESULTS: The C2 semispinalis cervicis was preserved in 47 patients (97.9%) in the wide-angled group but only in 14 patients (29.8%) in the narrow-angled group (P < .001). The postoperative C2-C7 lordosis extension and ROM were significantly greater in the wide-angled (P = .048 and .036). Postoperative neck pain was significantly greater in the narrow-angled (P = .018). CONCLUSIONS: The morphology of the C2 spinous process indicates that a C2 semispinalis cervicis insertion preservation is possible during a cervical laminoplasty that includes a C3 laminectomy. A careful surgical procedure should be conducted when the C2 inter-spinous angle is above 60° to increase the likelihood of achieving this preservation and thereby obtaining a more favorable clinical outcomes.