Risk Factors for Cervical Deformity After Posterior Cervical Decompression Surgery: A Multicenter Study.

ABSTRACT

STUDY DESIGN: Retrospective multicenter study. OBJECTIVE: Posterior decompression surgery for cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL) is a common surgery; however, it can cause postoperative cervical deformity (CD). The purpose of this study was to investigate the risk factors for CD. METHODS: The participants were 193 patients underwent laminoplasty or laminectomy for CSM or OPLL. CD was defined as a C2-7 sagittal vertical axis (SVA) ≥ 40 mm or a cervical lordosis angle (CL) ≤ -10°. The participants were divided into 2 groups NCD (without CD before surgery), CD (with CD before surgery). NCD group was divided based on the presence of CD 1 year after surgery as follows postoperative CD (PCD) and no PCD (NPCD). RESULTS: There were 153 patients (NCD), 40 (CD), 126 (NPCD), and 27 (PCD). There was significant difference in the number of decompressed lamina (NPCD PCD = 4.14.5), the presence of C2 decompression (2 11%), and C5 palsy (0 11%). The risk factors for onset of CD, PCD, and CL ≤ -10° as assessed by multiple logistic regression analysis were preoperative C2-7 SVA ≥ 30 mm (odds ratio [OR] 19.0), decompression of C2 or C7 lamina (OR 3.1), and preoperative CL ≤ 2° (OR 42.0), respectively. CONCLUSIONS: To prevent postoperative CD, it is important to avoid decompression of the C2 or C7 lamina. Moreover, in case with C2-7 SVA ≥ 30 mm or CL ≤ 2° before surgery, it is important to explain the risks and consider adding fusion surgery.