Factors predicting adjacent segment disease after anterior cervical discectomy and fusion treating cervical spondylotic myelopathy A retrospective study with 5-year follow-up

The purpose of this study is to explore perioperative factors predicting symptomatic adjacent segment disease (ASD) after anterior cervical discectomy and fusion (ACDF) for patients with cervical spondylotic myelopathy (CSM) at 5-year follow-up. This study included 356 patients who underwent ACDF for CSM from Jan. 2011 to Jan. 2013. Up to Jan. 2018, 39 patients suffered from ASD and 317 did not. Assessments include: age, sex, body mass index (BMI), diabetes, smoking, alcohol, duration of symptoms, preoperative Cobb angle of C2 to 7, T1 slope, C2 to 7 range of motion (C2-7 range of motion [ ROM]), C2 to 7 sagittal vertical axis (C2-7 SVA), fusion level involved, superior fusion segment, high signal intensity on T2-WI of magnetic resonance imaging (MRI), preoperative visual analogue scale (VAS)-neck, VAS-Arm, Neck Disability Index (NDI) and Japanese Orthopaedic Association (JOA). Factors were processed by univariate analysis and multivariate linear regression. Data analyzed by univariate and multivariate analysis shows that age (68.9 years old), duration of symptoms (18.8 months), superior fusion segment, more fusion level involved (2.7), high signal intensity on T2-WI (17 of 39 patients), Cobb angle of C2 to C7 (18.7 degrees), C2 to C7 SVA (31.0mm), T1 slope (28.4 degrees), preoperative VAS-neck (5.2), VAS-Arm (5.6) and NDI (36.7) in ASD group are significantly higher than those in non-ASD group, however, preoperative JOA (8.2 vs 11.2, P<.001) has an opposite trend in 2 groups. The rate of ASD after ACDF is 10.9% in 5-year follow up. Patients with cervical sagittal imbalance, advanced age and sever state of CSM, which have a positive relation with ASD before surgery should be paid attention for surgeons.