Clinicoradiological Risk Factors Associated with Inability to Achieve Minimum Clinically Important Difference in Operated Cases of Cervical Spondylotic Myelopathy

Study design: This is a retrospective cohort study.Purpose: This study aimed to identify the clinicoradiological risk factors associated with the inability to achieve minimum clinically important difference (MCID) on the modified Japanese Orthopaedic Association (mJOA) Scale in operated cases of cervical spondylotic myelopathy (CSM).Overview of literature: Only a few studies have evaluated the outcomes of surgery performed for CSM using MCID on the mJOA scale.Methods: We analyzed 124 operated CSM cases from March 2019 to April 2021 for preoperative clinical features, cervical sagittal radiographic parameters, and magnetic resonance imaging (MRI) signal intensities (SI). The risk factors associated with missing the MCID (poor outcome) on mJOA at the final follow-up were identified using binary logistic regression. Multivariate analysis was used to find significant risk factors, and odds ratios (OR) were computed.Results: A total of 110 men (89.2%) and 14 women (10.8%) with an average age of 53.5 +/- 13.2 years were included in the analysis. During the last follow-up, 89 cases (72.1%) achieved MCID (meaningful gains following surgery) while 35 (27.9%) could not. The final model identified the following parameters as significant risk factors for poor outcome: increased duration of symptoms (OR, 6.77; p=0.001), lower preoperative mJOA scale (OR, 0.75; p=0.029), the presence of multilevel T2-weighted (T2W) MRI SI (OR, 4.79; p=0.004), and larger change in cervical sagittal vertical axis (Delta cSVA) (OR, 1.06; p=0.013). Also, an increase in cSVA postoperatively correlated with a reduced functional recovery rate (r=-0.4, p<0.001).Conclusions: Surgery for CSM leads to significant functional benefits. However, poorer outcomes are observed in cases of greater duration of symptoms, higher preoperative severity with multilevel T2W MRI SI, and a larger increase in the postoperative cSVA (sagittal imbalance).