There were several reports describing the biomechanics and microstructure of multifidus muscles in patients with lumbar disc herniation. However, correlations between lumbar multifidus muscle atrophy (LMA), spinopelvic parameters, and severity of adult degenerative scoliosis (ADS) have not been investigated. The study evaluated the impact of LMA and spinopelvic parameters on the severity of ADS. One hundred and thirty-two patients with ADS were retrospectively reviewed. Standing whole-spine X-ray was used to evaluate the coronal (coronal Cobb angle, CA; coronal vertical axis, CVA) and sagittal (sagittal vertical axis, SVA; thoracic kyphosis, TK; lumbar lordosis, LL; pelvic incidence, PI; pelvic tilt, PT; sacral slope, SS) parameters. LMA was evaluated on axial T2-weighted magnetic resonance imaging (MRI) at intervertebral levels above and below the vertebra at the apex of the scoliotic curve. Clinical symptoms were evaluated by the Oswestry Disability Index (ODI) and the Japanese Orthopaedic Association (JOA) score. Multiple linear regression was used to assess correlations between LMA, spinopelvic parameters, and severity of scoliosis. LL and PT were negatively correlated with CA (P < 0.001); LL was positively correlated with SVA (P < 0.001). PI was positively correlated with CA (P < 0.001) and CVA (P < 0.001). PT (P < 0.001) and SS (P < 0.001) were negatively correlated with CVA. SS was negatively correlated with SVA (P < 0.001). Concave LMA at the upper or lower intervertebral level of the apical vertebra was positively correlated with CA (P ≤ 0.001); convex LMA at the upper or lower intervertebral level was negatively correlated with CA (P < 0.001). Convex LMA at the upper intervertebral level and concave LMA at the lower intervertebral level of the apical vertebra were negatively correlated with the SVA (P ≤ 0.001). At the upper intervertebral level, LMA on the concave side was positively correlated with CVA (P = 0.028); LMA on the convex side was negatively correlated with CVA (P = 0.012). PI was positively correlated with ODI (P < 0.001); PT (P < 0.001) and SS (P < 0.001) were negatively correlated with ODI. At the lower intervertebral level, LMA on the concave side was positively correlated with ODI (P = 0.038); LMA on the convex side was negatively correlated with ODI (P = 0.011). PI was positively correlated with JOA (P < 0.001); PT (P < 0.001) and SS (P < 0.001) were negatively correlated with JOA. Spinopelvic parameters are correlated with the severity of ADS. Asymmetric LMA at both upper and lower intervertebral levels of the apical vertebra is positively correlated with CA. LMA on the diagonal through the apical vertebra is very important to maintain sagittal imbalance via parallelogram effect. LMA at lower intervertebral levels of the apical vertebra may have a predictive effect on ODI. JOA score seems to be more correlated with spinopelvic parameters than LMA.

The aim of this study was to compare the reliability and validity of the CARDS and French classification systems for lumbar DS. Between May 2013 and December 2016, 158 consecutive patients diagnosed with single-level lumbar DS were included in this study, and all underwent lumbar fusion. All patients underwent long-cassette standing anterioposterior and lateral radiographs of the spine preoperatively and postoperatively. The images were graded according to the CARDS and French classification systems by two orthopedic spinal surgeons and two orthopedic spinal fellows, independently. Clinical outcome measures used were the visual analog scale, Oswestry Disability Index, and the 36-Item Short Form Health Survey. Clinical data were collected before surgery and 1 year after surgery. A total of 146 patients were finally included in this study and followed up for at least 1 year. When grading using the CARDS system, the κ values for inter- and intraobserver reliability were 0.837 and 0.869, respectively, representing perfect agreement. The interobserver κ value for the French classification was 0.693 and the intraobserver κ value was 0.743, both representing substantial agreement. CARDS Type D patients have higher preoperative back pain scores and better improvement after surgery compared with non-Type D patients. Mean back and leg pain was worse in French Type 5 patients, while the most significant improvement was also seen in Type 5 patients after surgery. Both CARDS and French classification systems have acceptable reliability and validity. The CARDS system is easier to utilize and has better reliability. IV