Risk prediction of degenerative scoliosis combined with lumbar spinal stenosis in patients with rheumatoid arthritis: a case-control study

The purpose of this study is to compare incidence of degenerative scoliosis (DS) in patients who diagnosed lumbar spinal stenosis (LSS) with or without rheumatoid arthritis (RA) and identify the risk factors of DS severity in RA patients. 61 LSS patients with RA (RA group) and 87 demographic-matched LSS patients without RA (NoRA group) from January 2013 to April 2018 were enrolled. The extracted information includes RA-related parameters such as Steinbrocker classification, disease-modifying anti-rheumatic drugs (DMARDs), and DS-related information such as Cobb angle, apical vertebra, along with osteoporosis and history of total knee arthroplasty (TKA). Comparisons between RA and NoRA group and between DS and non-DS subgroup with RA were performed, as well as the risk factors on DS severity in RA patients. The incidence of DS in RA group was 42.6%, larger than that of NoRA group (P = 0.002). The mean Cobb angle between the two groups was of no difference (P = 0.076). The apical vertebrae were both mainly focused on L3 and L4 vertebrae in both groups with no significant difference on the distribution of apical vertebrae (P = 0.786). Female took a larger proportion in DS subgroup than that of NoDS subgroup in patients with RA (P = 0.039), while Steinbrocker classification was irrelevant to the occurrence of DS and Cobb angle. Multiple regression analysis showed that TKA was a risk factor for the severity of Cobb angle (P = 0.040). The incidence of DS in LSS patients with RA is higher than non-RA patients. RA patients performed TKA sustained less severity of DS.