Hip, Abdomen, and Paraspinal Muscle Morphologies and Their Correlation With Pain and Disability in Degenerative Lumbar Scoliosis Patients

Design. Single-center, cross-sectional study. Objective. To investigate the correlation between core muscle morphology and pain and disability in DLS patients. Summary of Background Data. Sarcopenia has been shown to correlate with pain and disability in degenerative lumbar scoliosis (DLS) patients. The role of individual core muscle morphology, including paraspinal, hip, and abdominal muscles, has been poorly understood in their correlation to pain and disability in these patients. Methods. Ninety-one patients with de novo degenerative lumbar or thoracolumbar scoliosis at a single tertiary hospital with completed clinical questionnaires, whole-spine radiographs, and truncal computed tomography (CT) scans were included. Back pain visual analog scale (back VAS) and leg pain visual analog scale (leg VAS), Oswestry Disability Index (ODI), and Short Form-36 (SF-36) scores were primary outcomes of the study. Relative cross-sectional areas (rCSAs) and intramuscular fatty infiltration ratios (FIR) were calculated for each muscle based on CT scans. Results. In both univariable and multivariable analyses, gluteus maximus FIR correlated with back VAS ( P =0.022 and 0.045, respectively) and SF-36 PCS ( P =0.005 and 0.023, respectively), while gluteus medius FIR correlated with SF-36 PCS ( P =0.002 and 0.011, respectively). Abdomen and paraspinal muscles did not exhibit any significant relationship with pain and disability scores. Conclusions. Fatty infiltration of the gluteus maximus and gluteus medius muscles correlated with both back pain and disability in DLS patients. Paraspinal and abdominal muscles did not significantly correlate with pain and disability among DLS patients. The association between hip muscles and worse pain and disability in DLS patients suggests a new anatomic candidate for symptom variation in advanced lumbar pathologies. Level of Evidence. Level IV.