The influence of long-term shoulder loading on sagittal spino-pelvic morphology: a population-based retrospective study of Chinese farmers from radiology

Abstract

Abstract Background To investigate associations between long-term shoulder loading and sagittal spino-pelvic morphology in Chinese farmers from radiology evidences. Methods We retrospectively analyzed 463 back pain patients who attended outpatient and inpatient departments of two hospitals from January 2016 to December 2018, and who had long, standing lateral X-rays according to inclusion and exclusion criteria. One hundred eighty-four of them were farmers with a long history of heavy shoulder loading for over 20 years in their young age, while others were office workers with no reported long-term shoulder loading history. The following parameters were measured by three researchers independently and then analyzed statistically: thoracic kyphosis (TK), lumbar lordosis (LL), thoracolumbar kyphosis (TLK), T9 sagittal offset (T9SO), T1 sagittal offset (T1SO), sacral slope (SS), pelvic incidence (PI), pelvic tilt (PT), C7 tilt (C7T), spino-pelvic angle (SSA), and sagittal vertical axis (SVA). Results The “Loading group” included 86 males and 98 females with average age 73.3 (SD 8.3) years, whereas the “Non-loading group” included 126 males and 153 females with average age 63.7 (SD 14.1) years. Age was significantly higher in the loading group (p < 0.001), but gender, height, weight, BMI, and BMD were not significantly different (p > 0.05). The following spino-pelvic parameters were significantly greater (p < 0.05) in the loading group: TK (mean 39.1° vs 32.8°), TLK (25.8° vs 10.1°), and T9SO (12.2° vs 10.1°). Other values were not significantly different between the two groups (p > 0.05). Conclusion Long-term shoulder loading in youth is a risk factor for pathological thoracic kyphosis especially in the lower thoracic spinal segments when farmers getting older.