Bone Mineral Density and Spinal Sagittal Balance in Traditional Unassisted Breath-hold Women Divers after Osteoporotic Vertebral Fractures v1

Abstract

Study Design: A retrospective cross-sectional study. Objectives: The purpose of this study was to investigate osteoporosis and global sagittal alignment in the traditional women divers of Jeju Island. Summary of the Literature Review: Physical activity is beneficial to bone mineral density (BMD). Water pressure and muscle contraction may influence BMD in a positive way. However, divers experience weightlessness, which has a negative effect on BMD. Materials and Methods: Between January 2010 and December 2014, traditional women divers (known as Haenyeo in Korean), and non-diving women were investigated. The study population was divided into osteoporotic vertebral fracture and non-fracture groups. The BMD (in g/cm2) of the lumbar spine (L1–4) and femoral neck was measured using dual-energy X-ray absorptiometry. As part of the radiological assessment for global spinal sagittal balance, sagittal vertical axis, sacro-femoral distance, sagittal vertical axis to sacro-femoral distance ratio, and spino-sacral angle were measured. Results: Thirty women divers and thirty-three non-diving women were enrolled in this study. The mean age of the divers was 72.1 ± 4.7 years and that of the controls was 72.7 ± 4.0 years (P = 0.61). There was no statistical difference in BMD between the divers and controls. In the divers, there was a bigger positive sagittal balance in the fracture group compared to the non-fracture group (P = 0.001). Also in the divers, cervical lordosis and pelvic tilt were significantly increased in the fracture group compared to the non-fracture group (P = 0.028 and P = 0.008, respectively). Conclusions: Bone mineral density did not differ statistically between divers and controls during their postmenopausal period. When osteoporotic spinal fractures develop, compensation mechanisms, such as increased cervical lordosis and pelvic tilt, was more evident in traditional women divers. This may be due to the superior back muscle strength and spinal mobility of this group of women.