Epidemiology of Degenerative Lumbar Scoliosis

STUDY DESIGN: A 12-year prospective study of pre-existing and de novo degenerative lumbar scoliosis (DLS) among community-based female volunteers. OBJECTIVE: To investigate serial entire spine radiographs of healthy female volunteers and to clarify radiographical characteristics and predictors of pre-existing and de novo DLS. SUMMARY OF BACKGROUND DATA: DLS is among the most frequent spinal defomities in the aging spine; however, the onset or the natural course of this condition has not been elucidated. METHODS: A total of 144 female volunteers were recruited from population register. Radiographical measurements using entire spine radiographs included thoracic kyphosis (T4-12), lumbar lordosis (LL) (L1-5), sacral inclination angle, pelvic incidence, sagittal balance (C7 plumb), coronal L4 endplate angle (L4 tilt), and scoliotic angle by Cobb method. More than 10° of scoliosis was diagnosed as DLS. L4 vertebral size was measured (divided by body height) as well as lateral osteophyte formation and lateral disc wedge angle. RESULTS: Mean baseline age and follow-up period were 54.4 years and 12.1 years, respectively. Pre-existing DLS (pre-DLS) was found in 42 subjects (29.2%) at baseline. Among pre-DLS, 11 subjects (26%) showed more than 5° progression in scoliosis. De novo DLS has developed in 30 subjects (29.4%) among those without baseline scoliosis.Cox proportional hazards models revealed younger age, smaller L4 size, lower LL, greater DLS angle, and L4 tilt at baseline to be the risk factors of progression of pre-DLS and smaller L4 size, unilateral osteophyte formation, and lateral disc wedging to the risk of development of de novo DLS. CONCLUSION: This study indicated that younger age, smaller L4 size, lower LL, greater DLS angle, and L4 tilt at baseline should be evaluated as predictors of progression of pre-DLS. Early signs of asymmetric disc degeneration and smaller L4 size should also be evaluated as predictors of development of de novo DLS.