A histomorphometric study of the cancellous spinal process bone in adolescent idiopathic scoliosis.

PURPOSE: Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity with increased risk of osteopenia of unknown etiology. This study examined the dynamic histomorphometry of AIS patients to gain insight into the underlying pathogenesis of bone metabolism changes in AIS.

METHODS: Bone histomorphometry of the spinous process of the 12th thoracic vertebra was analyzed in 33 AIS patients and compared to age-matched normative data. Patients were classified into bone turnover subgroups, based on bone formation rate.

RESULTS: Bone volume was subnormal in 67% of AIS patients, but normal in 33%. Bone turnover was high in 76% of the patients, normal in 9%, and low in 15%. Compared to those in the low-turnover group, the high-turnover group patients were taller and had higher TRAP5b values.

CONCLUSIONS: Bone histomorphometry indicated that bone fragility and abnormal bone turnover were common in AIS patients. These abnormalities might contribute to the poor bone status and etiology in AIS.