Does thoracic kyphosis severity predict response to physiotherapy rehabilitation in patients with osteoporotic vertebral fracture? A secondary analysis of the PROVE RCT.

OBJECTIVES: To describe participant characteristics based on kyphosis severity, examine the relationship between kyphosis and physical function, and investigate whether kyphosis severity predicts improvement after physiotherapy intervention. DESIGN AND SETTING: Secondary longitudinal analysis of the PROVE trial, a multicentre RCT. Data from all three trial arms were pooled and divided into quartile groups according to baseline kyphosis severity for linear mixed model analysis. PARTICIPANTS: 604 men and women with osteoporotic vertebral fracture. MAIN OUTCOME MEASURES: Estimated marginal means reported from adjusted mixed models for thoracic kyphosis, Six-minute Walk Test (6MWT), functional reach and Short Performance Physical Battery (SPPB). RESULTS: Thoracic kyphosis improved at 4-months and 12-months in participants with moderate hyperkyphosis (-2.4 ° and -3.0 °) and severe hyperkyphosis (-5.7 ° and -8.0 °). Functional reach scores were lower in the severe hyperkyphosis group compared to normal and hypokyphosis groups by at least 2.3 cm. 6MWT scores were worse in the severe hyperkyphosis group compared to the normal kyphosis group by 39.6 m. SPPB scores were worse in severe hyperkyphosis group compared to the normal kyphosis group by 0.72 points, but all participants, regardless of kyphosis severity, improved SPPB at 4 months by 0.42 points and at 12 months by 0.25 points. CONCLUSIONS: Results suggest that presenting with hyperkyphosis and osteoporotic vertebral fracture does not prevent improvement in thoracic curvature and physical performance after physiotherapy compared with baseline values. While higher kyphosis correlated with poorer physical function scores, baseline kyphosis severity could not predict change in physical function measures. REGISTRY: ISRCTN 49117867.