Spinal deformities and lung function in adults with osteogenesis imperfecta

Introduction: There are no larger studies of adults with osteogenesis imperfecta (OI), focusing on the impact of spinal cord deformities on lung function assessment.

Objectives: To assess prevalence and severity of spinal deformities and lung function in an adult population with OI and to explore whether compromise of lung function correlated with deformities of the spine.

Methods: Ninety-two adults with OI had radiographs of the spine, 75 underwent spirometry. Deformities were assessed radiographically using a semi-quantitative (SQ) approach grading each vertebra from mild to severe (0-3 SQ grades). The spinal deformity index (SDI) was calculated by summing the SQ grades of all vertebrae from TH4 to L4. Scoliosis was measured using the Cobb method. Pulmonary function tests were performed; both current measured and arm-span height were used for calculating the predicted lung volumes and flow rates.

Results: Vertebral deformities were found in 67%, the majority of deformities were found in the mid thoracic region. Scoliosis was found in 46%, nine patients exhibited torsion scoliosis. Median values of SDI were 2.0 in type I, 4.0 in type IV and 2.5 in the total population. Only correction with arm-span height had a significant impact on the assessment of lung function. Significant negative correlations were obtained when spirometry variables were correlated to spine deformities.

Conclusions: OI patients show spinal deformities influencing body height and lung function. Lung function tests should be corrected for reductions in body height by using arm-span height. OI patients should be evaluated with spirometry when vertebral deformities are suspected.