Pulmonary function and spinal characteristics: Their relationships in persons with idiopathic and postpoliomyelitic scoliosis

Objective: To identify what influence the various features of spinal deform ity have on pulmonary function in persons with idiopathic and the postpolio myelitic scoliosis. Design: Prospective, cohort, observational study with clinical and radiolog ic evaluations. Setting: Hospital-based rehabilitation units. Patients: Forty-four patients with idiopathic scoliotis and 16 with postpol iomyelitic scoliotis. Each group was divided into subgroups: normal and abn ormal pulmonary function. Intervention: Clinical and radiologic evaluation of spinal deformity, full pulmonary functional test and respiratory muscle strength were performed. P resence of dyspnea on exertion and low back pain (LBP) was recorded. Main Outcome Measures: Pulmonary function: spirometry, lung volume test, an d diffusing capacity. Respiratory muscle strength: maximal inspiratory pres sure (MIP) and maximal expiratory pressure (MEP). Presence of dyspnea on ex ertion (DOE), and LBP were also recorded. Characteristics of spinal deformi ty: direction of convexity, uppermost vertebra, number of involved vertebra e, Cobb angle, the apical vertebra, degree of rotation at the apical verteb ra, type of scoliotic curve, and presence of balanced spine and pelvic obli quity. Chi-square analyses and Mann-Whitney U test for between-groups compa risons. Spearman's rho correlation coefficient to determine the existence a nd magnitude of a relationship. Results: We found significant differences between the idiopathic and postpo liomyelitis groups in the degree of rotation at the apical vertebra, MIP, a verage percentage of predicted vital capacity, residual volume/total lung c apacity, presence of double or triple curves, pelvic obliquity, and DOE. Be tween the idiopathic scoliotis subgroups we found significant differences i n the uppermost vertebra and number of vertebrae in the scoliotic curve. Be tween the subgroups of the postpoliomyelitis group were significant differe nces in the location of the apical vertebra and the uppermost vertebral bod y of scoliotic curve. In the idiopathic group, pulmonary function was mostl y related to scoliotic angle, number of vertebrae in the scoliotic curve, l ocation of the uppermost vertebra, and the patients' age; MIP and MEP were negatively related to the scoliotic angle and degree of rotation of apical vertebra. In the postpoliomyelitis group, pulmonary function was mostly rel ated to scoliotic angle, kyphotic angle, location of the uppermost vertebra of the scoliotic curve, and age. Conclusion: No single factor can predict the severity of impairment in scol iotic patients' pulmonary function. In both groups, severity of pulmonary i mpairment was related to the combined features of the spinal deformity. How ever, uppermost vertebra, scoliotic angle, and patient's age may play impor tant roles influencing pulmonary function in both groups.