Risk Factors of Impaired Pulmonary Function in Arthrogryposis Multiplex Congenital Patients With Concomitant Scoliosis: A Comparison With Adolescent Idiopathic Scoliosis.

STUDY DESIGN: A retrospective study.

OBJECTIVE: To investigate the severity of pulmonary function impairment for arthrogryposis multiplex congenital (AMC) patients with concomitant scoliosis and to determine risk factors associated with the impaired pulmonary function in these patients.

SUMMARY OF BACKGROUND DATA: AMC patients are generally believed to have impaired pulmonary function. However, the severity of respiratory morbidity and the associated risk factors have not been reported.

METHODS: The pulmonary function tests data including the percentage predicted values of forced vital capacity (%FVC), forced expiratory volume in 1 second (%FEV1), and the ratio of FEV1 to FVC (%FEV1/FVC) were reviewed and compared for 48 AMC patients with secondary scoliosis and 48 patients with adolescent idiopathic scoliosis. The radiographic parameters of coronal and sagittal plane deformities and body mass index (BMI) were measured and correlated with impaired pulmonary function in these AMC patients.

RESULTS: AMC patients with concomitant scoliosis had significant lower mean %FVC, %FEV1, and %FEV1/FVC than adolescent idiopathic scoliosis patients (48.8 vs. 70.3 for %FVC, P < 0.001; 45.3 vs. 69.7 for %FEV1, P < 0.001; 92.1 vs. 96.9 for %FEV1/FVC, P < 0.05, respectively). Seventy percent of AMC patients had severe pulmonary function impairment. A positive correlation was found between BMI and %FVC and %FEV1 (P < 0.01) and between hypokyphosis and %FVC and %FEV1 (P < 0.05). A negative correlation was found between coronal angle and pulmonary function (P < 0.05). Multiple regression analysis showed that all of the three variables were independent predictors associated with a reduced pulmonary function. With a combination of these variables, the multiple regression model could account for 38.7% of the variance in %FVC and 41.5% in %FEV1.

CONCLUSION: There exists severe impairment of pulmonary function in AMC patients with concomitant scoliosis. The scoliotic curve, hypokyphosis, and BMI were independent risk factors associated with the pulmonary dysfunction in these patients. As the majority of the variability of impaired pulmonary function tests are still poorly understood, more risk factors await to be uncovered in future studies.

LEVEL OF EVIDENCE: 4.