Abstract
BACKGROUND: Increment of lumbar lordosis, a frequent spinal finding in Duchenne Muscular Dystrophy (DMD), is a compensatory mechanism secondary to muscle weakness. However, excessive lumbar lordosis may change the position of the center of mass, and lead to balance and walking difficulties. OBJECTIVE: To study the relationship between factors that may influence ambulatory function in boys with DMD and to investigate the effects of lumbar lordosis increment on gait and balance perturbations. METHODS: Twenty-one ambulant patients with DMD and 10 healthy boys were included. Lumbar lordosis and thoracic kyphosis angles, dynamic and static balance tests, ambulatory function, muscle strength, and disease severity were assessed. Usage of steroids and orthotic devices were recorded. Scoliosis was assessed on radiographs. Receiver operator characteristic curves were formed and area under curve (AUC) measurements were performed to assess the ability of the tests to discriminate ambulatory status and optimal cut-off values were established according to the Youden index. RESULTS: The amount of lumbar lordosis correlated strongly and negatively with quality of ambulation (r = -0.710) and moderately with performance on balance tests. The strength of both upper limbs and lower limbs muscles were not associated with any of the variables. According to the AUC analysis, patients with a lumbar lordosis higher than 36° had worse scores on gait and dynamic balance tests. CONCLUSION: Ambulation and dynamic balance are negatively affected by the increment of lumbar lordosis with a cut-off point of 36°in boys with DMD.