Doctor of Philosophy (PhD) in Physical Therapy
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College of Health Care Sciences - Physical Therapy Department
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Nova Southeastern University
Tina Duong. 2020. Impact of Strength and Range of Motion on Loss of Ambulation and Functional Change Measures in Boys with DMD. Doctoral dissertation. Nova Southeastern University. Retrieved from NSUWorks, College of Health Care Sciences - Physical Therapy Department. (189)
Duchenne muscular dystrophy (DMD) is an x-linked lethal progressive disorder affecting boys who are typically diagnosed due to motor delays or weakness. Key features include loss of motor function throughout the lifetime resulting in early mortality from cardiopulmonary complications in the late 2nd and 3rd decades of life. Rates of progression are variable yet sequential due to a typical pattern of motor weakness that occurs from proximal to distal muscle groups. Current standards of care include contracture management and Glucocorticosteroids (GC). Timed function tests have been used to understand and predict loss offunctional milestones such as walking, getting off the ground and going upstairs. This study will describe contracture development; associated strength loss and its effect on function for boys with DMD. With differing rates of decline in boyswith DMD, this study will also determine minimal clinical important difference (MCID) based on annual progression rates of 3 critical timed function tests (supine to stand, climb 4 stairs and 10meter walk test).
This is a retrospective study of the largest natural history of 440 boys with DMD. Data was collected by physical therapists ina standardized manner across 22 sites in 9 countries. Mixed models with repeated measures were used to understand therelationship between knee strength, ankle range of motion, GC use and timed function tests. Linear regressions were used to assess the effect of ankle range of motion and strength measures on functional ability. Anchor based MCID measures were calculated based on change of the Vignos scale, an 8 point lower extremity functional scale.
Results found that there is great variability in contracture development in boys with DMD and that a 12-month time frame may be too short to assess contracture changes. Knee strength and ankle ROM are good predictors of loss of function. In an anticipatory care model, MCID values for these functional tests are important in clinical management and necessary for design of clinical trials.
Contractures, Duchenne, MCID, muscular dystrophy, Natural history, Timed tests