Patients with Duchenne muscular dystrophy (DMD) appear to have a higher rate of fractures than the average population. These fractures could have a significant long-term impact on their quality of life, according to a recently published study in Muscle and Nerve.

Due to the improvement in survival for patients with DMD in recent decades, there is a growing interest in developing interventions to improve long-term quality of life and prolong the functional capacity of patients, the study authors noted. Fracture prevention is currently regarded as 1 of these interventions, they added.

According to some series, pathological fractures occur in over 40% of patients with DMD. They are known to have detrimental effects on maintaining independent mobility and functional capacity, the researchers said.


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“Major contributors to fractures in boys with DMD are falls due to weakness, prolonged immobilization, and glucocorticoid-induced osteoporosis, particularly in vertebral bone,” the authors wrote. 

The authors aimed to determine the rate of fractures, investigate the factor influencing fractures and assess the impact of fractures on functional capacity through a retrospective cohort study using the medical records of 155 children with DMD treated in the Royal Children’s Hospital in Melbourne, Australia.

Researchers assessed the presence of risk factors in each fracture by analyzing clinical data up to 2 years before the fracture. Functional assessment of the included patients was carried out with timed function tests like 10 m walk/run and 4 stairs ascend as well as North Star Ambulatory Assessment scores for ambulatory boys and Egen Klassifikation Scale Version 2 scores for nonambulatory boys.

The majority of patients received treatment with corticosteroids. Of the studied cohort, 46% of patients had at least 1 fracture, and 95% of these patients had received corticosteroid therapy with either prednisolone or deflazacort. Cox regression analysis showed no significant correlation between corticosteroid treatment length and risk of fracture.

According to statistical analysis, a higher body-mass index at 6 to 9 years of age was directly correlated with greater fracture risk. Fifty-three patients received prophylactic bisphosphonate; of this group, 9 patients never reported a fracture event.

“While high BMI showed univariant relation to fracture risk, this needs to be interpreted with caution. This study does not infer an independent association of obesity with fracture risk as it did not adjust for the effect of individual steroid dosage or steroid regimen,” the authors concluded.

Fractures were classified into vertebral fractures and nonvertebral fractures. The authors noted that patients with a history of vertebral fracture were older and had a longer duration of corticosteroid treatment. Thus suggesting a link between longer corticosteroid use and vertebral fractures.

Reference

Liaw J, Billich N, Carroll K, et al. Fracture risk and impact in boys with Duchenne Muscular Dystrophy: a retrospective cohort study. Muscle Nerve. Published online December 7, 2022. doi:10.1002/mus.27762