Moving Beyond the 2018 Minimum International Care Considerations for Osteoporosis Management in Duchenne Muscular Dystrophy (DMD)

Individuals living with Duchenne muscular dystrophy (DMD) are at significant risk of bone fragility due to osteoporosis, with the most potent drivers of fragility fractures in this context stemming from the aggressive myopathy and long term oral glucocorticoid therapy. Young people with DMD have a high fracture burden, with reported total and vertebral fracture rates that are four [1, 2] and 535 times [1] higher than those of healthy growing boys, respectively. Vertebral fractures can occur as early as six months following daily glucocorticoid initiation [3]. Up to 75% of young people with DMD sustain at least one fracture after eight years of glucocorticoid therapy [4]. Fractures in DMD can lead to devastating outcomes, including steeper rates of functional decline, premature and permanent loss of ambulation, chronic pain, and even death from fat embolism syndrome or adrenal crisis following long bone fractures [2, 5–8]. The potential for serious consequences and medical complications linked to fractures has driven efforts to develop effective guidelines for timely bone health surveillance and treatment with more recent efforts to develop fracture prevention strategies.

To guide clinicians in the management of DMD and its related co-morbidities (including skeletal health), the first internationally-endorsed, minimum standards of care were published in 2010 under the moniker “Clinical Care Considerations” [9, 10]. This document recommends that osteoporosis monitoring include spine x-rays if back pain or kyphosis is present, followed by initiation of intravenous bisphosphonate therapy if vertebral fractures are identified [10]. In the years following the inaugural 2010 Clinical Care Considerations, studies were published showing that vertebral fractures, a key manifestation of bone fragility among children and adults living with glucorticoid-treated chronic conditions, were frequently asymptomatic, necessitating routine surveillance for early detection [3, 11]. It was also better appreciated that even a single long bone fracture can signal osteoporosis in a persistently high-risk setting such as DMD, and prompt initiation of bone protection therapy is important.

With this new knowledge, the latest international, minimum standards of clinical care for DMD published in 2018, known as Care Considerations [12–14], recommended routine, standardized spine imaging for early detection of vertebral fractures, combined with more timely bone-targeted (bisphosphonate) intervention in the presence of vertebral or low trauma long bone fractures [12]. At the same time, the ever-changing therapeutic landscape for the treatment of the underlying condition calls for ongoing examination of the intimate relationship between muscle and bone development in DMD, including the effect of different DMD treatment approaches on the skeletal and endocrine systems. The overall goal of such focus is to harvest discussions about optimal management that will foster bone strength and prevent fractures in this high-risk setting across all underlying disease-targeted treatment paradigms for people with DMD.