Muscle impairments in osteogenesis imperfecta: a narrative review

The aim of this review is to provide an overview of the available evidence on the effects of OI on skeletal muscle. This encompasses multiple components of muscle function, underlying biological and environmental factors, clinical and functional consequences, and relevant epidemiology and therapeutic options. OI is a rare connective tissue disorder causing bone fragility and skeletal deformity, and extraskeletal features, including cardiac and dental abnormalities and hearing loss. The condition is also characterized by pronounced deficits in multiple aspects of skeletal muscle function, including lower muscle strength and power, impaired balance, and greater fatigability, resulting from lower muscle mass and poor muscle quality. These deficits have important implications for multiple aspects of health and general function, including mobility, fall and fracture risk, and the ability to carry out activities of daily living. The muscle weakness and impaired function in OI appear multi-factorial in origin, and factors including deficits in sensory, ventilatory, and metabolic function may compound those observed in muscle mass and quality. Little is known about the epidemiology of muscle in OI, with the exception that more severe OI types are associated with greater impairments in function and mass. Consideration should be given to which aspects of muscle health and function are most relevant for individuals with different OI types. There is a limited evidence base for interventions to improve muscle in OI, and current findings from physical activity and pharmacological therapies are mixed. Muscle represents an important and under-researched area of health and function in OI.