Mobility in osteogenesis imperfecta: a multicenter North American study

Purpose: Osteogenesis imperfecta (OI) is a genetic connective tissue disorder that causes bone fragility. Phenotypic severity influences ability to walk, however, little is known about ambulatory characteristics of individuals with OI, especially in more severe forms. The purpose of this work was to characterize mobility in OI using standard clinical assessment tools and determine if patient characteristics could be used to predict mobility outcomes. Methods: We collected mobility data at five clinical sites to analyze the largest cohort of individuals with OI (n = 491) to date. Linear mixed models were developed to explore relationships among subject demographics and mobility metrics. Results: Results showed minor limitations in the mild group while the more severe types showed more significant limitations in all mobility metrics analyzed. Height and weight were shown to be the most significant predictors of mobility. Relationships with mobility and bisphosphonates varied with OI type and type used (oral/IV). Conclusion: These results are significant to understanding mobility limitations of specific types of OI and beneficial when developing rehabilitation protocols for this population. It is important for physicians, patients, and caregivers to gain insight into severity and classification of the disease and the influence of disease-related characteristics on prognosis for mobility.