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Osteogenesis imperfecta severity affects femoral fracture characteristics
Osteogenesis imperfecta type, and not bisphosphonate exposure, influences the location, type and pattern of fractures, according to findings published in The Journal of Clinical Endocrinology & Metabolism.
“Bisphosphonate treatment during childhood in children with [osteogenesis imperfecta] is safe and does not cause atypical femoral fractures,” Outi Mäkitie, MD, PhD, professor of pediatric endocrinologicy, Children’s Hospital, University of Helsinki and Helsinki University Hospital in Finland, Endocrine Today. “This study supports the long-term safety of this treatment.”
Mäkitie and colleagues evaluated 93 patients (age range, 1-22 years) with osteogenesis imperfecta born between 1990 and 2012 to determine the effect of bisphosphonates on characteristics of femoral fractures. Patients were divided into three groups based on bisphosphonate treatment: those without exposure to bisphosphonates, those with ongoing bisphosphonate treatment, and those with discontinued treatment.
Overall, 127 femoral fractures occurred in 24 patients; 11 had type 1 osteogenesis imperfecta, six had type 3 and seven had type 4. Most fractures occurred in patients with osteogenesis imperfecta type 4 (57%), followed by type 3 (22%) and type 1 (20%). The fractures were most commonly in the mid- or distal shaft (41%), followed by subtrochanteric (33%) and distal (20%). Most were the transverse type (65%), followed by oblique (28%).
Overall, 35% of femoral fractures occurred in the ongoing treatment group, 16% in the discontinued treatment group and 50% in the treatment-naive group. All three bisphosphonate treatment groups had similar distributions of fracture location and type and pattern of fractures. Participants in the naive treatment group experienced refractures more frequently (21%) compared with the ongoing treatment group (5%) and discontinued treatment group (10%; P = .049).
“There have been concerns related to long-term safety of bisphosphonate use in children with osteogenesis imperfecta,” Mäkitie told Endocrine Today. “In adults treated for age-related or secondary osteoporosis, bisphosphonates have in some cases caused so called atypical femoral fractures. We therefore evaluated this study in a cohort of [osteogenesis imperfecta] children for characteristics of femoral fractures to see whether the fractures were different in children who had received bisphosphonates as compared with those fractures that occurred in patients who had not received bisphosphonates. Our careful evaluation of all radiographs taken at the time of femoral fractures indicated that the characteristics or location of fractures was not influences by bisphosphonate treatment and there was no evidence of atypical femoral fractures in [osteogenesis imperfecta] children who had received bisphosphonates. In contrast, severity of [osteogenesis imperfecta] did correlate with fracture characteristics, distal location and transverse configuration being more common in the more severe types 3 and 4 compared with the mildest form, type 1 [osteogenesis imperfecta].” – by Amber Cox
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Outi Mäkitie , MD, PhD, can be reached at outi.makitie@helsinki.fi.
Disclosure: Mäkitie reports financial ties with Alexion, Kyowa Kirin and Merck.