Acetabular Protrusio and Proximal Femur Fractures in Patients With Osteogenesis Imperfecta.
BACKGROUND
Osteogenesis imperfect (OI) is a genetic disorder characterized by increased bone fragility, frequent fractures, and extremity deformities among other clinical findings. A frequent radiographic finding in OI patients is acetabular protrusio (AP). We hypothesized that AP incidence would be significant in OI patients and highest among type III OI patients, who have a more severe disease phenotype. In addition, we hypothesized that there would be a correlation between AP and proximal femur fracture incidence.


METHODS
We retrospectively reviewed radiographs and medical records of 49 patients with OI evaluated at our institution. Demographic information and modified Sillence classification were recorded. AP was diagnosed using previously published radiographic criteria using the center-edge angle of Wiberg, acetabulum relative to the iliopectineal line, teardrop figure relative to the ilioischial (Kohler) line, and acetabulum relative to the ilioischial (Kohler) line. Medical record and radiographs were reviewed for evidence of proximal femur or acetabulum fracture. Associations between OI type, AP, and fracture incidence were examined with χ or Fisher exact tests.


RESULTS
In this series of 49 OI patients, the overall incidence of AP was 55.1% (27/49) with the highest incidence among patients with type III OI (70.6%). There was an increased incidence of proximal femur, and particularly femoral neck, fractures among patients with AP compared with patients with normal hip anatomy. Overall, patients with AP had a 30% increased risk for proximal femur and acetabulum fractures (P=0.03).


CONCLUSIONS
AP is a common deformity in OI patients (55.1%) and particularly type III OI (70.6%). Patients with AP have an increased risk for proximal femur fractures and particularly femoral neck fractures. This novel finding adds to the growing body of literature on clinical implications of AP in OI patients.


METHODS
Level IV-Retrospective case series.
*Hospital for Special Surgery, New York ‡SUNY Downstate College of Medicine, Larchmont, NY †Royal Manchester Children's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK.
Samir K
SK
Trehan
Emmanouil
E
Morakis
Cathleen L
CL
Raggio
Kristin D
KD
Twomey
Daniel W
DW
Green
D000077:Acetabulum / Q000000981:diagnostic imaging / Q000293:injuries*; D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D005265:Femoral Neck Fractures / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology; D006801:Humans; D015994:Incidence; D008297:Male; D010013:Osteogenesis Imperfecta / Q000145:classification / Q000150:complications* / Q000000981:diagnostic imaging; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D055815:Young Adult