title: Hip flexion after Birmingham hip resurfacing: role of cup anteversion, anterior femoral head-neck offset, and head-neck ratio.
abstract: We aimed to investigate the factors affecting range of flexion after hip resurfacing. A total of 82 cases, operated by a single surgeon, were assessed at a mean of 43 months. The Einzel-Bild-Roentgen-Analysis for the acetabular cup software was used to measure socket orientation. Range of flexion had a moderate positive correlation with cup anteversion (R = 0.26, P = .017), weak but significant negative correlation with neck diameter (R = -0.23, P = .042), and none with anterior femoral head-neck offset. Using multivariate analysis that adjusted for age, sex, cup anteversion and inclination, head-neck offset ratio, head-neck ratio, and neck diameter, the only significant correlate of flexion was cup anteversion (P = .017). Care should be taken during cup placement to allow adequate anteversion to be maintained in Birmingham hip resurfacing because this can affect flexion range of motion.
authors.affiliation: Department of Orthopaedics, Freeman Hospital, Newcastle upon Tyne, United Kingdom.
authors.forename: Ajay
authors.initials: A
authors.lastname: Malviya
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Lingard
authors.forename: Atul
authors.initials: A
authors.lastname: Malik
authors.forename: Russell
authors.initials: R
authors.lastname: Bowman
authors.forename: James P
authors.initials: JP
authors.lastname: Holland
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D015999:Multivariate Analysis; D011859:Radiography; D016059:Range of Motion, Articular; D012044:Regression Analysis; D012189:Retrospective Studies; D016896:Treatment Outcome