title: Three-dimensional assessment of impingement risk in geometrically parameterised hips compared with clinical measures.
abstract: Abnormal bony morphology is a factor implicated in hip joint soft tissue damage and an increased lifetime risk of osteoarthritis. Standard 2-dimensional radiographic measurements for diagnosis of hip deformities, such as cam deformities on the femoral neck, do not capture the full joint geometry and are not indicative of symptomatic damage. In this study, a 3-dimensional geometric parameterisation system was developed to capture key variations in the femur and acetabulum of subjects with clinically diagnosed cam deformity. The parameterisation was performed for computed tomography scans of 20 patients (10 female and 10 male). Novel quantitative measures of cam deformity were taken and used to assess differences in morphological deformities between males and females. The parametric surfaces matched the more detailed, segmented hip bone geometry with low fitting error. The quantitative severity measures captured both the size and the position of cams and distinguished between cam and control femurs. The precision of the measures was sufficient to identify differences between subjects that could not be seen with the sole use of 2-dimensional imaging. In particular, cams were found to be more superiorly located in males than in females. As well as providing a means to distinguish between subjects more clearly, the new geometric hip parameterisation facilitates the flexible and rapid generation of a range of realistic hip geometries including cams. When combined with material property models, these stratified cam shapes can be used for further assessment of the effect of the geometric variation under impingement conditions.
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Robert J
authors.identifier: 0000-0001-5255-1486
authors.initials: RJ
authors.lastname: Cooper
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Marlène
authors.initials: M
authors.lastname: Mengoni
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Dawn
authors.initials: D
authors.lastname: Groves
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Sophie
authors.initials: S
authors.lastname: Williams
authors.affiliation: Guy's Hospital, Great Maze Pond, London, SE1 9RT, UK.
authors.forename: Marcus J K
authors.initials: MJK
authors.lastname: Bankes
authors.affiliation: Leeds Musculoskeletal Biomedical Research Unit, Chapel Allerton Hospital, Leeds, LS7 4SA, UK.
authors.forename: Philip
authors.initials: P
authors.lastname: Robinson
authors.affiliation: Institute of Medical and Biological Engineering, School of Mechanical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Alison C
authors.initials: AC
authors.lastname: Jones
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000473:pathology; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D014057:Tomography, X-Ray Computed
keywords: alpha angle; femoroacetabular impingement; geometric parameterisation; hip joint; parametric model; radiographic measures