Machine-learning derived acetabular dysplasia and cam morphology are features of severe hip osteoarthritis: findings from UK Biobank

Monika Frysz* (Corresponding Author), Benjamin G Faber, Raja Ebsim, Fiona Saunders, Claudia Lindner, Jenny Gregory, Richard Malcolm Aspden, Nicholas C Harvey, Timothy Cootes, Jonathan H. Tobias

*Corresponding author for this work

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The contribution of shape changes to hip osteoarthritis (HOA) remains unclear, as is the extent to which these vary according to HOA severity. In the present study, we used statistical shape modelling (SSM) to evaluate relationships between hip shape and HOA of different severities using UK Biobank DXA images. We performed a cross-sectional study in individuals with left hip DXA scans. Statistical shape modelling (SSM) was used to quantify hip shape. Radiographic HOA (rHOA) was classified using osteophyte size and number, and joint space narrowing. HOA outcomes ranged in severity from moderate (grade 2) or severe (grade ≥3) rHOA, hospital diagnosed HOA, and subsequent total hip replacement (THR). Confounder-adjusted logistic regression between the top ten hip shape modes (HSMs) and OA outcomes was performed. Further models adjusted for alpha angle (AA) and lateral centre-edge angle (LCEA), reflecting acetabular dysplasia and cam morphology respectively. Composite HSM figures were produced combining HSMs associated with separate OA outcomes. A total of 40,311 individuals were included (mean 63.7 years, 47.8% male), of whom 5.7% had grade 2 rHOA, 1.7% grade ≥3 rHOA, 1.3% hospital diagnosed HOA, and 0.6% underwent THR. Composite HSM figures for grade 2 rHOA revealed femoral neck widening, increased acetabular coverage, and enlarged lesser and greater trochanters. In contrast, grade ≥3 rHOA, hospital diagnosed HOA and THR were suggestive of cam morphology and reduced acetabular coverage. Associations between HSMs depicting cam morphology and reduced acetabular coverage and more severe HOA were attenuated by AA and LCEA adjustment, respectively. Relationships between hip shape and HOA differed according to severity. Notably, cam morphology and acetabular dysplasia were features of severe HOA, but unrelated to moderate disease, suggesting possible prognostic utility.
Original languageEnglish
Pages (from-to)1720-1732
Number of pages13
JournalJournal of Bone and Mineral Research
Issue number9
Early online date7 Aug 2022
Publication statusPublished - 1 Sept 2022

Bibliographical note

Acknowledgements and disclosures
The authors would like to thank Dr Martin Williams, Consultant Musculoskeletal Radiologist North Bristol NHS Trust, who provided substantial training and expertise in osteophyte assessment on DXA images. This research has been conducted using the UK Biobank Resource (application number 17295).
Financial Support:
RE, MF, FS are supported, and this work is funded by a Wellcome Trust collaborative award (reference number 209233). BGF is supported by a Medical Research Council (MRC) clinical research training fellowship (MR/S021280/1). CL was funded by the MRC, UK (MR/S00405X/1) as well as a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (223267/Z/21/Z). NCH acknowledges support from the MRC and NIHR Southampton Biomedical Research Centre, University of Southampton, and University Hospital Southampton. This research was funded in whole, or in part, by the Wellcome Trust [Grant number 223267/Z/21/Z].
NCH has received consultancy, lecture fees and honoraria from Alliance for Better Bone Health, AMGEN, MSD, Eli Lilly, Servier, UCB, Shire, Consilient Healthcare, Kyowa Kirin and Internis Pharma.
For the purpose of open access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.

Data Availability Statement

The data from this study will be available from UK Biobank in a forthcoming data release. Users must be registered with UK Biobank to access their resources (


  • osteoarthritis
  • hip shape
  • statistical shape modelling
  • cam morphology
  • acetabular dysplasia


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