Relationship between cam morphology, hip symptoms, and hip osteoarthritis: the Musculoskeletal pain in Ullersaker STudy (MUST) cohort

Background: The primary aim of this study was to determine the prevalence of cam morphology in a cohort of people aged 40–55 years. Secondary aims were to: (1) determine differences in participant characteristics, physical impairments, radiographic and ultrasound appearances of people with and without cam morphology; and (2) explore associations between cam morphology and radiographic measures of hip osteoarthritis (OA). Methods: 107 people (68% women; 49 ± 4 years) from the Musculoskeletal pain in Ullensaker (MUST) Study underwent the clinical and imaging examinations. Examinations included questionnaires, hip range, functional task performance, pelvic radiographs and ultrasound. Alpha angle and radiographic hip OA (Kellgren Lawrence (KL) and minimal joint space (MJS)) were determined. Results: The prevalence of cam morphology was 42% and was bilateral in 47%. People with cam morphology were 6 times more likely to have a KL score ⩾2 (adjusted odds ratio [95% confidence intervals, p-value]) 6.386 [1.582–37.646, p = 0.012]) and 4 times more likely to have MJS <2.0 mm (adjusted odds ratio 4.032 [1.031–12.639, p = 0.045]). The prevalence of radiographic OA features ranged from 4–13% in people with cam morphology, and 0–3% in those without. Those with cam morphology also demonstrated reduced hip flexion and rotation range (p = 0.018–0.036) compared with those without. There was no association between ultrasonic features and patient reported outcomes, and cam morphology. Conclusions: In a cohort aged 40–55 years, the prevalence of cam morphology was high (42%), with a significant relationship between cam morphology and radiographic measures of hip OA. Further longitudinal studies should explore the relationship between cam morphology and hip OA in younger people.

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