Abstract
SummaryObjectivesTo examine whether acetabular dysplasia (AD), cam and/or pincer morphology are associated with radiographic hip osteoarthritis (rHOA) and hip pain in UK Biobank (UKB) and, if so, what distribution of osteophytes is observed.DesignParticipants from UKB with a left hip dual-energy X-ray absorptiometry (DXA) scan had alpha angle (AA), lateral centre-edge angle (LCEA) and joint space narrowing (JSN) derived automatically. Cam and pincer morphology, and AD were defined using AA and LCEA. Osteophytes were measured manually and rHOA grades were calculated from JSN and osteophyte measures. Logistic regression was used to examine the relationships between these hip morphologies and rHOA, osteophytes, JSN, and hip pain.Results6,807 individuals were selected (mean age: 62.7; 3382/3425 males/females). Cam morphology was more prevalent in males than females (15.4% and 1.8% respectively). In males, cam morphology was associated with rHOA [OR 3.20 (95% CI 2.41–4.25)], JSN [1.53 (1.24–1.88)], and acetabular [1.87 (1.48–2.36)], superior [1.94 (1.45–2.57)] and inferior [4.75 (3.44–6.57)] femoral osteophytes, and hip pain [1.48 (1.05–2.09)]. Broadly similar associations were seen in females, but with weaker statistical evidence. Neither pincer morphology nor AD showed any associations with rHOA or hip pain.ConclusionsCam morphology was predominantly seen in males in whom it was associated with rHOA and hip pain. In males and females, cam morphology was associated with inferior femoral head osteophytes more strongly than those at the superior femoral head and acetabulum. Further studies are justified to characterise the biomechanical disturbances associated with cam morphology, underlying the observed osteophyte distribution.
Highlights
Hip osteoarthritis (OA) is a common condition that causes considerable morbidity often leading to costly total hip replacements (THR)[1,2]
alpha angle (AA) was greater in males [mean: 51.6] than females [44.2 (33.2e115.0)] and cam morphology, defined as AA !60, was more frequently found in males [519 (15.4%)] than females [63 (1.8%)] (Table I)
In a large cross-sectional study of 6,807 individuals, we found that cam morphology was associated with an increased risk of prevalent hip OA, as reflected by radiographic hip OA (rHOA) and self-reported hip pain
Summary
Hip osteoarthritis (OA) is a common condition that causes considerable morbidity often leading to costly total hip replacements (THR)[1,2]. Observational studies suggest cam morphology forms in adolescence when the metaphysis fuses, with increased physical activity implicated as a risk factor[13,14]. FAI syndrome is recognised as a cause of hip pain in younger individuals, diagnosis of which is supported by relevant examination findings and either cam and/or pincer morphologies in the absence of OA8,15. Several studies suggest that surgery to correct the hip morphologies implicated in FAI improves symptoms such as pain16e18. Surgery to correct these hip morphologies and prevent FAI might prove useful in reducing the risk of developing OA. FAI has been proposed to cause hip OA in patients with cam and/or pincer morphologies secondary to impingement[20] but as yet the precise mechanism remains unclear. No population studies have explored the distribution of osteophytes in individuals with these shape morphologies, which might give some indication as to any underlying biomechanical disturbance
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