Abstract
BackgroundFemoroacetabular impingement (FAI) is one factor known to cause pain and osteoarthritis (OA) of the hips. Although secondary OA due to hip dysplasia is common among Japanese populations, primary OA is seldom observed. Concomitantly, FAI is also thought to be uncommon in Japan, but relatively few epidemiological studies have addressed this issue. This study aimed to clarify the prevalence of radiographic findings of FAI in a Japanese population and to evaluate whether FAI is a risk factor for the development of arthritic changes.MethodsWe retrospectively examined 87 patients who underwent unilateral hip osteotomy with a Charnley category A hip joint on the contralateral side. Anteroposterior-view radiographs of the non-operated hip joint were assessed for the presence of hip dysplasia, as well as pistol grip deformity and crossover sign indicative of cam-type and pincer-type impingement, respectively. The presence of arthritic changes in the non-operated hip joint was assessed in follow-up radiographs, and factors contributing to the development of arthritis were determined by survival analysis.ResultsOf the 87 hips examined, dysplasia was noted in 38 (43.6%). While no pistol grip deformity was observed, crossover sign, which is indicative of pincer-type impingement, was identified in 9 of 38 dysplastic hips (23.7%) and 15 of 49 non-dysplastic hips (30.6%). Arthritic changes were present in 13 of 38 dysplastic hips (34.2%) and 11 of 49 non-dysplastic hips (22.4%). Survival analysis revealed that the presence of the crossover sign in non-dysplastic hips was significantly associated with the development of arthritis.ConclusionsThe prevalence of the crossover sign in hips in a Japanese population is similar to that reported in Western populations, despite the fact that FAI is believed to be less prevalent in the Japanese population. Furthermore, the presence of the crossover sign in non-dysplastic hip joints is associated with the development of arthritis. Based on our results, pincer-type impingement could be commonly associated with the development of arthritis in Japanese populations.
Highlights
Femoroacetabular impingement (FAI) is one factor known to cause pain and osteoarthritis (OA) of the hips
In the current study, we radiographically examined the prevalence of femoroacetabular impingement (FAI) in non-operated, asymptomatic, non-osteoarthritic hip joints in Japanese patients and assessed the development of arthritis in those with FAI
In the current study, survival analysis revealed that the presence of the crossover sign in non-dysplastic hips was significantly associated with the development of arthritis
Summary
Femoroacetabular impingement (FAI) is one factor known to cause pain and osteoarthritis (OA) of the hips. This study aimed to clarify the prevalence of radiographic findings of FAI in a Japanese population and to evaluate whether FAI is a risk factor for the development of arthritic changes. Gosvig et al [15] examined 4,151 individuals from the Copenhagen Osteoarthritis Substudy cohort between 1991 and 1994 for radiographical malformation and investigated the estimated risk of osteoarthritis between the hip morphological malformation. They concluded that a deep socket and a pistol grip deformity were common radiographic findings and associated with an increased risk of hip OA. Features of hip morphology among Europeans are thought to differ slightly from those of Asian populations, and whether their conclusions can be adapted to a Japanese population is unclear
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