Prevalence of radiographic findings of femoroacetabular impingement in the Japanese population

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.

Prevalence of radiological femoroacetabular impingement in Japanese hip joints: detailed investigation with computed tomography

“…Mori et al [8] identified radiographic evidence of FAI in 29.7 % of patients during an investigation of OA patients with hip pain corresponding to grade 0 or 1 in the Tönnis classification. Meanwhile, Fukushima et al [9] presented radiographic evidence of radiographic FAI in 27.6 % of 87 patients who had undergone total hip arthroplasty, with no pain on the contralateral side, during the procedure in a retrospective examination. Additionally, Takeyama et al [24] reported on the causes of hip OA in Japan.…”

“…A pincer deformity is defined as a morphological abnormality of the acetabular side of FAI, and is characterized by excessive anterior coverage at the superior acetabulum or acetabular retroversion. Many studies have described these radiographic deformities and the prevalence of FAI [3][4][5][6][7][8][9]. However, many of the reports were roentgenogram image investigations, which run the risk of being affected by the patient's position and posture [10,11].…”

Femoroacetabular Impingement: Prevalent and Often Asymptomatic in Older Men: The Osteoporotic Fractures in Men Study

“…In addition, most reports on the prevalence of FAI come from surgical populations and may not represent the prevalence in the general population [2,16,21]. Not only is the prevalence of FAI determined for all the ages, but, from recent studies, it is not yet clear (1) if FAI represents a normal variant or a condition associated with severe and aggressive arthritis; and (2) if this relationship changes with age [33,34].…”

“…The prevalence of FAI has been reported to range from 6% to 35%, depending on the criteria of inclusion of the population and the definitions of FAI [16]. In addition, most reports on the prevalence of FAI come from surgical populations and may not represent the prevalence in the general population [2,16,21].…”

CORR Insights®: Rotational Acetabular Osteotomy for Pre- and Early Osteoarthritis Secondary to Dysplasia Provides Durable Results at 20 Years

“…Anterior femoroacetabular impingement (FAI), a well-described cause of failure to preserve the re-orientated joint, could be another confounder for the poorer outcome after Bernese periacetabular osteotomy in Western populations. FAI is less prevalent amongst Japanese compared to Caucasians [3,8,9,11] and this could have a positive impact on the chances of preserving the re-orientated joint in this cohort. Future studies will need to address these gaps in our knowledge.…”