Are cam and pincer deformities as common as dysplasia in Japanese patients with hip pain?

Abstract

In Japan, osteoarthritis (OA) of the hip secondary to acetabular dysplasia is very common, and there are few data concerning the pathogeneses and incidence of femoroacetabular impingement (FAI). We have attempted to clarify the radiological prevalence of painful FAI in a cohort of Japanese patients and to investigate the radiological findings. We identified 176 symptomatic patients (202 hips) with Tönnis grade 0 or 1 osteoarthritis, whom we prospectively studied between August 2011 and July 2012. There were 61 men (65 hips) and 115 women (137 hips) with a mean age of 51.8 years (11 to 83). Radiological analyses included the α-angle, centre-edge angle, cross-over sign, pistol grip deformity and femoral head neck ratio. Of the 202 hips, 79 (39.1%) had acetabular dysplasia, while 80 hips (39.6%) had no known aetiology. We found evidence of FAI in 60 hips (29.7%). Radiological FAI findings associated with cam deformity were the most common. There was a significant relationship between the pistol grip deformity and both the α-angle (p < 0.001) and femoral head-neck ratio (p = 0.024). Radiological evidence of symptomatic FAI was not uncommon in these Japanese patients.

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

“…In the present study, we employed an abnormal cut-off of the AAFH of >50°; namely an α-angle of >50° [3,6,8]. According to this criterion, cam deformity was detected in 51.5 % of the hips.…”

“…However, several authors have recently reported the prevalence of FAI in Japanese populations using radiography. 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.…”

“…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

“…Radiologic characteristics of femoroacetabular impingement (FAI) are also present in individuals without clinical symptoms either because the symptoms only develop in more advanced stages of arthrosis associated with FAI features or because FAI features in some individuals may be only an anatomic variant [38]. Radiographic features of FAI have been defined by three distinct definitions of the underlying anatomic deformity: pincer, cam, and mixed.…”

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.…”