Prevalence of Cam and Pincer Deformities in the X-Rays of Asymptomatic Individuals.

Steffen Thier,Daniel Gerisch,Christel Weiss,Stefan Fickert,Alexander Brunner

doi:10.1155/2017/8562329

Abstract

Objective The presence of radiological signs of femoroacetabular impingement (FAI) is not necessarily associated with symptoms. Hence, the prevalence of cam and pincer deformities in the overall population may be underestimated. The purpose of this study was to screen an unselected cohort of people without hip symptoms for native radiological signs of cam and pincer deformities to determine their actual prevalence. Materials and Methods 110 asymptomatic patients had AP pelvis X-rays and cross-table hip X-rays performed. We evaluated the images for the presence of cross-over signs and measured lateral center edge (LCE) angles, alpha angles (α-angles), and femoral offset ratios. Results Positive cross-over signs were seen in 34%; LCE angles > 40° in 13%; and femoral offset ratios < 0.18 in 43%. In 41% of the patients, α-angles were >50°. Male patients showed significantly higher α-angles, lower offset ratios, and a higher prevalence of cross-over signs. In contrast, female patients had significantly higher LCE angles. Conclusion According to our data, radiological signs of cam and pincer deformities are common in asymptomatic people. In clinical practice, patients presenting with hip pain and radiological signs of FAI should undergo further diagnostic evaluation. However, in asymptomatic patients, no further evaluation is recommended.

Highlights

During the last decade, femoroacetabular impingement (FAI) has been commonly recognized as a cause of chronic hip pain and a possible predisposing condition for the development of early osteoarthritis [1,2,3,4,5]
We evaluated the images for the presence of cross-over signs and measured lateral center edge (LCE) angles, alpha angles (α-angles), and femoral offset ratios
Patients presenting with hip pain and radiological signs of FAI should undergo further diagnostic evaluation

Summary

Introduction

Femoroacetabular impingement (FAI) has been commonly recognized as a cause of chronic hip pain and a possible predisposing condition for the development of early osteoarthritis [1,2,3,4,5]. FAI may be caused by two major types of anatomic abnormalities. Cam-type FAI is characterized by an aspherical configuration of the femoral head-neck junction, and pincer-type FAI is associated with acetabular overcoverage or retroversion. A considerable percentage of people with cam or pincer deformities may not feel any pain, and their anatomic pathology may remain undetected. A number of studies have been performed to evaluate the prevalence of cam or pincer deformities in asymptomatic people. Hack et al reported a prevalence of 14% after screening 200 volunteers from their hospital staff using MRI [12]. Reichenbach et al evaluated a cohort of asymptomatic recruits with MRI and found a prevalence of 24% [13]. In regular participants of high impact sports (such as football, ice hockey, or skiing), even higher percentages—between 55% and 87%—have been reported [14,15,16]

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Conclusion