HIP ISSN 1120-7000 Hip Int 2016; 26 (2): 164-168 © 2016 Wichtg Publishing ORIGINAL ARTICLE had a combinaton of both forms which is called the mixed- type (3-5). Although, the exact pathomechanism respon- sible for osteoarthrits (OA) of the nondysplastc hip has remained unknown, emerging clinical evidence implicatng FAI as an aetologic factor for early coxarthrosis has devel- oped in recent years (4, 6). Several studies in the literature have demonstrated that in many of the cases with idiopathic coxarthrosis, FAI may be present as a predisposing factor (1, 2, 7-9). Furthermore, FAI plays a causatve role in the need for total hip arthroplasty (THA) in certain patents (10). The actvity levels of the patent as well as the morphological ab- normalites or variatons have been mentoned as potental predictors of progressive degeneratve changes (11, 12). Ac- cording to their study discussing whether the natural course of FAI could be predicted, Audenaert et al (2) concluded that it was difcult to accurately predict the age at which a patent with FAI would develop early degeneratve arthritc chang- es. A radiological study demonstrated that mild to moder- ate osteoarthrits in hips with a pistol-grip deformity would not progress rapidly in all patents; progression would take more than 10 years to manifest in 1/3, and a hip with cam DOI: 10.5301/hipint.5000323 The prevalence of femoroacetabular impingement as an aetologic factor for end-stage degeneratve osteoarthrits of the hip joint: analysis of 1,000 cases Ali Oner 1 , Alper Koksal 2 , Hakan Sofu 3 , Umit S. Aykut 4 , Timur Yıldırım 4 , Mehmet A. Kaygusuz 4 1 Mengücekgazi Educaton and Research Hospital, Erzincan - Turkey 2 Merzifon Kara Mustafa Pasa State Hospital, Amasya - Turkey 3 Department of Orthopaedics and Traumatology, Erzincan University Faculty of Medicine, Erzincan - Turkey 4 Baltalimani Bone and Joint Diseases Educaton and Research Hospital, Istanbul - Turkey Introducton Femoroacetabular impingement syndrome (FAI) has been described as a mechanical hip disorder which leads to early and/or repettve contact between the acetabular rim and the proximal femur during joint moton, potentally result- ing in damage to the hip joint cartlage and labrum (1, 2). Depending on the clinical and radiographic fndings, 2 main types of FAI have been distnguished: pincer- and cam-type; however it has also been demonstrated that most patents AbSTrAcT Objectve: The main purpose of the present study was to determine the prevalence of FAI among patents who underwent total hip arthroplasty (THA) with the diagnosis of end-stage osteoarthrits (OA) of the hip joint in a tertary referral centre. Design: A retrospectve search of the insttutonal archive database for patents who had undergone THA be- tween the years 2005 and 2010 was conducted with the analysis of the recorded radiographic images. A total of 1,004 patents including 690 (68.7%) females and 314 (31.3%) males were identfed. All radiographs were re- viewed by 3 of the authors. Intra- and interobserver consistencies were calculated. The prevalence of femeroac- etabular impingement (FAI) as a predisposing diagnosis resultng in end-stage degeneratve joint disease treated with THA was determined. results: The most common diagnosis was developmental dysplasia of the hip (DDH). The predisposing aetologic factor leading to end-stage degeneratve hip disease treated with THA was undetermined for 26 patents (2.6%). The number of patents who were diagnosed as cam-type FAI by all of the observers was 83, whereas it was 16 for pincer-type FAI. Interobserver agreement was very high in the evaluaton of the stated ethiologies of hip osteoarthrits. The contngency coefcient for the diagnosis of FAI was 0.71 between observers. conclusions: Our study may be a reference for further investgatons to develop a beter understanding of the underlying pathological factors in patents undergoing THA due to end-stage OA of the hip joint. Keywords: Femoroacetabular impingement, Hip, Osteoarthrits, Total hip arthroplasty Accepted: October 18, 2015 Published online: February 23, 2016 corresponding author: Hakan Sofu Department of Orthopaedics and Traumatology Erzincan University Faculty of Medicine Basbaglar Mahallesi 24030 Erzincan, Turkey hakansofu@yahoo.com