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Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players



Femoroacetabular impingement (FAI) represents a novel approach to the mechanical etiology of hip osteoarthritis. The cam-type femoroacetabular impingement deformity occurs frequently in young male athletes. The aim of our study was to evaluate the prevalence of FAI in male semiprofessional soccer players using clinical examination and magnetic resonance imaging (MRI), compared to amateur soccer players. In MRI, the α angle of Nötzli is determined for quantifying FAI.

Materials and methods

According to power analysis, a total of 22 asymptomatic semiprofessional soccer players with a median of 23.3 years of age (range 18–30 years) and 22 male amateur soccer players with a median of 22.5 years of age (control group, range 18–29 years) underwent an MRI to measure the hip α angle of Nötzli. The α angle of the kicking legs of the semiprofessional group and the amateur group were analyzed. The study group was moreover evaluated by the Hip Outcome Score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests.


In the semiprofessional group, 19 soccer players had a right kicking leg and 1 soccer player had a left kicking leg. 2 soccer players kicked with two feet. In the semi-professional group, the mean value of the α angle of the kicking leg (57.3 ± 8.2°) was significantly higher than in the amateur group (51.7 ± 4.8°, P = 0.008). In the semi-professional group, 15 (62.5 %) of 24 kicking legs had an increased α angle >55°, while 5 (27.3 %) kicking legs of the amateur group had an α angle >55°. Five semi professional soccer players had findings in clinical examination, whereof 4 had an increased α angle >55°. No participant of the amateur group showed pathological results in the clinical examination (P = 0.0484). Overall, semiprofessional soccer players had a higher proportion of an increased α angle than the amateur group.


Semiprofessional players have a higher prevalence of an increased α angle in the kicking leg than the amateur group at the same age. The kicking leg is predisposed for FAI.

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Activities of daily living


Center edge angle


Femoroacetabular impingement


Field of view


Hip outcome score


Magnetic resonance imaging


Range of motion


Echo times


Repetition times


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Parts of this study were presented and awarded at the conference 2013 of the German Speaking Association for Arthroscopy (AGA). The authors thank Priv.-Doz. Dr. Nina Lahner for linguistic support and preparation of the manuscript. The authors acknowledge Dr. Andreas Falarzik, Coach André Pawlak and the soccer players of the Sportgemeinschaft Wattenscheid 09.

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Correspondence to Matthias Lahner.

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Lahner, M., Walter, P.A., von Schulze Pellengahr, C. et al. Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players. Arch Orthop Trauma Surg 134, 1135–1141 (2014).

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  • Femoroacetabular impingement
  • α angle
  • Magnetic resonance imaging
  • Kicking leg
  • Soccer player