Hip range of motion and the prevalence of cam morphology in young athletes - clinical and radiological studies

Abstract: Abstract Hip and groin pain is common among athletes and the active population, and one important cause for this is femoroacetabular impingement syndrome (FAIS). To meet the diagnosis of FAIS, a combination of radiological findings (cam and/or pincer morphology), hip pain and clinical findings (reduced hip joint range of motion (ROM) and/or positive anterior impingement test (FADIR)) needs to be present. To quantify a cam morphology, the α-angle is often measured, and a cam morphology is usually considered present with an α-angle of ≥55°. Factors that have been associated with the development of cam morphology are genetics, ethnicity and participation in high impact sports during the pubertal growth spurt. Why some individuals develop FAIS and others do not, in the presence of a cam morphology, is still unknown. Therefore, there are still many questions that need to be answered regarding the aetiology, prevalence, impacts of different types of sports and loads, and treatment of cam/pincer and FAIS. Cam-type FAIS has also been associated with early hip osteoarthritis, and therefore this thesis focuses on cam morphology of the hip. The overall aim of this thesis was to investigate the prevalence of cam morphology, hip ROM, hip pain and FAIS among young elite skiers and football players. Further, to investigate the relationship between hip ROM and cam, and hip range of motion and pelvic tilt (with and without cam morphology). Study 1 is a cross-sectional study, including 87 skiers and 27 non-athletes with a mean age of 17.7 (SD1.4) years, where the aim was to examine the relationship between the clinical examination of the hip and cam morphology. The study population was divided into cam- and no cam-groups depending on the -angle measured with MRI. The main findings showed that reduced hip joint internal rotation, hip flexion and a positive anterior impingement test were associated with MRI-verified cam. Study 2 is a cross-sectional study with the aim to investigate the effect of changes in pelvic tilt on hip ROM in individuals with and without cam. The same study population was included as in Study 1. The main finding was that dynamic changes in pelvic tilt significantly influenced hip ROM, independent of cam morphology. Study 3 is a cross-sectional study investigating the prevalence of cam morphology (-angle >55°) in a group of elite Mogul and Alpine skiers, compared with non-athletes and between the sexes. The same study population was included as in Study 1. The skiers had a significantly higher prevalence of cam compared with the non-athletes. A significant difference was also found between males and females, with males having a higher prevalence of cam. Study 4 is a cross-sectional study with the aim to investigate the difference in hip ROM, hip pain, cam morphology and FAIS in young athletes. One-hundred-and-thirty-five athletes (60 male soccer players, 40 male skiers and 35 female skiers) with a mean age of 17.7 (SD 1.2) years were included. Please find results in manuscript.

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