While being a fairly recent addition to the diagnostic options for hip pain, cam impingement has quickly become a well-recognized cause of hip pain that might eventually lead to osteoarthritis of the hip. Cam impingement is most commonly seen in young, active male patients, but when does this deformity occur? At birth? During growth?
Agricola and colleagues wanted to determine onset age and prevalence of cam-type deformities in young male soccer players versus controls. They studies 89 elite pre-professional (“Academy”) soccer players and 92 controls, all between the ages of 12 and 19 years. Range of motion and impingement tests were performed in the soccer players. Antero-posterior (AP) pelvic radiographs and a frog-leg lateral radiograph were obtained using a standard protocol. Controls with both an AP pelvic and a frog-leg lateral radiograph and no diagnosis of hip disorders were pulled from radiology databases. A threshold value of 60o for the a angle (automatically determined in all radiographs) was used to define a cam-type deformity.
The antero-superior head-neck junction was classified using a 3-point scoring system: (1) normal, (2) flattened, or (3) having a prominence. An a angle >60o was already evident at the age of 12 years in both soccer players and controls. A cam-type deformity, defined by the a angle, tended to be more prevalent in soccer players (26%) than in controls (17%; P = .31). In 13% of soccer players, a prominence (score of 3) was visible and was first seen at the age of 13 years. Unlike the results for the a angle, the prevalence of antero-superior flattening (56% vs 18%, P = .0001) and prominence (13% vs 0%, P<0.03) were more prevalent in soccer players than in controls.
Their results showed that cam-type deformities were present beginning at the age of 13 years and were more prevalent in soccer players than in their non-athletic peers. The authors concluded that this deformity developed during adolescence and was probably influenced by high impact sports practice. A descriptive, cross-sectional project generates data that asks questions. Longitudinal studies of players upon enrollment in an Academy program will be needed to determine if sufficient evidence exists to verify their hypothesis.