Description
This study aimed to ascertain the prevalence of cam Femoroacetabular Impingement Syndrome (cam-FAIS) in Anterior knee pain (AKP) patients devoid of both structural patellofemoral joint (PFJ) abnormalities and lower limb skeletal mal-alignment. A secondary objective was to examine pain and disability differences between AKP patients with and without cam-FAIS. Methods: A total of 209 AKP patients were screened for eligibility. Inclusion criteria were normal radiological exam and normal lower limb alignment and exclusion criteria were previous knee surgery or patellofemoral chondropathy/osteoarthritis. Of those, 49 (23.4%) were eligible and this number matched a
previous power analysis. The first step in the study sequence was to ask the patient whether they had groin pain. If so, the impingement test was done, and the magnitude of pain was evaluated using the VAS. Then, the femoral cam morphology defined by an alpha angle greater than or equal to 55 degrees in a Dunn axial view of the hip was ruled out. Additionally, patients completed Kujala and IKDC functional knee scores for disability assessment. Results: The study included 9 males and 40 females, with an average age of 36 (20–50, ± SD 8.03) years. Groin pain and positive impingement test were found in 26/49 patients (53%). An alpha angle ≥ 55° was observed in 35/49 patients (71%). A combination of groin pain, positive impingement test and an alpha angle ≥ 55° was seen in 18/49 patients (37%). For each assessment, AKP patients have a much higher prevalence than the general population. AKP patients with groin pain, a positive impingement test and an alpha angle ≥ 55° exhibited similar pain and disability levels as AKP patients without cam-FAIS. Conclusions: The results of this study suggest that AKP patients without structural abnormalities in the PFJ and without lower limbs mal-alignment have a significantly higher prevalence of cam-FAIS than the general population. Moreover, AKP patients with cam-FAIS have a similar degree of pain and disability than AKP patients without it.
