Purpose: The purpose of this study is to determine the relationship between a symptomatic maximal squat and the presence of radiographic CAM-type femoroacetabular impingement (FAI) on magnetic resonance imaging (MRI) and to determine the sensitivity and specificity of a maximal squat test for the presence of radiographic CAM-type femoral deformity in an adult population.
Methods: In this pilot study, 76 consecutive patients were recruited from an outpatient clinic at McMaster University. All patients presented with pre-arthritic hip pain and were asked to perform a maximal squat. The results of this test were compared to magnetic resonance imaging and magnetic resonance angiographic (MRI and MRA) findings evaluating and characterizing CAM-type FAI deformity.
Results: The sensitivity and specificity of the maximal squat test were 75 % (56.6-88.5 %) and 41 % (27.0-56.8 %), respectively, for CAM-type FAI deformity. The positive and negative likelihood ratios were modest at 1.3 (0.9-1.7) and 0.6 (0.3-1.2), respectively. This means that a 30 % pre-test probability is improved to 36 % following a positive squat test and reduced to 20 % with a negative squat test.
Conclusion: The maximal squat test was found to have marginal incremental diagnostic ability for CAM-type FAI. Its utility in the diagnostic evaluation of FAI remains limited. This survey elucidates areas of research for future studies relevant to the clinical diagnosis of FAI.