Role of MRI in assessment of patello-femoral derangement in patients with anterior knee pain

Objective To assess the diagnostic accuracy of magnetic resonance imaging (MRI) in evaluating patello-femoral instability as a cause of anterior knee pain (AKP) and its predisposing factors. Methods 55 knees of 50 adult patients below 40 years complaining of AKP underwent MRI between February 2013 and February 2015. The patients were analyzed prospectively for the presence of bone, hyaline cartilage and soft-tissue abnormalities, as well as anatomic variants that may contribute to patello-femoral maltracking or impingement abnormalities. Our results were compared to those of the arthroscopic and mini open exploration procedures. Results In the 55 knees analyzed for patello-femoral instability cartilaginous injuries were found in 58%, with an MRI sensitivity of 88%, disruption of the medial patello-femoral ligament (MPFL) in 31% with an MRI sensitivity 84%, joint morphology abnormalities in 74.5% of patients, bone edema in 27% of patients and Hoffa's fat pad edema in 30 patients (55%). MRI had a sensitivity of 84% and accuracy of 81% in determining the injury site and pattern. Conclusion MRI is reliable imaging modality in identifying the risk factors that may contribute to the development of patello-femoral maltracking or impingement permitting individual tailored treatment.