Magnetic Resonance Imaging Findings of Suprapatellar Fat Pad Impingement Syndrome: A Retrospective Study

Abstract

Objective: Peripatellar fat pads are extrasynovial intracapsular fat tissues. Suprapatellar, perifemoral, and infrapatellar (Hoffa fat pad) fat pads are included in the peripatellar fat pad. This study aimed to describe the magnetic resonance imaging (MRI) signs of suprapatellar fat pad impingement syndrome, describe their prevalence and pattern, and look into the relationship between their MRI and clinical signs. Methods: Two radiologists retrospectively analyzed 5,700 patients’ knee MRI data between December 2010 and December 2015. We documented the MRI findings that were associated with suprapatellar fad pad impingement syndrome. The correlations between age, osteoarthritis, chondromalacia, and the patellofemoral joint were evaluated using Pearson’s correlations. Results: In our study group, the prevalence of suprapatellar fat pad impingement was 5.3%. Of the patients 52% were men and 48% were women. Patients who were admitted to the clinic complained of non-specific pain in 80.3% of patients. Twenty-seven patients (8.9%) presented with isolated suprapatellar impingement syndrome; 185 (60.9%) showed an increase in intra-articular fluid; 4 (1.3%) had synovitis findings; 17 (5.6%) had medial collateral ligament tears; 107 (35.2%) had quadriceps femoris tendinitis; 8 (2.6%) had patellar tendinitis; 80 (26.3%) had a medial meniscus tear; 23 (7.6%) had Baker’s cyst; and 30 (9.9%) had soft-tissue edema. Medial meniscus degeneration was observed in 51 (16.8%) patients, Hoffa edema was observed in 31 (10.2%) patients, and anterior cruciate ligament tears in 3 (1%) patients. There were positive correlations between age and osteoarthritis (r=0.4660, p<0.05), between chondromalacia and the grade of the chondromalacia (r=0.5198, p<0.05), and between lateral subluxation and lateral tilt as opposed to the normal patellofemoral relationship (r=0.3171, p<0.05).in patients with suprapatellar fat pad impingement. Conclusion: The most common symptom of suprapatellar impingement, that is one of the major causes of anterior knee pain, is non-specific pain. The most common additional MRI findings are increased intra-articular fluid and quadriceps femoris tendinitis.

Keywords

• suprapatellar fat pad impingement syndrome
• knee mri
• knee pain
• quadriceps fat pad