MRI characteristics of infrapatellar cysts

Abstract

ABSTRACT

Aim

The infrapatellar fat pad is one of the fat pads of the knee and is particularly important for knee movements. The volume and shape of this fat pad varies individually and can be affected by a variety of tumor and tumor-like pathologies. Cystic structures, which are extremely common in and around the knee joint, can cause various symptoms, especially pain.

Materials and Methods

69 knee MRI examinations performed in our center between October 2021 and December 2021 were included in the study. Presence, localization, contours and intensities of infrapatellar cysts and whether there is a compression effect on neighboring structures were investigated in MR images.

Results

The mean age of 69 subjects (41 females, 29 males) included in the study was 53.471±15.23 (52.08±17.375 in females, 58±3.367 in males). Findings of infrapatellar cysts were found in 17 (24.64%) of 69 patients. Of the detected infrapatellar cysts, 13 (76.5%) were in the posterior position and 4 (23.5%) were in the anterior position. While the cyst was in the lateral position in 14 (82.4%) patients, it was medial in 3 (17.6%) patients. While 16 (94.1%) patients with cysts in the inferior position were detected, 1 (5.9%) patient was observed in the superior position. According to the analysis results of spatial data, infrapatellar cysts are most commonly located posterior, lateral and inferior. The mean volume of the detected cysts was found to be 773.91±700.73 mm3. Cysts with smooth surface were observed in 12 (70.59%) patients and with lobulated contours in 5 (29.41%) patients. None of the cystic structures showed a compression effect. Finally, when the intensity structure of the cyst is examined, it has a homogeneous cystic appearance in 16 (94.12%) patients, while it has soft tissue intensity in 1 (5.88%) patient.

Conclusion

Cystic structures within the infrapatellar fat pad are not as rare as previously reported in the literature. Infrapatellar cysts, which are usually located posteriorly and laterally, should be carefully evaluated during MRI reporting, in terms of both its close relationship with anterior cruciate ligament lesions and the clinical symptoms it may cause alone.