A Case of Prefemoral Fat Pad Impingement Syndrome Caused by Hyperplastic Fat Pad

Abstract

Case We report a rare case of prefemoral fat pad impingement syndrome that was caused by a hyperplasia of the normal suprapatellar fat pad. Pain and catching were observed in the proximal-lateral patellofemoral joint, and MRI imaging confirmed a hyperplasic mass in the same area. Although conservative treatment showed no signs of improvement, symptoms improved after an arthroscopic excision of the mass. Conclusion Prefemoral fat pad impingement syndrome is related to patellar motion and should be considered as one of the underlying causes of anterior knee pain (AKP). Surgeons should recognize that a small hyperplasia composed of normal adipose tissue can cause AKP.

Qualitative and quantitative measures of prefemoral and quadriceps fat pads are associated with incident radiographic osteoarthritis: data from the Osteoarthritis Initiative

“…As the knee is flexed, the patella side moves downwards to engage in the trochlear groove, while the trochlea side moves upwards relatively to approach the patella side to stabilize the knee joint. Such an opposite-direction movement was reported to "sandwich" the PFP on the surface of distal femoral cortex 22 . When the size of PFP is abnormally larger than normal, the…”

“…We also examined the associations of PFP quantitative measure of maximum axial area with the development of iROA and found that PFP maximum axial areas at all three time points were significantly associated with an increased incidence of ROA, suggesting a detrimental effect of PFP size in knee OA development. Currently, only one case report reported that hyperplastic PFP was related to patellar motion and considered as one of the underlying causes of anterior knee pain 22 , but there are no studies showing the relation of PFP size to knee OA so far. In contrast, several studies reported that IPFP size might have a beneficial effect on knee OA.…”

Friction Syndromes of the Knee

“…40 Additionally, cases of prefemoral fat pad impingement have been reported due to lipomatous lesions, mass-like tissue protruding from the lateral femoral condyle, as well as hyperplasia of the normal adipose tissue. [41][42][43] Central fat pad edema is rarely present in individuals with patellofemoral arthritis, and osteophyte formation results in direct impingement of the fat pad itself.…”

Fat Pads as a Cause of Adolescent Anterior Knee Pain

“…This is rarely described in the literature and often overlooked, but in the limited reports available, it is a chronic process with pathophysiology similar to HD. 87,[90][91] There have been two case reports and one retrospective imaging study discussing this entity. The first case describes a chronic impingement of the PFP by the patella that caused fibrous changes, enlargement of the PFP, and a fatty soft tissue mass extending from the PFP to the femoral condyle which was excised arthroscopically with resolution of symptoms.…”

“…90 The second reported case involved hyperplasia of the SFP that was felt to be causing chronic compression of the PFP; symptom resolution was achieved with SFP excision. 91 In addition, PFP edema and alterations were identified in 68% of patients diagnosed with HD suggesting that it may be an unrecognized component of that pathology. 95…”