Method: The diagnosis of Hoffa’s disease with acute or chronic impingement of the fat pad was made by clinical signs and confirmed by arthroscopic examination in 180 patients. One hundred and forty two patients had one or more associated lesions. Thirty eight patients with isolated Hoffa’s lesion were treated by arthroscopic resection of the affected part of the fat pad and were assessed using the Lysholm knee and Tegner activity level scales. Their average age was 39 years (range, 19–65 years). Thirty five patients performed regular sporting activities. A history of acute onset following injury was present in only 23 patients (56 %). The average duration of symptoms prior to surgery was 10 months (range, 1–26 months). Fourteen patients had one or more previous failed arthroscopies at other centres.

Results: There was a significant improvement in the symptoms, function of the knees and level of activity after the surgery at an average follow-up of 68 months. The average improvement in Lysholm scores were 47 and 58 at 3 months and 1 year respectively. This improvement was maintained through to the latest follow-up (4 to 8 years after surgery) in all but three patients. On Tegner activity level all but 5 returned to their pre-injury status. Three had minimal symptoms and two chose to step down the level of activity due to non-physical reasons. Natural history of the disease was observed both with and without surgery as many persevered with symptoms while they were treated by analgesics, physiotherapy and arthroscopic surgery without resection of the impinging fat pad. Statistically significant negative correlation was found between duration of symptoms and gain in Lysholm score after surgery (Pearson r = − 0.58). Two distinct etio-pathogenesis and three stages of the disease were identified. Chondromalacia of the articular cartilage especially of the patella was a common association. Special surgical technique is important to avoid the pitfalls.