Hoffa’s fat pad ganglion cyst protruding from lateral retinacular rent: a case report

Ganglion cyst in and around the knee are quite rare occurrences. They are usually encountered as incidental findings in magnetic resonance imaging (MRI), or in arthroscopy. They may originate from both the cruciate ligaments and the menisci, from the popliteus tendon and alar folds, infrapatellar fat pad of Hoffa, and subchondral bone cysts. Those cysts which arise from fat pad, present as palpable mass at the anterior aspect of the knee. 45-year male, presented with a painless gradually increasing swelling at the anterior aspect of the left knee of 11 months’ duration. Patient complaints of discomfort in the left knee, occasional pain on walking, and climbing stairs. MRI scan revealed a multilobulated, cyst with septations within the anterior aspect of the knee joint, just inferolateral to the patella, with deep extension into the infrapatellar fat pad, and superficial extension into the subcutaneous space across the retinaculum. Proper preoperative evaluation of MR images of these cases is very important. Subcutaneous extension through lateral retinaculum renders these cyst incomplete resection via arthroscopic excision. There-fore open excision was performed.