Large Extrasynovial Intracapsular Ganglia of the Knee: A Report of 3 Cases

Purpose: Intra-articular ganglia of the knee are rare and usually incidental findings of little clinical significance. Nevertheless some are large, symptomatic, and require treatment. We report on 3 patients with an intra-articular knee ganglion and an extrasynovial extension that was contained within the joint capsule. This seems to be a rare condition; a review of the English-language literature revealed no reports of similar cases. Type of Study: Case series. Methods: Three patients, 1 man and 2 women aged 27 to 40 years, presented with an almost identical history of anterior knee pain that had been treated conservatively for a long time as chondromalacia patellae. The symptoms, which were ill-defined, appeared to be deteriorating until a localized swelling appeared on the lateral side of the patella tendon in each case. On examination, a lateral meniscal cyst associated with an underlying meniscal tear was suspected. However, magnetic resonance imaging revealed a ganglion arising from the substance of the anterior cruciate ligament (case 1) and from the area of the tibial insertion of the anterior cruciate ligament (cases 2 and 3). All 3 ganglia extended anteriorly and then laterally over and in front of the lateral meniscus. The ganglia were approached through an anterior midline incision and lateral parapatellar arthrotomy, which allowed direct and easy access for complete excision. Histologic examination confirmed the diagnosis of a ganglion in all 3 cases. Results: The postoperative course was uneventful in all patients with no signs of recurrence at 1 year (case 1), 2 years (case 2), and 3 years (case 3). Conclusions: Although the described condition seems very rare, we believe that it should be included in the differential diagnosis of cystic lesions about the knee joint. Level of Evidence: Level IV, case series, no, or historical control group.