Intra-articular Ganglionic Cysts of Knee: A Cause for Anterior Knee Pain

Ganglionic cysts are mostly found around the wrists, but they can occur in any part of the body. They are also common around the knees as popliteal cysts and meniscal cysts. Intra-articular cysts of the knee, however, are much rarer, with only sporadic cases being reported till 1990. Most of these cysts are asymptomatic and detected during routine magnetic resonance imaging (MRI) and arthroscopy for other pathologies. Most of the time, they are reported in relation to the anterior cruciate ligament (ACL) and rarely in relation to the posterior cruciate ligament, menisci, and very rarely in relation to the anterior fat pad. These patients occasionally report with knee pain, mechanical locking, and restriction of terminal flexion/extension. The symptoms depend on the site and size of the cysts.

We report a case series of 10 patients with ganglionic cysts of the knee who were studied over a period of 4 years. The study included four males and six females with an average age of 34.8 years. All reported with persistent knee pain at the outset. Clinical examination, preliminary X-ray, and MRI were done in all patients. Seven patients were examined arthroscopically, and their findings were recorded. Of these, three patients were treated with radiofrequency ablation and four with arthroscopic debridement of the cyst. Histopathology examination was carried out for the specimen material taken out.

Arthroscopic examination revealed two cystic masses originating from ACL, two from the anterolateral knee fat pad, one from the retropatellar fat pad, one from the anteromedial fat pad, and one from the anterior horn of the lateral meniscus. All were treated successfully with arthroscopic debridement or radiofrequency ablation. All were symptom-free at the latest follow-up. The mean follow-up duration for the surgically treated patients was 29 months (range, 24-34 months). Out of the three patients who did not undergo surgery, one had a spontaneous resorption of the cyst as evidenced by MRI taken at 3 years.

Although uncommon, intra-articular ganglion cysts should be considered in patients presenting with unexplained anterior knee pain. MRI facilitates early diagnosis, and arthroscopic management offers a safe and effective treatment with favorable clinical outcomes and low recurrence rates.