235 - Case Report: Compression of the Superomedial Genicular Nerve by a Ganglion Cyst in a Patient with Chronic Knee Pain

Case Diagnosis: Ganglion Cyst with compression of superomedial genicular nerve

Case Description: A 45-year-old female presented to a general PM&R clinic in October of 2023 for evaluation of chronic left knee pain. The pain was constant, localized to the medial aspect of her knee, and worse with ambulation. A left knee x-ray was without any osseous abnormalities. She had previously been treated conservatively with NSAIDs, ice/heat, and Physical Therapy. However, physical therapy worsened her pain. An MRI revealed tendinosis of the adductor magnus and adjacent ganglion cysts. Her physical exam revealed point tenderness of distal anteromedial thigh and pain with resisted knee extension. No weakness or sensory disturbances were appreciated. Ultrasound evaluation in clinic revealed a 2-cm complex ganglion cyst over the posteromedial femoral condyle. 5-cc of fluid was aspirated from the cyst at bedside under ultrasound guidance. The knee was injected with a lidocaine and steroid mixture. The patient noted 100% pain relief upon conclusion of the procedure.

Discussions: Medial knee pain can arise from various sources, including damage of the medial meniscus, saphenous nerve entrapment, or pes anserine bursitis. The most common cyst in the knee is the Baker's cyst. Ganglion cysts are more commonly seen along tendons or joints of the wrists or hands but can be found less commonly along other tendon sheaths/joints as well, including the knee. Ultrasound evaluation of patients with chronic knee pain can be critical in promptly and correctly identifying abnormalities in nearby structures that may be responsible for their pain and unresponsiveness to conservative treatments.

Conclusions: Compression of the genicular nerves should be considered in the differential diagnosis of patients with long standing knee pain. MRI may not be able to identify the course of the genicular nerves and emphasizes the importance of point of care ultrasound in the evaluation and treatment of musculoskeletal disorders.