A Rare Painful Mediopatellar Plica and Cord-Like Structure Complex in the Knee Joint

Abstract

Anterior knee pain is a frequent, yet relevant, symptom since mediopatellar plicae are found in approximately 20% of normal knees. We report the rare case of a painful mediopatellar plica and cord-like structure complex covering the suprapatellar pouch in the knee joint. The patient was a 13-year-old girl who complained of left anterior knee pain with restricted range of motion that had started 1 year earlier. She underwent arthroscopic treatment after unsuccessful conservative therapy. Intraoperative findings included a Sakakibara classification Type B mediopatellar plica and band-like structure complex located in the suprapatellar pouch of the knee. As Type A and B plicae are generally asymptomatic, the cause of the pain in this case was presumed to be impingement of the mediopatellar plica by the cord-like band. The plica and band-like structure complex was resected and ablated by arthroscopy. The patient was pain-free several months postoperatively and could resume normal school life. Since she was an adolescent in her growth phase, it is possible that joint growth resulted in tension on the remnant of the plica connected with the band-like structure in the suprapatellar pouch, which then intruded into the medial aspect of the patellofemoral joint and resulted in her symptoms. Keywords: Knee; Mediopatellar plica; Pain Case PresentationWe report a rare case based on the intraoperative finding of an abnormal cord under the patella. A 13-year-old girl visited our institution with a 1-year history of left anterior knee pain and difficulty in daily walking and running. She had no history of joint injury. Left knee range of motion (ROM) was 5° of extension to 120° of flexion, which had become restricted due to pain. Swelling or inflammation were not evident. Clinical tests for knee stability were comparable with those of the contralateral side, and the McMurray test for meniscal tear was negative. Magnetic resonance image (MRI) examination and plain radiographs of the affected knee did not reveal any notable abnormalities, nor did blood tests indicate signs of inflammation (data not shown). The patient commenced a conservative treatment regimen of joint-strengthening exercises, but no improvements were seen. Six months after presentation, she underwent arthroscopy under general anesthesia. There were no remarkable findings in the menisci, cartilage, anterior cruciate ligament, or posterior cruciate ligament.