Infra patellar plicae injury.

Reference

Normal infrapatellar plica. Schematic drawing of knee in sagittal section through intercondylar notch shows infrapatellar plica (black arrow) extending from inferior pole of patella (P) or immediately adjacent fat, through Hoffa's fat pad, to intercondylar notch of femur anterior to anterior cruciate ligament (white arrow).

Normal infrapatellar plica. Sagittal fast spin-echo T2-weighted MR image (TR/TE, 4000/72) with fat suppression through intercondylar notch shows normal infrapatellar plica as thin, linear low-signal-intensity structure (black arrow) in Hoffa's fat with more prominent intercondylar component (straight white arrows) lying anterior to anterior cruciate ligament (curved white arrows), proximal attachment in intercondylar portion of femur, and distal visualized portion attaching to prominent transverse ligament.

18-year-old woman soccer player with anterior knee pain. Sagittal fast spin-echo T2-weighted MR image (TR/TE, 4000/69) with fat suppression through intercondylar notch shows curvilinear high T2 signal along course of infrapatellar plica (arrow). Fluid signal immediately anterior to anterior cruciate ligament in intercondylar notch may be related to infrapatellar plica avulsion or may simply represent joint fluid. Other findings on MR imaging included discoid lateral meniscus and mediopatellar plica (not shown). At arthroscopy (not shown), infrapatellar plica was thickened and avulsed from its femoral attachment, and redundant infrapatellar plica interfered with full extension. Infrapatellar plica was resected; after surgery, patient was asymptomatic and resumed playing soccer.