Displaced medial meniscal tear

Case contributed by Dr Andrew Dixon

Presentation

Acute effusion and posterior pain after twisting injury. Pain with flexion and rotation. ? Meniscal tear

Patient Data

Age: 35
Gender: Female

MRI Knee

Modality: MRI

The ACL and PCL are intact however there is scarring and synovitis between the cruciate ligaments and associated with the posterior knee capsule.  The MCL and LCL are intact and of normal signal.  Popliteus tendon is intact.

There is a large displaced vertical tear of the medial meniscal body and anterior horn, with meniscal fragment flipped across the intercondylar recess to lie superior to the anterior horn of the lateral meniscus. There is additional horizontal tearing of the posterior horn of the medial meniscus with associated parameniscal cyst indicating that this is longstanding.

The lateral meniscal body is peripherally extruded and there is intrasubstance signal within the anterior horn and body.  The anterior root attachment demonstrates cystic degeneration and the posterior root attachment appears irregular, possibly due to a incomplete radial tear.

The tibiofemoral compartment cartilage is preserved apart from lowgrade chondral signal change within the weightbearing medial femoral condyle.  Subchondral marrow signal is preserved.  There is partial thickness fissuring involving the patellar cartilage at the median eminence and at the medial facet.  Trochlear groove cartilage is preserved.  Normal subchondral marrow signal.  There is lowgrade oedema interposed between the proximal patellar tendon and the lateral femoral condyle within Hoffa's fat pad suggestive of patella maltracking.  Mild chronic appearing quadriceps enthesopathy is noted.  Normal appearance of the patellar tendon.

There is no Baker's cyst. fluid is seen within the pes anserine bursa.

Incidental note is made of a well-defined 1 cm marrow lesion within the proximal fibula metaphysis.  This has similar signal to cartilage is favoured to represent a lowgrade chondroid lesion such as an enchondroma.

Case Discussion

  1. Displaced vertical tear of the medial meniscus body and anterior horn producing a large unstable fragment flipped through the intercondylar recess anteriorly to sit above the anterior horn and root attachment of the lateral meniscus.  Additional chronic horizontal tear of the medial meniscal posterior horn with parameniscal cyst and associated pes anserine bursitis. 
  2. Degenerative signal within the anterior root attachment, anterior horn and body of the lateral meniscus, with incomplete radial tear suspected in the posterior root attachment of the lateral meniscus.
  3. Superficial patellar cartilage fissuring and Hoffa's fat pad oedema suggestive of patella maltracking.
  4. Incidental nonaggressive appearing bone lesion within the proximal fibula, most likely a lowgrade chondroid lesion such as an enchondroma.
  5. Synovitis associated with the synovial covering of the cruciate ligaments but no cruciate ligament tear.
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Case Information

rID: 32216
Case created: 19th Nov 2014
Last edited: 24th Nov 2015
Inclusion in quiz mode: Included

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