Meniscal tear

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Meniscal tears arethe failure of the fibrocartilaginous menisci of the knee. There are several types and can occur in an acute or chronic setting. Meniscal tears are best evaluated with MRI.

Clinical presentation

Acute meniscal tears occur after rotatory trauma of the knee, whereas chronic degenerative meniscal tears often occur in the elderly after minimal rotatory trauma or stress on the knee.

Types

There are different types of meniscal tears, describing the morphology of the injury. Identifying and accurately describing the type of meniscal tear can help the surgeon in patient education and planning of the surgical procedure. Meniscal tear types include ^1,5:

horizontal tear (cleavage tear): parallel to the tibial plateau
longitudinal tear: perpendicular to the tibial plateau; parallel to the long axis of the meniscus
radial tear: perpendicular to the tibial plateau and the long axis of the meniscus
~~root tear: often a radial-type tear located at the meniscal root~~
complex tear: combination of all or some of horizontal, longitudinal and radial-type years
displaced tear: tear involving component that is displaced, either still ~~attached~~ attached to the parent meniscus, or detached:
- flap tear: displaced horizontal or ~~detached~~longitudinal tears
- bucket-handle tear: displaced longitudinal tear ~~with medial displacement of~~
- parrot beak tear: displaced radial tear
root tear: often a radial-type tear located at the ~~central fragment~~meniscal root

Radiographic features

Plain film

On plain radiographs meniscal tears are not visible. In rare cases secondary signs can be seen, such as a soft tissue swelling next to the meniscus when a meniscal cyst is present ⁴. Only when associated with more complex injuries plain film may suggest a meniscal tear, e.g. arcuate sign, reverse Segond fracture, tibial plateau fracture.

MRI

With a sensitivity of ~95% and a specificity of 81% for medial meniscal tears and a sensitivity of ~85% and a specificity of 93% for lateral meniscal tears ^2,5, MRI is the modality of choice when a meniscal tear is suspected, with sagittal images being the most sensitive ⁵.

There are two basic MR characteristics of meniscal tears ⁵:

high intrameniscal signal extending to at least one (if not both) articular surfaces on two slices (do not have to be contiguous, e.g. sagittal and coronal slices)
distortion of the normal meniscal morphology if no prior surgery

Each type of meniscal tear has its own characteristics on MRI, but in most cases the following can be seen ³:

T1: a hyperintense line in the meniscus can be seen, but it is difficult to differentiate between degeneration and meniscal tear on this sequence; in the case of a bucket-handle tear an empty groove can sometimes be seen
T2: ~~hyperintense~~a hyperintense line in the meniscus, which indicates synovial fluid in the meniscus
- high T2 signal in mid substance of the meniscus without extension to the surface is not necessary a tear and can be:
  - in adult: secondary to degeneration
  - in children: high vascularity of meniscus

(See MRI grading system for meniscal signal intensity)

Associated features that are suggestive of a meniscal tear include ⁵:

tibial subchondral bone oedema
parameniscal cyst

Treatment and prognosis

Surgical arthroscopy is done in most of the cases. Meniscopexy or complete or partial meniscectomy can be performed, depending on the degree and type of meniscal tear.

Pitfalls

oblique ligament: with intercondylar bucket handle component
transverse ligament
femoromeniscal ligaments
meniscocapsular fibrofatty junction
previous surgery
fluid in normal central knee recesses
fluid in popliteal hiatus
ligamentum mucosum

Differential diagnosis

~~-<a href="/articles/horizontal-tear">horizontal tear</a>: parallel to the <a href="/articles/tibial-plateau">tibial plateau</a>~~
+<a href="/articles/horizontal-tear">horizontal tear</a> (cleavage tear): parallel to the <a href="/articles/tibial-plateau">tibial plateau</a>
~~-<a href="/articles/root-tear">root tear</a>: often a radial-type tear located at the meniscal root</li>~~
~~-<li>~~
~~-<li>displaced tear: tear involving component that is displaced, either still attached to the parent meniscus, or detached</li>~~
+<li>displaced tear: tear involving component that is displaced, either still attached to the parent meniscus or detached:<ul>
+<li>
+<a href="/articles/flap-tear">flap tear</a>: displaced horizontal or longitudinal tears</li>
~~-<a href="/articles/bucket-handle-tear">bucket-handle tear</a>: longitudinal tear with medial displacement of the central fragment</li>~~
+<a href="/articles/bucket-handle-tear">bucket-handle tear</a>: displaced longitudinal tear </li>
+<li>
+<a href="/articles/parrot-beak-tear">parrot beak tear</a>: displaced radial tear</li>
+</ul>
+</li>
+<li>
+<a href="/articles/root-tear">root tear</a>: often a radial-type tear located at the meniscal root</li>
~~-<li>distortion of the normal meniscal morphology</li>~~
+<li>distortion of the normal meniscal morphology if no prior surgery </li>
~~-<strong>T2: </strong> hyperintense line in the meniscus, which indicates synovial fluid in the meniscus</li>~~
+<strong>T2: </strong>a hyperintense line in the meniscus, which indicates synovial fluid in the meniscus<ul><li>high T2 signal in mid substance of the meniscus without extension to the surface is not necessary a tear and can be:<ul>
+<li>in adult: secondary to degeneration </li>
+<li>in children: high vascularity of meniscus</li>
+</ul>
+</li></ul>
+</li>
-</ul><h4>Treatment and prognosis</h4><p>Surgical arthroscopy is done in most of the cases. Meniscopexy or complete or partial meniscectomy can be performed, depending on the degree and type of meniscal tear.</p><h4>Differential diagnosis</h4><ul>
+</ul><h4>Treatment and prognosis</h4><p>Surgical arthroscopy is done in most of the cases. Meniscopexy or complete or partial meniscectomy can be performed, depending on the degree and type of meniscal tear.</p><h4>Pitfalls</h4><ul>
+<li>
+<a href="/articles/oblique-ligament">oblique ligament</a>: with intercondylar bucket handle component</li>
+<li><a href="/articles/transverse-ligament-of-the-knee">transverse ligament</a></li>
+<li><a href="/articles/femoromeniscal-ligament">femoromeniscal ligaments</a></li>
+<li><a href="/articles/meniscocapsular-fibrofatty-junction">meniscocapsular fibrofatty junction</a></li>
+<li>previous surgery</li>
+<li>fluid in normal central knee recesses </li>
+<li>fluid in popliteal hiatus</li>
+<li><a title="Ligamentum mucosum" href="/articles/ligamentum-mucosum">ligamentum mucosum</a></li>
+</ul><h4>Differential diagnosis </h4><ul>

References changed:

6. Perdikakis E, Skiadas V. MRI characteristics of cysts and "cyst-like" lesions in and around the knee: what the radiologist needs to know. Insights Imaging. 2013;4 (3): 257-72. <a href="http://dx.doi.org/10.1007/s13244-013-0240-1">doi:10.1007/s13244-013-0240-1</a> - <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3675245">Free text at pubmed</a> - <a href="http://www.ncbi.nlm.nih.gov/pubmed/23479129">Pubmed citation</a><span class="auto"></span>

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