Ultrasound of the knee
Updates to Article Attributes
Ultrasound of the knee allows high resolution imaging of superficial knee anatomy anatomy while simultaneously allowing dynamic evaluation of some of the tendons tendons and ligaments. Knee ultrasound is somewhat limited compared with ultrasound examinations of other joints because the cruciate ligaments and the entirety of the meniscus is usually difficult to visualize.
Approach
There are multiple possible approaches to imaging the knee with with ultrasound. A typical overall protocol protocol is as follows1:
Anterior knee
Knee is flexed 20-30 degrees (flexion of the knee tightens the extensor tendons, decreasing the chance of anisotropy occuring in a lax tendon):
- Transverse and longitudinal images of the quadriceps tendon from its
myotendinousmyotendinous junctions to its attachment on the superior patella (rectus femoris myotendinous junction is more cranial than the vastus junctions). - Evaluate the suprapatellar and parapatellar joint recesses.
- suprapatellar fat pad
- prefemoral fat pad
- small amounts of synovial fluid may preferentially locate to the parapatellar joint recess
- Evaluate the femoral trochlea
- best examined in full knee flexion
- useful for examination of the trochlear cartilage
- Evaluate the patellar retinacula
- Evaluate the medial patellar articular facet (lateral facet not visible on ultrasound)
- Evaluate the patellar tendon and patellar bursa
- prepatellar bursa normally not visible
- infrapatellar bursa
- small amount of fluid in the deep infrapatellar
bursabursa is normal - normally no fluid in the superficial infrapatellar bursa
- small amount of fluid in the deep infrapatellar
Lateral knee
Knee is flexed 20-30 degrees:
- Evaluate the distal iliotibial band in long axis(located between anterior and middle third of the lateral knee).
- Evaluate thelateral collateral ligament in long axis.
- may detect para-articular ganglia
- May see lateral meniscal pathology (e.g. meniscal cyst)
- extreme knee flexion may bring out a meniscal abnormality
Medial knee
Knee is flexed 20-30 degrees, with external rotation:
- Evaluate medial collateral ligament and pes anserinus tendons in long axis
- valgus stress may be useful to examine the ligament
Posterior knee
Often examined with patient prone and knee extended, thereby gaining access to the dynamic fat-filled popliteal fossa:
- Evaluate the medial tendons in short axis (medial to lateral):
- sartorius
- gracilis
-
semitendinosissemitendinosus
- Moving even more medially, evaluate the semimembranosus-gastrocnemius bursa in short axis
- apopliteal cyst (Baker's cyst) arises between these tendons
- Evaluate
thethe popliteal neurovascular bundle and intercondylar fossa in short axis. - Evaluate the posterolateral corner and biceps femoris in short and long axis.
- Evaluate the
peronealperoneal nerve- start with the common peroneal nerve branching off the sciatic nerve above the knee
- follow it around the fibular head
Pathology
A number of knee abnormalities can be identified on ultrasound, including:
-<p><strong>Ultrasound of the knee</strong> allows high resolution imaging of superficial knee anatomy while simultaneously allowing dynamic evaluation of some of the tendons and ligaments. Knee ultrasound is somewhat limited compared with ultrasound examinations of other joints because the cruciate ligaments and the entirety of the meniscus is usually difficult to visualize.</p><h4>Approach</h4><p>There are multiple possible approaches to imaging the knee with ultrasound. A typical overall protocol is as follows <sup>1</sup>:</p><h6>Anterior knee</h6><p>Knee is flexed 20-30 degrees (flexion of the knee tightens the extensor tendons, decreasing the chance of <a href="/articles/anisotropy">anisotropy</a> occuring in a lax tendon):</p><ol>-<li>Transverse and longitudinal images of the quadriceps tendon from its myotendinous junctions to its attachment on the superior patella (rectus femoris myotendinous junction is more cranial than the vastus junctions).</li>- +<p><strong>Ultrasound of the knee</strong> allows high resolution imaging of superficial knee anatomy while simultaneously allowing dynamic evaluation of some of the tendons and ligaments. Knee ultrasound is somewhat limited compared with ultrasound examinations of other joints because the cruciate ligaments and the entirety of the meniscus is usually difficult to visualize.</p><h4>Approach</h4><p>There are multiple possible approaches to imaging the knee with ultrasound. A typical overall protocol is as follows <sup>1</sup>:</p><h6>Anterior knee</h6><p>Knee is flexed 20-30 degrees (flexion of the knee tightens the extensor tendons, decreasing the chance of <a href="/articles/anisotropy">anisotropy</a> occuring in a lax tendon):</p><ol>
- +<li>Transverse and longitudinal images of the quadriceps tendon from its myotendinous junctions to its attachment on the superior patella (rectus femoris myotendinous junction is more cranial than the vastus junctions).</li>
-<li>small amount of fluid in the deep infrapatellar bursa is normal</li>- +<li>small amount of fluid in the deep infrapatellar bursa is normal</li>
-<li>Evaluate the distal iliotibial band in long axis (located between anterior and middle third of the lateral knee).</li>-<li>Evaluate the <a href="/articles/lateral-collateral-ligament-of-the-knee">lateral collateral ligament</a> in long axis.<ul><li>may detect para-articular ganglia</li></ul>- +<li>Evaluate the distal iliotibial band in long axis (located between anterior and middle third of the lateral knee).</li>
- +<li>Evaluate the <a href="/articles/lateral-collateral-ligament-of-the-knee">lateral collateral ligament</a> in long axis.<ul><li>may detect para-articular ganglia</li></ul>
-</li></ol><h6>Posterior knee</h6><p>Often examined with patient prone and knee extended:</p><ol>- +</li></ol><h6>Posterior knee</h6><p>Often examined with patient prone and knee extended, thereby gaining access to the dynamic fat-filled <a title="Popliteal fossa" href="/articles/popliteal-fossa">popliteal fossa</a>:</p><ol>
-<li>sartorius</li>-<li>gracilis</li>-<li>semitendinosis</li>- +<li><a href="/articles/sartorius-muscle">sartorius</a></li>
- +<li><a href="/articles/gracilis">gracilis</a></li>
- +<li><a href="/articles/semitendinosus-muscle">semitendinosus</a></li>
-<li>Moving even more medially, evaluate the semimembranosus-gastrocnemius bursa in short axis<ul><li>a <a href="/articles/baker-cyst-1">popliteal cyst (Baker's cyst)</a> arises between these tendons</li></ul>- +<li>Moving even more medially, evaluate the semimembranosus-gastrocnemius bursa in short axis<ul><li>a <a href="/articles/baker-cyst-1">popliteal cyst (Baker's cyst)</a> arises between these tendons</li></ul>
-<li>Evaluate the popliteal neurovascular bundle and intercondylar fossa in short axis.</li>- +<li>Evaluate the popliteal neurovascular bundle and intercondylar fossa in short axis.</li>
-<li>Evaluate the peroneal nerve<ul>- +<li>Evaluate the peroneal nerve<ul>
-<li><a href="/articles/baker-cyst-1">popliteal cyst (Baker cyst)</a></li>- +<li><a href="/articles/baker-cyst-1">popliteal cyst (Baker cyst)</a></li>
References changed:
- 3. Moore KL, Dalley AF. Anatomy. Lippincott Williams & Wilkins. (1999) ISBN:0683061410. <a href="http://books.google.com/books?vid=ISBN0683061410">Read it at Google Books</a> - <a href="http://www.amazon.com/gp/product/0683061410">Find it at Amazon</a><span class="ref_v3"></span>