Methods of performing an ultrasound of the knee

When performing ultrasound (ultrasound) of the knee joint, you should follow a certain sequence and strive to obtain standard positions (slices). To display the ultrasound examination of all the elements of the joint, four standard accesses are used: anterior, medial, lateral and posterior.

Front access

This access provides visualization of the tendon of the quadriceps femoris, anterior curvature, patella, supernumerary bag, patellar ligament, podnkolennoy bag, fatty body of the knee joint. The patient is lying on the back, the limb is straight. The study begins with an assessment of the condition of the tendon of the quadriceps femoris muscle, for which its longitudinal section is obtained. The tendon of the quadriceps femoris has no synovial membrane and is surrounded by a hyperechoic band along the edges. To reduce the effect of anisotropy, the limb can be bent 30-45 degrees, or a roll placed under the knee.

In the distal part behind the tendon of the quadriceps femoris is a suprapatellar sac. Normally, it may contain a small amount of liquid.

Following proximally upward, the structure of the muscle tissue is studied, the transverse and longitudinal sections of the quadriceps femoris are obtained. Panoramic scanning mode provides visualization of all four muscle beams that make up the quadriceps muscle of the thigh.

Next, an image of the patella and its own patellar ligament is obtained. At the same time, the condition of the fatty body of the knee and the podnkolennoy bag.

Media Access

This access provides visualization of the inner lateral ligament, the body of the inner meniscus, the medial part of the articular space.

The patient is lying on the back, the limb is straight. The sensor is mounted on the medial surface of the joint, in the longitudinal position, along the median line with respect to the joint slot.

If the sensor is installed correctly, the joint gap should be clearly visible on the monitor screen. Improved visualization of the meniscus can be achieved by flexing the leg in the knee joint to 45-60 degrees. The condition of the joint gap, the contours of the femoral and tibia bones, the thickness and condition of the hyaline cartilage, and the presence of effusion in the joint cavity are evaluated.

Above the joint slit, the medial lateral ligament fibers are visible, which begin from the proximal part of the medial condyle of the femur and attach to the proximal part of the metaphysis of the tibia. To improve the visualization of the body of the inner meniscus, the limb needs to be rotated outward, with a divergence of the joint gap arises, and the meniscus is located posteriorly from the medial lateral ligament.

From the medial access, it is sometimes possible to visualize the anterior cruciate ligament. For this, the patient is asked to maximally bend the leg in the knee joint. The sensor is located below the patella and the scan plane is guided into the joint cavity. Bony cues are the condyle of the femur and the epicondyle of the tibia. The fibers of the anterior cruciate ligament are partially visualized. Due to the anisotropy effect, the ligament can be hypoechoic, and only a fraction of the fibers located perpendicular to the ultrasound are hyperechoic.

Lateral access

This access provides visualization of the distal part of the broad fascia of the thigh, the popliteal tendon, the outer lateral ligament, the distal part of the biceps femoris tendon, the outer meniscus body, the lateral part of the articular space.

The patient is lying on the back, the leg is bent at the knee joint at an angle of 30-45 degrees, rotated to the inside. The sensor is mounted on the lateral surface of the joint, in the longitudinal position, along the median line in relation to the joint slot. Bone marks are the head of the fibula, Gerdi's tubercle of the tibia, and the lateral condyle of the femur. Scanning in the cranial direction allows you to examine the fibers of the wide fascia of the thigh. The bony orientation of attachment of tendon fibers is the Gerdian tubercle on the anterior-lateral surface of the tibia. Between the Gerdian tubercle of the tibia and the lateral condyle of the femur in the notch is the tendon of the popliteal muscle attached to the posterior surface of the tibia.

Visualization of a part of this tendon is possible when scanning the outer lateral ligament. The fibers of the outer lateral ligament pass over the joint slit.

The outer lateral ligament begins from the lateral condyle of the hip, passes over the tendon of the popliteal muscle and is attached to the fibula head, merging with the fibers of the tendon of the lateral head of the biceps femoris.

With a fixed position of the sensor in the area of the fibula head and rotation of the proximal end of the sensor, the tendon of the lateral head of the biceps femoris is determined downward. To assess the body of the outer meniscus or determine the integrity of the fibers of the outer lateral ligament, the limb should be rotated to the inside, the meniscus will be located posteriorly from the outer lateral ligament and separated from its fibers by the tendon of the popliteal muscle. With a three-dimensional reconstruction of the meniscus, a frontal cut of the articular surface of the tibial and femur bones can be obtained, and the length of the meniscus tears can be estimated.

Rear access

With this access, the neurovascular bundle of the popliteal fossa, the medial and lateral heads of the gastrocnemius, the distal part of the fibers of the semimembranous muscle tendon, the horn of the inner meniscus and the horn of the outer meniscus, the posterior cruciate ligament are visualized.

The patient is in the supine position. The sensor is located transversely to the long axis of the limb in the popliteal fossa. The vascular bundle is displaced laterally in the popliteal fossa. The popliteal artery is located behind the vein, muscular tufts of the popliteal muscle are visualized below. With panoramic scanning using energy mapping, you can trace the progress of the popliteal artery. Tendons of the medial and lateral heads of the gastrocnemius muscle start from the corresponding condyle surfaces of the femur. The tendon of the semimembranous muscle is attached to the posterior-medial surface of the proximal part of the tibia. Between the tendon of the semimembranous muscle and the medial head of the gastrocnemius muscle is a small bag, in which the cervical cyst of Baker is usually located. The guidelines for visualization of this bag during transverse scanning are: the posterior surface of the medial condyle of the femur, covered with hyaline cartilage, the tendon of the semimembranous muscle, and the gastrocnemius fiber.

In longitudinal scanning of the popliteal fossa, the sensor is laterally displaced and rotated, respectively, in the plane of the joint cavity. In this case, the posterior horn of the external meniscus is visualized. From this position, the posterior cruciate ligament is also visualized, while the sensor rotates counter-clockwise by 30 degrees while examining the right limb and 30 degrees clockwise when examining the left limb. The posterior cruciate ligament, as well as the anterior cruciate ligament, is partially visualized. Its fibers due to the anisotropy effect are hypoechoic.

To assess the posterior horn of the medial meniscus, it is necessary to shift the sensor medially in the popliteal fossa and obtain an image of the tendon fibers of the medial head of the biceps femoris attached to the medial epicondyle of the tibia. From this position, the body of the medial meniscus is visualized.

From the rear access, one can also assess the peroneal nerve, which, leaving the lateral part of the sciatic nerve in the distal femur, follows laterally and down along the posterior surface of the distal part of the hamstrings' tendon before moving to the popliteal region, then - around the fibula head on the anterior surface of the tibia. In this zone, nerve damage often occurs between fibrous tunnel fibers.