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Topography and Pathotopography of Lower Extremity
Presently, ultrasonic scanning is the most informative up-to-date method for examination of joints. This is due to the continuous progress in the technology, wide accessibility, and lower cost as compared to computed tomography and magnetic resonance imaging.
The diagnostic capacity of ultrasonic examination of the knee joint is the subject of an ongoing discussion. Ultrasonic methods of diagnostic examination of the knee joint cannot completely replace such methods as MRI and standard X-ray. Nevertheless, ultrasonic diagnosis has certain advantages. The most substantial advantage is the ability to test soft tissues of the knee joint, including ligaments, tendons, connective tissue elements, subcutaneous fat, and neurovascular bundles.
The trial was implemented using the Medison-128 ultrasonic scanner with a 7.5 MHz line scan sensor. The standard method focusing on examination of bursae and tendinoligamentous apparatus in the anterior and posterior projections was used. A total of 1,416 patients have been tested: 800 males (56.4%) and 616 females (43.5%). The average age of the patients was 43.6 years.
Four standard access methods were used to provide ultrasonic visualization of all elements of the joint: lateral, medial, anterior, and posterior. In ultrasonic visualization of the knee joint, the anatomy of the joint was considered. Anterior access provided visualization of the tendon of the quadriceps muscle of the thigh, anterior recess, knee cap, suprapatellar bursa, patellar ligament, infrapatellar bursa, and bursa of the knee fat pad. Tendons of the quadriceps muscle of the thigh do not have synovial sheaths; at the edge they are surrounded by a hyperechogenic stripe, while at the distal zone, behind the tendon of the quadriceps muscle of the thigh, the suprapatellar bursa is situated. In the norm, the suprapatellar bursa may contain a small amount of liquid. The panoramic scanning mode provides visualization of all four muscle bundles comprising the quadriceps muscle of the thigh.
Medial access provides visualization of medial collateral ligament, medial meniscus body, and medial joint space of the knee. The state of joint space, contours of the femoral and shin bones, the thickness and the state of hyaline cartilage, and presence of gaps in joint cavity are estimated. The epiarticular space contains fibers of medial lateral ligament, which starts from the proximal medial femoral condyle and is attached to the proximal metaphysis of the shin bone. The fibers of the anterior cruciate ligament are visualized only partially.
Lateral access provides visualization of the distal segment of fascia lata, the tendon of the popliteus muscle, the fibular collateral ligament, the distal part of the tendon of the biceps muscle of the thigh, the lateral meniscus body, and the lateral joint space. Cranial scanning provides visualization of the fascia lata fibers. Tendon fibers are attached to the bone near the Gerdy’s tubercle on the anterolateral surface of the tibial bone. Fixation of the sensor at the head of the fibula and rotation of the proximal end of the sensor toward the bottom provides detection of the tendon of the lateral head of the biceps muscle of the thigh.
Posterior access provides visualization of the neurovascular bundle of popliteal fossa, medial and lateral heads of the gastrocnemius muscle, the distal part of fibers of the tendon of the semimembranosus muscle, the posterior horn of the medial meniscus, the posterior horn of the lateral meniscus, and the posterior cruciate ligament. The neurovascular bundle is shifted in a lateral direction in the popliteal fossa. The popliteal artery is located behind the vein. The muscular fascicles of the popliteus muscle are visualized below. Panoramic scanning using energy mapping provides visualization of the popliteal artery. A small bursa with collum of Baker’s cyst is located between the tendon of the semimembranosus muscle and the medial head of the gastrocnemius muscle. To visualize this bursa, transverse scanning should be performed in the region of the posterior surface of the medial condyle of the femur covered with hyaline cartilage, tendons of the semimembranosus muscle, and fibers of the gastrocnemius muscle. Longitudinal scanning of the popliteal fossa provides visualization of the posterior horn of the lateral meniscus, as well as the posterior cruciate ligament. Posterior and anterior cruciate ligaments are visualized only partially. Their fibers are hypoechogenic because of the anisotropy effect. The posterior access also provides visualization of fibular nerve, which diverges from the lateral part of the sciatic nerve in the distal femur, passes down laterally along the distal tendon of the biceps femoris, reaches the popliteal fossa, and turns around the head of the fibular bone toward the anterior surface of the shin.
Specific anatomical features and functional loads of the knee joint increase the probability of its overstrain, trauma, and development of various diseases. Even insignificant dysfunction of the knee joint leads to substantial discomfort and impairment of work capability. More significant dysfunctions can lead to disability.
Ultrasonic examination provides detection of changes in bone structure at an early stage, which cannot be detected by X-ray. The main features of the pathotopographic ultrasonic anatomy of deforming arthrosis are heterogeneous thinning of hyaline cartilage, irregular contour...
