Ultrasound signs of diseases and injuries of the knee

Features of the anatomical structure and functional loads in the knee joint create a high probability of its overload and traumatization, the development of various diseases. Even minor violations of the function of this joint lead to considerable discomfort for the person, to disability, and with significant damage and disability. All pathological changes in the knee joint can be conditionally divided into several main groups.

1. Damage to the tendon-ligament apparatus:
   • damage to the tendon of the quadriceps femoris muscle;
   • damage to the patellar ligament;
   • damage to the inner lateral ligament;
   • damage to the lateral ligament;
   • anterior cruciate ligament injury;
   • damage to the posterior cruciate ligament.
2. Pathological changes of the meniscus:
   • degenerative changes;
   • breaks;
   • operated meniscus;
   • cysts;
   • dysplasia.
3. Pathological changes in the synovium:
   • hyperplasia of the synovial fold;
   • vylonodular synovitis;
   • osteochondromatosis;
   • synovial sarcoma;
   • rheumatic synovitis.

Tricks of the quadriceps femoris tendon

Damage to the tendon of the quadriceps femoris occurs due to compression or excessive muscle contraction. Isolate partial and complete breaks. Most often, the gaps are localized in the zone of the transition of the tendon part to the muscle or in the place of the transition of the tendon of the quadriceps femoris to a patellar patella, rarely at the attachment of the tendon to the bone. The causes of ruptures are trauma, degenerative processes or systemic diseases, such as diabetes mellitus, rheumatoid arthritis, erythematosis, hyperparathyroiditis. Clinically, at the time of the rupture, the patient feels a crash, which is sometimes heard from a distance. The function of the quadriceps muscle disappears at full ruptures, with partial ruptures in the acute period, knee extension is impossible. With partial ruptures, patients complain of pain, swelling of the knee and restriction of knee extension.

In ultrasound examination, the complete rupture of the quadriceps femoris tendon during compression by the sensor looks like a complete disruption of the integrity of the fibers and the fibrillar structure of the tendon. The defect is replaced by a hematoma, an effusion appears in the front turn. When the rupture of the tendon is accompanied by rupture of the articular bag, hemarthrosis occurs. With a partial rupture, there is a local disturbance of the integrity of the fibers and the fibrillar structure with the appearance of hypoechoic sites in their place. The contours of the tendon do not usually change, the tendon itself is not thickened.

When intramundial - partial ruptures, the contours of the tendon are preserved, however, at the site of the rupture a hypoechoic region is visualized, where there is a break in the fibrillar structure of the tendon. With MRI on T2-weighted images, a high intensity signal is visualized in the projection of the fibers of the quadriceps femoris muscle. After the treatment course, the fibers of the tendons and ligaments do not regenerate completely and do not restore their original structure. In case of recurring partial fractures, in spite of the remaining contours of the tendon, the replacement of fibrillar fibers with connective tissue takes place at the site of injury. At the site of the rift, scar tissue forms, which, with ultrasound, looks like a hyperechoic fibrosis zone.

Fracture of patella

With a sports injury, very often there are ruptures of the quadriceps muscle of the thigh and its tendon, sometimes in combination with a patellar fracture. The mechanism of this trauma is the forced reduction of the quadriceps muscle, for example, in weightlifters or in football players.

Most often encounter transverse fractures of the patella, less often - comminuted, segmental, stellate, vertical and others. Divergence of fragments always points to ruptures of the lateral ligaments of the knee joint. With the integrity of the lateral ligaments, there is no discrepancy between the fragments. Always marked in varying degrees of hemarthrosis, extending into the upper volvulus. In ultrasound examination, the patella fracture appears as a violation of the integrity of the patella contours with varying degrees of divergence of the edges of the fragments, depending on the type of fracture and concomitant rupture of the lateral ligaments.

Discontinuities of the patellar ligament

Disruptions of the patellar ligament are due to direct injury, for example, when falling, on a bent knee. The rupture is localized under the patella, often closer to the tuberosity of the tibia. Damage to the ligament is combined with an effusion in the area of the podnkolennoy bag. The patella, due to the contraction of the quadriceps muscle, shifts to the top. With complete rupture, the fibrillar structure of the ligament disappears, in its place there is a hematoma and effusion into the podnkolennuyu bag. At partial rupture the fibrillar structure of the ligament is partially preserved. Also, ligament ruptures easily arise against a background of chronic tendinitis.

[1], [2], [3]

Suprapatellar bursitis

The heeled bag is the biggest bag. It extends 6 cm up from the proximal part of the patella and is called the upper curvature. From the 5th month of intrauterine development in the wall of the bag there may be holes, through which communication is made between the bag and the cavity of the knee joint. This phenomenon occurs in 85% of adults. Any changes within the knee joint are reflected as an effusion in the knee bag.

With ultrasound, the suprapatellar bursitis quite often looks like a triangular section of a reduced echogenicity. Depending on the content, the echogenicity of the bag may be increased or decreased.

Semi-membranous, tibial-collateral bursitis

Semi-membranous, tibial-collateral bursitis is a bag filled with liquid in the form of the letter "U", which covers the tendon of the semimembranous muscle from the medial and the front side. Inflammation of the bag causes local pain at the level of the medial line of the joint and clinically resembles a meniscus tear.

Bursitis of internal collateral ligament

The bag of the inner collateral ligament is located between the medial meniscus and the inner lateral ligament. The effusion occurs due to the inflammatory process, menisco-capsular separation or damage to the inner lateral ligament. Inflammation of the bag causes local pain along the medial surface of the joint, reminiscent of clinically breaking the medial meniscus.

[4], [5], [6], [7], [8]

Exudation in the joint cavity

Damage to the knee joint is often accompanied by hemorrhages in the joint. Hemorrhagic effusion, formed two hours after the injury, may indicate a rupture of the lateral or cruciate ligaments, menisci, patella dislocation, intra-articular fracture of the condyles of the thigh. The amount of blood with hemarthrosis of the knee joint is different. Blood in the joint cavity stimulates the production of synovial fluid, leading to an even greater stretching of the bag and capsule of the joint. The more fluid in the joint, the greater the pain.

For a better visualization of fluid in the joint, functional tests are performed in the form of tension of the quadriceps muscle of the thigh or compression of the lateral synovial curvature. The fluid in the joint cavity is better defined by medial and lateral access.

[9], [10], [11], [12],

Tendinitis

The tendinitis of the tendon of the quadriceps muscle of the thigh, patella, biceps muscle is most common. With tendinitis, the tendon thickens, its echogenicity decreases. Disappears the anisotropy effect, characteristic of the tendon. In the course of tendon fibers there is an increase in vascularity.

Tendonitis of the tendon of the quadriceps muscle of the thigh . Patients complain of local pain and swelling in the ligament or tendon area. Depending on the location, the symptoms are similar to those of the meniscus and patella. With tendinitis, the tendon of the quadriceps femoris thickens at the attachment to the patella, its echogenicity decreases. In chronic tendinitis, micro-ruptures, fibrous inclusions in tendon fibers, calcification sites can occur. These changes are united under the common name of degenerative tendon changes.

Tendonitis of the patellar ligament. The most commonly occurs tendonitis of the patellar ligament. It can be: local (in the area of attachment to the patella or the tibia) or diffuse. Local tendonitis often occurs with a constant load of jumpers, runners for long distances, when playing volleyball and basketball. He was called the "knee jumper" and "inverted knee jumper." In tendonitis, the deep sections of the ligament are predominantly affected at the attachment site. However, any part of the ligament can be involved in the pathological process. In this case, the ligament thickens either in the area of its attachment to the patella, or in the area of attachment to the tibia. With chronic tendinitis, the place of attachment of the ligament to the bone appears calcifications, areas of fibrosis.

In the chronic process, dystrophic calcification in the affected segment is observed. The fat cushion of Goff can increase due to infringement and inflammation. With ultrasound, the hypertrophy of the Hoff fat pad, as a consequence of mucoid degeneration, is defined as a hyperechoic structure.

Friction syndrome of the orotibial tract

Friction syndrome orotibial tract or "knee runner" is more fasciitis than tendonitis. It arises from the constant mechanical friction or the ootibial tract about the deformed lateral epicondyle of the thigh, which leads to the inflammation of the fascia that forms the orotibial tract. This syndrome is most common in runners, especially in sprinters, which are characterized by running with a high leg raising.

Ultrasound should be performed immediately after the physical exertion causing pain. On ultrasound over the lateral condyle of the femur, an enlarged fascia, reduced echogenicity will be seen.

Osgood-Schlatter disease

This is a kind of chondropathy affecting its own patellar ligament and tuberosity of the fibula. It occurs as a result of repeated microtrauma of this area. In this disease, the patient has spontaneous pain in the knee, which is aggravated by bending the knee joint.

Ultrasound signs are the same as in inflammation of the ligament, but with this pathology there are bone inclusions in the ligament.

The distal part of the patellar ligament is thickened and hypoechoic areas with fragments of anterior tuberosity of the tibia are determined in it.

Rupture of inner lateral ligament

Damage to the inner lateral ligament is most frequent. The mechanism of its traumatization: with a bent knee and a fixed foot, a sharp external rotation of the shin occurs when the thigh rotates internally. Clinically, pain and swelling occur in the area of injury.

There is a symptom of lateral swing of the lower leg, when the calf is simultaneously withdrawn at the pressure on the outer surface of the knee joint. If the inner lateral ligament is damaged, the valgus position of the knee is markedly increased. Damage can occur anywhere in the ligament: in the proximal part, in the area of its attachment to the inner condyle of the femur; in the distal part where the ligament is attached to the tibia condyle and at the attachment point to the inner meniscus - above the joint line. If a rupture occurs at the level of the joint line, where the inner ligament is fused to the meniscus, then such a trauma can be combined with simultaneous damage to the inner meniscus and anterior cruciate ligament. The ruptures of the inner lateral ligament are possible at different levels, due to the complexity of the structure of its fibers. There are partial and complete rupture of the lateral ligaments of the knee joint. Only surface fibers, either superficial or deep, can be observed, as well as ruptures with detachment of the bone fragment. A complete rupture of one of the lateral ligaments leads to instability in the knee joint. At ultrasound examination, the following are revealed: violation of the integrity of the ligament fibers, displacement of fibers under functional load, hypoechoic region (hematoma), decrease in echogenicity due to soft tissue edema.

Rupture of the lateral ligament

The outer lateral ligament is less often damaged than the inner ligament. Her tears are caused by a strong inner rotation of the shin. Sometimes, instead of rupturing of the ligament, the bone fragment of the fibula head with a lateral ligament attached here is torn off. Often damaged is passing near the peroneal nerve. Ultrasound signs are the same as in the case of rupture of the inner lateral ligament: disruption of the integrity of the ligament fibers, displacement of fibers under functional loading, formation of a hypoechoic region (hematoma), decreased echogenicity due to edema of soft tissues and subcutaneous fat.

Dystrophic calcification of the lateral ligament is encountered mainly in athletes, in particular, in long distance runners.

Calcification of Pellegrini-Stiege

The syndrome is a post-traumatic ossification of pararticular tissue that occurs in the region of the inner condyle of the thigh. The disease is usually observed in young men who suffered a traumatic injury of the knee joint. Damage can be light or heavy, direct or indirect. After the disappearance of acute symptoms of damage, a period of improvement may occur, but complete recovery of the knee joint does not occur. Extension in the knee joint remains limited. Ultrasound in the structure of the inner lateral ligament determines multiple ossification in the form of a soft hyperechoic focus, located mainly in the attachment zone of the ligament to the epicondyle of the femur.

[13]

Damage of anterior cruciate ligament

Injury of the anterior cruciate ligament is most common. The mechanism of damage is overvoltage in the conditions of rotation, falling at a fixed foot and excessive over-extension in the knee joint. Gaps occur more often in combination with other injuries: for example, with the rupture of the inner lateral ligament and the inner meniscus.

The main symptoms of trauma are a feeling of instability in the joint, swelling and tenderness when moving to the primary post-traumatic period. The most valuable clinical symptom in the rupture of the anterior cruciate ligament is the symptom of the "front drawer". To do this, the patient should bend the knee to the right angle, while the shin can be easily pushed forward with respect to the thigh. Most often, the ligament is damaged in the proximal and less often in the central departments. It is very important to identify the ligament rupture in time, as this will determine the nature of the operation.

MRI is a more accurate and reliable method of diagnosing anterior cruciate ligament damage. On MP tomograms with a fresh trauma in the rupture zone there is an increase in signal intensity, which normally has a moderate intensity at T1 and is more intense on T2-weighted images. The damaged fibers of the anterior cruciate ligament are not clearly differentiated or not defined at all. MRI diagnosis of partial fracture with fresh trauma can be difficult due to local edema and discontinuity of the fibers. There are indirect indications for the diagnosis of anterior cruciate ligament rupture: its displacement is below 45 ° with respect to the tibial plateau, local change of its trajectory and displacement of the back of the outer meniscus by more than 3.5 mm relative to the tibial plateau. With chronic ruptures, a ligament is noted for thinning without edema of the synovial membrane.

[14], [15], [16], [17], [18], [19], [20], [21], [22]

Rupture of posterior cruciate ligament

The rupture of the posterior cruciate ligament is rare. The main mechanism of the rupture is hyperflexion during the jump. More often the rupture is localized in the body of the ligament or at the level of its attachment to the tibia.

Damage to meniscus

Meniscus ruptures are considered the most common type of knee injury. Meniscal lesions can occur at any age. With age, menisci become weak and fragile. Any wrong and abrupt movement can provoke their break. The medial meniscus is damaged 10 times more often than the lateral one. This is due to the anatomical and morpho-functional features of the internal meniscus. The mechanism of an isolated trauma is a fall from the height to the legs straightened at the knee joint, with sharp and deep bending in the knee joints at the moment of squatting and trying to straighten up at the same time. However, more often the meniscus is damaged by a sharp rotational motion in the knee joint - the rotation of the thigh inwards with a fixed shin and foot. The predisposing moment is undoubtedly the preceding microtrauma. The main clinical symptom of meniscus damage is the "blockade" of the knee joint. The part of the meniscus, torn off by damage, can move and occupy the wrong position in the joint, being trapped between the articular surfaces of the tibial and femur bones. Injury blocks the joint in the forced bent position. Detachment and infringement of the anterior horn of the inner meniscus block the knee joint so that the final 30 ° extension is impossible. The infringement at rupture by the type of "handle of the watering can" limits the last 10-15 ° extension. Blockade of the joint with infringement of the ruptured meniscus does not limit bending of the knee joint. A severed rear horn very rarely blocks the joint. Blockade of the joint is usually temporary. Unlocking restores all movements in the joint.

In ultrasound examination, meniscus rupture, as a rule, is accompanied by an effusion in the area of the damaged meniscus. The meniscus acquires an irregular shape with the presence of a hypoechogenic band at the site of the rupture. It should be taken into account that, in norm, the meniscus can have a hypoechoic band in the middle part of the meniscus.

The use of tissue harmonic regimen improves the visualization of meniscus ruptures, by improving contrasting detailing. Three-dimensional reconstruction has a certain value in determining the extent. It should also be emphasized the importance of energy mapping for diagnosing a meniscus rupture. The presence of local vascularization amplification around the affected area, helps to suspect and determine the localization of the rupture.

The main signs of meniscus damage include:

• violation of the integrity of the meniscus contours;
• fragmentation or presence of hypoechoic sites;
• the appearance of a hypoechoic band in the structure of the meniscus;
• formation of effusion;
• swelling of soft tissues;
• displacement of the lateral ligaments of the knee joint;
• an increase in the degree of vascularization in the area of meniscus rupture.

Some types of meniscus ruptures can be detected by ultrasound. These include transchondral and paracapsular ruptures. Typically, a typical, longitudinal injury of the meniscus occurs, in which the middle part of the meniscus opens, and the ends, front and back, remain intact. This gap was called the "leukey handle" gap. The rupture passing along the radially extending fiber to the inner free edge is called a "parrot-beak" tear. Repeated microtraumas of the meniscus lead to a secondary rupture with damage to the anterior, middle and posterior parts of the meniscus.

The ruptures of the anterior horn and the "handle of the watering can" often occur with recurrent blockages that occur when the shin is rotated; with the same mechanism, in which a break occurred. Sometimes the knee "jumps out", according to the patient, without a certain reason when walking on an even surface and even in a dream. Displacement of the detached rear horn sometimes causes the patient to feel the knee joint flexing.

The rupture of the meniscus is accompanied by an effusion in the knee joint, which appears a few hours after the injury. It is caused by concomitant damage to the synovial membrane of the joint. Subsequent relapses of blockade attacks and "bending" also occur with an effusion in the joint. The more blockades and "bending" occur, the less subsequent transudation in the joint. There may come a state where, after the usual blockade, the effusion is no longer determined. The rupture of the external meniscus arises by the same mechanism as the inner one, with the only difference that the rotational motion of the shank is performed in the opposite direction, i.e. Not outward, but inside. Blockade of the joint with rupture of the external meniscus occurs rarely, and if it occurs, it is not accompanied by an effusion in the joint.

On MP-tomograms with true rupture, the signal intensity increases to the periphery of the meniscus. A true rupture is clearly visible when the axis of the scanning layer is perpendicular to the axis of the lesion. If the gap is oblique, then the resulting artifacts can mask the damage.

[23], [24], [25], [26]

Degenerative changes and meniscus cysts

With degenerative changes of menisci, heterogeneity of their structure, fragmentation, hyperechoic inclusions and cysts are noted. Similar changes are observed with chronic meniscus lesions. Cysts of the outer meniscus are often observed. Cysts cause pain and swelling along the joint line. Cysts of the inner meniscus reach a larger size than the outer one, and less fixed. The meniscus cyst looks like a rounded structure with smooth, distinct internal and external contours, with an anechoic internal structure and the effect of distal amplification of the ultrasound signal. Additional scan modes (tissue harmonics and adaptive coloring) improve the visualization of cyst contours. Over time, the fluid in the cyst becomes uneven, with thick contents. With an increase in size, cysts tend to soften.

[27], [28], [29], [30], [31]

Baker's cysts

Cysts Baker - one of the most frequent pathologies in athletes. As a rule, these cysts are asymptomatic and are an ultrasound or clinical finding. The substrate for the development of this cyst is the stretching of the bag located between the semimembranous and gastrocnemius tendons. A differential diagnosis of Baker's cyst is the visualization of the cervix, communicating with the knee cavity in the medial region of the popliteal fossa: between the medial head of the gastrocnemius muscle and the tendon of the semimembranous muscle. As the manifestation of the inflammatory reaction in the surrounding tissues, there is an increase in vascularization, which is recorded in the energy mapping mode. Increased fluid in the joint cavity leads to accumulation of fluid in the bag and the occurrence of a cyst. Cysts have different sizes and lengths. The contents of the cysts are different: "fresh" cysts have anechogenous contents, chronic - non-uniform. With fresh Baker cysts, the contents are liquid, whereas with old forms, it is jelly-like. A rupture of the Baker cyst is diagnosed when there is a characteristic pointed edge and a strip of fluid along the tendons of the gastrocnemius tendon. More characteristic are ruptures in the lower part of the cyst. Panoramic scanning mode allows you to visualize the cyst all over.

[32], [33], [34], [35]

Deforming arthrosis

The disease occurs as a result of metabolic disorders in the articular cartilage, mechanical loads with excessive body weight, physical overload. Regardless of the cause of the onset, clinical manifestations of arthrosis are similar and depend on the phase: exacerbation, subacute phase or remission. Ultrasound can detect the most initial changes in bone structures, which are not detected by X-ray examination. The main ultrasound signs that allow determining the presence of deforming arthrosis are: uneven thinning of the hyaline cartilage, uneven contours of the femoral and tibia bones, the presence of marginal osteophytes, narrowing of the joint gap and prolapse of the meniscus. The presence of hyperechoic marginal osteophytes at normal sizes of the joint gap and the thickness of the hyaline cartilage characterize the early manifestations of the disease. Progression of the disease is characterized by the formation of marginal osteophytes with acoustic shade, narrowing of the joint gap and pronounced thinning of the hyaline cartilage. Subsequently, thinning of the hyaline cartilage (less than 1 mm) occurs with the formation of coarse osteophytes and the prolapse of the meniscus by a third of the width. In the stage of pronounced changes there is a complete prolapse of the meniscus, deformation of its intraarticular part, absence of an articular gap, rough massive osteophytes along all the edges of the joint surface.

[36], [37], [38]

Pathology of cartilage tissue

Pathological changes in hyaline cartilage are characterized by a violation of its normal thickness and calcifications. Thinning of hyaline cartilage is more common in older people. With inflammatory synovitis or septic arthritis, there is also a sharp destruction of proteoglycans and thinning of the cartilage. With the progression of the pathological process, the formation of necrosis zones, the formation of cysts and ossifits. Single osteophytes are formed primarily along the edge of the hyaline cartilage in the cortical layer of the bone. Such changes are the norm for older people.

Thinning of the cartilage is observed in osteoarthritis. The cartilage is destroyed, and the new cartilage is formed already in the form of osteophytes. Some surface defects of the cartilaginous tissue are replaced by scar tissue, which is close to cartilaginous in its morphological composition. This occurs as a result of local lesions with the formation of the so-called fibrous cartilage. Such changes are well defined in MP-tomograms because of the low signal intensity in the affected area. Thickening of cartilage occurs with acromegaly. These are the first signs of the disease. Also, the cartilage may increase in size with myxedema and some mucopolysaccharidoses, with extensive erosion.

König's disease

The disease occurs at a young age and affects the epiphysis of the tibia, cartilage, tendon and serous bag. The lesion is usually one-sided. The area of articular cartilage along with the adjacent bone is separated from the joint surface.

A typical lesion is the inner condyle of the hip, less often other joints and the patella. In adults, exfoliating osteochondritis can sometimes occur after mechanical damage. The torn loose body in the joint can grow and reach a fairly large size.