How is the knee joint arranged, and what can damage it? Articular bag, synovial membrane, synovial fluid.

The knee joint is one of the most difficult. The accessibility of the joint to external influences causes frequent trauma to it.

The tibiofibular joint is an independent articulation, and only in 20% of cases, according to individual authors, this joint communicates through the bursa mucosa m. poplitei with a knee joint.

The articular surface of the femoral condyles is convex, the condyles are separated by a deep intercondylar cavity. The articular surface of the tibial condyles, on the contrary, is slightly concave, while the condyles are separated by an intercondylar eminence.

Articular surfaces the femur and tibia are incongruent, but this discrepancy is smoothed out by the cartilaginous formations between them - the menisci. The outer meniscus has the shape of a circle that is not closed inside, the inner meniscus is crescent-shaped. The posterior horns of both menisci and the anterior horn of the outer meniscus are fixed to the eminentia intercondylaris, the anterior horn of the inner meniscus passes into lig. transversum genu. Apparently, the latter circumstance has a certain significance in the sense of more frequent traumatization of the inner meniscus.

Articular surfaces are held within the joint cruciate ligaments.

The anterior cruciate ligament is attached to the inner surface of the lateral condyle of the femur and to the anterior intercondylar fossa of the tibia just behind the anterior horn of the internal meniscus.

The posterior cruciate ligament is attached to the outer surface of the internal condyle of the femur and to the posterior intercondylar fossa of the tibia, partly to the posterior surface of the latter. A bundle of fibers departs from the posterior cruciate ligament to the posterior section of the external meniscus - lig. menisci lateralis (Roberti).

The cruciate ligaments inhibit the hyperextension of the lower leg, prevent rotational movements and keep the tibia from moving in the anteroposterior direction, in part they also prevent excessive flexion of the lower leg. When the cruciate ligaments are torn, there is a drawer symptom and sometimes subluxation of the lower leg occurs.

Articular bag The knee joint consists of two layers - synovial and fibrous. It is attached on the femur above the border of the articular cartilage (0.5-2 cm), on the tibia - slightly below the border of the cartilage. In the anterior section, the capsule is attached to the edge of the articular surface of the patella and fuses with the tendon of the quadriceps femoris.

The epiphyseal zone of the femur (with the exception of the lateral sections) is located in the cavity of the knee joint, and the epiphyseal line of the tibia lies outside the cavity of the joint.

The fibrous layer of the capsule has an unequal thickness throughout and does not have great strength. The capsule is strengthened in front by tendons m. quadriceps, laterally - lig. collateralia tibiale and fibulare, behind - lig. popliteum obliquum, lig. popliteum arcuatum.

In addition, the anterior part of the joint capsule is reinforced by the own fascia of the knee region, thickened by the tendon fibers of the sartorius muscle and tractus iliotibialis.

The synovial membrane is attached strictly along the edges of the cartilage. In the posterior region, it covers the cruciate ligaments, and laterally it passes to the menisci.

Synovial membrane joint forms a series of folds, inversions and bags. There are nine torsion of the knee joint. The largest, unpaired, anteriosuperior torsion is located 4-6 cm above the patella, and in the presence of communication with bursa suprapatellaris - 10-11 cm. There is a layer of fatty tissue between the torsion and the femur, which allows skeletonization of the bone at an atom site without opening the joint. However, in the distal femur (eg, supracondylar osteotomy, sequestrectomy), this torsion can easily be damaged.

The remaining inversions - anterior lateral, anteroinferior lateral, posterior superior and posterior inferior (medial and lateral) - are much smaller and have less practical significance.

Torsion is a place of accumulation of pathological fluid (blood, pus), while significantly stretching, they greatly increase the volume of the joint cavity. In the upper and posterolateral torsions, the development of the tuberculous process occurs first when it passes to the joint.

Under normal conditions, the cavity of the knee joint is one, however, with the development of the inflammatory process, narrow gaps (between the cruciate ligaments and on the sides of the condyles), connecting the anterior and posterior sections of the cavity, due to swelling of the synovial membrane, can close, and the joint cavity is divided into anterior and posterior sections.

In addition, swelling of the pterygoid folds of the synovial membrane and plica synovialis infrapatellaris during the development of the inflammatory process leads to the separation of the anterior part of the knee joint into the inner and outer halves. P. G. Kornev attaches great importance to these folds in the process of delimiting tuberculous inflammation in the joint. Finally, the posterior section of the joint, with inflammatory swelling of the synovial membrane covering the posterior cruciate ligament, the ligament of the external meniscus, is also divided into disjunct internal and external sections.

Between the pterygoid folds, the fibrous layer of the capsule of the knee joint, there is a rather large lump of fat, which sometimes undergoes degenerative changes (Goff's disease). In this case, there are indications for the removal of the fat lump.

The joint cavity reaches its greatest capacity with a slightly bent knee joint, in an adult it is 80-100 cm3.

blood supply The knee joint is carried out by branches of the femoral, popliteal, anterior tibial arteries and the deep artery of the thigh. There are permanent branches and non-permanent ones. Permanent branches include: a. articulationis genu suprema; upper and lower (paired) arteries of the knee (from a. poplitea); the middle artery of the knee, supplying the cruciate ligaments, as well as the region of the intercondylar fossa of the femur and the intercondylar eminence of the tibia; two recurrent arteries (from the anterior tibial). All these branches form the arterial network of the knee - rete genu. Within this network, separate segments can be distinguished: in the region of the patella, in the region of the condyles of the thigh.

innervation the knee joint is carried out by branches of the femoral, obturator, sciatic nerves.

The main nerve branches of the anterior surface of the knee are located on the inside of the latter, and the nerve branches of the posterior surface of the joint are mainly on the outside.

The common innervation of the hip and knee joints sheds light on the cause of pain in the knee joint in the initial period of tuberculous coxitis. These pains depend on irritation due to inflammatory infiltration of the capsule of the obturator and femoral nerves, giving branches to both the hip and the knee.

movements in the knee joint are complex. When the lower leg is flexed, the tibia, in addition to rotation around the transverse axis, performs some posterior sliding along the articular surface of the femoral condyles. This anatomical detail provides a large range of motion in the knee around its transverse axis (or rather, the transverse axes).

Active knee flexion is possible up to an angle of 50°. In addition, passive flexion can be further increased by 30° and induce hyperextension from the middle position by 10-12°. With a bent knee, due to the relaxation of the lateral ligaments, rotational movements with an amplitude of up to 35-40 ° are also possible. Finally, with full extension in the knee, a small so-called final rotation (supination) is noted, depending on the unequal size and shape of the femoral condyles.

The article was prepared and edited by: surgeon

S.P. Mironov, N.A. Eskin, A.K. Orletsky, L.L. Lyalin, D.R. Bogdashevsky.

Federal State Institution "CITO named after N.N. Priorov" ROSZDRAVA.
Moscow, Russia.

Introduction

Despite the significant progress in instrumental diagnostics, a full-fledged clinical examination remains the main method for detecting knee joint pathology. However, the conditionality of clinical and morphological parallels in various soft tissue injuries and diseases causes significant difficulties in recognizing the nature of the pathological process, as well as in assessing its severity. Therefore, it is not surprising that the proportion of diagnostic errors in this pathology reaches 76-83%.

In connection with the development of modern medical technologies, the diagnostic arsenal has been replenished with a complex of such highly informative instrumental methods as CT, MRI, ultrasound, etc. Each of them has its own advantages and disadvantages. To obtain complete information about injuries of the soft tissues of the musculoskeletal system (MT of the musculoskeletal system), a whole range of techniques was required, sometimes tedious and expensive, and sometimes unsafe for the patient, especially immediately after the injury.

Currently, preference is given to those research methods that, in addition to being highly informative, have such qualities as non-invasiveness, harmlessness, and are also characterized by simplicity in performing and interpreting the results, reproducibility and high cost of research. In our opinion, real-time high-resolution ultrasonography meets most of the above requirements, therefore, in the course of our study, we tried to answer the question of the diagnostic effectiveness of ultrasound in determining soft tissue injuries of the musculoskeletal system in patients with orthopedic and traumatological profile.

Materials and methods

The total number of patients in the group was 816, including 661 men (81%), 155 women (19%), mean age 43.3±3.9 years.

Patients were admitted to the clinic or examined on an outpatient basis within a period of several hours to 3 weeks from the onset of the disease. Unilateral lesion was in 553 (67.8%) people, bilateral - in 134 (16.4%). 487 (59.7%) patients of this group were treated surgically, 129 (15.8%) patients were treated conservatively.

All patients in accordance with the clinical diagnosis were divided into three subgroups: with meniscus injuries - 465 (56.9%) people; with injuries of the ligamentous apparatus (medial and lateral ligaments) - 269 (32.9%) people; with pathology of the patella and own ligament - 82 (10.1%) people.

We analyzed the severity of such major non-specific clinical symptoms as pain, limited mobility of the knee joint, and changes in muscle strength (Table 1).

Table 1. Clinical symptoms in patients with injuries and diseases of the knee joint.

Subgroup of patients	Pain in the knee joint		Limitation of mobility in the joint		Change in muscle strength
Subgroup of patients	moderate	intensive	Yes	No	norm	reduced
meniscus injury	184	281	281	184	152	128
Ligament injury	175	94	109	160	185	84
Pathology of the patella and own ligament	53	29	59	23	28	54

The studies were carried out on an HDI-3500 and IU 22 ultrasonic scanner (Philips) in real time. As a result of the data obtained, the following main indications for ultrasonography in the pathology of the knee joint were determined:

synovitis;
damage and inflammation of the ligamentous component and muscles;
the presence of free bodies in the joint, cysts;
damage to the menisci, cartilage;
bone pathology;
tumors and tumor-like diseases.

results

Most often, synovitis occurs in the suprapatellar space (upper volvulus). The suprapatellar bursa is the largest in the human body and extends 6 cm upward proximal to the superior pole of the patella. Any impact on the knee joint (traumatic, inflammatory, gouty) leads to the occurrence of an increased amount of synovial fluid in the upper torsion of the joint (Fig. 1 a, b).

Rice. one. Sonograms of synovitis of the knee joint.

a) Pronounced synovitis of the knee joint with the presence of a thickened, with marginal growths of the synovial membrane (arrow).

b) Prolonged chronic synovitis with thickened synovial membrane and areas of sclerosis (arrow).

Frictional and gouty bursitis is the most common pathology. In acute frictional bursitis, the contents of the suprapatellar bursa are usually anechoic. Increased hyperechogenicity of the walls of the bag and contents develops after a while. With gouty bursitis, the content is hypoechoic, sometimes with the presence of hyperechoic inclusions. In the acute stage of the disease, inflammation of the surrounding soft tissues is noted.

Rice. 2. Hemarthrosis in varying degrees of organization.

a)
An excessive amount of effusion of a heterogeneous structure in the form of small hyperechoic inclusions (blood cells) and a hyperechoic band, indicating a rupture of the synovial membrane.

b)
Organized hematoma with its division into two environments. Upper - with a more pronounced organization, lower - with less organization and the presence of synovial fluid.

Hemorrhagic bursitis in most cases is observed in athletes as a result of injury. The hemorrhagic contents of the bursa are echogenic with or without the presence of hyperechoic blood clots (Fig. 2). If there is a large amount of hemorrhagic content in the suprapatellar and prepatellar bursa, it is necessary to exclude a rupture of the tendon of the quadriceps muscle (Fig. 3).

Rice. 3. Complete rupture of the quadriceps tendon. Hypoechoic hematoma at a typical tendon location. In the liquid formation, a fragment of the tendon is visualized in the form of a "bell tongue" (arrows).

In a conventional gray scale examination, a complete rupture of the quadriceps femoris tendon is defined as a complete disruption of the anatomical integrity of the fibers and fibrillar structure of the tendon. The defect is replaced by a hematoma, an effusion appears in the anterior volvulus.

With tendinitis, the tendon of the quadriceps femoris at the site of attachment to the patella thickens, its echogenicity decreases. In chronic tendinitis, microtears, fibrous inclusions in the tendon fibers, and areas of calcification may occur. These changes are combined under the general name - degenerative changes in the tendon (Fig. 4).

Rice. four. Ossified tendonitis of the tendon of the quadriceps muscle with the presence of synovitis in the upper torsion. In the place of attachment of the tendon to the upper pole of the patella, ossification with uneven contours is determined (arrow). The tendon is thickened, heterogeneous in structure and hypoechoic in the upper part with a slight synovitis.

H - the upper pole of the patella.
B - distal femur.

Prepatellar (Fig. 5) and infrapatellar (Fig. 6 a, b) bursitis are rare, mainly in rheumatoid and infectious arthritis, fractures of the patella, partial injuries of the patellar ligament, and also as a result of the activities of patients (parquet). Bursitis, as a result of long-term use of anticoagulants, is quite rare.

Rice. 5.

a) Longitudinal section of prepatellar hemorrhagic bursitis in the first 2 hours after injury. The anechoic content of bursitis is determined with the presence of thin hyperechoic inclusions.

b) Longitudinal section of hemorrhagic bursitis 16 hours after injury. In the anechoic contents, more pronounced hyperechoic inclusions are revealed.

Rice. 6.

a) Longitudinal section of the patellar ligament at the point of attachment to the tibial tuberosity.

When evaluating the prepatellar bursa, it is necessary to carry out a sonographic assessment of the contour of the patella (Fig. 7) and the place of attachment of the own and supporting ligaments (Fig. 8), since as a result of traumatic impact, damage to the periosteum and supporting ligament, most often the medial one (with dislocation of the patella), occurs. Injuries to the medial lateral ligament are the most common knee injuries.

Rice. 7.

a) With a slight dislocation of it in the distal direction, the presence of a hematoma at the fracture site (thick arrow) and hemorrhagic prepatellar bursitis (arrow).

b) Fracture of the lower pole of the patella with its pronounced dislocation in the distal direction.

In the interval between the bone fragments, a large semi-organized hematoma (arrow); N - patella.

Rice. eight. Longitudinal sonograms of damage to the medial patellar suspensory ligament and change in the contour of the patella at its insertion.

The site of damage to the ligament (arrows) is determined in the form of its thickening, decreased echogenicity and impaired structuring of the ligament. Under the distal part of the ligament there is a small hematoma in the form of a hypoechoic formation (thin arrow). Avulsion of a bone fragment of the patella (curly arrow).

Sonography in the diagnosis of pathology of extra-articular ligaments has a high diagnostic value and must be performed in a longitudinal section, parallel to the long axis of the ligament. When stretched, the ligament thickens, its structure becomes hypoechoic.

With partial or complete damage to the ligaments, a violation of its anatomical continuity is determined. The size and extent of damage depends on the type of rupture. The hyperechoic structure of the ligament at the rupture site becomes hypo- or anechoic, the injury site is filled with a hematoma, which can be detected as a hypoechoic or anechoic zone with or without hyperechoic inclusions (Fig. 9). Ultrasonographic examination determines the location of the ends of the damaged ligament.

Rice. 9. Complete damage to the medial tibial collateral ligament.

a) rupture of the upper layer of the ligament with filling of the ligament defect with a hematoma (arrow) and partial damage in the medial part of the ligament (arrow).

b) complete damage to the ligament at the site of attachment to the medial femoral condyle.

Thickening at the site of injury and filling with a hypoechoic hematoma with hyperechoic inclusions (arrow);
B - distal femur.

The external peroneal lateral ligament is less damaged than the internal one. Tears of the external peroneal lateral ligament occur with strong internal rotation of the lower leg (Fig. 10).

Rice. ten. Longitudinal sonogram of a complete rupture of the lateral peroneal collateral ligament of the knee with hypoechoic areas (arrow) and small bone fragments (thick arrows) at the insertion to the lateral femoral condyle.

M - head of the fibula.
B - lateral condyle of the thigh.

Tears of the lateral collateral ligaments are often associated with meniscal tears (Fig. 11), and sometimes with damage to the anterior cruciate ligament. According to different authors, ruptures of the cruciate ligaments of the knee joint occur with a frequency of 7.3-62% among all injuries of the capsular-ligamentous apparatus of the knee joint.

Rice. eleven. Complete tear of the medial tibial collateral ligament (arrows) and medial meniscus of the knee. In the interarticular gap, a cartilaginous intraarticular body is determined.

B - distal end of the thigh.
T - tibia.

The diagnostic efficiency of the sonography method in the study of injuries of the anterior and posterior cruciate ligaments depends on the experience of the researcher, the availability of modern ultrasound equipment, knowledge of the clinical signs and anatomy of the knee joint. The most accessible and convenient place to study the cruciate ligaments is the popliteal fossa. This is the site of attachment of the distal ligaments. The anterior cruciate ligament is attached to the posterior surface of the femur, and the posterior cruciate ligament is attached to the posterior surface of the tibia.

Both cruciate ligaments appear as hypoechoic streaks on sonograms on sagittal view. The anterior cruciate ligament is best examined transversely in the popliteal fossa, since full flexion of the knee joint is not possible in acute trauma. A comparative study of the contralateral joint is necessary. A complete ligament injury is identified as a hypo- or anechoic mass at the site of attachment to the femur. The posterior cruciate ligament can be injured in severe sprains or autoinjury from a knee impact on a dashboard. Partial or complete damage is detected as a global thickening of the ligament (Fig. 12 a, b, c).

Rice. 12. Injuries to the cruciate ligament in the popliteal region using a 3.5 MHz transducer.

b) Transverse sonogram. A hypoechoic zone (arrow) is defined at the site of attachment of the anterior cruciate ligament.

in) Damage to the anterior and posterior cruciate ligaments (thin arrows) with detachment of the bone fragment (curly arrow), damage to the posterior joint capsule (thick arrow). In the posterior part of the knee joint, fragments of damaged ligaments floating in a hypoechoic fluid component (hematoma).

B - femur.
T - tibia.
L - lateral condyle of the thigh.
M - medial condyle of the thigh.

Ultrasonographic examination must be carried out in two projections: in the transverse - this requires visualization of both femoral condyles - and at an angle of 30 ° from the longitudinal projection with capture in the image under study of the lateral part of the medial tibial condyle and the medial part of the lateral condyle of the femur.

According to the CITO Sports and Ballet Injury Clinic, where mostly athletes are treated, meniscal injuries rank first among internal injuries of the knee joint.

There are the following types of meniscal injuries:

detachment of the meniscus from the attachment sites in the region of the posterior and anterior horns and the body of the meniscus in the paracapsular zone;
ruptures of the posterior and anterior horns and the body of the meniscus in the transchondral zone;
various combinations of the listed damages;
excessive mobility of the menisci (rupture of intermeniscal ligaments, degeneration of the meniscus);
chronic traumatization and degeneration of the menisci (post-traumatic and static meniscopathy - varus or valgus knee);
cystic degeneration of menisci (mainly external).

Meniscus ruptures can be complete, incomplete, longitudinal ("watering can handle"), transverse, patchy, fragmented (Fig. 13 a, b).

Rice. 13. Paracapsular injury to the medial meniscus.

a) Almost complete damage to the meniscus, manifested by a hypoechoic zone (arrow) at the site of attachment of the meniscus to the ligament.

b) Partial damage to the medial ligament (thick arrow) and meniscus (arrows).

In the clinical picture of meniscus injury, acute and chronic periods are distinguished. Diagnosis of meniscal injuries in the acute period is difficult due to the presence of symptoms of reactive non-specific inflammation that also occurs with other internal joint injuries. Characterized by local pain along the joint space, corresponding to the area of damage (body, anterior, posterior horn), a sharp limitation of movements, especially extension, the presence of hemarthrosis or effusion. With a single injury, bruises, tears, infringements and even crushing of the meniscus without tearing and separating it from the capsule often occur (Fig. 14 a-d). Predisposing moments for a complete rupture of a previously intact meniscus are degenerative phenomena and inflammatory processes in it. With proper conservative treatment of such an injury, complete recovery can be achieved (Fig. 15 a-d).

Rice. fourteen.

a) Complete detachment of part of the meniscus (arrow) and its migration into the joint cavity.

b) Transverse rupture of the body of the meniscus (arrow).

The most complete answers to questions on the topic: "upper volvulus of the knee joint fluid."

Arthritis (synovitis) of the knee joint.
Fluid in the joint cavity is present normally, but in a very small amount. Usually, it is not even detected on ultrasound. Arthritis is inflammation of the joint. On ultrasound, you can often find the wording "synovitis", which, in essence, is about the same. But "arthritis" is a clinical diagnosis. The wording "synovitis" indicates that fluid has been found in the joint cavity. There can be many reasons for the appearance of fluid - inflammation, trauma, reactive arthritis, cancer, etc.

The fluid in the joint cavity is clearly visible on ultrasound. It accumulates in the upper inversion of the knee joint. As in other organs, the fluid on ultrasound is anechoic (black). The fluid can be homogeneous or inhomogeneous. An inhomogeneous fluid can become due to a long-term inflammatory process in the joint cavity. Against the background of anechoic fluid, a thickened synovial membrane can be detected. The synovial membrane produces synovial fluid, which serves to lubricate the joint. But with inflammation, it thickens, sometimes villous growths form on it, which are clearly visible against the background of the liquid. The synovial membrane on ultrasound has increased echogenicity. Its contour is uneven, clear. According to the amount of fluid, the ultrasound doctor can subjectively indicate in the conclusion the severity of synovitis.

Often, the fluid descends from the upper inversion into the popliteal region, where it takes on a characteristic appearance (it resembles a comma on ultrasound). This formation is called a Baker's cyst. Sometimes free bodies can be found in the cyst cavity - bone fragments, calcifications.

Hemarthrosis- the presence of blood in the cavity of the joint. Hemarthrosis occurs due to joint injuries. On ultrasound in the first day after injury, the blood has a characteristic appearance. It is a heterogeneous liquid, mixed echogenicity.
Sometimes, clots of increased echogenicity can be detected. In the future, blood on ultrasound can be difficult to distinguish from ordinary fluid. As a rule, it becomes anechoic, homogeneous. And as hemarthrosis "maturity", the fluid begins to organize, a large number of fibrin fibers appear in it and it becomes heterogeneous, with areas of increased echogenicity. It is impossible to say with accuracy about the nature of the fluid in the joint cavity by ultrasound. If the doctor, with the eyes of a specialist, suspects that the fluid he has taken is blood, then most likely he will write this in the ultrasound report. But the wording "synovitis" in this case will not be considered a mistake. Because synovitis on ultrasound is the presence of fluid in the joint cavity of any nature.

articulation genus

Knee-joint form: condyles of the femur, condyles of the tibia and patella. In half of the cases, the length of the condyle of the femur is equal, in the second half, the length of the external condyle predominates. The medial condyle is in all cases wider and higher than the outer one. The articular areas of the tibia have the following dimensions: at the medial condyle - length 4.1-5.3 cm, width - 2.8-3.8 cm, at the lateral condyle - length 3.3-4.9 cm, width - 3 0-4.1 cm. The thickness of the cartilaginous cover at the condyles of the femur in the center is 1.6-6 mm, and gradually decreases towards the periphery. The patella has on average: a length of 3.3-5.3 cm, a width of 3.6-5.5 cm and a thickness of 2-2.8 mm.

The articular surface of the condyles of the femur is convex, the upper articular surface of the tibia is concave. The congruence of the articular surfaces is increased by cartilaginous menisci. Meniscus lateralis is wider and shorter than the medial meniscus, resembles an incomplete ring in shape, but may have the form of a disk (1.6%), completely separating the articulating surfaces, or approach it in shape (6.5%), having a hole in the center. Meniscus medialis, semi-lunar in shape, has an unequal width, tapering in the middle part. The anterior horns of the menisci are fixed by the anterior ligaments to the tibia and are interconnected by lig. transversum genus (occurs from 56 to 73.5% of cases). In addition, the medial meniscus with lig. meniscofemorale anterius, which starts from the anterior part of the meniscus and is attached to the inner surface of the lateral condyle in front of the posterior cruciate ligament (occurs from 20.6 to 45.3% of cases). Lateral meniscus with lig. meniscofemorale posterius (occurs from 33.3 to 60% of cases), which starts from the posterior edge of the lateral meniscus behind the posterior cruciate ligament and is attached to the outer surface of the medial condyle of the femur. The inner, thin edge of the menisci is free, the outer one is fused with the joint capsule, with the exception of the posterolateral surface of the lateral meniscus, which is in direct contact with the tendon of the popliteal muscle, covered with a synovial membrane within the recessus subpopliteus. The length of this section is on average equal to 1/5 of the outer circumference of the meniscus.

Rice. 150. Opened knee joint; front view.

The cavity of the knee joint is a complex complex of communicating fissures bounded by articulating bones, menisci, joint capsule, synovially covered intra-articular ligaments, and fatty protrusions. The capacity of the joint cavity in adults with a bent knee ranges from 75-150 cm3. The limiting capacity of the joint cavity in men is 150 cm3, in women 130 cm3.

The capsule of the knee joint has an outer fibrous and inner synovial membranes (layers). The synovial membrane is attached along the edges of the menisci and articular cartilage and, adjoining in certain areas to the femur and tibia, to the inner surface of the fibrous layer of the joint capsule, fatty tissue, intraarticular ligaments and the tendon of the quadriceps femoris, forms protrusions in various places - inversions. The fibrous membrane of the capsule on the tibia is attached, somewhat retreating down from the articular cartilage and reaching the tuberosity of the tibia in front; it is firmly fixed to the edges of the patella, above which the capsule is attached to the tendon of the quadriceps femoris, then passes much higher than the articular cartilage to the anterior-lateral surfaces of the femur, descends along them, goes around the bottom, and then behind the epicondyle and is attached above the condyles along the linea intercondylaris.

The knee joint has nine twists: five in front and four behind. The protrusion of the synovial membrane, located above the patella and forming the upper patellar torsion, is limited: in front - by the quadriceps femoris muscle, behind - by the femur, above and partially from the sides - by a fold resulting from the transition of the synovial membrane from the posterior surface of the quadriceps femoris to the anterior surface of the femur bones. According to the data in 90.5% of cases, in the arch of the upper torsion there is a larger or smaller hole through which the torsion communicates with the bursa suprapatellaris, and sometimes forms a joint protrusion that rises 10-12 cm above the patella. The length of the upper torsion is 5-8 cm (average 6.4 cm), width - 3-10 cm.

From above, from the sides and behind the upper inversion is surrounded by fiber. From above, m. articularis genus. The inferolateral sections of the upper torsion pass from the medial side into the anterior superior medial torsion, from the lateral side into the anterior superior lateral torsion. Both last inversions are located on the sides and above the patella, respectively, in front of the anteromedial and anterolateral surfaces of the femoral condyles and behind the fibrous layer of the joint capsule covered by mm. vastus medialis and lateralis, as well as retinacula patellae mediale and laterale. On the sides of the articular surfaces of the femur, these inversions go down to the menisci. Through the gaps between the menisci and the articular surface of the tibia, they communicate with the lower torsions, and through the gaps between the outer surfaces of the condyles and the joint capsule and between the inner surfaces of the condyles and the cruciate ligaments, covered with a synovial membrane, they communicate with the posterior upper torsions. In this case, the medial condylar-capsular fissure is wider than the lateral one. The narrowest part of the condylar-ligamentous fissure is located at the intercondylar eminence of the tibia, and the condylar-ligamentous fissures themselves are smaller and shorter than the condylar-capsular fissures.

Rice. 151. Articular surfaces, menisci and ligaments of the knee joint on a transverse cut at the level of the joint space (3/4).
Individually expressed folds protrude into the anterior part of the joint cavity on the sides of the patella - plicae alares, from which or from the top of the patella to the anterior cruciate ligament, plica synovialis infrapatellaris is directed. These folds of the synovial membrane are formed by a protrusion of adipose tissue - corpus adiposum infrapatellare, which is located below the patella and behind the lig. patellae and the fibrous membrane of the joint capsule, separating bursa infrapatellaris profunda from the joint cavity.

Rice. 152. Ligaments that strengthen the bag of the knee joint; back view.

Below the medial and lateral menisci, between the joint capsule and the anterior superior medial and superior lateral parts of the tibia, the anterior inferior medial and anterior inferior lateral inversions are located, respectively. At the top, both inversions with a gap between the meniscus and the cartilaginous surface of the tibia communicate with the common cavity of the knee joint. The ends of the inversions, facing the midline of the joint, are closed and limited in front of the corpus adiposum infrapatellare. The anterior lower medial and lateral inversions each pass from their side into the posterior lower medial and lateral inversions, limited, like the anterior ones, from above by the menisci, in front and from the sides by the tibia, and behind by the bag of the joint. The ends of the inversions facing the midline of the joint are closed: in the medial inversion along the inner edge of the posterior cruciate ligament, in the lateral one - somewhat outward from the lateral edge of the same ligament.

The posterior superior medial and lateral inversions are each located on their own side above the menisci, between the posterior parts of the medial and lateral condyles and the parts of the knee joint capsule that cover them. The posterior upper inversions, like the lower ones, do not communicate with each other. They are separated by the tissue of the intercondylar fossa covered with a synovial membrane on the medial and lateral sides. In front, this fiber is adjacent to the cruciate and meniscofemoral ligaments, in the back - to the fibrous membrane of the joint capsule. The tendon of the popliteal muscle is adjacent to the posterior upper and lower lateral torsion, which here is covered in front and laterally by a synovial membrane, forming a recessus subpopliteus. This pocket can communicate with the posterior superior and inferior lateral volvulus with larger or smaller openings, with the result that both volvulus communicate with each other by a canal that occurs in 85% of cases. In other cases, this channel is closed and is represented by a protrusion from the side of the posterior superior lateral inversion. The lower end of the recessus subpopliteus in 88% of cases is directly adjacent to the posterior surface of the articulatio tibiofibularis, and in 18.5% of cases it communicates with it, connecting the cavities of the knee and tibial and peroneal joints. Of great practical importance (the penetration of pus when driving outside the joint, the occurrence of paraarticular phlegmon) are the messages of the cavity of the knee joint with the synovial bags of the muscles, which are the weak points of the capsule of the knee joint. According to the observations of V. M. Ambarjanyan, such messages are found between the posterior superior medial torsion of the knee joint and bursa subtendinea m. gastrocnemii medialis (80%) or bursa m. semimembranosi (10%) and between the posterior superior lateral torsion and bursa subtendinea m. gastrocnemia lateralis (24%). The weak points of the knee joint capsule also include the recessus subpopliteus and the upper patellar torsion. Breaking through weak spots, pus can form anterior deep swells of the thigh in the form of inter- and subfascial phlegmons under the heads of m. quadriceps femoris. With popliteal streaks, pus from the popliteal fossa can spread to both the thigh and lower leg. The capsule of the knee joint is strengthened by the tendons of the adjacent muscles, internal and external ligaments. In addition to the menisco-femoral ligaments described above, the cruciate ligaments of the knee are located between the synovial and fibrous membranes of the joint. Lig. cruciatum anterius starts from the back of the inner surface of the lateral condyle of the thigh, goes down, forward and medially and is attached to the back of the area intercondylaris anterior and to the front of the tuberculum intercondylare mediale of the tibia.

Rice. 153. Opened knee joint; back view.
The length of the ligament along the medial edge is 3.3 cm, along the lateral edge - 2.6 cm. Lig. cruciatum posterius starts from the outer surface of the medial condyle of the thigh, goes down and slightly back and, crossing with the anterior cruciate ligament, is attached to the area intercondylaris posterior and to the posterior edge of the upper articular surface of the tibia. The length of the ligament along the lateral edge is 3.9 cm, along the medial - 2.9 cm.

Rice. 154. Opened knee joint; view from the medial side.

Rice. 155. Opened knee joint; view from the lateral side.

In front, the joint is reinforced lig. patellae, running from the patella to the tibial tuberosity. Anteriorly and medially - retinaculum patellae mediale, consisting of transverse fibers running from the medial epicondyle to the patella, and longitudinal fibers. Anteriorly and laterally, the retinaculum patellae laterale is located, the transverse fibers of which run from the lateral epicondyle to the patella, and the longitudinal fibers from the patella to the anterolateral edge of the tibia and to the tractus iliotibialis. On the lateral side, the joint is reinforced lig. collateral fibulare. The peroneal circumferential ligament originates from the lateral epicondyle of the femur and attaches to the head of the fibula in the form of a flat-rounded cord. The length of the ligament is 4-7 cm, the thickness is 2-8 cm. The ligament goes in isolation from the articular bag. Below, at the head of the fibula, it is covered with a case or simply adjacent to it behind or outside the tendon of the biceps femoris. On the medial side, the capsule of the knee joint is strengthened by lig. collaterale tibiale. It originates from the medial epicondyle of the femur and inserts on the medial surface of the tibia. The length of the ligament is 7.1-12.5 cm, the width is 5-15 mm. In almost half of the cases, the ligament has the form of a wide limited band, sometimes (22%) only the anterior part of the ligament is developed, sometimes (13%) the entire ligament is underdeveloped. Behind the articular bag of the knee joint, the oblique popliteal ligament is isolated from the outside, but intimately connected with the bag. Lig. popliteum obliquum runs from the posterior medial edge of the tibia to the lateral condyle of the femur; most often well expressed. The ligament is a continuation of the lateral bundle of the tendon of the semimembranosus muscle. Another ligament is lig. popliteum arcuatum - arcuately covers the back of the upper lateral part of the popliteal muscle and is part of its fibrous sheath. The knee joint is block-spherical in shape, and block-rotatory in function.

Rice. 156. Sagittal cut of the knee joint.

The blood supply to the knee joint comes from the rete articulare genus. From the arterial network of the knee joint, networks of the synovial membrane are formed, located in the subsynovial layer and in the thickness of the synovial membrane. The menisci are supplied with blood vessels from the adjacent sections of the synovial membrane, from the middle and lower medial and lateral arteries of the knee. The cruciate ligaments are supplied with blood by the middle artery of the knee, which near the ligaments is divided into ascending and descending branches, feeding not only the ligaments, but also the epiphyses of the femur and tibia, fiber, synovial membrane, menisci. The descending branch of the anterior cruciate ligament forms a permanent anastomosis with branches penetrating the plica synovialis infrapatellaris from the inferior arteries of the knee and the anterior tibial recurrent artery.

Rice. 157. Frontal cut of the knee joint.

Veins from all parts of the knee joint originate from capillary networks. Small veins run independently of the arteries, while large veins accompany the arteries one or two at a time. The small veins of the condyles of the femur are combined into a single plexus, from which larger veins are formed that emerge on the surface of the bone along the lateral surfaces of the condyles above the facies patellaris, in the region of the intercondylar fossa and in the lower part of the popliteal surface. In the condyles of the tibia, the intraosseous veins are located in the frontal plane perpendicular to the long axis of the diaphysis and 8-10 trunks come to the surface of the bone in the region of the lateral surfaces of the condyles.

Lymph from the knee joint flows through the lymphatic vessels that accompany the blood vessels. From the upper medial part of the bag of the knee joint, the lymphatic vessels along the course of a. genus descendens and a. femoralis go to the deep inguinal lymph nodes. From the region of branching of the upper and lower medial and lateral arteries of the knee and the anterior tibial recurrent artery, lymph flows into the popliteal lymph nodes. From the posterior sections of the joint bag, from the cruciate ligaments, the lymph flows into the lymph node located on the capsule, most often near a. genus media.

Numerous branches of the femoral, obturator, and sciatic nerves approach the knee joint. The capsule and ligaments of the anterior surface of the joint are innervated: I) in the region of the medial quadrants - branches from rr. cutanei anteriores and the musculocutaneous branch of the femoral nerve (sometimes very large - from 0.47 to 1.2 mm in diameter), descending down m. vastus medialis and dividing into 3-5 branches. Sometimes smaller branches from this branch penetrate into the anterior inferolateral quadrant; 2) stems of the muscular branch that innervates m. vastus medialis; 3) d. infrapatellaris from n. saphenus innervates the infero-medial and infero-lateral quadrants of the joint capsule. Branches of Mr. infrapatellaris can also penetrate into the upper quadrants of the capsule. Branches of the obturator nerve, which are part of n. saphenus, innervate more often the upper medial and less often the upper lateral quadrants of the capsule; 4) the capsule and ligaments of the upper-lateral quadrant are innervated by branches from the muscular branch to m. vastus lateralis from the femoral nerve and a branch of the sciatic nerve emerging from under the biceps femoris above the lateral epicondyle of the femur; 5) the lower lateral quadrant of the anterior surface of the joint is also innervated by branches n. peroneus communis, departing in the region of the head of the fibula, and the branches of p. peroneus profundus, accompanying the branches of a. recurrens tibialis anterior.

The posterior surface of the joint capsule is innervated by: 1) lateral quadrants - branches of the sciatic nerve, extending 6-8 cm above the level of division of the sciatic nerve with its low division, and from the tibial nerve - with high division. The branches are located laterally from the vascular bundle. From the common peroneal nerve in the region of the head of the fibula, branches begin that return back and innervate the joint capsule in its lower sections. Branches to the joint can also depart from the muscle branches to the short head of the biceps femoris; 2) the medial quadrants of the capsule are innervated by branches of the tibial nerve and the posterior branch of the obturator nerve, which emerges from the adductor magnus muscle and reaches the joint capsule along its posterior surface.

The most developed intraorgan nervous apparatus is present in the retinaculum patellae mediale, lig. collaterale tibiale and in the area of the medial surface of the capsule of the knee joint. In the fibrous and synovial membranes of the capsule there is a single nerve plexus. The nerves enter the meniscus from the side of the synovial membrane and, to a lesser extent, from the side of the cruciate ligaments. In ligaments, nerve elements are localized mainly in the peritenonium and endotenonium. Connected to each other, the nerves of the ligaments, menisci and capsule form an integral nervous apparatus of the knee joint.

Anatomy

Three bones of the knee joint are involved in the formation of the articulation: the femur, tibia and patella. Inside the joint, on the plateau of the tibia are located, increasing the stability of the structure and providing a rational distribution of the load. During movement, the meniscus springs - they are compressed and unclenched, ensuring a smooth gait and protecting the articulation elements from abrasion. Despite their small size, the significance of the menisci is very high - when they are destroyed, the stability of the knee decreases and arthrosis inevitably occurs.

In addition to bones and menisci, the articulation components are the articular capsule, which forms the torsion of the knee joint and synovial bags, and ligaments. The ligaments that form the knee joint are formed by connective tissue. They fix the bones, strengthen the joint and limit the range of motion. Ligaments provide stability to the joint and prevent displacement of its structures. Injury occurs when the ligaments are stretched or torn.

The knee is innervated by the popliteal nerve. It is located behind the articulation and is part of the sciatic nerve that runs to the foot and lower leg. The sciatic nerve provides sensation and movement to the leg. The popliteal artery and vein, which repeat the course of the nerve branches, are responsible for the blood supply.

The structure of the knee joint

The main joint-forming elements are considered to be the following:

condyles of the femur
tibial plateau
knee cap
menisci
joint capsule
bundles

The knee joint itself is formed by the heads of the femur and tibia. The head of the tibia is almost flat with a slight depression, and it is called a plateau, in which the medial, located along the midline of the body, and the lateral parts are distinguished.

The head of the femur consists of two large, round, spherical projections, each of which is called the condyle of the knee joint. The condyle of the knee joint located on the inside is called medial (internal), and the opposite is called lateral (external). The articular heads do not match in shape, and their congruence (correspondence) is achieved due to two menisci - medial and lateral, respectively.

The articular cavity is a gap, which is limited by the heads of the bones, menisci and the walls of the capsule. Inside the cavity is synovial fluid, which provides optimal gliding during movement, reduces friction of the articular cartilage and nourishes them. The articulating surfaces of the bones are covered with cartilaginous tissue.

Hyaline cartilage of the knee joint is white, shiny, dense, 4-5 mm thick. Its purpose is to reduce friction between the articular surfaces during movement. Healthy cartilage of the knee joint has a perfectly smooth surface. Various diseases (arthritis, arthrosis, gout, etc.) lead to damage to the surface of the hyaline cartilage, which, in turn, causes pain when walking and limited range of motion.

Knee cap

The sesamoid bone, or patella, covers the front of the knee joint and protects it from injury. It is located in the tendons of the quadriceps muscle, has no fixation, has mobility and can move in all directions. The upper part of the patella has a rounded shape and is called the base, the elongated lower part is called the apex. On the inside of the knee is the goose foot - the junction of the tendons of 3 muscles.

joint capsule

The articular bag of the knee joint is a fibrous case that limits the articular cavity from the outside. It is attached to the tibia and femur. The capsule has a low tension, due to which a large amplitude of movements in different planes is provided in the knee. The articular bag nourishes the articulation elements, protects them from external influences and wear. Located on the inside of the knee, the posterior part of the capsule is thicker and resembles a sieve - blood vessels pass through numerous holes, and blood supply to the joint is provided.

The capsule of the knee joint has two shells: inner synovial and outer fibrous. A dense fibrous membrane performs protective functions. It has a simple structure and is firmly fixed. The synovial membrane produces a fluid, which has received the corresponding name. It is covered with small outgrowths - villi, which increase its surface area.

In places of contact with the bones of the joint, the synovial membrane forms a slight protrusion - a torsion of the knee joint. In total, 13 inversions are distinguished, which are classified depending on the location: medial, lateral, anterior, lower, upper inversion. They increase the articulation cavity, and in pathological processes they serve as places for the accumulation of exudate, pus and blood.

Knee bags

They are an important addition, thanks to which the muscles and tendons can move freely and painlessly. There are six main bags, which look like small slit-like cavities formed by the tissue of the synovial membrane. Internally, they contain synovial fluid and may or may not communicate with the articulation cavity. Bags begin to form after the birth of a person, under the influence of loads in the area of the knee joint. With age, their number and volume increases.

Biomechanics of the knee

The knee joint provides support for the entire skeleton, takes on the weight of the human body and experiences the greatest load when walking and moving. It performs many different movements, and therefore has complex biomechanics. The knee is capable of flexion, extension and circular rotational movements. The complex anatomy of the human knee joint ensures its wide functionality, well-coordinated work of all elements, optimal mobility and shock absorption.

Pathology of the knee joint

Pathological changes in the musculoskeletal system can be caused by congenital pathology, injuries and diseases. The main signs that signal the presence of violations are:

inflammatory process;
painful sensations;
restriction of mobility.

The degree of damage to the articulation elements, coupled with the cause of their occurrence, determines the localization and intensity of the pain syndrome. Pain can be diagnosed periodically, be permanent, appear when trying to bend / straighten the knee, or be the result of physical exertion. One of the consequences of ongoing inflammatory and degenerative processes is the deformity of the knee joint, leading to serious illnesses up to disability.

Anomalies in the development of the knee joint

There are valgus and varus deformities of the knee joints, which can be congenital or acquired. Diagnosis is made by x-ray. Normally, the legs of a standing person are straight and parallel to each other. With valgus deformity of the knee joint, they are bent - an open angle appears on the outside in the knee area between the lower leg and thigh.

The deformity may affect one or both knees. With a bilateral curvature of the legs, their shape resembles the letter "X". Varus deformity of the knee joints bends the bones in the opposite direction and the shape of the legs resembles the letter "O". With this pathology, the knee joint develops unevenly: the joint space decreases from the inside and expands from the outside. Then the changes affect the ligaments: the external ones are stretched, and the internal ones atrophy.

Each type of curvature is a complex pathology that requires complex treatment. If left untreated, the risk of excessive knee mobility, habitual dislocations, severe contractures, ankylosis, and spinal pathologies is quite high.

Valgus and varus deformity in adults

It is an acquired pathology and most often appears with deforming arthrosis. In this case, the cartilaginous tissue of the joint undergoes destruction and irreversible changes, leading to loss of knee mobility. Also, the deformation can be the result of injuries and inflammatory and degenerative diseases that caused changes in the structure of bones, muscles and tendons:

compound fracture with displacement;
ligament rupture;
habitual dislocation of the knee;
immune and endocrine diseases;
arthritis and arthrosis.

In adults, the treatment of a deformed knee joint is inextricably linked to the underlying cause and is symptomatic. Therapy includes the following items:

painkillers;
NSAIDs - non-steroidal anti-inflammatory drugs;
glucocorticosteroids;
vasoconstrictor drugs and venotonics;
chondroprotectors;
physiotherapy treatment;
massage.

Drug treatment is aimed at eliminating pain, restoring cartilage, improving metabolism and tissue nutrition, and maintaining joint mobility.

Valgus and varus deformity in children

The acquired varus or valgus deformity of the knee joints that manifests itself by 10-18 months in children is associated with deviations in the formation of the child's musculoskeletal system. As a rule, the deformity is diagnosed in weakened children with muscular hypotension. It appears as a result of a load on the legs against the background of a weak muscular-ligamentous apparatus. The reason for such a deviation may be the prematurity of the child, intrauterine malnutrition, congenital weakness of the connective tissue, general weakness of the body, rickets.

The cause of the secondary pathology that caused abnormalities in the formation of the knee joint is neuromuscular diseases: polyneuropathy, cerebral palsy, myodystrophy, poliomyelitis. Articulation deformity not only causes curvature of the legs, but also has an extremely detrimental effect on the entire body.

Quite often, the feet and hip joints suffer, flat feet and coxarthrosis develop with age.

Treatment of hallux valgus and varus deformity in children includes:

limitation of loads;
wearing orthopedic shoes;
use of orthoses and splints;
massage;
physiotherapy, most often - paraffin wraps;
physical therapy classes.

Conclusion

Having a complex structure, the knee joint bears a heavy load and performs many functions. He is a direct participant in walking and affects the quality of life. Attentive attitude to your body and taking care of the health of all its constituent elements will help you avoid knee pain and maintain an active lifestyle for a long time.