Knee

The knee joint ( IE ǵenu, Latin articulatio genus) is the largest joint of mammals. The thigh bone ( femur), the tibia (tibia ), and the kneecap ( patella) form the bony joint partner.

The knee joint is a joint compound. It consists of two single joints, the knee cap joint ( articulatio femoropatellaris ), which is located between the femur and patella, and the popliteal joint ( articulatio femorotibialis ), located between the femur and tibia head (caput tibiae ). Anatomically also includes the joint between the tibia and fibula ( fibula ) ( articulatio tibiofibularis ) to the knee joint.

At the back of the knee joint is the knee ( popliteal fossa ), located on major blood vessels and nerves in their depth. In addition, here the popliteal lymph nodes ( lymph poplitei ) are formed.

• 2.1 kneecap joint 2.1.1 Forces in the knee cap joint
• 2.1.2 Special features of four-footed mammals

• 4.1 Outer layer
• 4.2 Inner layer
• 4.3 fat body
• 4.4 bursa 4.4.1 Aussackungen

• 5.1 Front tape backup
• 5.2 Lateral tape backup
• 5.3 Rear tape backup
• 5.4 Central Tape Backup 5.4.1 Anterior Cruciate Ligament
• 5.4.2 posterior cruciate ligament

• 6.1 Strecker
• 6.2 flexors
• 6.3 flexors and Einwärtsdreher
• 6.4 Away Dreher

• 9.1 fractures and Auskugelungen
• 9.2 degenerative joint
• 9.3 inflammation 9.3.1 Baker cyst
• 9.3.2 bursitis
• 9.3.3 effusions

• 9.8.1 torn ACL
• 9.8.2 sideband crack

Bony structures and joint surfaces

The bone partners have a very close contact with each other. This also can occur at the contact surfaces a pain-free and undisturbed movement of the knee joint, they are (like all joint surfaces in the body) with a very smooth, whitish layer of cartilage, hyaline cartilage of the so-called excessive.

Femur

The femur ending knee forward ( distally ) ( femoral lateral condyle and medial femoral condyle ) with two rather broad, slightly curved outward ( convex ) condyle, which is running from front to back and between those on the back of a narrow pit ( intercondylar notch ). The surface of the condyles ( condyles ossis femoris) is helically applied so that the center of rotation of the hinge of the movement describing a spiral trajectory. The inner condyle is in a horizontal direction ( sagittal) one to two inches larger than the outside and is farther away from the joint.

The cartilage layer of the femoral condyle is thinner than that of the kneecap, wherein the outer sliding surface is covered with a cartilage layer thicker than the inner.

The femoral condyle diverge somewhat further joint and back. The outer condyle is the front wider than the rear, while the inner condyle has a uniform width. In horizontal planes, the condyles are slightly curved about a vertical axis. In the vertical plane, the curvature increases towards the rear, that is, the radius of curvature becomes smaller. The inner condylar is additionally curved about a vertical axis (rotation curvature ).

On the articular surface of the femur (front) runs a flat, lying between the two condyles slide groove for the kneecap ( patellar surface femoris and femoral trochlea ). This chute divided the articular surfaces in two facets. The outer facet is slightly larger and runs joint closer and farther forward than the smaller inner. The difference is that they can absorb more pressure so especially during flexion.

Special features of four-footed mammals

Which femurs exhibit a bend in four-footed mammals outwards, the radius of curvature becomes larger rearward. This results in excessive deflection ( hyperflexion ) to an increased voltage of the side bands ( collateral ligaments ), whereby the movement is braked (so-called spiral joint). The joint is always in a flexed position. The maximum extension is for example in dogs do not have a rearwardly opening angle of 150 ° out.

Special features in birds

The femur is short in birds. It is used to shift the starting point of the leg above the center of gravity of the bird, so as to enable an energy-efficient as possible standing and walking. The focus of most birds is very low, at about the level of the knee joint (see also bird skeleton).

Shin

The upper end of the tibia also ( lateral condyle of the tibia and the medial tibial condyle ) runs in two, slightly inwardly curved condyles from. In between are a raised bone ridge ( tibial ), which is divided into two small bumps ( tubercle of intercondylar media and tubercle of intercondylar lateral) and two trough configurations ( anterior intercondylar area - in animals intercondylar area cranialis - and posterior intercondylar area - in animals intercondylar area caudalis ). The entire upper surface of the tibia, is designated as the tibia plateau, which forms the articulating surface of the tibia (facies superior articular tubercle ) for the knee joint. Since the bone ridge extends over the entire tibial plateau, the rotation is maintained as a possible direction of movement of the joint.

Kneecap

The kneecap is triangular and arched on its front face slightly outward. It is stored as a sesamoid bone in the tendon of insertion of four thigh muscle ( quadriceps femoris), which it embeds coming from above. From its lower tip (apex patellae ) arise from the fibers of the patellar ligament ( patellar ligament ). On the back of the kneecap ( patellar articular facies ) is a ridge that divides the joint surfaces in two facets. Your cartilage layer is about six millimeters thick.

With the knee flexed, the patella is fixed in the groove just above the joint space between the femur and tibia, leg extended further up. Therefore, they can not be true shift in the extended position and the muscles relaxed a little to the right and the left, but in flexion.

The main task of the patella is the extension of the lever arm and thus the torque of the quadriceps, as it increases the distance of its line of action from the center of motion of the knee joint. It also serves to guide the tendon and reduces the resistance of the sliding movement of the tendon over the bone.

Special features in dogs

Besides the kneecap still exist three other sesamoid bones at the knee joint in dogs. The Fabellae located in the tendon of origin of the two heads of the two-headed calf muscle ( gastrocnemius muscle ). Fabella lateral is greater than the center. Both articulate with the femur. The third sesamoid bone is located in the tendon of origin of the popliteal muscle (musculus popliteus ) in the popliteal fossa.

Joints

Patellar joint

The patellar joint ( articulatio femoropatellaris ) is the joint between the femur and the patella. Here, the covered with hyaline cartilage joint surface are opposite on the back of the kneecap ( patellar articular facies ) and on the front of the thigh bone ( femoral patellar surface ). The kneecap slides in flexion and extension in the groove provided for it about five to ten millimeters above the thigh bone, the entrance into the trough occurs at approximately 30 ° of flexion. This form joint is also referred to as a slide joint ( articulatio delabens ).

Forces in the patellar articular

The force with which affects the kneecap to the femur is called the joint reaction force of the patellofemoral joint ( patellofemoral joint reaction force, PFJR ). It is the resultant force vector from the vectors of the tendon of the quadriceps femoris and the patellar ligament. The size of the PFJR is the angle at which the knee joint is located, and of the force exerted by the quadriceps femoris dependent. The contact surfaces of the joints to move proximally with increasing knee flexion, the entire contact area increases between 20 ° and 90 °. At about 90 ° the joint surfaces have their maximum contact. With increasing flexion, the contact pressure increases, and reaches at an angle of 70-75 ° at a maximum.

The PFJR can exceed several times the own body weight. When walking, it is about the half of the body weight ( bw) ( 0.2-0.4 KG, 0.5 KG ), climbing stairs 3.3 KG and deep squats 7.6 KG. Running the joint reaction forces can be between 7 to 11.1 KG, 17.5 KG weight lifting to 24 times body weight in a downward jump ( downward jump).

Special features of four-footed mammals

The patellar ligament is divided into three parts in horses and cattle. One distinguishes a pointing towards the middle (medial ), a lateral ( lateral ) and a medium ( intermediate ) patellar tendon ( patellar ligament medial, lateral patellar ligament and patellar ligament intermedium ). Only the middle is where the shin bruise on the other two each side of it.

For the lateral attachment of the patellar two stops (ligamentum femuropatellare medial and lateral ligament femuropatellare ) are formed between the side edges and the femur. In carnivores (dogs, cats) they are very inconspicuous.

In horses, the patellar joint has a further feature. The pointing to the center knot has at the end of periarticular a significant increase in the so-called "nose" ( tubercle trochleae ossis femoris). On this bead, the patella may be hooked with the loop between the inner and middle patellar ligament. The knee is so passive in the extended position - largely without the use of muscle power - fixed, which allows an almost fatigue-free standing. A leg is fixed in this way, while the other laid- on Hufspitze resting ( " tags "). After a while the rested leg is fixed and the previously latched leg completely relieved. By train the quadriceps femoris and biceps femoris muscle Seitwärtszug of the kneecap is solved from this rest position, whereby the full mobility of the joint is restored.

Popliteal joint

The popliteal joint ( articulatio femorotibialis ) is the actual, responsible for flexion of the knee joint. It is a mixture of a wheel and a hinge, known as a rotary hinge, swivel angle ( Trochoginglymus ) or bikondyläres joint ( thus allowing the flexion and extension, as well as in the 90 ° bent knee easy inward and outward rotation) and is between the outwardly curved femoral condyle and the tibial plateau. It must withstand high loads, but at the same time allow sufficient mobility.

Menisci

Since the intercommunicating ( articulating ) joint surfaces not fit together exactly, is this " inequality " ( mismatch ) by crescent-shaped fibrocartilage disks, balanced the menisci, which can follow the rotation. Another object of the menisci is to increase the contact surface between the tibia and femur.

We distinguish a medial meniscus ( medial meniscus ), the C-shaped, larger and somewhat immobile ( as with the fused inner band ), and a lateral meniscus ( lateral meniscus ), which is circular, smaller and more flexible (because it is grown with no sideband ). The menisci are wedge-shaped in cross section. The high edge is on the outside, low inside. Since the femoral condyle lie exactly in the center directly on the tibial plateau and peripherally to the menisci, this represents a considerable part of the load.

When moving the knee menisci are pushed from the femoral condyle in front of it: In the diffraction bone roll back and pushing the menisci to the rear, when stretched they will return to the front. In outward rotation of the lower leg of the lateral meniscus is pushed on the tibia forward, pulled back the medial meniscus in the inward rotation is reversed.

The menisci each having at its front and rear horn connect by a short, strong holding tape ( transverse ligament genus) to the tibia plateau. In addition to these four horns on the shin they are of variable- scale bands ( ligaments meniscofemoralia ) connected to the inner femoral condyle.

The medial meniscus is palpable in the joint space toward the center at the patellar ligament. In medial meniscus damage here a pressure pain can be triggered. Useful for diagnosis are further comprises the assessment procedures, known meniscus sign:

• Steinmann -I ( Steinmann I sign): When flexed lower leg, the knee is rotated. Pain in internal rotation indicate a violation of the outer, at an outdoor rotation on a violation of the inner meniscus.
• Steinmann -II ( Steinmann II characters): With flexion of the knee joint, the pressure pain from the front ( the menisci since bending over backwards walk ) shifts to the rear.
• Apley Grinding - test: rotation at the knee flexed in the prone position. Pain similar to Steinmann I sign.
• Böhler- sign: pain in abduction or adduction ( valgus and varus stress) in the knee joint.
• Payr sign: pressure to the inside cross-legged. Faults or pain indicate a Innenmeniskusläsion.

Joint capsule, liquid and space

Envelops the knee joint is of a wide knee joint capsule ( capsula articular genu ). This is very tense and stabilized at full extension. With increasing diffraction she relaxed.

Outer layer

The outer layer of the capsule ( membrane fibrosa capsulae ) is only on the rear side of the joint is very stable, where it attaches to the edge of the femur near the joint, and pulling the groove between the bones. There they inserted into the front of the tibia plateau Einmuldung. The enclosed by the two layers of joint space has a horseshoe shape in horizontal section. Laterally, the outer layer on a gate that serves as a passage point for the popliteal muscle (musculus popliteus ). Joint distance is where the capsule at the edges of the shin bone, where it is anchored firmly to the menisci. Front the joint cavity is limited by the patella and the patellar ligament with which it is also grown.

An important task of the outer layer is in the sensitive care of the knee. In their embedded receptors provide important information on status and change of the train and allow a cooperation with the muscles of the entire lower extremity.

Inner layer

The inner layer of the joint capsule is called the synovium ( synovial membrane capsulae ). It is the front surface of the femur on, following the rear of the bone boundary, and there takes on the groove between the femoral condyle.

The inner skin is the important for the nutrition of the cartilage joint fluid ( synovial fluid ). Movements of the knee joint by mixing the joint fluid, thereby improving the absorption of nutrients by the cartilage cells ( chondrocytes). The correct amount and composition of the synovial fluid is also used for the lubrication of the knee joint is vital. By the friction between the corresponding surfaces of cartilage is minimized in the rolling-sliding motion.

Fat body

The knee joint has a fat body (corpus adiposum infrapatellar, also called " body fat Hoff Ash " ), which is located between two layers of the joint capsule of the joint. In this diffraction is compressed from the set under tension band under the kneecap ( compressed) and bulges mainly out to the side.

The continuations of the fat body along the sides of the kneecap and the ribbon beneath the kneecap are called ( alar plicae ) as fat wrinkles. They can be divided into two trains:

• Infrapatellar plica, which originally divided the joint into two chambers.
• Plica alar, which pulls to the side edges of the kneecap.

Bursa

To prevent damage to the pulling on the joint ligaments, the knee joint at particular points of friction has above, above and below the knee joint bursa ( bursae ), some of which connect to the joint space have ( bursa or recess, suprapatellar and infrapatellar bursa ). The infrapatellar bursa comes between patellar ligament and tibia. A bursa is located in the back of the joint cavity under the tendon of insertion of halbhäutigen muscle ( musculus semimembranosus ) (Bursa musculi semimembranosi ). Two further below the tendon of origin of the two-headed calf muscle ( gastrocnemius ) (Bursa musculi gastrocnemius lateralis and subtendinea subtendinous bursa musculi gastrocnemius medialis).

Two bursae are not connected to the joint space and are therefore self-contained. One is located under the skin in front of the kneecap (Bursa subcutanea prepatellaris ), the other is between the patellar ligament and the outer layer of the joint capsule ( deep infrapatellar bursa ).

Aussackungen

Before the kneecap ( suprapatellar ), the joint capsule is formed at the front of the femur a sac ( bursa or suprapatellar recess ) smoothing at diffraction or unfolded and so allows movement of the knee cap of up to seven centimeters. On the sides of the kneecap, in addition envelope folds of the capsule ( recess parapatellaris ). On the rear side of the joint, under the tendon of origin of the popliteal muscle, the recess is subpopliteus.

Bands

Because the knee is very unstable due to its bony structure, it is backed by numerous bands. So you reinforce the joint capsule in the outer layer are usually fitted. The ligaments of the knee are classified according to their location in front ( ventral ), lateral ( collateral ), posterior ( dorsal) and central bands.

Front tape backup

The five to six millimeters thick patellar tendon ( patellar ligament, " patellar tendon " ) is part of the joint capsule and pulls as a continuation of the quadriceps tendon from the lower edge of the patella to the anterior roughening of the tibia, the shin bump ( tibial tuberosity ) where it attaches a large area. In the middle and lateral to the patella and patellar ligament runs another tape ( patellar retinaculum ). This is divided into a central portion ( patellar retinaculum medial ), which from the wide thigh muscle directed towards the center (vastus medialis) arises and a lateral portion ( patellar retinaculum lateral ) extending from the lateral wide thigh muscle (vastus lateralis) is. They are part of the outer layer of the joint capsule.

Lateral tape backup

The knee has two sidebands. , An inner ( ligament tibial collateral ) and an outer ( ligament of fibular collateral ) In the extended position, the two sidebands (also called collateral ligaments ) tensioned and thereby prevent rotational movement in flexion, the radius of curvature, the origin and insertion reduced approach at each other and the bands are consequently relaxed. Both sidebands stabilize the knee joint in the lateral direction ( frontal plane ), so that a buckling in a bow-leg ( genu varum ) or knock-knee ( genu valgum ) deformity is prevented.

The inner ligament ( tibial collateral or medial ) is a triangular, flat band, which over a wide area from the top of the inner femoral condyles ( medial epicondyle of the femur ) to the inside of the shin bone ( medial tibial facies ) runs. It is incorporated into the outer layer of the joint capsule and adherent to the medial meniscus.

There are three different sets of fibers:

• The front long fibers run from the top of the inner femoral condyles to the inside of the shin bone.
• The rear upper short fibers radiate into the medial meniscus.
• The rear lower long fibers pass from the medial meniscus to the tibia.

With a rupture of the medial band of the lower leg can be moved to the side ( " Aufklappphänomen ").

The outer ligament ( fibular collateral or lateral) is a strong band which in its dorsal portion of the cylindrical attachment of the lateral femoral condyles ( lateral femoral epicondyle ) to the fibula head ( fibular head ) pulls. It has no fixed connection to the joint capsule and the menisci.

The described 2013 ( Anterolateral ligament ) extends from the same origin as the outer band to the anterolateral shin and there is intergrown centered between head of the fibula and the tibial tuberosity. Moreover, it is firmly attached to the lateral meniscus.

Rear tape backup

At the back of the knee, there are two bands. The oblique popliteal ligament ( oblique popliteal ) arises from the insertion of the halbhäutigen muscle ( musculus semimembranosus ) on the inner shin knots and reinforced the rear side of the joint capsule, with which it merges. The arcuate popliteal ligament ( arcuate popliteal ), however, draws from the posterior fibula head across the neck of the popliteal muscle and also attracts as an amplifier of the capsule in the middle upwards.

Central Tape Backup

The cruciate ligaments ( ligaments cruciata ) off the pit between the femoral condyle to the tibia. Viewed from the side and from the front they cross one another in their course.

By preventing the cruciate ligaments of the joint surfaces, a slide -shifted forward or backward ( translational ), to stabilize the knee. In addition, they inhibit the rotation, especially pronation, in which they wrap themselves around each other and the anterior cruciate ligament is stretched. In the eversion wrap itself apart, causing the knee is always turned outwards at maximum stretch a little (closing rotation). The classic injury of the anterior cruciate ligament occurs, therefore, such as skiing, with the knee flexed and under pronation trauma to.

A special feature is due to the location of the cruciate ligaments of the joint capsule. They are indeed within the outer layer of the joint capsule ( intracapsular ), but outside the inner skin. This saves the cruciate ligaments back from open sharply U-shaped. Thus they lie outside the actual joint space ( extra-articular ). This fact can be evolutionarily explained by the fact that the cruciate ligaments have immigrated during the evolution from behind while the capsule inner skin have pushed forward.

In cases of isolated injury of the two cruciate ligaments occurs the " drawer " phenomenon on: For a complete tear (rupture ) of the anterior cruciate ligament can be the tibia relative to the femur further forward move as the uninjured knee, with a tear of the posterior cruciate ligament corresponding to the rear.

Anterior cruciate ligament

The anterior cruciate ligament ( anterior cruciate ligament - in animals cranial cruciate ligament ) moves from the front Einmuldung between the tibial condyle to the side and slightly to the rear to put on the inside of the lateral femoral condyles. It is divided into a front - and -center in a rear - lateral bundle. Due to the wide diversification of the origin area of ​​this bundle a part of the anterior cruciate ligament is stretched in both diffraction, as well as stretching. Thereby, it prevents the free leg hyperextension ( hyperextension ) while in flexion to the feed of the tibia counteracts ( " front drawer ").

Posterior cruciate ligament

The posterior cruciate ligament ( posterior cruciate ligament - in animals caudal cruciate ligament ) is stronger and has its origin in the rear Einmuldung the tibial plateau and moves to the front -center to put on the front side surface of the inner femoral condyles. It tightens in flexion, thereby preventing a rearwardly from slipping off of the tibia ( posterior drawer ). With an outstretched leg the posterior cruciate ligament supports the front in preventing hyperextension. However, his main task is to stabilize the knee in flexion and under load.

Musculature

The ligamentous apparatus is supported by the surrounding muscles. Only through cooperation and changing settings of ligaments and muscles, precise execution of movements, especially in flexion, done.

Strecker

The femur is the front of a large four -headed extensor muscle (musculus quadriceps femoris) includes. The three broad muscles (vastus medialis, vastus lateralis and vastus intermedius ), and the straight muscle ( rectus femoris), these four heads. Straighten the knee by attach to the shin bruise. Between these muscles and their common approach, which expires as patellar ligament, the kneecap is embedded. The extensor muscle ( extensor ) that is initially set to the kneecap. From there, the power is transmitted to the lower leg on the patellar ligament.

In birds, the iliotibial muscle is the only cranial extensor muscle of the knee joint.

Flexors

Flexors ( flexor ) of the knee is inside the longest muscle in the body, known as the sartorius muscle (musculus sartorius ). It forms with two other muscles, slim thigh muscle ( gracilis ) and the semitendinosus muscle ( semitendinosus ) a common approach on the inside of the shin bone, the so-called Goosefoot ( Pes anserinus superficialis ). More flexors of the knee joint are the two-headed thigh muscle ( biceps femoris) and the two-headed calf muscle ( gastrocnemius muscle ), which is part of the three-member lower leg muscle ( triceps surae ) is.

In birds, the muscle iliofibularis, ischiofemoralis muscle, musculus iliotibialis lateralis, the musculi femorotibiales, the ambiens muscle, the flexor cruris medialis and the flexor cruris lateralis take over the flexion of the knee joint.

Flexors and Einwärtsdreher

The semitendinosus muscle ( semitendinosus ), the halbhäutige muscle (musculus semimembranosus ), the slim thigh muscle ( gracilis ) and the popliteal muscle (musculus popliteus ) also act as flexors, but are also responsible for pronation ( medial rotator ).

Away Dreher

The eversion ( external rotation ) takes over the biceps femoris.

Movements

The knee allows humans because of the surrounding joint capsule and is located within and outside the same, only the diffraction bands (flexion ) and stretching ( extension ) to about 150 °. Due to lack of conclusiveness pair of loose bodies not a local movement center exists (such as in the hip joint ), but it comes in flexion and extension to a combination of rolling and sliding movement of the joint body, the roll is called plain bearings. At maximum elongation occurs beyond - with intact ligaments - to a minor movement, the so-called final rotation, in which the tibia rotates a few degrees to the outside.

The knee joint is a so-called rotating - hinge ( Trochoginglymus ). It has five degrees of freedom. There are three different shift and two rotational degrees of freedom. Among the displacement degrees of freedom, the shift to the front-back ( anterior -posterior) and to-center - side ( medio- lateral) and pressure ( compression) and train understood ( traction ). As rotational degrees of freedom, the flexion and extension as well as inward and outward rotation (rotation) can be defined. The rotations are only possible in a bent condition.

• Diffraction to about 120-150 °
• Stretching to about 5-10 °
• Pronation of 10 ° ( at 90 ° of flexion )
• Away rotation around 30-40 ° ( at 90 ° of flexion )

At the house dog's knee joint at rest position is approximately at an angle of 130 ° to 140 °. The entire range of motion in flexion and extension between 90 and 130 ° and may even be exceeded on passive movement. In the normal course, however, the knee moves only between 110 ° to 150 ° flexion and in extension, range of motion amounts to only about 40 °. Internal and external rotation are in the extended position only to a very small extent (5-10 °) in flexion posture the knee about 10-20 ° outwards and 20-45 ° inwards is rotatable.

Arteries

The arterial supply of the knee joint is activated by a variety of arteries, which anastomose with each other and as a dense Kollateralnetzwerk ( articular rete genus ) form. Among them are:

• Descending artery genus
• Arteria genus media
• Artery superior lateralis genus
• Artery superior medial genus
• Artery inferior lateralis genus
• Artery inferior medial genus

Diseases

Fractures and Auskugelungen

After dislocation ( luxation ), the knee joint is rarely fully usable again, because with this injury a variety of band structures tears. The jumping out of the kneecap is called the patella luxation. The knee joint bones forming parts can break. Such fractures ( fractures) must be treated surgically by osteosynthesis. The bone parts with steel or titanium plates and screws or intramedullary nails so-called fixed ( plate osteosynthesis ). Frequently, a restoration of the accidental sunken articular surface and a lining with autologous bone material or ceramic material is required. Pure gap breaks can also be simply fixed with screws. Damage to the kneecap ( patella fractures = patella ) are very rare. They are usually the result of a direct fall on the patella. The patella is broken into several parts. There can arise the longitudinal, lateral or mixed fractions. Simple fractures heal with convenient treatment without permanent damage. Complex comminuted fractures usually leave an impairment. A transverse fracture must always be treated surgically because otherwise lead the mighty forces of the quadriceps to nonunion with all its complications (eg joint steps).

Joint degeneration

A very common disease of the knee joint is the joint disease (arthritis ). At the knee it is called osteoarthritis. It can be as a result of injuries, deformities and overloads, but occur in age without apparent cause. Are particularly frequent knee osteoarthritis as a result of bends in the form of O-( genu varum ) and X - leg ( genu valgum ). Osteoarthritis is diagnosed by x-rays and also usually treated in the form of an arthroscopic surgery.

Inflammation

Acute inflammation of the knee joint (arthritis) may be due to an overload and then treated primarily through conservation. The joint disease of the knee joint may be flammable enabled. In the context of rheumatic diseases may occur inflammatory involvement of the knee joint. The joint infections are rare, but very dangerous and require immediate treatment with a systematic antibiotic treatment and a so-called Suction-Irrigation drainage with highly effective antibiotics.

Baker cyst

At the Baker 's cyst ( popliteal cyst or ) is a bulge of the knee to the back of the knee. This arises in the context of chronic inflammation due to increased production of synovial fluid from a protuberance of the posterior knee joint capsule. Due to increase in circumference can cause discomfort, pain and restricted movement in the knee.

Housemaid's knee

The knee bursa (especially ahead of the patellar bursa ) are easily offended eg abrasions or lacerations, and because they often communicate with each other, spreading infections easily from above the knee. Permanent minor injuries ( Mikrotraumatisierungen ) can cause a chronic inflammation ( prepatellar bursitis ), which is usually to eliminate just about the removal of the bursa.

Effusions

Effusions of the knee joint, which spread to the behind the kneecap bursa, causing a swelling above the kneecap. Here it is lifted out of its guide channel and can be moved when the button is aside. By finger pressure, it can be again reconciled with the femoral condyle in contact, but fast upon release of the pressure back ( "dancing patella ").

Joint mouse

In the joint mouse ( osteochondritis dissecans ) is a cartilage injury, which occurs at the cartilage - bone interface. In extreme cases, a piece of cartilage with adherent bone Shares may be totally detached from the bone and wander through the joint. Mainly coming joint mice against in young athletes, as they strain their joints a lot, although the exact cause is not known. Therefore, a diagnosis is often difficult.

Shaky knees

The loose knee or knee - flail joint ( Genu laxum ) is a congenital or acquired phenomenon, which arises for example in connective tissue or injuries, inflammation or muscle paralysis with disorders of tissues. It is characterized by a lateral instability of the knee, which is caused by over extended sidebands. The over-stretching of the ligaments can be the result of stiffened hip joints among other things, because transmit the rotation of the pelvis while walking on the knee joints.

Hollow knee

The hollow knees ( genu recurvatum, often called " saber leg " ) is very rare. The cause is often in a quadriceps paralysis ( common result of polio ). Quadriceps is responsible for extension of the leg and the knee joint secures against collapsing. In paralysis the knee joint can not be stretched. Sufferers try to compensate for this by an pantoscopic angle of the upper body. This can be done by a strain of gluteal muscles (particularly the gluteus maximus gluteus maximus) and calf muscles (especially the two-headed calf). The consequences are overstretched knee ligaments and a strain on the rear knee joint capsule. During the pre-tilt occurs in the leg, a bending moment which the knee joint to the rear pushes (you can easily test in self- test in the state and feel ). It is located in a hyperextended posture ( hyperextension ).

Meniscus Tear

Meniscus lesions are relatively common. You usually caused by overloading, but can also occur due to an accident. If the meniscus only slightly affected, for example during horizontal tear ( tear along the course, with an upper and lower lip is formed ), the crack can conservatively be treated so without surgery. Only when a massive crack, for example, a so-called " bucket handle " ( = longitudinal meniscal tear with displacement of torn meniscus parts into the joint into it ), cross-sectional view ( from the free edge to the base ) or cloth tear in the rear or front horn ( = A combination of longitudinal and cross-sectional view ), or a tear in the meniscus base is present, typically the removal of torn-off portion of the meniscus is required. This is done by arthroscopic surgery. The torn part affects otherwise in the joint like a foreign body, which also damages the cartilage in a special way and thus leads to premature osteoarthritis. Cracks in the boundary region of the capsule can optionally be treated by Menikoplexie ( " Antackern " or " stitching "). Since the fibrocartilage has only weak blood circulation and for this reason has little metabolic reserves, damage to the meniscus can rarely heal.

Torn ligaments

Cruciate ligament

ACL tears are quite common. They are formed by the so-called flexion -valgus external rotation position. This means that the knee flexed involuntarily, is rotated in the X - leg position and outward, the lower leg is detected. Typically, such injuries occur while skiing, handball or football games. By the breaking of the band structure, it is at the same time vessel cracks that cause bleeding into the knee joint ( hemarthrosis ). ACL tears are detected in the rapid test by means of the anterior or posterior drawer test, that is flexed knee joint allows the tibia to move against the femur and indeed to the front ( tear of the anterior cruciate ligament, " front drawer phenomenon " ) or backwards ( tear of the posterior cruciate ligament, " rear drawer phenomenon "). After that ACL tears are usually diagnosed by magnetic resonance imaging. It will address a torn ACL usually by removing a piece of another band or tendon is removed to produce a cruciate ligament reconstruction from it.

Sideband crack

Inner or outer ligament ruptures are relatively common. Here is only operated when the tape is pulled from the bone. Otherwise, a motion splint for six weeks with concomitant physical therapy is sufficient for exercising the leg muscles.

Study opportunities

When scanning can cause pain in suspected meniscal or ligament injury. The passive exercise test (so-called "front " and " rear " drawer test ) is used to detect a cruciate ligament, as well as the verification of the stability of rotational movement ( pivot-shift test). In the active movement testing the function of the knee joint is controlled in motion.

As imaging radiography, sonography, arthrography are ( hardly used ), magnetic resonance imaging ( MRI) and computed tomography ( CT ) are used. Arthroscopy can be applied for displaying internal structures.

Swell