The hinge joint between the femur (thighbone) and tibia (shin). The patella (kneecap) lies across the front of the joint. Two protective discs of cartilage called menisci (see meniscus) cover the surfaces of the femur and tibia to reduce friction. Bursas (fluid-filled sacs) are present above and below the patella and behind the knee. External ligaments on each side of the joint provide support. Cruciate ligaments within the joint prevent overstraightening and overbending of the knee. The quadriceps muscles on the front of the thigh straighten the knee; the hamstring muscles at the back of the thigh bend it.
Knee injuries are common.
They include ligament sprains, torn meniscus, dislocation of the patella, and fracture of any of the bones in the joint.
Chondromalacia patellae is common in adolescents.
The joint formed by the FEMUR, TIBIA and patella (knee-cap). It belongs to the class of hinge-joints, although movements are much more complex than the simple motion of a hinge, the condyles of the femur partly rolling, partly sliding over the ?at surfaces on the upper end of the tibia, and the acts of straightening and of bending the limb being ?nished and begun, respectively, by a certain amount of rotation. The cavity of the joint is very intricate: it consists really of three joints fused into one, but separated in part by ligaments and folds of the synovial membrane. The ligaments which bind the bones together are extremely strong, and include the popliteal and the collateral ligaments, a very strong patellar ligament uniting the patella to the front of the tibia, two CRUCIATE LIGAMENTS in the interior of the joint, and two ?brocartilages which are interposed between the surfaces of tibia and femur at their edge. All these structures give to the knee-joint great strength, so that it is seldom dislocated. The cruciate ligaments, although strong, sometimes rupture or stretch under severe physical stress such as contact sports or athletics. Surgical repair may be required, followed by prolonged physiotherapy.
A troublesome condition often found in the knee – and common among athletes, footballers and other energetic sportspeople – consists of the loosening of one of the ?bro-cartilages lying at the head of the tibia, especially of that on the inner side of the joint. The cartilage may either be loosened from its attachment and tend to slip beyond the edges of the bones, or it may become folded on itself. In either case, it tends to cause locking of the joint when sudden movements are made. This causes temporary inability to use the joint until the cartilage is replaced by forcible straightening, and the accident is apt to be followed by an attack of synovitis, which may last some weeks, causing lameness with pain and tenderness especially felt at a point on the inner side of the knee. This condition can be relieved by an operation
– sometimes by keyhole surgery (see MINIMALLY INVASIVE SURGERY (MIS)) – to remove the loose portion of the cartilage. Patients whose knees are severely affected by osteoarthritis or rheumatoid arthritis which cause pain and sti?ness can now have the joint replaced with an arti?cial one. (See also ARTHROPLASTY; JOINTS, DISEASES OF.)
n. the hinge joint (see ginglymus) between the end of the femur, the top of the tibia, and the back of the *patella (kneecap). It is commonly involved in *sports injuries (such as a torn meniscus or ligament) and is a common site of osteoarthritis and rheumatoid arthritis; it can be replaced by an artificial joint (see also arthroplasty).
Knock-knee, or genu valgum, is a deformity of the lower limbs in such a direction that when the limbs are straightened the legs diverge from one another. As a result, in walking the knees knock against each other. The amount of knock-knee is measured by the distance between the medial malleoli of the ankles, with the inner surfaces of the knee touching and the knee-caps facing forwards. The condition is so common in children between the ages of 2–6 years that it may almost be regarded as a normal phase in childhood. When marked, or persisting into later childhood, it can be corrected by surgery (osteotomy).... knock-knee
A surgical operation to replace a diseased – usually osteoarthritic – KNEE with an arti?cial (metal or plastic) implant which covers the worn cartilage. As much of the original joint as possible is retained. The operations, like hip replacements, are usually done on older people (there is some restriction of movement) and about 90 per cent are successful.... knee-joint replacement
(prepatellar bursitis) inflammation and resultant swelling of the bursa in front of the kneecap, usually due to repetitive friction and pressure over the kneecap, as from frequent episodes of prolonged kneeling. Treatment includes pressure bandaging, *NSAIDs, and avoidance of kneeling. See bursitis.... housemaid’s knee
(patellar tendinitis) a form of *tendinitis that is common in athletes and dancers. Repeated sudden contracture of the quadriceps muscle at take-off causes inflammation of the attachment of the patellar tendon to the lower end of the patella. Treatment includes rest, physiotherapy, and anti-inflammatory medication.... jumper’s knee
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