Physiotherapy special test for knee osteoarthritis
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Knee Osteoarthritis
Description of Knee Osteoarthritis
According to JAMA more than 10 million Americans are affected with knee osteoarthritis.[1]Most commonly affecting a population age 45 and greater this condition occurs as the cartilage in the knee wears away eventually causing bone on bone contact between joint surfaces. Most common complaints include joint swelling, joint stiffness, and pain. Knee osteoarthritis can be diagnosis via radiographs indicating boney cysts, narrowing joint space, and scelrosing of the bone.
Knee osteoarthritis is the occurrence of osteoarthritis(OA) in the knee joint. Osteoarthritis has many definitions, but Kuttner et al . defined it as follows: “Osteoarthritis, also known as degenerative arthritis or degenerative joint disease, is a group of overlapping distinct diseases, which may have different etiologies but with similar biologic, morphologic, and clinical outcomes.”[2]
In other words osteoarthritis involves the degradation of joints, including articular cartilage and subchondral bone. But also ligaments, the capsule and the synovial membrane degenerate. This will eventually lead to pain and loss of function.[3]
Osteoarthritis is the most common disease of joints adults suffer from worldwide. The name ‘osteoarthritis’, a Greek word, can be divided in ‘osteo’, ‘arthro’ and ‘it is’. If we translate the word we become ‘of the bone’, ‘joint’ and ‘inflammation’.”[4] Thus, simply put, we can say that osteoarthritis is an inflammation of the bone and joint. Besides knee osteoarthritis, which is the most common, you also have hand and hip osteoarthritis.
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Anatomy and Pathological Process
The knee joint consists of both approximation of the proximal tibia and the distal end of the femur. The cartilage located on the ends of the femur and tibia contain an extra cellular matrix that contains type 2 protoglycans that function by drawing fluid into the joint causing increased shock absorption and proper joint nutrition.[7] There is some evidence to support that as the aging process occurs the type 2 collagen fibers decrease in size and therefore less fluid an nutrition gets into the joint surfaces eventually leading to decreased protection along boney surfaces.
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The knee (art. genus) is a synovial joint, which consists of 3 articulations. The primary joint, art. tibiofemoral, is located between the convex femoral condyles and the concave tibial condyles.[8] There is also the art. patellofemoralis between the femur and the patella and the art. tibiofibularis located between the tibia and fibula. OA can only occur in the two primary articulations of the knee, namely the tibiofemoral and patellofemoral joint, because they have to sustain more motion than the art. tibiofibularis.[2]
“The pathogenesis of knee OA have been linked to biomechanical and biochemical changes in the cartilage of the knee joint.” (Kirstin Uth et al, 2014)[9] The cartilage ensures that the bone surfaces can move painless and with low friction to each other. In OA, the cartilage decreases in thickness and quality, it becomes thinner and softer, cracks may occur and it will eventually crumble off. Cartilage that has been damaged, cannot recover. Finally the cartilage will disappear. The bone surfaces can also be affected, the bone will expand and spurs (osteophytes) will develop.[10][11]
Not only the cartilage can be affected, there can also occur laxity of the ligaments and muscle atrophy