What is knee orthosis ?
The knee is our body?s largest joint. It consists of the distal ending of the upper thigh bone and the proximal ending of the lower thigh bone. Contrary to other joints, these two bone endings do not directly link together. In order to increase the contact surface, to level out the uneven joint surfaces and to convert the enormous motion range of the knee joint, an intermediate layer is necessary the menisci.
These are c /shaped or round cartilage discs of fibroid structure. The knee joint is supported solely by ligaments. The most important ligaments are the intra-articluar ligament, the lateral collateral ligament ( LCL / MCL ) and the anterior and posterior cruciate ligament ( ACL / PCL).
A speciality of the knee joint is the knee cap (patella). Located in the front of the joint, it slides in a guiding groove along the upper thigh bone during flexion and extension. It provides guidance for the quadriceps tendon,which is responsible for the extension of the knee joint. Depending on the activity, the pressure of the patella on the knee joint can reach far more than the twentyfold of the own body weight.
The knee joint has a very big motion range it can be overextended by approximately 10° and during flexion,it reaches an angle of approximately 150°. In flexion, the joint is also able to perform rotary movements, during which the rotation to the outside of 40° is considerably bigger than the rotation to the inside of 10°.
The knee joint is the most strained joint of our body. With every step, it must absorb approximately three times the amount of our own body weight. Even during light activity, this figure increases remarkably. Considering that each human being walks approximately fivethousand steps per day, in the course of a lifetime this adds up to a distance of approximately three times around the world. Or, relating to the absorbed weight, several millions of tons. This explains why the kee joint is subject to an increased wearout and furthermore, irritations,overstraining and injuries are very common.
Considering mechanical aspects, the knee is a hinge-sliding-joint. Consequently, it does not have a fixed centre of rotation, around which the joint is moving. When treating the knee with an braces and supports, this is of high importance. As knee orthoses have a fixed centre of rotation, it is especially important that the orthosis provides enough flexibility to follow the anatomical centre of rotation as good as possible.
Typical diseases, injuries and deformities of the knee joint and their treatment:
Knock / knees resp. bowlegs .
With knock / knees, the lateral joint parts are overloaded, whereas with bowlegs, the medial joint partsare overloaded. During childhood, these leg deformities can be treated with long-term effect by use of orthopedic insoles. Sometimes, more extensive manifestation requires the treatment with orthotic braces worn at night. Deformities during adulthood are treated with leg orthoses, to help preventing possible joint pain.
Overextension of the knee .
The knee joint may be overextended by more than the usual 5° - 10°. This causes an overstrain on the joint capsule as well as on the ligaments of the knee joint, which leads to increasing worsening of this deformity.For lighter cases, often a knee support with lateral reinforcement .or a knee brace with extension lock , like post op knee support braces.
After surgery, it is often necessary to completely immobilise the knee joint for a few days.Depending on the kind of surgery, the joint must be fixed with a knee brace in 0 ° extension, Inflammatory conditions Inflammatory conditions, joint effusions and swellings, cartilage and meniscus damages, arthrosis and arthritis, light deformities, postsurgical or traumatic irritations, bursitis or general light knee joint instabilities are advised to be treated with a compression active knee brace with lateral reinforcement and patella ring made of silicone.