Knee joint – Cartilage damage
Alongside the capsule ligament apparatus, joint cartilage covering the bones is a significant component of the joint. The cartilage is not well supplied with blood, and must therefore be fed through the joint fluid. Only an intact layer of cartilage guarantees a "frictionless" course of movement. The causes of cartilage damage are many and varied. Knee fractures affecting the joint, joint instability, meniscus tears, and overloading in sports or at work can damage the important cartilage layer. The symptoms depend on the size and location of the damage. At first, symptoms appear only when load bearing, but at a later stage, the patient complains about ongoing pain. Over several years, the cartilage damage increases and the destruction of the joint progresses. The joint swells up and can no longer be completely bent or extended. At this stage we speak of an arthrosis. The treatment design depends on the size and location of the cartilage damage The age of the patient also plays an important role, since in younger patients the potential for regeneration of the cartilage is still very high. We have available various treatment designs, which are determined very exactly for the individual patient.
Close questioning and examination of the patient allow making a diagnosis. An x-ray is necessary in order to assess axial deviations or reduction of the joint cavity. An additional MRI is necessary only in a few cases. The main goal of this form of treatment is to end the pain and improve the functioning of the joint. Conservative treatment is the treatment of choice in the beginning stages. This includes physical therapy exercises and taking medications. Adjustments to the shoes, such as height increases on the inside or outside edges or buffering heels, are part of this treatment complex. The injection of cartilage stimulating substances (e.g., hyaluronic acid) into the joint can be helpful. Athletic activity should be restricted to bicycling and swimming (crawl and backstroke). For overweight patients, weight loss is recommended.
If conservative treatment does not work, an operation is necessary. Exact assessment of the joint surfaces, of both menisci, and of the ligaments is possibly only through joint imaging (arthroscopy). The goal of arthroscopic treatment is to remove loose or separated pieces of the meniscus or cartilage and to rinse out the material that has been rubbed off. All of these items contribute to inflammation of the joint. As a further step, the formation of substitute cartilage can be stimulated by rubbing off or boring through diseased and altered cartilage areas. The choice of the type of operation depends on the type of damage and on the individual situation of the patient.
Cleaning the joint
The operating principle is limited to slowing the progress of the destruction of the cartilage. This also occurs arthroscopically, in that the affected areas of the cartilage are carefully smoothed out and the abraded dust is rinsed out of the joint. In many cases improvement can be achieved in this manner.
In cartilage defects that have already reached the bone, stimulating the formation of weight-bearing substitute cartilage is attempted. Tiny holes are bored into the defective zones using a special instrument. In this way multi-potent cells may appear that allow the formation of the substitute cartilage. Cartilage defects over a large area can also be treated with this technique.
If there are completely destroyed joint surfaces where the bones lie free, small motor driven cutters can remove the surface of the bones (abrasion). After a few months substitute cartilage is formed. Abrasion arthroplasty is one of the last joint supporting operations before the insertion of a prosthesis. In many cases the symptoms improve.
In this technique, several round cartilage-bone cylinders are taken out of areas of the joint that are less burdened and inserted into the defective zone in the cartilage. This involves material from one's own body, which has a very good potential for healing. This technique is suitable only for isolated cartilage defects in younger patients.
Cartilage cell transplantation
This procedure is recommended only for patients for whom the ability to regenerate the cartilage is still very high. Initially, small pieces of cartilage are taken out of the joint using arthroscopy; they are then grown into a cell structure in a complicated laboratory procedure. A few weeks later the cartilage cells that have been grown are implanted into the defective zone. These cells must grow there, multiply, and fill in the defective area. This procedure is very expensive and ambitious. Despite the high costs, which are seldom covered by health insurance funds, this operation is to be recommended when the conditions are correct.
These treatment possibilities, also called "bioprosthesis", can only partially replace the original cartilage. A complete recreation of the original cartilage layer is not possible. Good results can be achieved only when joint instabilities that cause the cartilage damage are operated on at the same time. This applies as well to previously existing incorrect axial positions (e.g., bowlegs, knock knees). These patients also require a correction of the axis.
After cartilage operations, relief of load bearing by using crutches lasts for 8-12 weeks. This long relief phase is necessary in order to allow the formation of substitute cartilage. Physical therapy follow-up treatment is necessary for 3 months. Immediately after the operation, we begin with passive motion on the motorized splint. Training to build up the muscles begins early on with the use of a stationary bicycle and with water exercises.