Classification according to severity

Different degrees of severity can be distinguished in the course of gonarthrosis. The classification is based on the appearance and degeneration of the joint cartilage. At this stage, the joint cartilage appears slightly frayed.

At this stage, the function of the knee joint of the affected person is not yet impaired and usually free of symptoms. Now the arthrosis causes broad fraying on the surface of the cartilage and half-layer tears to become visible. But even at this stage, the patient is usually still free of symptoms.

From grade 3 on, however, gonarthrosis leads to pain and loss of function. The first thing you notice at grade 3 is that the surface of the cartilage in the knee joint is no longer smooth. The cartilage is riddled with deep cracks and craters and is very strongly fibrillated.In contrast to grade 3, bone in grade 4 is no longer completely covered by cartilage.

Many areas are exposed (bone glands). The bone rubs against each other at these points. This leads to serious complaints such as stiffening or joint effusions.

Therapy

Gonarthrosis is a progressive (progressive) clinical picture, which is why, in addition to pain relief, its progression should also be curbed. Numerous conservative forms of therapy are used to reduce the pressure of suffering and to maintain the joint as long as possible. The conservative methods of therapy for gonarthrosis are limited.

Relieving measures are recommended, including damping the shock in the knee by means of special orthopedic buffer heels on the shoes, but also weight reduction. Non-drug measures also include physiotherapy and physical therapy (electrotherapy/cold and heat applications), which is used to maintain or build up the atrophic thigh muscles. Drug therapy is used to relieve pain and inhibit inflammation in the knee joint.

Non-steroidal anti-inflammatory drugs (NSAIDs) are used particularly frequently for this purpose. These include the following drugs: Ibuprofen, Aspirin® or Diclofenac. However, due to their side effect profile, these drugs should not be taken over a longer period of time without consulting a physician, as they can be harmful to the digestive tract, liver and kidney.

Their use should also be carefully considered in cases of cardiovascular disease. Stronger morphine-based painkillers can also be prescribed by a specialist in orthopedics. These substances should be taken with care because of their side effects and the dosage should be adjusted and controlled by a specialist.

If necessary, the pain therapy can also be further optimized by a pain therapist (anesthetist). Drug therapy is used in the early stages of the disease or to alleviate existing complaints after conservative or surgical therapy. In addition, drug therapy is used for patients who have contraindications for further therapy.

The drug cortisone is also used in the therapy of gonarthrosis. However, it is not applied in tablet form, but locally in the knee joint. Cortisone reduces the current irritation and alleviates pain and effusion.

The administration of cortisone in crystalline form roughens the cartilage even further. The poor initial condition of the knee does not change, however. This procedure is technically not too difficult to perform, but the risk of infection is relatively high with intra-articular injections.

The drug must be applied under sterile conditions and care must be taken to ensure very precise disinfection of the patient’s skin and sterility of the tools required. Otherwise, bacterial infections from the knee can spread throughout the body and lead to sepsis (blood poisoning). A further possibility to improve the suppleness of the joint is the injection of hyaluronic acid, the effectiveness of which is evaluated quite differently.

The use of knee bandages is also possible. However, gonarthrosis bandages are only helpful to a very limited extent, as they cannot directly influence the wear and tear of the cartilaginous joint surfaces. Nevertheless, the use of gonarthrosis bandages can be recommended by the physician, for example to ensure stability during exercise and the practice of knee-sparing sports (swimming, yoga).

Knee orthoses are in contrast to bandages, which are mainly made of soft material and have a compressive effect. Orthoses are made of harder material and stabilize the knee more strongly. In addition, the knee orthoses with their belt systems can relieve pain and improve the quality of life.

Surgery can be somewhat delayed with knee orthoses. Depending on which region of the knee is affected, the orthoses can provide relief. If several regions are involved, knee guiding orthoses can be used.

Such orthoses can also be custom-made, depending on how badly the knee is affected. In the operative therapy of gonarthrosis, a distinction can be made between joint-preserving and joint-replacing operations. In the case of damage to the knee joint that is not too advanced, an attempt should be made to perform joint-preserving surgery.Malpositions of the leg axes, such as varus or valgus deformities (bow legs or knock-knees), which in the long term lead to arthritic changes in the joint, can be corrected by means of a repositioning osteotomy to prevent the development of gonarthrosis or, in the case of existing gonarthrosis, to relieve the affected region.

In an initial stage, the cartilage can also be smoothed arthroscopically (by arthroscopy) to stem the progression of the damage and reduce the irritation of the joint. Since the basic problem of arthrosis is the reduction and destruction of the joint cartilage, various measures are taken to preserve or restore cartilage. One possibility is microfracturing (also called abrasion arthroplasty or Pridie drilling).

During this procedure, the exposed bone is injured. This causes stem cells to leak out of the bone during the healing process, from which fibrous cartilage is formed. This cartilage fills the gaps in the articular cartilage and closes the previously existing defect.

A disadvantage of this procedure is that the newly formed fibrocartilage is not as resistant as the articular cartilage. A further development of this procedure is cartilage transplantation. Healthy cartilage cells are grown on a collagen fleece in the laboratory and this fleece with the cartilage cells is surgically applied to the damaged area in the joint.

This procedure is limited to patients under 50 years of age who have a fresh cartilage defect larger than 2.5 square centimeters. Patients should also be younger than 50 for cartilage-bone transplantation. However, in this case it is better if the cartilage damage is less than 25 millimeters.

In the procedure of cartilage-bone transplantation, small bone cylinders are taken from regions of the joint that are not under a lot of stress, and thus the defective areas are replaced. The donor sites are in turn filled with the cylinders removed from the defective region. Operations with joint replacement are operations in which the joint affected by gonarthrosis is replaced with a knee prosthesis.

There are different types of prostheses. There are so-called sled prostheses, which guarantee a unilateral surface replacement. This type of prosthesis is only used when only one bone roll (either external or internal) is damaged, as is often the case with arthrosis associated with leg axis malalignment, and all ligaments in the knee are still intact.

The so-called total knee endoprosthesis refers to a complete surface replacement of the knee joint. It replaces all joint surfaces in the knee joint, occasionally even the back of the kneecap. It is only important that the stability in the knee is still largely guaranteed by the ligament systems.

In the event that not only bone and cartilage but also the ligamentous apparatus of the knee joint is destroyed, an axis-guided knee prosthesis is indicated to stabilize the knee in the longitudinal axis. All prostheses are made of special metals, plastics or ceramics. For patients with metal allergies, titanium alloys can also be used.

Each prosthesis consists of at least three parts: One part for the thigh (femoral component), one part for the tibia (tibial component) and a plastic pad for the tibial component. Depending on the bone quality and the physical activity of the patient, the knee prosthesis can either be cemented into the bone or anchored without cement. A mixed form of both is possible.

As with all operations, numerous complications can occur: Damage to surrounding structures (soft tissue, nerves, vessels) with blood loss, swelling and pain, thrombosis, infection and wound healing disorders. In addition to the general complications, there are also special complications for operations with knee prostheses. Like wounds, prostheses can also become bacterially infected and this infection can lead to sepsis (blood poisoning).

However, these are very rare complications that do not usually occur. Furthermore, lack of movement of the knee joint after the operation leads to adhesions and scarring of the prosthesis, which can result in restricted movement. In addition, the prosthesis may loosen over time.

This loosening manifests itself as pain, instability in the knee joint and, in extreme cases, a malposition of the leg axis. Such prosthesis loosening must be corrected, otherwise the surrounding bone is damaged.In general, it should be said that knee prostheses are not durable for life. After 15-20 years the prostheses have to be renewed.