Information on knee osteoarthritis
What is osteoarthritis in the knee?
Knee osteoarthritis, or gonarthrosis in technical jargon, is premature wear of the knee joint including the joint cartilage. Women are affected far more often than men. This degenerative, non-inflammatory destruction of the knee joint can affect only individual or all of the bones of the knee joint (thigh bone, shin bone and kneecap). Knee osteoarthritis is one of the most common joint diseases in old age. Knee osteoarthritis usually begins in the fifth decade of life.
What are the causes of knee osteoarthritis?
There are many causes of gonarthrosis. Orthopedists generally distinguish between a primary cause and a secondary cause. The cause of primary knee osteoarthritis is still unclear.
The secondary form can be triggered by misalignments, knee injuries or inflammation. But various metabolic and hormonal disorders (uric acid gout, chondrocalcinosis, etc.) can also lead to progressive destruction of the knee joint.
As knee osteoarthritis can be triggered by constant excessive strain (e.g. being overweight, certain professional activities), it was classified as an occupational disease a few years ago.
Symptoms of osteoarthritis in the knee joint
The main symptom of knee osteoarthritis is knee pain. At first it only occurs when the knee is fully extended or bent, but later also when the knee is under any strain. Active movement is usually accompanied by an unpleasant crunching sound (crepitus) in the joint.
The so-called morning stiffness is particularly noticeable. You can imagine this as a tight screw coming loose. After periods of rest, the knee joint is very stiff and slightly painful. After some time of movement (30 minutes), it is easy to move again and well lubricated (synovial fluid).
Over time, pain can lead to restricted movement. As a result, full flexion or extension of the knee joint is avoided, the tendons begin to shorten (flexion contracture). This results in difficulty walking, instability, increasing axial misalignment of the knee joint and the resulting unsteady gait.
If inflammation of the joint (knee synovitis) occurs alongside knee osteoarthritis, this is referred to as activated gonarthrosis. This is significantly more painful and can be recognized by swelling and overheating of the knee joint.
How is gonarthrosis diagnosed?
The symptoms mentioned above usually lead the patient to a knee specialist. Here, the doctor will first ask about your medical history. During the subsequent physical examination, the orthopedist will see restricted movement, misalignments and bony swellings.
This is usually followed by a visit to the radiologist. The radiologist can use your X-ray images to identify changes typical of osteoarthritis. These include new bone formation (osteophytes) on all bones involved in the joint and a narrowing of the joint space.
Another helpful diagnostic method is joint aspirate. This involves obtaining some synovial fluid under sterile conditions, which then shows typical changes when analyzed.
Treatment of osteoarthritis of the knee
The treatment options for knee osteoarthritis are very varied. They range from conservative, non-surgical therapy to minimally invasive joint arthroscopy to total joint replacement. The aim of treatment is to both relieve pain and improve joint function and the associated everyday movements.
Conservative therapy generally aims to slow the progression of wear and tear of the articular cartilage in the knee joint, as regeneration or regrowth does not occur.
Depending on the severity of the knee arthrosis, various surgical procedures are recommended. The first step is usually minimally invasive knee arthroscopies (keyhole joint endoscopy). In cases of severe bowlegs or knock knees, a corrective osteotomy may also be recommended, in which the axis of the leg is straightened again to allow the cartilage in the knee joint to wear down evenly.
Surgical procedures end with partial or total joint replacement, in which the joint surfaces of the knee are replaced.
Conservative therapy
If it is a so-called secondary knee joint arthrosis, i.e. without a previous injury to the joint, the cause of the arthrosis is usually a disproportion between the load and the resilience of the joint structures such as cartilage, menisci and ligaments. If there is primary arthrosis in the knee joint, the patient has often suffered one or more knee injuries such as meniscus tears, cruciate ligament tears or bone fractures in the joint partners shinbone, femur and kneecap.
Preventive measures are not only a very important part of prevention, but also of therapy or slowing down the progression of cartilage wear in the knee joint. Recommended measures are:
Weight loss if you are overweight, dietary adjustment (BMI > 25)
Reduction of activities and exercises in everyday life that put strain on the knee
Practice a sport that is easy on the joints, such as aqua jogging, swimming, cycling, as a lack of exercise reduces cartilage nutrition and thus osteoarthritis progresses more quickly
As a further conservative treatment, patients with knee osteoarthritis are also recommended to undergo physiotherapy (manual therapy, physical therapy) and exercise training to improve strength, mobility and endurance. This allows the knee to be actively stabilized and controlled better, which has a positive effect on pain and everyday activities.
Orthopedic insoles, shoes or orthoses can also help with pain.
Drug therapy initially relies on common anti-inflammatory painkillers (e.g. ibuprofen), as osteoarthritis is also accompanied by inflammation of the synovial membrane as the disease progresses. Paracetamol is not recommended.
If the combination of preventive measures, physical training, painkillers and aids is not promising, there is also the option of injections into the arthritic knee joint. In this case, either anti-inflammatory drugs or substances that are said to have cartilage-regenerating properties are injected into the joint under sterile conditions. However, this should only be carried out by an experienced doctor.
Injection therapy
Needles or injections are usually used when the usual therapy with painkillers and other conservative methods, such as exercise training, weight reduction and the provision of aids, is no longer sufficient.
If the affected knee joint is very swollen and difficult to move, it can be punctured with a puncture needle, i.e. fluid is drawn out of the joint. This relieves pain and improves mobility, as the structures in the joint are relieved.
Corticosteroids (anti-inflammatory medication) can also be injected into the joint space to relieve the pain for a short time (a few weeks). It is strongly recommended that this technique is only carried out by particularly experienced doctors.
Hyaluronic acid
If the standard therapy with painkillers is no longer sufficient, hyaluronic acid can be injected intra-articularly (into the joint). The scientific results on its effectiveness are not clear, but it is said to be effective in relieving pain.
The combination with painkillers and hyaluronic acid as an injection is also recommended if patients have an inflammatory flare-up of their osteoarthritis.
This therapy should be carried out by an experienced doctor in order to exclude side effects and negative consequences as far as possible.
Alternative therapy methods
As an alternative healing method from natural medicine, in addition to a number of medicinal herbs that are said to have an osteoarthritis-relieving effect, white cabbage wraps can have a pain-relieving effect on knee osteoarthritis pain.
According to experts, acupuncture can also be used and this has a positive effect on the symptoms of knee osteoarthritis.
Electrotherapy using TENS is also recommended for pain reduction. Homeopathy, on the other hand, is not said to have any demonstrable effect.
Joint-preserving operations
If the patient's symptoms such as pain and restricted mobility can no longer be controlled with conservative methods such as therapy and pain treatment, the treating surgeon first tries to choose a joint-preserving surgical method. This involves joint arthroscopies in which, based on the findings, small skin incisions are used to minimally invasively remove loose joint bodies, disruptive menisci, or bone protrusions. Removing inflamed synovial membrane and cleaning the joint can also be useful.
If the patient suffers from a severe leg axis deformity (bow legs/knock knees), which results in an uneven distribution of forces with uneven wear of the cartilage, an osteotomy (straightening of the leg axis) can be performed.
Knee prosthesis
If the cartilage or the joint is so badly affected by arthrosis that injections and arthroscopic (joint endoscopy) procedures do not provide the patient with relief, the joint is replaced with an implant. The patient's bone and joint material is used as sparingly as possible, as it is not possible to replace joint implants as often as required.
If the arthrosis is only in one part of the knee joint, e.g. inside and outside, or between the femur and the kneecap, a partial joint replacement between the affected joint surfaces is an effective solution.
As knee arthrosis usually develops further in a more severe stage, pangonarthrosis (knee arthrosis in the entire knee joint) often occurs and must be treated surgically with a knee TEP (total knee replacement).
Implementing a knee replacement too early can be problematic, as the lifespan of such a prosthesis is stated to be around 10-20 years and replacing the prosthesis is associated with risks. Likewise, a necessary joint replacement should not be delayed for too long in order to minimize damage to the tissue surrounding the joint, such as ligaments, muscles and bones.
After a joint replacement operation, patients can generally expect an improved quality of life, reduced pain and better mobility.
What are the prognosis and disease progression for knee osteoarthritis?
If left untreated, knee osteoarthritis leads to constant pain, instability of the joints and even severe restrictions in movement. Therapy can help here.
Whether it is conservative therapy with muscle building and injections or whether a knee prosthesis is fitted by an orthopedic surgeon if the knee joint cannot be preserved, both options offer you the opportunity to explore the world on foot without pain and with the same enthusiasm as before.
Knee endoprostheses have excellent survival times. For example, a maximum of five percent of patients have to have their full prostheses replaced within 10 years.
