Function of the knee | Treatments | Consultation
What makes up the knee?
The knee is the largest joint in the human body and is composed of three bones, namely the femur, the tibia and the fibula, as well as the patella. The knee joint itself consists of two joints: the joint between the thigh and the lower leg, and the joint between the kneecap and the thigh.A fibrous articular capsule surrounds the entire knee joint and keeps the synovial fluid in the joint. This fluid is produced by the synovial cells that line the inside of the articular capsule. The synovial fluid provides nutrients to the cartilage cells and facilitates gliding of the joint.
The movement of the knee joint is very complex and is made up of a rolling and a sliding movement. This mobility is made possible by the interplay of muscles, ligaments and tendons. Two crescent-shaped disks of connective tissue called menisci are located between the femur and the tibia on the inside and outside of the knee joint. They distribute the load in the joint evenly on the lower leg and act as a buffer or shock-absorbing system. Within the joint, smooth cartilage covers the entire surface of the bone in a layer that is about five millimetres thick. The cartilage tissue is very elastic and contains fluid. It allows for low-friction, gliding movements in the knee. In contrast to the underlying bone, the cartilage has no pain receptors. That is why, when the cartilage is intact, we do not feel any pain on movement.
FREQUENTLY ASKED QUESTIONS ABOUT KNEE PAIN
What are the most common causes of pain in the knee joint?
For active people, excessive strain on the tendons and ligaments or inflammation of the bursa can often lead to knee problems. Other causes of knee pain include injury of the meniscus, cruciate ligaments or cartilage damage. In older people, most problems are caused by wear and tear, leading to conditions such as osteoarthritis of the knee.
Are there any risk factors for knee problems?
Sports that place excessive strain on the knee can cause problems. Rapid changes in direction and hard landings after jumping put the tendons, meniscus and cartilage in the knee under particularly high stress. Weight also plays a role here. When you are standing, a load of twice your body weight is placed on the knee. When you’re going down stairs, the load on the knee joint is actually six times your body weight. This means that the heavier you are, the greater the load on the knee. However, the load that the knee can successfully carry is very individual.
What preventive measures can you take to help your knees?
Although sports can be a risk factor, they are generally very positive, because they train the muscles around the knee and stabilise the knee. Sports with controlled movements are particularly gentle on the joints. These include classic cross-country skiing, swimming, cycling and fitness training with gym equipment. A healthy, varied diet also makes a significant contribution to the prevention of knee problems. This is important for both the cartilage and the synovial fluid.
How do you know when you have put too much stress on your knee?
If the ligaments or the internal structure of the knee joint are placed under too much stress, they react with pain or swelling. The pain may be experienced in very different ways, and may be dull, burning stabbing or pulling. Pain may occur on movement, under strain or at rest. In addition, a distinction is made between acute knee pain that starts suddenly, and chronic knee pain that develops over time. The location and type of pain give us an indication of what sort of problem may be causing it. Swelling, which is often associated with instability of the knee, is a sign that something may be wrong with the ligaments.
It should be noted that if knee instability and knee pain are impacting on everyday life, it is time to investigate and treat the underlying problem in order to avoid long-term damage.
Many athletes develop jumper’s or runner’s knee. What does that mean, exactly?
These are two different problems. However, they are both caused by excess strain on a tendon. In jumper’s knee, the patellar tendon is subject to excess stress due to repeated jumping or abrupt changes in direction. This causes tiny tears in the patellar tendon at the lower edge of the kneecap. This leads to the formation of new connective tissue, nerves and blood vessels in response and causes the typical pain on exertion.
As the name suggests, runner’s knee mainly affects long-distance runners. The pain occurs on the outside of the knee and is also triggered by tendon problems. Muscles and tendons in the thigh extend down the side of the femur (thigh bone) to the head of the tibia (shin bone). The tendons usually slide by the knee joint easily. However, in runner’s knee, there is repeated rubbing on the prominent bone, putting strain on the tissue, which can become inflamed.
Long-term knee problems can have a huge impact on quality of life. At what stage is surgery recommended?
First, it is important to have any knee problems carefully investigated. Depending on the cause, good results can be achieved using conservative measures such as medication, physiotherapy or breaks in training. If the pain persists and the symptoms impact quality of life, surgery should be considered.
Osteoarthritis is a gradual process accompanied by increasing pain. When is a knee replacement necessary?
As a general rule, if the quality of life is limited or if daily life is dominated by pain and uncertainty, you should consider a knee replacement. Pain relief and mobility can be restored with an artificial knee joint. An artificial joint usually lasts around 10 to 15 years. The life span of an artificial joint can be limited by the following: overweight, activity, increase in osteoporosis, infections, allergies, instability of the joint and accidents.
Our doctors have many years of experience and are highly skilled in sports and joint surgery. We guarantee rapid, expert assessment and consultation and treatment in line with the latest medical findings. Don’t hesitate to get in touch if you would like a second opinion.