Knee encyclopaedia

The knee is the largest joint of all mammals. It is made up of the tibia, patella and femur. Internal structures include an anterior and a posterior cruciate ligament, as well as an inner and an outer collateral ligament. There is an inner and outer meniscus in the joint space between the upper and lower leg. To ensure smooth and pain-free movement, their contact surfaces are covered with a white layer of cartilage, the hyaline cartilage. These cartilage layers are thicker or thinner within the knee joint as required.

Viewed from the front, the kneecap is a triangular, disc-shaped bone that protects the knee joint. It also acts as the centre of force transmission in the knee. Its overloading and incipient instability is often the cause of knee pain.

Cartilage is a smooth surface between neighbouring bones. Together with the meniscus and synovial fluid, it compensates for stresses that lead to lasting damage, which in turn is responsible for premature joint wear and tear.
Complete wear and tear of the articular cartilage is the cause of osteoarthritis. Fresh cartilage damage that occurs as a result of sports injuries is often accompanied by joint effusion and severe pain.

The meniscus is a disc-shaped elastic cartilage and consists of approx. 90 % type I collagen fibres. We distinguish between an inner (medial) and an outer (lateral) meniscus in the knee joint. The inner meniscus (medial meniscus) has a C-shaped appearance and is firmly attached to the joint capsule and the medial ligament. Due to its reduced mobility, it is much more susceptible to injury in the event of rotational trauma than the outer meniscus. The outer meniscus is more mobile as it is only slightly fused to the joint capsule. The meniscus has an anterior (anterior horn), middle (pars intermedia) and posterior part (posterior horn). We differentiate between horizontal, basket handle and radial tears, and also between degenerative (worn) and traumatic (accident-related) tears. Depending on the type of tear, the meniscus is partially removed, refixed (sutured) or smoothed.

Injuries to the meniscus are the most common limitations of the knee joint. A meniscus tear can occur during rotational movements with a bent knee, such as when playing football and other ball sports, skiing and also during everyday movements. The inner meniscus in the rear section is usually affected. This injury, which is often ignored for too long, leads to persistent pain during normal exercise or sport and causes lasting damage to the knee joint. Magnetic resonance imaging (MRI) is the diagnostic tool of choice in addition to a medical history including a clinical examination. Depending on the depth of the tear and the type of injury, arthroscopy with partial meniscus removal or meniscus suturing may be necessary.

The two cruciate ligaments, anterior and posterior, together with the collateral ligaments and menisci, ensure central stability in the knee joint. During the flexion and extension movements of the knee joint, they are responsible for the complicated rolling-sliding mechanism.

The gold standard of cruciate ligament surgery is the removal of 2 tendons from the thigh (semitendinosus gracilis tendon). The functionality of the knee joint can be restored using minimally invasive incisions.

Revision cruciate ligaments: We have also been using allograft implants for revision cruciate ligaments for several years.

Rupture of the anterior cruciate ligament is the most common ligament injury to the knee joint, while the posterior cruciate ligament is rarely affected. Here too, the causes are jerky bending and twisting movements during sport, but also in the course of road traffic accidents.
Fresh cruciate ligament ruptures cause swelling (haematoma) and often severe pain. There is often an inhibition of extension and the injured person hears a tearing, snapping sound.

Depending on the patient's activity level and personal needs, the cruciate ligament is reconstructed using the body's own tendons (semitendinosus gracilis, patellar tendon, rectus tendon) as part of a cruciate ligament replacement operation.