The knee joint plays an important role in our life, our society and our health system. Knee pain can be very severe and affect all age groups. Injuries to the knee are the second most common and almost weekly we can read about knee injuries of well-known athletes and follow their recovery process almost live on e.g. social media. No wonder, patients with knee joint complaints are in the majority in our clinical everyday life. In most cases, good conservative results can be achieved and the patient can return to sport soon.

The medial and lateral meniscus serve for load distribution, enlargement of the joint surface, stabilization and lubrication of the joint cartilage. The medial meniscus is crescent-shaped, has a narrow anterior and a broad posterior horn and is fixed to the joint capsule. The latter leads to less mobility and a higher load. As a result, the medaiel meniscus is more frequently and severely affected by degenerative changes and traumatic injuries. The lateral meniscus is ring-shaped or C-shaped with horns of approximately the same thickness and is flexibly suspended from the anterior and posterior horn roots.

Meniscus injuries are characterized by acutely shooting pain at flexion with pain amplification when rotating or on uneven ground. Occasionally feelings of entrapment or blocking can occure.

Unfortunately, surgery is all too often recommended.

Articular cartilage is a resilient coating that covers the joint forming bone. This is called hyaline cartilage. It functions as a pressure transducer and, so to speak, as a shock absorber between two bones. In addition, it´s very smooth surface improves the sliding process when the joint is moved. Focal, well defined cartilage injuries are associated with a reduction in quality of life, represent a risk factor for arthritic joint degeneration and primarily affect young sports patients. In addition to purely accidental cartilage lesions, bone diseases can also lead to secondary cartilage changes with consecutive destruction of surface integrity. If there is a large-area cartilage alteration, possibly affecting several areas, this is referred to as arthrosis. The primary goal of cartilage surgery is the restoration of a cartilage surface that is as intact as possible. However, this requires a ligament-stable joint with a physiological leg axis so that corrective surgery (e.g. osteotomy) may have to be performed before the actual operation. The therapeutic options depend strongly on the size of the cartilage defect. There are two basic principles of therapy: bone marrow stimulating techniques and transplantation techniques. If a small defect of less than 4cm² is present, microfracturing is usually performed (bone marrow stimulating technique). To do this, first the remains and loose parts of the defective cartilage are removed and then small holes are drilled into the underlying bone. From these holes it bleeds into the defect. A stable blood clot forms. This transforms into a replacement cartilage in the following weeks.

In the Osteochondral Autograft Transfer System (OATS) procedure, hyaline cartilage is transferred from another, unloaded point of the joint to the defect zone. A special transfer system first punches out a cartilage-bone cylinder at the donor site and transfers it into the defect. In principle, this technique can be performed arthroscopically. This method is used for minor cartilage injuries, especially if bone involvement is present (e.g. osteochondrosis dissecans).

In the case of large cartilage defects of more than 4 cm² or if one of the above procedures has not been successful, an autologous chontrocyte transplantation is performed. In a first arthroscopy several bone-cartilage cylinders are removed. In a second step, the cartilage-forming cells are separated from these and cultured. These can then be applied to a dissolving fleece and transplanted into the defect zone (during a second procedure).

The anterior and posterior cruciate ligaments stabilize the knee joint and prevent excessive mobility of the femur on the lower leg bone. The rupture of the anterior cruciate ligament (ACL) is much more frequent than that of the posterior cruciate ligament. ACL ruptures typically occur in sports with rapid changes of direction, contact sports and sports with uncontrolled landings (in decreasing frequency: soccer, skiing, handball, volleyball). In almost 70% of the cases there is no contact with an opponent! Patients often report a whiplash or “plop” sound. In the majority of cases, the trauma is followed by a painful, bloody joint effusion with restricted range of motion. Therapy planning (conservative or operative) depends on the patient’s age, knee joint instability, sporting ambitions and any accompanying injuries. Replacement surgery is not absolutely necessary! Several studies have shown that the risk of osteoarthritis after cruciate ligament plastic surgery is comparable to that without cruciate ligament replacement. If there is a low level of activity, if there are few knee straining sports or if the patient is willing to reduce his sporting demands, conservative treatment is possible.

If accompanying injuries are present (e.g. meniscus lesion, cartilage damage), if sports with high knee load are practised or if the patient complains of permanent instability, reconstruction of the cruciate ligament is recommended. The autologous tendon replacement has established itself here. Different tendons are available for this purpose. A restriction of mobility by a knee joint orthosis does not occur after the operation. Rehabilitation is standardised and the vast majority of patients return to their original sporting level.

The dislocation of the knee cap is extremely painful and must be evaluated. As a rule, an x-ray and an MRI are necessary to exclude concomitant injuries. In the case of initial luxation without concomitant injuries and in the case of patients without predisposing factors, conservative therapy is the preferred treatment. Surgical measures depend on the patient’s age, the nature of the underlying causes and any accompanying injuries. If the passive patella stabilizers are torn, a reconstruction of the medial patella-femoral ligament (MPFL plastic) can be performed. Similar to cruciate ligament plastic surgery, the body’s own tendon is removed (but in this case the so-called Gracillis tendon) and attached to the knee cap and femur in such a way that renewed luxation is not possible.

If a bow leg is present the body weight is distributed unevenly over the knee joint and mainly the inner half of the knee joint is loaded. As a result, the joint cartilage of the inner half of the knee joint is subjected to greater stress and is subject to greater and faster wear and tear. In the case of an knock knee (valgus malalignement), the outer half of the knee joint is overloaded.

Depending on the patient’s age and level of activity (the younger and the more active), an adjustment operation is recommended in these cases. This causes the still intact cartilage to be subjected to greater stress, the worn part of the knee to be relieved and the patient to experience less or no pain and the insertion of an artificial knee joint to be delayed by years or completely prevented.

The shoulder joint is the most mobile joint in humans. This is achieved by a relatively small socket and a large humeral head. However, the stability of the joint partners to each other is not particularly high and therefore secured by ligaments and muscles. For this reason, dislocations occur more frequently than in any other joint.

A torn rotator cuff is one of the most common degenerative diseases of the upper extremity. Timing actually plays a major role here, so that we generally advise the patient to undergo surgery at an early stage.

An impingement syndrome is a bottleneck under the acromion. Due to various changes (calcific shoulder, arthrosis of the acromioclavicular joint, etc.), pain may occur during the course of life when the upper arm is spread. Initially, treatment is always conservative. Arthroscopic surgery can only be useful in cases of persistent pain.

As already mentioned, the great mobility of the shoulder joint is achieved by a small joint socket. This is surrounded by a cartilaginous joint lip, the so-called labrum, and the joint surface is thus slightly enlarged. If a shoulder dislocation occurs, this labrum often tears off – the joint becomes unstable. The aim of the operation is to reattach the labrum to the acetabulum. This operation is performed arthroscopically (“keyhole technique”) with the help of so-called thread anchors. To put it simply, these suture anchors are sunk into the joint socket and the labrum is stabilised by means of the sutures attached there. The chances of success of this procedure are consistently good to very good.

The rotator cuff consists of a total of four tendons. It stabilizes and centers the humeral head in the acetabulum of the shoulder joint, counteracts the strong deltoid muscle and is of great importance for shoulder mobility.

A rotator cuff tear is a partial or complete interruption of the continuity of one or more tendons. The predominant cause is a tendon degeneration that has developed over years. Therefore, rotator cuff tears are one of the most common diseases of the upper extremity and is present in about 35% of all people over 65 years of age in varying degrees.

The complaints described by the patient are manifold and can occur acutely as well as slowly. Nocturnal (resting) pain, pain when spreading the arm or the inability to lift the affected arm are the main characteristics. The suspected diagnosis is confirmed (or excluded) by a physical examination and subsequently by an ultrasound examination and X-ray or MRT. Not every tear of the rotator cuff must or can be operated on. It is indispensable to discuss the existing findings in the context of patient age, affected side, tear size and severity of the symptoms with the patient and to discuss the best possible therapy concept. In fact, however, timing also plays a major role here. The longer a tear exists, the worse the results after the operation. If an operation is necessary, it is performed arthroscopically or using the so-called “mini-open” technique.

An impingement syndrome (shoulder bottleneck syndrome) is pain caused by the trapping of soft structures under the acromion. There can be different causes for this. The bursa below the acromion can be irritated and trapped by calcification (calcified shoulder or tendinosis calcarea), arthrosis of the acromioclavicular joint or a bone spur. Pain occurs mainly when the arm is lifted forwards and sideways. Pain can also occur when the affected arm is moved backwards (e.g. when grabbing the seat belt in the car). The typical pain is felt above the humeral head, but can also radiate to the neck and elbow. Impingement syndrome is primarily treated conservatively. Through short-term application of so-called non-steroidal anti-inflammatory drugs (e.g. Voltaren ®) or selective infiltration, the pain can usually be eliminated reliably and quickly. Physiotherapy to strengthen the muscles must be carried out consistently on one’s own initiative. In very persistent, therapy-resistant cases, an operation can be performed as a last resort. The aim of an operation is to eliminate the underlying pathology. In the case of a calcific shoulder, for example, this can mean that the calcific deposit is removed. In the case of a protruding bone spur, this is removed. These operations are all performed arthroscopically and are not very painful.