Knee
Osteonecrosis is also a typical disease for the knee, or the lower end of the thigh bone. If the knee is affected, the medical term is “Ahlbäck’s disease” (synonym: aseptic bone necrosis of the knee). The cause for the death of the bone substance is primarily a disturbance of the regular blood circulation of the joint forming thigh.
This reduced blood flow is triggered by various mechanisms. After serious accidents or the use of force, for example, the smallest vessels can be damaged, resulting in an undersupply of blood to the thigh bone. In addition, osteonecrosis in the knee is frequently observed in patients with blood coagulation disorders.
Regular consumption of tobacco and/or alcohol can also be linked to the development of osteonecrosis in the knee. Although Ahlbäck’s disease is a rather rare form of osteonecrosis, observations of the disease cases have led to the conclusion that many patients with a history of osteoporosis have been treated with bisphosphonates. Consequently, a connection between the long-term intake of bisphosphonates and the occurrence of osteoporosis in the knee can be assumed.
The typical symptoms of Ahlbäck’s disease are sudden, severe pain in the knee. These pains can occur following a minor injury or without any apparent reason. A patient suffering from osteonecrosis in the knee does not only feel these pain phenomena during or after periods of stress.
A typical symptom of Ahlbäck’s disease is above all the so-called resting or night pain. In addition, swelling and limited range of motion can be observed during physical examination of patients with osteonecrosis of the knee. In such cases, treatment can usually be carried out non-surgically by means of hyperbaric oxygen therapy (HBO for short), shock wave therapy and the intake of painkillers. Surgical replacement of the affected bone parts is only necessary in very pronounced cases.
Ankle joint / Talus
The ankle joint represents the articulated connection between the leg and the foot. In the upper ankle joint (Articulatio talocruralis) mainly the lower (distal) ends of the tibia and fibula articulate with the foot, mainly with the so-called talus.The most common form of osteonecrosis in the ankle joint or talus is known as osteochondrosis dissecans. Osteochondrosis dissecans is an aseptic bone necrosis of a circumscribed joint surface area, which can be accompanied by its rejection.
This results in bone death close to the cartilage. The disease is more common in the growing age or in young adulthood and is associated with frequent injuries to the ankle (traumatic etiology), e.g. by “twisting”. Young people who do a lot of sport also seem to be predisposed.
Symptomatically, osteochondrosis dissecans is characterized by pain in the upper ankle joint, which occurs under stress and subsides at rest. Therapy in children is usually conservative and involves immobilization, whereas surgical refixation is usually unavoidable in adults. Therapy should be started as early as possible, as otherwise wear and tear to the cartilage and bone of the joint can occur as the disease progresses (arthrosis).
In most cases of osteochondrosis dissecans of the ankle joint, the anklebone (talus) is affected. Most frequently, the upper inner edge of the talus (trochlea tali, ankle bone roll) is affected. This bears most of the weight bearing on the joint, which in turn indicates a load-dependent genesis of osteochondrosis dissecans. Another special bone necrosis is Renander’s disease, which affects the sesamoid bone of the big toe.
