The thigh bone widens towards the knee to form an extension(femoral rollers, also known as femoral condyles). This is covered with articular cartilage on the inside and outside. If bone tissue dies off(necrosis) on the inside of the femoral condyle pointing towards the center of the body, doctors speak of Ahlbäck's disease.
This is an aseptic bone necrosis, as the death of the bone tissue is not caused by an infection.
The reasons for the tissue loss have not yet been clarified, but a circulatory disorder is suspected as the cause. As a result of the impaired blood flow, the bone tissue can no longer be supplied with sufficient oxygen and nutrients. It dies off.
Favoring factors are
The disease mainly occurs after the age of 60.

The femoral condyles are widened bony processes at the lower end of the thigh bones © CLIPAREA.com | AdobeStock
Ahlbäck's disease is characterized by the following symptoms:
- Pain on the inside of the knee joint
- Joint effusion with restriction of movement
- Increasing bow leg position (varus deformity) as the disease progresses
The disease is typically characterized by sudden onset of pain. It occurs in the anterior and mid-body area of the knee joint. It usually intensifies under stress. Depending on the extent of the affected bone area, the symptoms can be mild to very severe.
The further course can also vary greatly. If, for example, only a small area is affected, the joint often calms down again after a painful acute phase.
As the disease progresses , the dying bone tissue collapses. This leads to fractures, as a result of which the painful irritation of the knee persists.
In the long term, the bone fractures are accompanied by increasing deformation of the upper joint surfaces. This in turn leads to poor posture and, in severe cases, can lead to impairment of the entire body axis.
In addition, joint effusions often develop, leading to swelling and restricted movement in the affected knee joint.
The doctor palpates the knee as part of the physical examination and carries out various functional tests. Patients with Ahlbäck's disease have pain in the inner knee joint area. This is tested in the so-called positive rotation/compression test of the inner femoral condyle.
In advanced stages, the bony defect can be visualized using an X-ray. Early stages, on the other hand, can be detected using magnetic resonance imaging (MRI). MRI can also be used to precisely assess the extent of the tissue loss.
In addition, bone scintigraphy can also be used. This involves injecting a radioactive substance into the patient's vein. This is then deposited in bone areas with high metabolic activity (including pathologically altered bone tissue).
A few hours after the injection, the body is scanned using a special camera and the distribution of the injected substance is recorded. Accumulation in the areas with altered bone metabolism allows Ahlbäck's disease to be diagnosed at an early stage and its exact extent to be assessed.
In around a fifth of those affected, Ahlbäck's disease does not progress or heals on its own.
If the disease does not progress, conservative treatment or joint-preserving surgery is sufficient in many cases.
Non-surgical treatment in the event of disease arrest
If Ahlbäck's disease does not progress, conservative treatment is usually sufficient. This is primarily aimed at protecting the affected leg by providing support and avoiding sport.
In the case of leg malalignment (bow leg or knock-knee), shoes are adjusted by raising the outer edge. This can correct the knee misalignment and relieve the knee.
Physiotherapeutic measures are also recommended
- to maintain the mobility of the knee joint and
- to strengthen the leg muscles.
Hyperbaric oxygen therapy (HBO therapy) can also be used to improve blood circulation and reduce pain. Bone-building medication (e.g. biphosphonates) can also promote the vitality and regenerative capacity of the affected bone tissue.
Joint-preserving surgery if the disease is at a standstill
Various surgical procedures can be used to surgically preserve the joint. One option is to drill into the affected bone tissue(relief drilling). This can stimulate the bone tissue to heal itself.
Another method is the transplantation of healthy bone tissue from another part of the body. This type of cancellous bone transplant can be used to replace the destroyed tissue.
To relieve the area affected by the necrosis, the position of the femur and tibia in relation to each other can be changed. At the same time, the surgeon often drills into the area of necrosis in order to stimulate the regeneration of the bone tissue(valgus osteotomy).
In around four-fifths of those affected, Ahlbäck's disease progresses and the necrotic bone areas collapse.
In these cases, removal of the affected bone area and insertion of a partial knee prosthesis or total knee prosthesis is recommended. This measure prevents further progression of the tissue loss.

Ahlbäck's disease causes knee pain © westfotos.de / Fotolia
Physiotherapy should be carried out after every surgical procedure. As part of this therapy, the knee joint is gradually loaded more and more until normal everyday weight-bearing is possible again.
In addition, special exercises are used to train the leg muscles that stabilize the knee joint.
The prognosis for Ahlbäck's disease depends
- the age of the patient,
- the progression of the disease and
- the choice of treatment
treatment. In the early stages of the disease, spontaneous healing can be observed in some cases. As the circulatory disorder recedes, new cartilage tissue forms and the pain decreases.
However, the destruction of the bone tissue progresses in 80 percent of cases. If left untreated, this leads to increasing pain and osteoarthritis of the knee.
However, due to the ability of bone tissue to regenerate, the prognosis is generally good, even when an artificial joint is used. However, the healing process can be lengthy.
If you suspect Ahlbäck's disease, you should consult a specialist in orthopaedics and trauma surgery. After completing a 6-year medical degree, they have specialized in the treatment of diseases of the musculoskeletal system, including the knee joint.
Orthopaedists are experts in the joint structures of the knee, i.e.
- bones,
- muscles,
- tendons and
- cartilage.