Aseptic Bone Necrosis: Causes, Symptoms & Treatment

Necrotic degradation processes of human bone substance that are not attributable to infection but to vascular infarction are called aseptic bone necrosis. Depending on the location and form of aseptic bone necrosis, both sexes may be affected with different frequency.

What is aseptic bone necrosis?

The term aseptic bone necrosis includes necrotizing diseases of the bone system that, in the absence of infection (aseptic), can be attributed to a deficiency of blood supply (ischemia) to the affected bone areas. The occlusion of the supplying vessel (vascular infarction) causes a deficiency in the supply of oxygen, nutrients and minerals to the affected bone, as a result of which there is a gradual degradation up to a possible functional failure of the bone area. In principle, all bones of the human skeletal system can be affected on one or both sides by aseptic bone necrosis. Characteristically, aseptic bone necrosis is manifested by abrupt or successively increasing pain in the area of the necrotizing bone segment, which intensifies under stress and may radiate to adjacent skeletal segments. In addition, limitation of motion of the affected area, especially later in the course of the disease, is possible with aseptic bone necrosis.

Causes

Aseptic bone necrosis is generally due to occlusion of the blood vessel supplying the necrotic bone area. The exact etiology for this occlusion has not been clearly established. Constitutional factors, recurrent or iterative (repetitive) microtrauma, and locally restricted circulatory disorders are discussed in this context. In addition, therapies with high-dose and systemically applied immunosuppressants (including sirolimus, glucocorticoids) or bisphosphonates (exclusively in aseptic bone necrosis with involvement of the mandible), radiotherapeutic and chemotherapeutic therapies (especially in lymphoma, leukemia), high pressure or activities in compressed air (scuba diving or compressed air environments such as mining or tunneling), chronic nicotine and/or alcohol abuse, sickle cell anemia, Gaucher disease, HbSC disease, endocrine disorders, hyperlipidemia, metabolic disorders (diabetes mellitus), vascular and blood coagulation disorders, and the systemic form of lupus erythematosus (SLE) as identified risk factors for aseptic bone necrosis, although the exact causal relationship is not known in every case.

Symptoms, complaints, and signs

Aseptic bone necrosis shows an insidious disease course, meaning that symptoms manifest almost unnoticed at first, but then become more pronounced. Due to the damage and degradation of the bone and often also of the surrounding tissue, there is discomfort in the directly affected area. The patient experiences an increasingly severe pain, which is usually described as dull and persistent. However, stabbing pain may also occur under stress in the affected region. If the surrounding tissue is also affected, it feels numb and may hurt. Damaged muscles lose their strength and resistance. The entire affected area feels numb and can no longer be loaded. In the advanced stage of the disease, fractures usually occur in the bones. These are very painful and usually occur suddenly under load. The bone material loses stability. Comminuted and spiral fractures are also diagnosed very frequently. Unlike healthy bone, which usually breaks due to an event, bone affected by bone necrosis is inherently unstable and breaks into many pieces or fibers. Bone necrosis cannot be reliably diagnosed by the patient himself, but is usually detected during a medical examination or when a fracture has already occurred. If left untreated, it can lead to blood poisoning and death.

Diagnosis and course

In addition to a physical examination, functional tests of the affected bone and joint sections provide initial evidence of aseptic bone necrosis. Diagnostic imaging techniques such as x-ray or sonography allow conclusions to be drawn about possible pathologic bone changes such as bone remodeling or destruction (especially in the later course of the disease).Early characteristic remodeling activities of the affected bone segments as well as the expression and shape of the bone necrosis can be precisely determined in the course of magnetic resonance imaging or computed tomography. In terms of differential diagnosis, aseptic bone necrosis must be distinguished from septic necrosis, tumors, and neoplasms of the bone and skeletal system as well as from bone cysts, osteomyelitis (inflammation of the bone marrow), or osteitis (inflammation of the bone). The course and prognosis of aseptic bone necrosis depend on the severity and extent of the bone vascular infarction and the resulting damage to the affected joint or bone segment and the time of diagnosis or initiation of therapy. In some cases, spontaneous healing of aseptic bone necrosis may be observed.

When should you see a doctor?

In the event of sudden onset of bone pain and limitation of movement, a physician must be consulted immediately. Medical diagnosis can then determine whether aseptic bone necrosis is present. If it is a different disease of the bones or the musculoskeletal system, the doctor will refer the affected person to the appropriate specialist. If aseptic bone necrosis is indeed present, surgical measures must usually be initiated immediately. People at risk for bone necrosis are primarily those suffering from sickle cell anemia, Gaucher’s disease, metabolic disorders, vascular and blood coagulation disorders, or HbSC disease. Patients undergoing chemotherapy or radiation therapy are also more likely to develop aseptic bone necrosis. These high-risk groups should consult a physician if they experience unusual symptoms and have the cause clarified. As part of surgical treatment, the patient often receives an artificial hip replacement or a bone chip graft. If complaints occur during the follow-up care, this must be reported to the responsible physician immediately. There may be an inflammation or the body may be rejecting the hip replacement. In any case, with aseptic bone necrosis, the physician must be consulted regularly to avoid complications.

Complications

As a general term, aseptic bone necrosis involves the disintegration of one or more bones in the body. The symptom is not due to infection but occurs as a result of vascular infarction. This no longer supplies the bone structure and surrounding tissue with sufficient blood. As a result, the bone structure is destroyed. Aseptic bone necrosis affects men and women equally. However, there are risk groups. These include patients with metabolic diseases, sickle cell anemia, divers, mountain farmers and alcoholics, as well as those taking immunosuppressive drugs or undergoing radiation or chemotherapy. If the first signs of bone pain, which occur at rest as well as with exertion, are ignored, the symptom worsens. Complications include limited mobility, chronic constant pain, rapid muscle loss in the affected bone, and loss of function in the arm or leg if the shoulder or hip are affected. In some cases, the affected area can be so painful that it affects adjacent skeletal segments. Imaging techniques are used to identify the symptom. Because each ischemia of the bone progresses differently, therapeutic measures vary. In general, if recognized early, aseptic bone necrosis can be treated successfully. In particularly acute cases, medications and radiation or chemotherapy are used. If bones or joints are completely destroyed, surgical procedures for artificial replacement become necessary. The latter methods can cause complications for the affected person in terms of tolerance.

Treatment and therapy

In aseptic bone necrosis, therapeutic measures correlate strongly with the stage and extent of the disease and the general health of the specific affected individual. In mild forms, treatment is aimed at mechanical unloading of the necrotic bone segment by forearm supports or orthoses, immobilization, and physiotherapy with possible traction treatment. At the onset of the disease, hyperbaric oxygenation (oxygen therapy) may be used concomitantly or monotherapeutically, which has been shown to be particularly effective in painful bone marrow edema.In more pronounced forms of aseptic bone necrosis, surgical measures such as femoral head relief drilling (Pridie drilling), medullary cavity decompression, repositioning osteotomies such as varisation osteotomy in Perthes disease (femoral head necrosis), and transplantation with bone chips are usually indicated. For example, in pridie drilling, the defective cartilage section is drilled into to allow blood vessel sprouting and to stimulate tissue regeneration accordingly. Medullary decompression or core decompression (for femoral or femoral head necrosis) is aimed at reducing intraosseous (inside the bone) pressure and slowing the progression of necrotizing processes. In punch cylinder reversal surgery, the necrotic areas are additionally removed and autologous cancellous bone (spongy bone trabecular system) is introduced, while intertrochanteric repositioning osteotomy rotates the necrotic focus out of the main loading zone, minimizes intraosseous pressure, and stimulates vascularization (formation of small blood vessels). If advanced bone destruction can be detected, endoprosthetics (artificial joint replacement) is usually indicated to treat aseptic bone necrosis.

Outlook and prognosis

The prognosis of aseptic bone necrosis depends on the existing bone vascular infarct. Its severity and influence on the supply to the bones as well as the joints is decisive for the prospect of recovery. Without medical treatment, the patient suffers pain and limited mobility. Since there is no self-healing of the organism, the complaints either remain abruptly or continuously increase in intensity. It is extremely unlikely that the patient will be cured in this way. With medical treatment of the vessels, the probability of a positive prognosis increases significantly. However, if additional pre-existing conditions are present, the prospects of cure decrease again. In patients without additional diseases and with a stable immune system, recovery takes place within a few weeks or months. Complete freedom from symptoms is possible, but not always given. Corrections are made in a surgical procedure. In severe cases, transplantation or replacement of the damaged joints is performed. The healing process is delayed because the organism has to come to terms with the new conditions and the patient learns a new perception of the body. Following the inpatient stay, rehabilitation therapy involves the teaching of targeted training and exercises. In these, the movement sequences are optimized and adapted to the changed possibilities.

Prevention

Because the exact causes of aseptic bone necrosis have not yet been clearly established, the disease cannot be prevented. However, chronic alcohol abuse, for example, which is considered a possible risk factor, should be treated accordingly. In addition, the risk of radiation therapy-induced aseptic bone necrosis (osteoradionecrosis) can be reduced by prophylactic administration of anti-inflammatory drugs.

Follow-up

Patients need to consult an orthopedic surgeon regularly as part of their follow-up care. The physician will perform various routine examinations, such as an ultrasound scan, and may have other discussions to allow an assessment of the condition. These regular progress checks will determine whether the necrosis has receded or spread. On the basis of this, further measures are then initiated by which the healing process is further optimized. Aseptic bone necrosis progresses progressively and therefore requires long-term follow-up. Initially, patients must see their physician every month or every two weeks. If the progression is positive, the intervals can be extended. However, patients must see their physician at least every four to six months, regardless of the progression of previous aseptic bone necrosis. If complications have been detected, further examinations are necessary in any case. Follow-up care also includes a review of mobility. A physiotherapist will examine the patient and, if necessary, provide tips for further treatment. The details of the follow-up measures required always depend on the individual course of the disease.Patients should contact the physician while they are still undergoing treatment to discuss next steps.

What you can do yourself

In addition to medical therapy, patients with aseptic bone necrosis can help improve the disease and well-being themselves. Therapy-promoting measures include observing rest periods and avoiding stress. Mechanical relief through orthoses or crutches can be useful, as can the avoidance of medications containing cortisone. The attending physician will put together the ideal medication. Physical therapy and massage help maintain and improve joint mobility. Physical therapy can also teach exercises and acupressure handles, which can then be used at home. It is advisable to support medical therapy with moderate exercise. The blood flow should be gently increased. Yoga and moderate exercise such as cycling on a bicycle ergometer, swimming or walking are good supplements. Exercise has a positive effect on mood as well as on metabolism and circulation. A balanced diet is also part of the therapy for aseptic bone necrosis. The focus here is on controlling or reducing blood lipid levels and weight. The Mediterranean diet is ideal, with a high proportion of omega-3 fatty acids, little red meat and plenty of fish. Fresh vegetables and fruit should not be missing. Avoiding alcohol and nicotine, on the other hand, promotes the success of the therapy. The same applies to good self-monitoring and early consultation with a doctor if symptoms appear or worsen.