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Pathological osteolysis: when the bone substance dissolves
Osteolysis describes the physiological process of bone metabolism of bone loss, which is normally in balance with the bone structure (osteogenesis) or which gradually increases with the natural aging process. If osteolysis is of pathological importance, it is a disease-related bone disintegration or bone decomposition of different forms and due to different causes. Osteolytic processes are often associated with osteoporosis or bone marrow cancer. In addition to the treatment of the underlying disease, the administration of drugs from the bisphosphonate group is of great importance in order to counteract bone loss.
A brief overview
The following overview of the most important facts provides a brief summary of the comprehensive article below
- definition: Osteolysis is the physiological process of bone breakdown, which takes place through so-called osteoclasts (phagocytes) and is part of the natural bone remodeling process. The term osteolysis only gets a pathological meaning when there is talk of an abnormally increased bone loss.
- Causes and underlying diseases: Active bone resorption is caused by various disorders or underlying diseases, such as osteoporosis or bone (marrow) cancer. But there are also forms without a recognizable trigger. The diverse causes cause the occurrence of different forms and forms of bone decomposition.
- Symptoms: The symptoms are very variable with the different forms and underlying diseases. In the advanced stage, various bone or joint pain can occur. Bones that have become unstable can break more easily and cause complaints of excess calcium (due to the release of calcium in the bone degradation process).
- diagnosis: In addition to the classic X-ray examination, nuclear medicine procedures, such as a skeleton or bone marrow scintigraphy, can provide information about possible osteolysis and its sequelae.
- treatment: The treatment depends primarily on the underlying disease and its symptoms. In addition, bisphosphonates are often used to protect the bone substance and to inhibit its breakdown.
First of all, osteolysis describes the natural physiological process of bone loss, which is normally in balance with the bone structure (osteogenesis). This so-called bone remodeling process fulfills important functions in a healthy person to maintain and constantly renew and adapt our bone and skeletal system.
At the cellular level, osteoclasts are responsible for bone loss. These are controlled by hormones of the bone metabolism and act as bone-decomposing "phagocytes". This decomposition process is offset by the activity of bone-building osteoblasts. If this process is disrupted due to various causes, this can become pathological. In such cases, one also speaks of active bone resorption or pathological bone dissolution.
Causes and underlying diseases
If the body breaks down more bone tissue than it builds up, this does not have to lead to general bone loss in the sense of pathogenic osteolysis. For example, the natural aging process also causes a shift in the balance in bone metabolism. From an age of around 50 years, therefore, even in healthy people, there are a total of more bone loss processes than in turn new bone tissue is built up.
The causes of pathogenic osteolysis are very diverse and can occur due to various disorders in the body, other underlying diseases or without a recognizable trigger.
Bone remodeling disorders
In the sense of an abnormal increase in bone loss in relation to the bone structure, this can occur with very different disorders and diseases. A relatively common condition associated with loss of bone tissue is osteoporosis (bone loss). With this osteopathy (bone disease) there is premature or accelerated bone breakdown, which leads to a reduction in the organic and mineral bone substance and thus to brittle bones. Hormonal causes are often crucial, especially in postmenopausal women.
In addition, there is a reduced bone mass when an osteomalgia occurs. In contrast to osteoporosis, the breakdown of the bone substance concentrates here on the mineral portion. Calcium deficiency in connection with a vitamin D deficiency or an impaired phosphate metabolism is usually the triggering factor in this context.
These bone diseases can be systemic, which means that all bones can be affected.
In addition, other underlying diseases can cause local bone loss. Here local osteoclast overactivity causes spatially limited degradation processes. This is commonly referred to as circumscribed osteolysis. With this clinical picture, real holes appear in the bone, which can appear to be punched out.
Many diseases come into consideration as triggers for such processes. This includes, for example, bone tumors or bone cysts, chronic inflammatory diseases (chronic polyarthritis, osteomyelitis) or hormonal disorders.
If cancer is the cause, both benign and malignant bone tumors can be considered. But cancers of other organs or malignant hematological tumors, such as various leukemias (white blood cancer), can also lead to circumscribed osteolysis.
Another disease that may be associated with local bone loss is the isolated form of a multiple myeloma called plasmacytoma. This is a lymphoma disease in which a malignant tumor originates from the lymphocytes (bone marrow cancer). The typical image of the punched holes then arises at the places where the tumor cells grow in the bone. This is often in the area of the skull and in this context one speaks of a "shotgun skull".
Metabolic diseases and hormonal disorders are less often the cause. If, for example, hyperfunction of the parathyroid gland (hyperparathyroidism) triggers osteolytic changes, these can occur in the jaw and face area, among other things.
Bone degradation can also occur in the area of inserted endoprostheses or implants (periprosthetic osteolysis). A constant foreign body contact between the bone and the material used can lead to abrasion and thus loss of your own bone substance. This can cause the prosthesis or the dental implant to loosen. In addition, inflammatory processes and reactions of the immune system to infection can lead to bone breakdown processes - not only in the areas of the prostheses.
Such processes are also observed in the area of bone trauma and fractures, which is due to disturbances in the healing process. For example, harmful trauma can result from excessive weight lifting in the shoulder area (
So-called idiopathic osteolysis can very rarely occur. The causes of these forms are unknown. One of these rare diseases is phantom bone disease (Gorham-Stout syndrome), which leads to the complete dissolution of a single bone.
According to different classifications, further rare hereditary (inheritable) idiopathic osteolyses are described. This includes, for example, multicenter osteolysis with or without nephropathy (kidney disease). This syndrome usually occurs already in childhood and there is a progressive loss of bone substance with increasing age. The carpal and tarsal bones are mostly affected. As a result, bone deformities lead to physical movement restrictions. Sometimes mental deficits and abnormalities develop on the face.
Possible symptoms depend on the particular cause or underlying disease and its location. Complaints often only appear in the advanced stage of the disease and it is not uncommon for symptoms to appear that are uncharacteristic and that are not easily assigned.
If bone dissolution has already progressed, the affected bones are unstable and, as a result, fractures are more likely to occur. The process also releases more calcium, which can lead to an excess of calcium (hypercalcaemia). An example of this is osteolytic hypercalcemia in a plasmacytoma. The symptoms of an increased calcium level in the blood are different in nature. In addition to limescale deposits in various organs (e.g. the kidney), the following symptoms can occur:
- Nausea and vomiting,
- Muscle weakness,
- Irregular heartbeat,
- inflammation of the pancreas,
- frequent urination,
- mental impairments (lack of concentration, depression).
Different pain may also occur in the diseased bones and body regions. These are often described as stress pain, chronic pain or rheumatoid joint pain.
The diagnosis is based primarily on the causes and triggering diseases and includes the age and personal information of those affected about possible complaints.
Classical X-ray examinations usually provide information about existing osteolyses. Fracture-prone areas and existing bone fractures can be localized using the X-ray images. If bone cancer is the cause of the decomposition processes, certain radiological signs can indicate whether the tumor is benign or malignant.
Nuclear medicine examination methods can also help to detect signs of bone dissolution. However, the examination is not always highly sensitive to the different osteolytic processes. Corresponding possibilities are offered by the skeletal scintigraphy (also bone scintigraphy) or the bone marrow scintigraphy. A scintigraphy of the skeleton shows the local bone metabolism, which can be increased early in some diseases. In bone marrow scintigraphy, the hematopoietic bone marrow is imaged, whereby very small osteolyses can possibly also be recognized, which can arise, for example, as a result of tumor spreading.
The therapy concept depends on the respective underlying disease, insofar as this could be diagnosed, and varies accordingly.
In addition to other treatment approaches, drug therapy with bisphosphonates is often used. These drugs (e.g. pamidronate or zolendronate) are said to inhibit osteoclast activity by forming a kind of protective layer around the bones. This can delay the progressive bone loss and reduce the risk of fractures.
The active substances also interfere with calcium metabolism, so that hypercalcemia is counteracted with harmful calcium deposition processes in other organs. If the desired result occurs, pain is also alleviated indirectly. In principle, those affected can choose between intravenous infusions or tablets. Sometimes calcetonin (for example synthetic salmon calcitonin) is used instead of the corresponding bisphosponate.
Various measures from the field of naturopathy can also be used in addition. Here, too, the recommendations are primarily based on the clinical picture of the triggering disease. (tf, cs)
Author and source information
This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.
Dr. rer. nat. Corinna Schultheis
- Agarwal, Sanjeev: Osteolysis — basic science, incidence and diagnosis, Current Orthopedics, Volume 18, Issue 3, 2004, orthopedicsandtraumajournal.co.uk
- Ruchholtz, Steffen / Wirtz, Dieter Christian: Orthopedics and trauma surgery essentials: Intensive course for further training, Thieme, 3rd edition, 2019
- German Cancer Research Center: Bone Metastasis Basics (accessed: 03.07.2019), krebsinformationsdienst.de
- Amboss GmbH: Benign bone tumors (accessed: 03.07.2019), amboss.com
- Freyschmidt, Jürgen: Difficult diagnoses in skeletal radiology, Thieme, 2013
ICD codes for this disease: M89ICD codes are internationally valid encodings for medical diagnoses. You can find e.g. in doctor's letters or on disability certificates.