Osteolysis

Classification according to ICD-10
M89.5	Osteolysis
ICD-10 online (WHO version 2019)

The osteolysis ( ancient Greek ὀστέον Osteon , German , bone ' and λύσις lysis , Resolution') generally indicates a bone loss . On the one hand, this can be used to describe bone loss at the cellular level, as it occurs constantly in bone metabolism in the context of physiological bone remodeling , and on the other hand, excessive bone loss in the context of pathological bone remodeling. Secondly, particularly referred to in the Radiology and Oncology a circumscribed osteolysis a local bone defect with complete loss of bone within the defect.

Osteolysis in bone remodeling

Osteoporosis (hand)

In general, the osteoclasts are the cells that can break down bones, which is why this form of osteolysis can also be referred to as an osteoclastic reaction. They are controlled by hormones of the bone metabolism and their activity in physiological bone remodeling is in equilibrium with the bone-building osteoblasts .

In the case of disorders of the physiological balance, two forms of osteopathy can be distinguished, in which there is a reduced bone density :

Osteoporosis and the precursor osteopenia with an equally strong reduction in organic substances and mineral content. These forms can occur systemically and affect all bones or occur only regionally.
Osteomalacia with reduced mineral content in the natural or less reduced content of organic constituents by disorder of phosphate metabolism or a lack of active vitamin D .

Localized osteolysis

The circumscribed osteolysis is also carried out exclusively by osteoclasts, which, however, are locally strongly overactivated without simultaneous osteoblast activity. This creates areas in the bone without bone substance, which can act like punched holes (typical picture in a plasmacytoma ).

Example: osteolysis in the thigh bone in a plasmacytoma

The causes of a specific osteolysis are varied and can sometimes be deduced from the localization of the osteolysis, the underlying disease and the age of the patient:

When implants are mechanically loosened , osteolysis can form as loosening seams or through foreign bodies (abrasion). This can occur on endoprostheses , but also on osteosynthesis and often requires the removal of the osteosynthesis or, if the prosthesis is loosened, a change of the endoprosthesis.
In peri-implantitis, osteolytic processes can lead to loosening or loss of a dental implant , which is triggered by a mixed anaerobic microflora in which gram-negative bacteria are in the foreground.
Another form of osteolysis is the breakdown of the alveolar processes of the jaw . The bone loss of the jawbone can occur through tooth loss , periodontitis or through the pressure applied by dentures. In the latter, the alveolar ridge degradation in the first year after tooth loss is around 0.5 mm in the upper jaw and 1.2 mm in the lower jaw. In the following years the reduction is 0.1 mm in the upper jaw and 0.4 mm in the lower jaw. The extent of degradation is divided into the resorption classes according to Cowood and Howell .

Benign and malignant bone tumors can also present themselves as osteolysis, some of which are only noticeable through a pathological fracture of the bone weakened by the osteolysis. The spectrum ranges from a simple bone cyst to an osteosarcoma . Osteolyses also occur through metastases of malignant tumors in other organs, or as a manifestation of hematological tumors, i.e. in leukemia or lymphoma diseases such as plasmacytoma. There are radiological signs such as a sclerosing margin around the osteolysis that suggest a benign cause. This is recorded in the Lodwick classification of radiological findings of osteolyses and bone tumors.

In the context of metabolic diseases, osteolysis can also rarely occur, an example are the "brown tumors" in an overactive parathyroid gland ( hyperparathyroidism ). In primary hyperparathyroidism, osteolytic changes in the mouth, jaw and face, in contrast to the rest of the skeletal system, are rarely observed, but can represent the first clinical indication of the endocrine disorder. Osteolysis can also be observed in the context of amyloidosis .

Also near the joint bone cysts represent osteolysis and occur in advanced arthrosis as "geodes" and inflammatory joint diseases such as rheumatoid arthritis on.

Infections such as suppuration of the bone marrow ( osteomyelitis ) also lead to osteolysis, sometimes even with very low virulent germs, such as Brodie's abscess . Very rare causes can also tuberculosis or fungal infection to be

Idiopathic osteolysis

Very rarely is the complete dissolution of a single bone observed. This condition, known as Gorham-Stout Syndrome , Idiopathic Massive Osteolysis, or Phantom Bone Disease, is idiopathic , so the cause is unknown.

Idiopathic osteolyses are also classified according to Spranger-Langer-Wiedemann from 1974

Multicenter carpotarsal osteolysis with or without nephropathy
the group of hereditary idiopathic osteolyses

In 1985, F. Hardegger presented an alternative classification of hereditary multicenter osteolyses:

Type 1 with dominant inheritance ( type-Lamy Maroteaux , type Tieffry-Shurtleff and Hajdu-Cheney syndrome )
Type 2 with recessive inheritance ( type Joseph , type Hozay , type François and type Torg )
Type 3 non-hereditary forms with nephropathy
Type 4 Gorham-Stout Syndrome
Type 5 MONA spectrum (Winchester syndrome)

Individual evidence

^ Fritz U. Niethard, Joachim Pfeil: Orthopädie. 2nd Edition. Hippokrates-Verlag, Stuttgart 1992, ISBN 3-7773-1015-8 .

↑ N. Schwenzer, M. Ehrenfeld: Tooth-mouth-jaw medicine. 5 volumes, volume 3: Dental surgery . Thieme Verlag, Stuttgart 2000, ISBN 3-13-116963-X , GoogleBooks

↑ W. Millesi, B. Niederle u. a .: Osteolyses in the jaw area as the first indication of primary hyperparathyroidism. In: European Surgery. 26, 1994, pp. 410-414, doi: 10.1007 / BF02620046 .

^ Adam Greenspan: Skeletal Radiology. 3. Edition. Urban & Fischer-Verlag, Munich 2003, ISBN 3-437-23060-3 .

↑ Bernfried Leiber (founder): The clinical syndromes. Syndromes, sequences and symptom complexes . Ed .: G. Burg, J. Kunze, D. Pongratz, PG Scheurlen, A. Schinzel, J. Spranger. 7., completely reworked. Edition. tape 2 : symptoms . Urban & Schwarzenberg, Munich et al. 1990, ISBN 3-541-01727-9 .

↑ JW Spranger, LO Langer, HR Wiedemann: Bone Dysplasias: An Atlas of Genetic Disorders of Skeletal Development Saunders, 1974, pp. 211-218.

↑ Multicenter carpotarsal osteolysis with or without nephropathy. In: Orphanet (Rare Disease Database).