What is substitute material cement

Curettages and filling - tumor orthopedics

Curettages and fillings are among the most common procedures, especially for benign bone tumors. If a bone defect occurs as a result of a benign bone tumor, it may be sufficient to merely curette it, i.e. to "scrape" the tumor out of the healthy bone with sharp instruments. A so-called "intralesional" approach. Aggressive benign tumors then have a high risk of recurrence with such a "simple" curettage. As a rule, the bone defect is therefore also milled out, ideally with a high-speed milling cutter, which is not unlike a "dentist's drill". You can actually think of it as treating a carious tooth, only on a larger scale. In addition, adjuvants such as alcohol, extreme cold (e.g. liquid nitrogen), heat (coagulation), phenol (carbolic acid) etc. can be applied to certain tumors, which, depending on the procedure, sterilize a thin layer of bone with adhering tumor cells. The advantage of curettage, which is sometimes also carried out in the case of bone metastases (supplemented e.g. by radiation therapy), is that it is gentle on the bone and the potential nearby joint itself, since only what is absolutely necessary is removed without a large safety distance.
Depending on the size of the defect, it must or should be filled with bone, bone substitute material or plastic (bone cement). There are clinics that do not fill up even large defects. These then heal "from the inside", but have a considerable risk of breakage until they heal, which can be very uncomfortable near a joint. Small defects (or those in unloaded areas) do not need to be filled. There are a variety of options for replenishment. The naturally best quality is your own bone, which cannot be obtained in any quantity (e.g. from the pelvis or the marrow spaces of long tubular bones). Such a bone removal is always an additional operation, small, but with possible problems, be it "just" a skin incision or pain. Accordingly, donor bones are often used, e.g. from femoral heads donated to osteoarthritis patients that have been sterilized. Donor bones, which have been completely freed from any human tissue and ultimately only corresponds to the pure mineral basic substance, is a classic substitute. Artificial bone exists in a variety of products and preparations and is also used very frequently. What they all have in common is the somewhat worse, slower, waxing and remodeling behavior at the defect point (and the price!), The advantage of avoiding additional intervention.
In many cases, the defect is filled with bone cement (polymethyl methacrylate), basically the same substance as plexiglass. The bone cement, which is made up of two components, a powder and a liquid, theoretically allows substances such as chemotherapeutic agents to be mixed in; it heats up to 70 ° -80 ° C during hardening (polymerisation) and therefore has an additional sterilizing effect on the bone interface. This fact makes its use particularly attractive for aggressive bone tumors. Of course, it is immediately fully resilient, but it remains forever in its original form without conversion or installation. This can be disadvantageous in joints in which an endoprosthesis, for example, is to be installed later. There have been and are discussions as to whether the use of bone cement directly under a joint surface ("subchondral") might lead to premature osteoarthritis in the long term due to the heat during hardening and its rigidity, but the current literature is rather optimistic here. Nevertheless, there are clinics which either place a thin layer of bone between the cement and the joint surface with the cement directly on the joint or remove the cement a few years after the tumor is considered "healed" and then fill the defect with bone or biological bone substitute material .
In addition to curettages and bone fillings, naturally stabilizing osteosynthesis or the implantation of strong cortical transplants (fibula) can be carried out.

Typical examples where curettages and fillings can be made: