Orthopedic Oncologists Recommended for Consult on Bone Sarcoma Treatment After Osteointegration

R. Lor Randall, MD, FACS

For patients with bone sarcomas who undergo limb preservation, reconstruction with osteointegration may be a next step. However, before going on chemotherapy and/or radiation therapy after osteointegration, R. Lor Randall, MD, FACS, cautions that medical oncologists should always connect with an orthopedic oncologist to determine whether such treatment is safe, as it can have an impact on bone growth into the prosthesis.

“Never hesitate to call your friendly, neighborhood orthopedic oncologist. We always love to have questions asked of us if there are any concerns,” said Randall. “The orthopedic oncology community would love to hear from any medical oncologist who has any concerns about a patient’s limb salvage procedure. These are very complicated surgeries that take many, many hours. Every orthopedic oncologist is hopefully very invested in not only the limb salvage, but the overall wellbeing of the patient, and we would love to hear from medical oncologists.”

In an interview with OncLive, Randall, professor and The David Linn Endowed Chair for Orthopaedic Surgery and professor and chair of the Department of Orthopaedic Surgery, University of California, Davis Health, discussed the cautions medical oncologists should take for their patients with bone sarcomas who undergo limb preservation with osteointegration, and the importance of keeping orthopedic oncologists in the loop.

OncLive: Could you discuss the process of osteointegration for patients who are undergoing limb preservation?

Randall: For bone sarcomas, we do a lot of limb preservation. We take out the tumor, there is a bone defect, and we have to reconstruct it. Ideally, what we try to do is reconstruct it with an implant of an artificial joint, which has the ability to osteointegrate. This means the bone grows into the interface—at the prothesis bone interface—to get a “biologic spot weld”—so that the device can last a long time and stay fixed to the bone.

The issue that arises, from the standpoint of a medical oncologist, is that some of the treatments, specifically chemotherapy and/or radiation, can interfere with that process and lead to complications. The orthopedic oncologist knows this, but the medical oncologist may not. The message to the medical oncologist is: if your patient has a limb salvage procedure with something that is osteointegrating, you need to talk to the orthopedic oncologist about [your patients undergoing] chemotherapy and/or radiation.

Now, the simplest way to explain that is when a patient is on chemotherapy, they cannot grow hair. When a patient, therefore, is on chemotherapy, they probably have a hard time growing bone to interface. Therefore, while the patient is on chemotherapy, the bone isn’t really integrating. Therefore, the patient needs to be on a prolonged period of using crutches or some sort of assisted device, so that the device doesn’t fail before integrating.

The advantage from a medical oncologist is if they have a patient who has recently undergone a limb salvage procedure, they might want to ask the patient: “Is this an osteointegrating device? If it is, check with the orthopedic oncologist about the risks of chemotherapy and osteointegration.”

Are all of these patients with sarcomas normally on chemotherapy and/or radiation?

Not all of them—patients with osteosarcoma and Ewing sarcoma are [on chemotherapy and radiation], but not patients with chondrosarcoma and some other subtypes.

Could you give some background on exactly how osteointegration works? Is this a normal procedure a patient with limb preservation would undergo?

We could blow the roof off of the whole subject of limb salvage, and we could have multiple talks about this. [Osteointegration] is a relatively new technology within the last decade or so; it is a way by which the bone will grow into the prothesis. Historically, we used stemmed implants; the bone is a tube and the stem goes up or down the bone, and it was filled with acrylic bone cement—like a grout, as one can imagine potting a plant. You are trying to pot a stem into a bone and you’re using grout to seal it.

The problem is, over time, when that patient survives their cancer, that grout starts to wear out, and the prosthesis loosens and comes apart. Now, they have a whole set of other problems from the limb salvage itself. Therefore, at 10 years, probably 30% or 40% of those [stemmed implants] were coming loose. New technology was brought to market to use this osteointegration, such that there would be biological ingrowth to the prosthesis for the life of the patient. As the patient is turning over bone, it’s healthy, and it’s constantly spot welding into the device over the length of their life, as opposed to the acrylic bone cement, which wears out similar to how a car part wears out.

Could you speak more to the steps that medical oncologists should take if chemotherapy is a treatment option for these patients?

There is no suggestion that someone should not get chemotherapy. What happens with the chemotherapy is it slows down cell turnover in a variety of fronts. Therefore, the ability of the bone to interface with the prosthesis will also be slowed. Therefore, a patient should probably be on crutches or something during that period of time to prevent that from having a problem.

Another important point is that [we are talking about] cytotoxic chemotherapy. This may not apply to biotargeted agents; we don’t have any data to support that biotargeted agents necessarily interfere with it. However, if they have an osteointegrated implant, it is still probably appropriate for the medical oncologist to reach out to the orthopedic oncologist and say “Hey, this patient is going to be on agent ‘X,’ do you have any concerns? Should I put this patient on crutches?”

What other pieces of advice can you offer to medical oncologists with these patients?

The number one question would be, “Are there any weight-bearing questions? Along with that, are there any activities they should be avoiding to not put the device in a position of risk?” If it’s a bone sarcoma of the upper femur or pelvis, then it’s involving the hip. There are certain restrictions the orthopedic surgeon likes to limit the range of motion on while things heal so you don’t dislocate the prosthesis.

For radiation oncologists, radiation therapy is something that should be avoided. Sometimes the decision is made by the medical therapist to refer the patient to a radiation therapist, and so they need to realize that radiation therapy may have a really adverse event on the interface. They can do things, such as shielding, and they need to keep that in mind. It’s not just the systemic treatments [that can impact the osteointegration]; it’s the radiation that interferes with the interface of the prosthesis.

What are the barriers to medical oncologists reaching out for this information and advice?

The barriers are that some patients are being treated in relative isolation, versus centers with a tumor board. We have a strong preference that patients with bone and soft tissue sarcomas should be treated at sarcoma centers. Almost unbearingly, those centers have tumor boards and are in the same room—or now, on the same Zoom—and we all have a conversation around that patient. Usually the conversation in those settings will evolve naturally. [For example], “Mrs. Jones” is 2 weeks out from her limb salvage [operation], and she has an osteointegrated implant. If we are going to resume chemotherapy, we need to keep her on crutches for a prolonged period of time. Or, [the case could be] that Mrs. Jones had a close margin and there is consideration for using adjuvant radiation. This is an area where we want to avoid radiation.

If there are places where our patients are treated at non-sarcoma centers—and the medical oncologists are not having routine tumor boards with orthopedic oncologists at regular intervals—they should make the point of reaching out.