Compressive Osseointegrated Endoprostheses Provide Long-Term Benefit in Bone Sarcoma

Patients with primary bone sarcoma who had compressive osseointegrative endoprosthetic devices of the femur implanted derived long-term benefit without late revisions because of periprosthetic fracture, aseptic loosening, or implant breakage at a minimum follow-up of 10 years, said R. Lor Randall, MD, FACS, who added that this technology offers patients an alternative option to stemmed protheses that are associated with late failures from stress shielding.

Patients who undergo endoprosthetic reconstruction after oncologic resection of bone tumors require stable fixation between the device and the residual host bone. Several technologies, such as stemmed implants, can successfully perform this reconstruction; however, many patients experience long-term complications after achieving this fixation.

A single-center, retrospective study evaluated 110 patients with primary bone sarcoma of the proximal or distal femur. Of these patients, 25 were treated with a compressive osseointegration implant and 85 were treated with a conventional stemmed implant or amputation.

The results of the study, which were published in Clinical Orthopaedics and Related Research, revealed that the risk of reoperation for aseptic loosening, periprosthetic fracture, or mechanical breakage of the implement was 12% at 10 years (95% CI, 0%-26%). Moreover, these complications occurred within the first 29 months following surgery.

“Although there may be some issues with early incorporation of compressive osseointegration at the interface, we now have a converse situation to the stemmed implants, which tend to fail later in life,” Randall said.

“We’re hoping that with further follow-up at 15 and 20 years, these patients [who received compressive osseointegration implants] will be doing just fine with their endoprostheses. The real beauty of this is that we have some robust long-term data to show that these are durable reconstructive options for patients afflicted with bone cancers,” he added.

In an interview with OncLive, Randall, The David Linn Endowed Chair for Orthopaedic Surgery, a professor, and chair of the Department of Orthopaedic Surgery at the University of California Davis Health, discussed the 10-year results of the retrospective analysis, potential strategies to mitigate early failures in recipients, and the need for communication between medical oncologists and orthopedic surgeons to ensure patients on chemotherapy receive optimal care.

OncLive: How have limb salvage technologies evolved?

Randall: As a trainee back in the 1990s, my mentor James Johnston, MD, [of Kaiser Permanente Medical Center] developed [Compress] in partnership with his resident at the time Daniel L. Martin, MD, [of Syntorr, Inc.] to address an issue for patients with bone cancers who needed aggressive, large resection of bones [that needed] to be fixed with an endoprosthesis. By convention, endoprostheses had been historically done with a stemmed prosthesis, wherein the stem was fixed into the bone canal with polymethylmethacrylate or press-fit technology to try to get endosteal apposition and bone ingrowth into the stem.

Both the cemented stem and press-fit implants showed some good results early on. However, the problem is that over time, through a process called stress shielding, many of these endoprostheses become loose at the stem interface. As such, they can go on to fail and cause pain, fracture, and a variety of other things that are a source of morbidity for these patients.

Early on, in the 1970s and 1980s, we were just coming online with neoadjuvant and adjuvant chemotherapy. Many of these patients were unfortunately succumbing to their disease and dying, so the idea of limb salvage was just that: a salvage limb on which to walk but in fear that the patient would ultimately succumb to their disease. With the advent of chemotherapy, as a broad statement, many of these patients are outliving their disease and surviving. Therefore, [with historic implants], patients are left with a limb salvage that becomes a new orthopedic disease that they must deal with for the rest of their lives.

Because many of these stem processes were going on to fail, Dr Johnston and Dr Martin came up with this idea of compressive osseointegration, which is a novel technique by which we harness a force called Wolff’s law. The bone responds, adapts, and grows in response to the physical force of this compressive osseointegration.

What did the results of the 10-year follow-up analysis of compressive osseointegration implants in patients with primary bone sarcoma reveal?

[We recently saw] the minimum 10-year follow-up for patients who underwent limb salvage with the Compress^® device, which is not so novel now. [Compress] has been around [for some time], so many orthopedic oncologists and revision-joint surgeons are aware of the technology. However, this paper is one we are particularly proud of because it [demonstrated] the 10-year minimum follow-up data with this device.

We published our minimum 2-year data and saw some early failures, like many investigators [using Compress]. We then published our minimum 5-year follow-up data and saw that we had those same early failures as [in the first publication] but no additional failures. Now, at a minimum of 10 years, we are pleased to see that only those early complications have arisen and none of these patients in the late setting have had any problems.

Are there strategies that patients or physicians could implement to prevent early failures of compressive osseointegration implants?

This technology, relatively speaking, requires osseointegration, which happens over time. As is seen in the paper, there is a bony hypertrophy that happens at the collar where the prosthesis attaches to the bone. Until the bone hypertrophies, it is going to be subjected to a lot of torsional force and could come loose early. That is why investigators have seen that [the osseointegration] is vulnerable early on.

We strongly recommend that in those first 6 weeks, if not 3 months, patients are protected in their weight bearing. The assistive device that they use for ambulation should share some of the load that the prosthesis would otherwise experience. That would hopefully preclude these early failures.

How is this technology being utilized among orthopedic surgeons? What points should be underscored for medical oncologists treating patients who have received compressive osseointegration implants?

Compress is something that is available off-the-shelf, so to speak, for orthopedic oncologists doing any sort of limb salvage in the United States. It is also approved in a few other countries around the world. Any orthopedic oncologist who would be interested in this can certainly do it.

Medical oncologists should know that during chemotherapy, bony ingrowth can be delayed [with Compress]. I joke with families that, “If one can’t grow hair, they can’t grow bone.” Many of these patients are on cytotoxic chemotherapy that causes alopecia. Until we start seeing hair growth, we won’t see bone growth.

Therefore, for medical oncologists, it is important to realize as they give chemotherapy that they are not in charge of limb salvage, but they are part of the stewardship team. They need to reemphasize to their patients that while [the patients] are on cytotoxic chemotherapy that kills any microscopic residual disease after limb salvage surgery, the patient needs to protect that limb and talk to their orthopedic surgeon.

What is next for this technology?

There are some exciting emerging applications [of Compress]. The device, for the most part, is pretty much as it is now. Again, with these 10-year data, we are happy with [Compress].

However, now we are starting to use it in new capacities. A trial will be coming forward that I can’t speak too much about now for patients who have had an amputation for whatever reason, including cancer or trauma. [In the trial], this osseointegrated technology can be used transdermally to hook up a prosthesis of which otherwise would be a suction prothesis. This will mechanically link to this device transdermally across the skin so that the exo-prosthesis would attach through the skin to the bone, which enables the patient to get proprioceptive feedback. Their femur, for example, will be experiencing the load rather than the soft tissue. That’s going to be coming forward.

This type of technology has been used in custom ways. I’ve done a handful of cases where we have done [osseointegration] as a custom [approach].

Other types of devices still use that stemmed technology. The concern I have in using the stemmed technology in these amputees is that if there is a long-term stress-shielding phenomenon that we see in a sterile environment for an endoprosthesis for limb salvage in the conventional way, then surely there is likely to be some of that stress shielding for these stemmed implants. We worry that if that comes loose, the patient has less residual bone with which to work with for a revision.

What should be emphasized about this technology amid these encouraging long-term data?

It’s important to reemphasize the point of multidisciplinary or transdisciplinary care. If medical oncologists have any concerns about [this type of limb salvage technology], they should talk to their orthopedic surgeon. [Medical oncologists] need to be aware that the chemotherapy can affect the osseointegration of this prosthesis.

Dr Randall does some consulting for Zimmer Biomet.

Reference

1. Groundland J, Brown JM, Monument M, et al. What are the long-term surgical outcomes of compressive endoprosthetic osseointegration of the femur with a minimum 10-year follow-up period. Clin Orthop Relat Res. Published online October 1, 2021. Accessed November 15, 2021. doi:10.1097/CORR.0000000000001979