Advances in prosthetic design and embodiment research could help address ongoing challenges for patients with sarcoma who require amputation, according to R. Lor Randall, MD, FACS.
Although limb-salvage procedures are common in the management of sarcoma, amputations remain necessary in certain cases, and some patients—such as those with ankle sarcomas—may achieve better function with below-knee amputation. However, above-knee amputations are more difficult, with high energy demands leading to frequent prosthesis abandonment.
In an interview with OncLive®, Randall spotlighted key findings from a narrative review exploring prosthesis embodiment after lower-extremity limb loss.1 Randall emphasized the need for patient-centered design and more rigorous research to address unmet needs for patients undergoing amputation.
Randall serves as the David Linn Endowed Chair for Orthopedic Surgery and chair of the Department of Orthopedic Surgery at the University of California, Davis in Sacramento.
OncLive: What are the primary challenges patients with musculoskeletal tumors face with prosthetic use following amputation?
Randall: In sarcoma and musculoskeletal oncology, unfortunately, even in the current era with limb salvage, there are cases where we have to do limb ablation or amputation. In many situations, [this is actually the preferable approach]. For example, with sarcomas around the ankle, we do have technologies to perform limb salvage in those situations, but sometimes—details matter here—we proceed with a below-knee amputation because the functional results with a suction prosthesis are predictable enough that patients often have better outcomes than if they [uunderwent] limb salvage.
It gets trickier [with] above-the-knee amputations because of the energy expenditure with suction devices is really a challenge for patients. [Historically], there is a large degree of prosthetic abandonment in patients with sarcomas who have to, unfortunately, undergo amputation.
What are the current rates of prosthetic use among patients who undergo amputation, particularly above-knee amputations, and what interventions are currently being done to help mitigate prosthesis abandonment in this population?
Approximately 150,000 people undergo an amputation annually in the United States, and approximately 50% do not wear their prosthesis regularly. A significant portion of those [cases] are patients with above-knee amputations. Of those who abandon prosthetic use, approximately 75% rely on wheelchairs because locomotion with an above-knee prosthesis requires such high energy expenditure. [Wheelchair use] leads to further deconditioning, psychological burdens, and additional complications.
A major driver of prosthetic abandonment is what we call a lack of embodiment, [where] the prosthesis never feels like part of the body [to the patient]. Embodiment refers to the integration of a prosthesis into one’s overall body perception. Three critical dimensions of embodiment are ownership, agency, and co-location. High embodiment correlates with greater satisfaction and sustained prosthesis use.
Interventions that enhance embodiment include aesthetics, haptic and sensory feedback, and advanced interfaces. Some patients prefer anthropomorphic designs for social confidence, and others may prefer a high-tech look. Personalization is key. Haptic feedback through vibration, skin stretch, and cutaneous signals enables proprioception, improving balance and reducing falls.
One area of research we are heavily involved in is osseointegration, [defined as] the direct skeletal attachment of the prosthesis. This approach provides stability and osseoperception, enhancing natural control. Some patients even sleep with their prosthesis because it feels like an extension of themselves. Additional strategies include agonist/antagonist myoneural interfaces, a surgical approach that reestablishes muscle dynamics and proprioception of motor control. Then there are europrosthetic interfaces that connect electrodes to nerves, restoring tactile sensation and reducing phantom limb pain.
What are the key barriers to sustained prosthetic use for patients with sarcomas who undergo amputation?
There are standard embodiment metrics in the clinical arena; most evidence is small scale and short term, and there are [limited] longitudinal studies that have examined all of these variables. Prosthetic design has to be patient-centered and [must] consider individual preferences.
There are also real risks [associated with some of these techniques], especially with osseointegration. While patients [benefit] from that [enhanced] proprioception and perception through the prosthesis, [osseointegration involves] something [that penetrates] through the skin, and there is [an inherent] risk of wound problems and infection.
What future research directions or next steps do you see as most critical for advancing the understanding of prosthetic embodiment and improving outcomes for patients with sarcoma undergoing amputation?
Prosthetic embodiment is a real factor in predicting prosthetic acceptance and sustained use. Considerations of aesthetics, sensory feedback, surgical techniques, and skeletal integration are transforming this space, and we really need to [continue moving this research forward]. Everything I’ve talked about here is [largely] a review. If you ask about head-to-head studies and trials, there are very few.
There is a [phase 3] trial [NCT06134167] going on right now with a compressive osseointegration device, and in full disclosure, I am one of the investigators on that study at UC Davis.2 [Additionally], there is the already approved OPRA device, which has [demonstrated] a good track record for osseointegration. However, other aspects beyond osseointegration really haven’t been studied stringently; as I’ve mentioned, they are just small case series.
It’s [important] to raise awareness around these embodiment issues for patients who undergo amputation. Invariably, whether you’re a surgeon, medical oncologist, radiation therapist, or any allied oncologic provider, you will interface with these patients, and these are some of the struggles they will face.
References
- Nguyen TT, Wang B, Alas H, et al. Prosthesis embodiment in lower extremity limb loss: a narrative review. Appl Sci. 2025;15(9):4952-4952. doi:10.3390/app15094952
- A study to evaluate the safety and effectiveness transdermal compress device in participants with transfemoral amputations. ClinicalTrials.gov. Updated July 28, 2025. Accessed August 25, 2025. https://clinicaltrials.gov/study/NCT06134167