CORR Insights®: What Functional Outcomes Can Be Expected With Osseointegrated Prostheses in Transfemoral Amputations?

Where Are We Now? Approximately 2 million Americans live with limb loss, a figure that has been estimated to increase to 3.6 million by 2050 [17]. Prosthesis-related problems are common in these patients, and these problems include difficulty donning and doffing, increased oxygen requirements, gait disturbances, and activity limitations. Seventy-five percent of lower extremity amputees experience skin issues [5], and 50% of lower extremity amputees have pain with and are dissatisfied with their prosthesis [2, 4]. Moreover, 31% of armed forces members with lower extremity amputations reject their prosthesis [6]. Most of these prosthetic difficulties can be attributed directly to the soft tissue–prosthetic interface. The concept and application of the bone-anchored/osseointegrated prosthetic interface in patients with limb amputation have emerged as an answer to this glaring problem and have garnered much attention in recent years. The concept replaces the standard socket prosthetic designs, which rely solely on the soft tissue envelope for stability, with a prosthetic attachment that is anchored to the bone through intramedullary fixation at the end of the residual limb. From this bone anchor, a metal extension or post then connects the anchor to the outside world, creating a stoma or aperture interface at the skin exit site. This post then connects to the prosthesis such that the prosthesis is then one with the bone. Despite its seemingly novel nature, osseointegration has been used in these applications for over 30 years, with the first procedure having been performed by its pioneer, Richard Brånemark, in 1990. Early results have been promising, and consequently, the number of cases has increased exponentially in recent years. Qualitative improvements include a reduction in skin problems, ease of application and removal, improved leverage and more efficiency, improved osseous proprioceptive tactile feedback, improved body image, and ease and comfort of sitting. Early studies show quantitative increases in patient satisfaction, Short Form–36, Questionnaire for Persons with a Transfemoral Amputation (Q-TFA) global, and health-related quality of life scores; prosthetic use; hip abductor strength; K-level, walking distance, and 6-minute walk test results; along with decreased oxygen and energy consumption, timed up and go test results, and wheelchair boundedness [1, 3, 6-11, 14, 16]. Qualitative disadvantages of the technique include the potentially long period from initiation to prosthetic wear, need for long distance travel for care and subsequent follow-up, lack of prosthetist familiarity, expense, insurance approval issues, and aperture (stoma) problems. Quantitative complications revealed in the research include superficial infection (0% to 68% [most ∼30% to 50%]), deep infections that result in implant removal (0% to 18% [most ∼3%]), periprosthetic fracture (0% to 10% [most ∼4% to 6%]), fixture loosening or failure of ingrowth (1% to 20% [most ∼3% to 6%]), aperture or stoma problems requiring revision (3% to 38% [most ∼20% to 30%]), connecting post or abutment mechanical failure in 8% to 46% of patients (most ∼20%), and a fixture or stem mechanical failure of 3% [1, 3, 6-11, 14, 16]. In this issue of Clinical Orthopaedics and Related Research®, Potter et al. [12] address this timely and important problem and offer a new solution with a study of their prospective cohort of 37 military service members who underwent prior transfemoral amputations (14 of whom had bilateral amputations) and had severe prosthetic wear problems. These patients underwent staged implantation of an osseointegrated device. The authors found clinically important improvements in all domains measured by the Q-TFA (prosthetic use, prosthetic mobility, quality of life, and problems in daily life) as well as in two of the three Patient-Reported Outcomes Measurement Information System (PROMIS) domains (pain interference and physical function). Thirty-five percent (18 of 51) of limbs developed infection (29% [15 of 51] superficial and 14% [7 of 51] deep), with 14% (7 of 51) developing recurrent infection, but these and other soft tissue problems generally responded well to treatment. Likewise, although mechanical problems related to the device were relatively common, and some were treated with further surgery, in aggregate, the problems were fewer, less severe, and more manageable than one might imagine. And, importantly, no patient underwent implant removal. Helpfully, the authors also were able to calculate a minimum clinically important difference (MCID) for the Q-TFA; this will certainly be of use as a standard for future researchers on this topic. This is exciting work, and it points to the promise of this treatment approach. The risk of infection (superficial and deep) seemed on the low end compared with the findings of previous studies [1, 3, 6-11, 14, 16], which I attribute to the expertise of the group and a relatively healthy, motivated patient population. At the same time, this study reminds us of the serious risks associated with these devices, and the fact that unplanned surgery should be part of the plan. After reading Potter et al. [12], surgeons will be in a better position to educate and inform patients about the risks and benefits of this exciting technology to help ensure that patients who would greatly benefit from this technology will have access to it. The results of this study will also help us target areas for future research and improvement, especially in the realm of infection; its establishment of an MCID for the Q-TFA will certainly aid in this future study as well. Where Do We Need To Go? The study by Potter et al. [12] affirms the improvements in function, quality of life, and prosthetic use that osseointegration offers in this context. With continued study and publication, it is not a stretch to predict that this procedure will soon become part of routine care for all active patients with long-bone amputations. The reliability of implant fixation and prosthetic attachment seems to be well established; however, as Potter et al. [12] demonstrate, certain procedure-related complications remain. Infection is the obvious concern, and further research regarding patient risk factors, surgical soft tissue technique, and implant modifications may decrease this risk. Issues with aperture (stoma) and residual limb soft tissue remain a problem, and modifications and improvements in surgical soft tissue technique may be an answer. Securing a sealed aperture would likely go a long way to decreasing infection risk as well. Abutment and interface screw failures are a relatively minor concern, as they can usually be fixed without intervention into the body; however, they are inconvenient and can be even more dangerous if they occur during activities like certain competitive sports. The frequency of periprosthetic fracture was very low in this study (2%), but prior research has demonstrated that it may occur in as many as 10% of limbs; a fracture around a transfemoral osseointegrated implant can be problematic, especially fractures at the femoral neck. The osteopenic bone that inevitably occurs in longstanding above-knee amputations is the clear risk factor in these patients. It would be beneficial to study ways in which we could mitigate this inherent risk. Although the clear functional benefits of osseointegration in this setting are evident, modification of the potential complications will be the key to driving this technology forward. How Do We Get There? When it comes to finding ways to reduce infection in osseointegrated devices, we might look at antimicrobial surfaces, such as silver coating, which have reduced infection risk in patients undergoing megaprosthetic limb salvage [13]. It is quite possible that the same application could decrease the risk of infection in this setting. Randomized controlled trials, or even case series, may help elucidate this potential difference. Larger paired-samples prospective case series exploring more outcome measures, such as gait analysis, using each patient’s preoperative status as his or her own control would also help us meet our goal. The body already allows for similar stomal-type interfaces, so further investigation into how epithelium and mucosa incorporate into these exogenous surfaces could yield great insight in terms of improving osseointegrated amputation devices. Basic science research regarding hair, nail, and teeth interfaces in humans, and potentially horns in animals, may offer insight that could translate well here. Continued study of which patients are at higher risk for fracture, where such fractures could occur, and how we can best prevent them (for instance, implant modifications, rehabilitation protocols) would be a big step in preventing this potentially devastating complication. As more of these procedures are performed, modifications in surgical technique, specifically regarding handling of the soft tissue aperture where the extension (post) extrudes, could result in decreased stomal complication rates; in this setting, even limited case series or case reports could yield valuable knowledge. Further evolution of abutment and connection post designs may decrease the incidence of mechanical failure even in highly active patients such as those in this cohort. Read This Next This article highlights the research since the inception of bone-anchored/osseointegrated prosthetic interfaces and supports their widespread application while also demonstrating their downsides [9]. The Terry Fox Foundation [15] is worth your attention. Terry Fox was tenacious young man undeterred by the hip disarticulation he underwent to treat his osteosarcoma. With a 1970’s hip disarticulation prosthesis, he made the arduous journey across Canada by foot, raising desperately needed awareness of the disease that had an over 95% mortality rate at the time. Although he died of lung metastases before the end of his journey, because of his efforts, pharmaceutical manufacturers dedicated more attention to osteosarcoma and subsequently, long-term survival increased from 5% to ∼70%.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.