No perfect transfemoral prosthesis exists. The ideal of having a prosthesis that closely duplicates the lost limb has been the goal of all prosthetic and surgical developments since before the American Civil War. The prosthesis-residual limb interface has always been problematic for the transfemoral amputee. Traditional sockets often fail in load transfer and skeletal control because of the large soft-tissue envelope surrounding the femur. To gain control and stability, sockets often extend up onto the ischial and pelvic area, which can be very uncomfortable.
Research on direct skeletal attachment of prosthetic limbs dates back to the 1940s. Patients who have had early-prototype osseointegrated implants have been very enthusiastic, self-reporting improvements in proprioception, walking ability, comfort, and quality of life.
This article describes the complications in a series of 86 patients who underwent implantation of a custom-made intramedullary device that allows for osseointegration over time within the femoral canal but protrudes through the skin to allow prosthetic attachment without a socket. Patients were followed for a median of 34 months (range, 24 to 71 months) and reported a high complication rate, with only 31 patients (36%) having an uneventful course over the short-term follow-up period of the study. The reminder of the patients (55 [64%]) had low-grade infection, lack of integration, or other complications (periprosthetic fracture, prosthetic breakage, breakage of the pin used as a fail-safe mechanism, stoma problems, and implant exchange because of inadequate osseointegration).
Most infections (41 in 23 patients) were classified as minor by the authors; they involved soft-tissue inflammation and cellulitis from the stoma site of the prosthesis as it exited the limb and were treated with oral antibiotics. Another 2 patients required intravenous antibiotics, and 5 patients (6%) required operative treatment for the infections. The authors found that infection was associated with a body mass index of >25 kg/m2 and with smoking.
This intramedullary implant protrudes through the skin to allow for direct connection to the prosthesis, but at this time there is no biological barrier to prevent the eventual bacterial colonization at the prosthesis-skin interface (stoma) and bacteria tracking up the metal implant to the femur1. Without a biological barrier, deep infection, osteomyelitis, and prosthesis removal are likely over time. The treatment of the deep infection might well require more shortening of the residual limb, making prosthetic fit ultimately more difficult than it was before the attempted osseointegration surgery.
The potential benefits of direct skeletal attachment are indeed great, including better gait, proprioception, comfort, and quality of life. We absolutely support continued research and development efforts, especially for the development of a barrier to bacterial colonization as the implant enters the body. Whether this can be done with a bactericidal coating, a mechanical barrier, or some other new innovation remains to be seen. We also support research to refine the indications, exclusion criteria, and education regarding the long-term risks for amputees seeking this treatment. Finally, the costs of the surgery, implant, external prosthesis, and treatment of complications are not precisely known and are likely greater than those for conventional prosthetic management. As we approach the era of value-based medicine, defining who benefits most from this procedure and specialized prosthesis will help both patients and policy makers to make decisions.
↵* The authors indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest forms, which are provided with the online version of the article, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work.
- Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated