Doctor Rickard Branemark MD, MSC, PHD and his team at Sahlgrenska University Hospital in Sweden have perfomed an operation on a transhumeral amputee that is nothing short of groundbreaking. According to the publication O and P Edge, they have implanted electrodes into the patient’s muscle and nerves that will allow him to control an osseointegrated prosthetic arm. By implanting the electrodes, the arm will receive stronger signals and therefore make a larger amount of movements possible. This technology can also cut down on the mental fatigue that occurs when an amputee begins to use and train muscles to signal the prosthesis. Doctor Branemark sees other potential advantages to using these electrodes, “The next step will be to test electrical stimulation of nerves to see if the patient can sense environmental stimuli.”
There are, of course, several issues that a surgery like this can bring up. For example, the surgery was performed, but it still remains to be seen how the patient is able to tolerate the electrodes and the arm, and to what functional level he will be able to return to. There is also the risk of infection with osseointegration. According to a study by Branemark et al. Osseointegrated Titanium Implants for Limb Prostheses Attachments: Infectious Complications, osseointegrated limbs have up to an 18% infection rate. It is for this reason that the FDA here in the United States is reluctant to approve this technology.
The group 1 implant systems had two major components: the endomodule and the skin protruding bridging connector, both made with medical grade cobalt chrome alloy. In design A (), the outer surface of the endomodule consisted of tripod-like microstructures, the Spongiosa-Metal 2 (Orthodynamics GmbH; Lübeck, Germany), intended to facilitate the osseointegration of the bone with the device. In the hope that skin would attach to the device, the bracket and the distal surface of the shaft of the prosthesis (the portion adjacent to the soft tissue interface) () were also coated with the same rough, textured surface as the tripod-structured outer layer of the endomodule.
In the final device design (design C, ), the bracket was eliminated, the bridging connector was shortened to adjust to the 2 cm-deep soft tissue channel, and the connector as well as the bone-capping portion of the osseointegrated implant was coated with a nonabrasive titanium niobium oxynitride ([Ti,Nb]ON) ceramic (Orthodynamics GmbH).
Final implant iteration (design C). Implant surface that comes in contact with inner lining is coated with inert, abrasion-free surface (titanium niobium oxynitride). (a) Assembled Integral-Leg-Prosthesis implant (design C). (b) Modular components of iteration: (1) femoral stem, (2) temporary cover screw, (3) dual cone adapter, (4) safety screw, (5) sleeve, (6) rotating disc and temporary screw (until prosthetist has made final adjustments), (7) final propeller screw, and (8) provisional screw.
Over 150 patients in Sweden, Germany, the Netherlands, and Australia have been operated on with DSA.– Analysis of an in-depth interview with patients living with osseointegrated prostheses– showed that participants described living with an osseointegrated prosthesis as a revolutionary change. The change went beyond the objectively confirmed functional improvements,, but also impacted the broad concept of quality of life.–
We acknowledge several limitations. First is the relatively short followup, although some patients had been living with the implant for more than 10 years. Most patients were young or middle-aged and probably will require use of their implants or other prostheses for numerous decades. We cannot predict the long-term durability of these implants. Second, we included some patients initially treated during a learning phase. The enrolled patients represent all phases of method development. We presume with experience the infection rates will diminish. Third, we did not review all patients. Rather, we studied a subgroup of 39 patients recruited during a 6-month period. As all patients attending (regular and emergency visits) the clinic during the inclusion period agreed to participate, we presume this cohort represents the entire population. A retrospective analysis of implant infection and risk factors in 100 patients treated with femoral osseointegrated implants and a prospective analysis of patients treated with the refined protocol are in progress.
Transcutaneous osseointegrated titanium implants for prosthetic systems in patients with amputations provide improved performance and less socket-caused complications in selected patients [, ]. Our aim was to describe the frequency, clinical presentation, and bacterial occurrence in local and implant-related infections.
Skin-penetrating implants were long regarded as unattainable owing to the high rates of failure caused by infection. The transcutaneous osseointegrated titanium implant challenges this claim. In our cohort, seven of 39 (18%) patients either had an implant infection or one developed within 3 years. The implant-infection/implant-year ratio (7/135) is slightly less (5%) than comparable results from Queen Mary’s Hospital in London where four of 16 patients treated with the same method had an implant-related infection develop during a cumulative 67-year period (6%) (unpublished data, Sooriakumaran S, Robinson KP, Ward DA, D′Arcy R, Chittoor SN, Written communication from 12th ISPO Congress in Vancouver, Canada, July 29, 2007). In our cohort, hematogenous and ascending bacterial spread must be suspected. Poor primary osseointegration may have facilitated an ascending infection as seen in two patients. Only one of seven patients was diagnosed and treated for an implant-related infection earlier than 31 months (mean, 34 months) after the surgical procedure. With arthroplasty, late infection (> 24 months) is considered more indicative of hematogenous seeding compared with early (]. In our four cases with more virulent bacteria, late onset of symptoms clearly indicates that intraoperative contamination was not the cause of infection. However, we cannot know whether some of the infections were either of hematogenous or new origin, rather than as a result of residual surgical contamination.
The clinical presentation varied. Two patients had chronic skin fistulas to the implant with occasional secretion but without pain, fever, or implant loosening. Fistulas were present more than 5 years before inclusion and were not treated with antibiotics during the observation time. They were registered as implant infections at inclusion and at followup. Staphylococcus aureus and coagulase-negative staphylococci were suspected etiologic agents. Two patients had implant infections with poor primary osseointegration. One had an infected femoral implant extracted. Preoperative cultures showed coagulase-negative staphylococci, alfa streptococci, and Peptostreptococcus sp. The other patient had a humeral implant infection caused by Escherichia coli. It was verified by biopsies of the culture specimens and treated with ciprofloxacin for 6 months. One year later, there were no signs of relapse. Distal infection involving bone and soft tissue was seen in two patients with good primary osseointegration. The etiology was mixed with Staphylococcus aureus/coagulase-negative staphylococci and Staphylococcus aureus/Enterococcus faecalis being suspected. Both patients underwent surgical revision and prolonged antibiotic treatment. Acute osteomyelitis occurred in one patient who had no fever but had acute pain develop in an osseointegrated femur. Radiography revealed signs of osteomyelitis at the midfixture level. Intraoperative cultures yielded Staphylococcus aureus and coagulase-negative staphylococci (Table ). In two of seven patients with implant infections at followup, prosthetic use was not affected at any time, three patients were affected only briefly during the time around surgical intervention, and for the patient with acute osteomyelitis, the treatment outcome is still pending.
The first contemporary system for DSA, called Osseointegrated Prostheses for the Rehabilitation of Amputees (OPRA), was introduced by Dr. Branemark himself in the 1990s following his experience in using titanium in dental implants.–