Page 271 - Handbook of Biomechatronics

Lower-Limb Prosthetics 265

6 STATE-OF-THE-ART RESEARCH THREADS AND
ENABLING TRENDS
It is interesting to identify current research threads, which are going to
enable amputees and shape up novel prostheses in the market.

6.1 Osseointegration

Professor Per-Ingvar Bra ˚nemark discovered in the 1950s that bone can inte-
grate and coexist “peacefully” with titanium components. He defined
osseointegration as “A direct structural and functional connection between
ordered living bone and the surface of the load-covering implant”
(Branemark et al., 1969). Osseointegration has been proposed as an alterna-
tive technique for prostheses since the 1980s, after the success of dental
implants (Childress, 1997, 1998). The major problem of this technique
has been the risk of infection at the skin of the implant area (Childress,
1997, 1998). There has been a lot of effort in the past years to optimize
implants design, the process, and the rehabilitation protocol in order to min-
imize the risk of infection. In 1999, a treatment protocol called
osseointegrated prostheses for the rehabilitation of amputees (OPRA) was
established (Li and Branemark, 2017). The first bilateral transfemoral fitted
with osseointegrated prostheses is shown in Fig. 18. Although there is more
than 20years of experience in transfemoral osseointegration procedures, the
orthopedic community still is skeptical of this technique (Frossard et al.,
2013; Nebergall et al., 2012; Vertriest et al., 2015, 2017).
The biggest benefit that osseointegration provides as a procedure and
methodology, other than that it eliminates the need of a socket and provides
wider range of motion, is that there is direct link between the bone, muscles,
tendons, receptors, and the prosthesis. This direct link and engagement pro-
vides osseoperception, the ability of the amputee to “feel” where his or her
prosthesis is without seeing it. The information comes integrative to the
amputee by using the remaining afferent (sensory) pathways which are
now integrated with the prosthesis and give us an extended physiological
proprioception (EPP) type of control, which even for lower-limb prostheses
is beneficial (e.g., amputee “feels” when foot touches the ground). This leads
to increased controllability of the prosthesis and improved balance for the
bilateral amputees. It is true that ossoeintegration might be the only feasible
option/hope for high-level bilateral transfemoral amputees to ambulate.