SLR - March 2012 - Steven Hoffman
Reference: Segal, A. D., et al. The effects of a controlled energy storage and return prototype prosthetic foot on transtibial amputee ambulation. Human Movement Science (2011), doi:10.1016/j.humov.2011.08.005
Scientific Literature Review
Reviewed by: Steven Hoffman, DPM
Residency Program: Southern Arizona VA Healthcare System
Podiatric Relevance:
Podiatrists do not fabricate nor fit prosthetic devices designed for transtibial amputees. However, this article is relevant to podiatric surgery due to the interests in gait restoration after amputation.
Methods:
Seven traumatic unilateral transtibial amputees where examined. Participants were all males between 18 and 80 years old, wore a prosthetic device for at least eight hours per day for a minimum of two years, could ambulate without upper-limb aides and had no history of injurious falls within the previous six months. They were considered moderately active community ambulators, were free from neurological deficits, and there was no history of underlying musculoskeletal disorders that may have impacted gait characteristics by self-report. Three prosthetic feet were fit and optimally aligned for each participant by the same experienced prosthetist in random order: (1) Controlled Energy Storage and Return prosthetic foot, (2) a conventional prosthetic foot, (3) each participant’s previously prescribed prosthetic foot in their own shoe.
Results:
Unilateral transtibial amputees wore the Controlled Energy Storage and Return prosthetic foot (CESR), a conventional foot (CONV), and their previously prescribed foot (PRES) in random order. Three-dimensional gait analysis and net oxygen consumption were collected as participants walked at constant speed. The CESR foot demonstrated increased energy storage during early stance (33 percent), increased prosthetic foot peak push-off power (58 percent and 41 percent) and work (61 percent and 44 percent). The CESR foot also demonstrated increased prosthetic limb center of mass (COM) push-off work (55 percent and 40 percent) and decreased intact limb COM collision work (59 percent and 46 percent) as compared to CONV and PRES.The biological contribution of the positive COM work for CESR was reduced (17 percent and 15 percent) as compared to CONV and PRES. However, the net metabolic cost for CESR did not change compared to CONV, and increased compared to PRES. This may partially reflect the greater weight, lack of individualized size and stiffness and relatively less familiarity for CESR and CONV
Conclusions:
The authors demonstrated the ability of transtibial amputees wearing the CESR foot to restore push off energy on their prosthetic limb and reduce collision on their contra-lateral intact limb during constant speed ambulation. However, there was not a corresponding reduction in metabolic rate. The authors state the rate of release of the energy and its associated need for greater muscle work to control the energy release, or possibly inadequate adaptation time may have interfered with the amputees’ ability to use this energy. It was proposed by the authors that future generations of this technology should focus on optimizing the foot characteristics to minimize compensatory strategies involving ineffective contractions which may ultimately lead to overall systemic improvements during daily ambulation.