Amputations can occur at many different levels and on any limb. Most are familiar with lower limb amputation as new and exciting “robotic” technology in prosthetic legs seems to get people’s attention. What may come as a shock is that partial foot amputations are actually one of the most common; nearly 75% of all lower limb amputations being at various levels through the foot (2). Although it may seem beneficial to save the majority of the lower limb, amputation at this level can leave patients with a multitude of different complications following surgery. Compromised skin integrity, abnormalities while walking, poor balance and increased energy expenditure are just a few things patients experience following partial foot amputation.
Understanding foot function
In order to fully understand the complications that accompany partial foot amputation, we must understand how the foot functions. The foot is responsible for various functions while walking (this is also known as “gait”). Arguably the most important foot function is propulsion. During gait, our great toe, or hallux, becomes rigid and serves as the primary force propelling us forward (1). In many levels of partial foot amputation, the hallux is amputated. This leaves the amputee with no propulsive force, causing them to expend more energy and develop gait abnormalities.
Additionally, as more of the foot is amputated, the lever arm of the foot becomes shorter, creating a mechanical imbalance. This mechanical imbalance can lead to several complications. First, it compromises the integrity of the skin at the end of the residual foot. More force is experienced in this area, causing callousing and even wounds. It is estimated that up to 50% of partial foot amputees experience skin breakdown, ulceration, and wound failure (3).
This can also lead to leg-length discrepancies. As the foot is amputated and made shorter, the angle of the remaining bones within the foot change, leaving up to a 1 3/8” difference in leg length. Additionally, high-energy expenditure is still required as more of the foot is amputated. Up until recently, there has not been a truly successful intervention to restore the natural function of the foot and prevent these complications from occurring.
Partial foot prostheses innovation can help
Traditional orthotic intervention for partial foot amputees consists of soft toe filler inserts, shoe rocker modification, and plastic ankle orthoses. Even with these interventions, patients are likely to still experience gait abnormalities, expend more energy, and experience skin breakdown as propulsion is not fully restored. This is where the innovation behind our partial foot prosthesis differs from traditional devices.
The carbon-fiber frame, flexible inner boot, and custom toe filler insert is a lighter, more streamlined option compared to traditional intervention. The carbon-fiber frame absorbs and releases energy, recreating propulsion and restoring a more natural gait in comparison to plastic materials more commonly used. The elongated toe lever restores balance and stability to the patient, while also distributing more even pressure and reducing force on the residual foot. Lastly, the custom insert within the brace allows for ankle correction and leg-length adjustment. These features combine to reduce the patient’s energy expenditure, allowing them to get back to their desired activities.
A better quality of life for partial-foot amputees
As O&P professionals, it is our job to find and create the best devices for our patients, and we have seen firsthand the benefits of the partial foot prosthesis. Many of our patients with this level of amputation come into our clinic walking with an assistive device. Within a few days of wearing our partial foot prosthesis, they are walking without assistance. In addition to feeling more confident when walking, our patients report decreased skin breakdown, more stability, and increased desire to wear the device compared to previous interventions. Not only does this improve the quality of life for the patients, but it keeps them from spending more time in the doctor’s office.
Resources
- Bolgla, L. A., & Malone, T. R. (2004). Plantar fasciitis and the windlass mechanism: a biomechanical link to clinical practice. Journal of athletic training, 39(1), 77 –82.
- Dillon, M. P., Fatone, S., & Quigley, M. (2015). Describe the outcomes of dysvascular partial foot amputation and how these compare to transtibial amputation: a systematic review protocol for the development of shared decision-making resources. Systematic reviews, 4, 173. https://doi.org/10.1186/s13643-015-0161-9
- Groner, C. (2013, October). Debating the complexities of partial foot amputation. Lower Extremity Review Magazine. https://lermagazine.com/article/debating-the-complexities-of-partial-foot-amputation