Motorized Hip Orthoses to Improve the Gait Ability of Transfemoral Amputees
Abstract
This proposal addresses the Rehabilitation Focus area, in particular, improving Prosthetic and/or Orthotic Device Function and Secondary Physical Health Effects. We aim to find out whether using a lightweight motorized hip orthosis can help persons with transfemoral amputation walk more naturally and efficiently when using their prosthesis. Amputation of the leg, either at the transfemoral (above knee) or transtibial (below knee) level, is one of the most debilitating types of combat-related injury, and accounts for 41.8% and 34.5%, respectively, of amputations sustained in recent military conflicts. The best treatment for lower limb amputation is use of an artificial leg, or prosthesis; however, the leg prostheses that are currently available are not good replacements for a missing leg. Most prostheses are passive, which means they don t provide any power to help the user propel the body during walking. This makes walking around the home and community more difficult, especially for people with amputations at or above the knee, who use far more energy while walking than able-bodied people and do not walk in a natural way, which can cause injuries in other parts of the body. Some newer prostheses can provide power, thanks to inbuilt electrical motors and batteries. Unfortunately, powered prostheses are much heavier than passive devices. Walking with a heavy prosthesis is very hard, especially for above-knee amputees. A heavy prosthesis cancels out the potential benefits of providing power, so that these devices have limited clinical usefulness. After more than 10 years of research, and 5 years on the market, most people still do not use powered lower-limb prostheses. An alternative solution may be to use a passive prosthesis together with a lightweight motorized orthosis that provides help at the hip joints during walking. Such orthoses have been under development for quite some time now; Honda Motor Company recently launched the first market-available device. Motorized hip orthoses can be very lightweight -- much lighter than powered prostheses. The motor and gearbox of a motorized hip orthosis do not need to support the user s body weight while providing power, so they can be very small, and as these devices require low battery power, they need smaller batteries. In addition, the mass of a hip orthosis is less of a burden because it is located close to the center of the body rather than at the ankle. Finally, as the weight of the orthosis is not carried through the prosthetic socket, it does not affect balance or socket fit. A lightweight hip orthosis may be very effective in helping amputees walk using their existing lightweight passive prosthesis. By improving the ability to walk with a passive prosthesis, a powered hip orthosis may provide immediate health benefits to lower-limb amputees, enabling a more active and independent life. Being able to walk more normally can increase use of the prosthesis and can prevent the secondary physical problems that often affect prosthesis users -- such as back pain and osteoarthritis. Our previous research showed that able-bodied persons significantly decrease their muscle effort when they receive help from a motorized hip orthosis. In addition, our preliminary experiments in two individuals with transfemoral amputations showed that using a motorized hip orthosis reduced metabolic energy expenditure in walking by 11.8% and 32.5%, a result that no powered prosthesis has been able to achieve. Based on these results, we expect that providing amputee subjects with appropriate assistive power at the hip joint will help them walk more naturally and efficiently. We now need to more thoroughly test this idea. Our first goal is to optimize the function of a motorized hip orthosis for amputee subjects, who have different needs than able-bodied individuals. To accomplish this goal, using the same approach that we have successfully used for able-bodied subjects, we wi
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 31, 2017
- Source ID
- W81XWH1610701
Entities
People
- Tommaso Lenzi
Organizations
- Shirley Ryan AbilityLab
- United States Army