Ongoing Projects

Dr. Tommaso Lenzi

Ergonomics and Safety

 W81XWH-22-1-1028 - T. Lenzi (PI)
Department of Defense, Congressionally Directed Medical Research Program (CDMRP-PRORP-CTRA)
09/01/2022-07/31/2026 -- $1,499,000

This project seeks to develop a novel motorized hip orthosis to improve whole-person performance in patients with amputation. Specifically, we aim to find out whether a lightweight powered hip orthosis can improve hip function of individuals with above-knee amputations and enable these individuals to walk more efficiently and with better balance.

Amputation of the leg is one of the most debilitating types of combat-related injury. Amputation of the leg above the knee accounts for 41.8% of amputations sustained in recent military conflicts. The best treatment for lower-limb amputation is the use of an artificial leg, or prosthesis. However, the leg prostheses that are currently available are poor replacements for a missing biological leg as they do not provide any power to help propel the body during walking, climbing stairs, or standing up, nor do they provide power to restore balance in the case of a slip. Additionally, during above-knee amputation surgery, the muscles of the hip and thigh are surgically rearranged, and the resulting residual limb is significantly impaired. This makes walking around the home and community and balancing on uneven terrain much more difficult and tiring. Moreover, the weakened hip muscles and the use of a prosthetic knee and ankle cause unnatural and asymmetric gait, resulting in long-term injuries to other parts of the body. Supplementing the flexion/extension and abduction/adduction capabilities of the residual hip with a lightweight powered orthosis may help restore hip strength and offset the additional demand placed on the intact limb. While preliminary research exists, the functional outcome of assisting individuals with above-knee amputation with a motorized orthosis is unknown.

To address this knowledge gap, we have developed novel lightweight motorized orthosis to assist with hip flexion and extension motions. Due to the uniquely designed structure, our custom device is smaller and more efficient than other powered hip orthoses and requires less power. This allows us to use smaller and lighter batteries without sacrificing assistive performance or device run-time. The smaller and lighter orthosis removes any encumbrance potentially felt by the user. Our innovations resulted in a lightweight powered hip orthosis that can produce greater assistance at higher speed than devices of similar or greater weight.

Our preliminary experiments have shown that our lightweight powered hip orthosis decreases the amount of effort required for people with above-knee amputations to walk, compared to walking without our device. As a result, our device empowers amputees to walk further for the same amount of required energy. Based on these results, we expect that providing amputee subjects with a lightweight powered orthosis will help them walk more naturally and confidently at home and in the community. This device may provide immediate health benefits to people with lower-limb amputations, enabling them to lead more active and independent lives and potentially prevent secondary health problems that often affect prosthesis users, such as back pain and osteoarthritis.