Development of a Next-Generation Dynamically Adaptive Ankle Brace

Anthony Petrella

apetrell@mines.edu

Significance and Aims of Proposed Project

Ankle sprains are one of the most common distal extremity injuries occurring among both civilian and military populations in the United States. The incidence of ankle sprains is approximately 23,000 – 25,000 per day in the civilian population alone, with an estimated direct medical cost in the range of $2-6 Billion^1-6. Approximately 80% of all sprain cases are inversion sprains⁴. Ankle sprains among military Service members occur at a rate more than five times greater than that seen in civilian populations⁷, with significant negative impacts on operational readiness of the fighting force. Ankle injuries comprise the greatest proportion of musculoskeletal injuries among active-duty Service members and create a considerable burden on the military healthcare system⁸. Indirect costs associated with lost workdays, decreased quality of life, and long-term health conditions (e.g., chronic ankle instability, osteoarthritis) are difficulty to quantify but acknowledged to be substantial^9,10. Currently available orthoses capable of protecting against lateral ankle sprain include sleeve, lace-up, and stirrup braces⁸. All these contemporary technologies provide varying levels of ankle protection, which are offset by undesirable effects that reduce user compliance. Such undesirable effects may include (a) impairment of non-injurious joint biomechanics^11,12, (b) user discomfort¹³, (c) excessive time and effort to don/doff the device, and (d) negative user perceptions (e.g., performance limitations, perceived risk of injury to more proximal joints)⁸. Although ankle bracing has been shown to reduce sprain injuries in both civilian¹⁴ and military¹⁵ populations, user compliance is clearly essential – i.e., a brace can only be effective if it is worn. The goals of this study, therefore, are to develop and apply a new paradigm for orthosis design that empowers the creation of a next-generation solution to protect against lateral ankle sprain – a solution that overcomes the undesirable effects listed above and promotes effective distal extremity protection through high user satisfaction and compliance. This technology will seek to leverage the latest advances in materials, manufacturing, and mechatronics (i.e., sensing, actuation, power) to deliver an intelligent solution capable of adapting to both the user and the environment. The following specific research aims are proposed: R1.  Define stakeholders, needs, and functional specifications. Perform a comprehensive assessment of ankle brace perceptions, needs, and use cases among active-duty Service members as well as other stakeholders (e.g., healthcare providers). The goal is to identify causes of low compliance with prophylactic ankle brace use and to define the functional specifications for a next-generation brace design. Musculoskeletal simulation of inversion sprain biomechanics will be leveraged to corroborate previously published metrics associated with sprain risk. These functional and biomechanical specifications embody the design inputs (performance requirements) of the device. R2.  Prototype development and design verification. Medical device design best practices will be applied to drive ideation and prototype development. Computer simulation and physical testing will be used for structural evaluation of brace performance, which is the basis for verification that design outputs (performance outcomes) satisfy the design inputs (performance requirements). R3.  Human trials and design validation. EACE member facilities will conduct a controlled trial to evaluate user satisfaction and efficacy of prophylactic bracing solutions comparing one or more prototype next-generation designs to current standards of care (e.g., stirrup brace). Outcome metrics collected will comprise both user feedback and biomechanical measures to establish the validity of prototype designs to meet user needs as defined in R1.

Grand Challenge: Not applicable.

Anthony Petrella, Mechanical Engineering, apetrell@mines.edu | Mykola Mazur <mazur@mines.edu>, PhD Student