Study related activities were delayed and effort was instead focused on recruitment and testing for the iterative design study (NCT04562896).

The proposed study evaluates the effect of carbon fiber brace design on forces across the ankle. Research suggests that ankle arthritis develops following ankle fracture due, in part, to elevated forces on the cartilage. It is expected that carbon fiber braces can reduce forces in the ankle joint thereby reducing the risk of developing arthritis following injury. In this study, carbon fiber braces will be tested to determine how they influence the forces acting on the ankle cartilage. The proposed study will provide evidence that can be used by clinicians and researchers to design carbon fiber braces to effectively reduce forces on ankle cartilage.

The primary purpose of this line of research is to investigate the effects of carbon fiber custom dynamic orthosis (CDO) use on forces and contact stress at the ankle, with the goal of reducing the development of post traumatic osteoarthritis (PTOA). Research suggests that PTO develops, in part, due to increased ankle contact stress following fracture. It is expected that reducing articular contact stress has the potential to delay or prevent PTOA development. CDOs have been shown to significantly improve function after extremity injury, and show promise for offloading the injured ankle joint after severe lower extremity injuries. Therefore, the proposed effort is designed to evaluate CDOs effects on forces and articular contact stress at the ankle.

Adult participants who have sustained a traumatic ankle fracture of the tibial pilon will be evaluated while wearing two CDOs, with a primary dependent measure of ankle joint contact stress. Following consent and enrollment weight bearing computerized tomography (CT) images will be collected and used to determine the geometry of the joint, and the articular contact stress using discrete element analysis.

Participants will be cast and fit for two CDOs. Participants will be blinded to the design variation of each device and will only know them as CDO-A or CDO-B. Testing will be completed under 3 conditions: No-CDO, CDO-A, CDO-B, with each bracing condition (A/B) representing a different CDO. Physical performance measures will incorporate tests of agility, speed, and lower limb power to ensure that the CDOs do not negatively affect physical function. Questionnaires will be used to evaluate participants' current and desired activity level, pain with and without using a CDO, satisfaction with the study CDOs, perception of comfort and smoothness between CDOs, and preference between CDOs. Semi-structured interviews will be completed to fully capture the participant's perspective with each study CDO. Lower limb forces and motion will be assessed using a computerized motion capture system and force plates embedded in the floor. Forces between the foot and CDO footplate will be measured using force sensing insoles, and muscle activity data will be collected using wireless surface electromyography sensors. Each CDO will be mechanically tested, and participant demographic and anthropometric data will be recorded.

Inclusion Criteria:

• Between the ages of 18 and 65
• Sustained unilateral fracture of the tibial pilon
• The fracture has completely healed
• Ability to walk 50 feet without use of an assistive device (cane, crutch, etc.)
• Ability to walk at a slow to moderate pace
• Shoe size between women's 8 and 13.5 or men's 6.5 and 12
• Ability to read and write in English and provide written informed consent
• Individuals with elevated contact stress according to model generated using standing CT images (will be answered after completing visit one)

Exclusion Criteria:

• Pain > 6/10 while walking
• Increase in pain during testing of 3/10 or greater
• Neurologic, musculoskeletal (including bilateral fractures) or other condition limiting function of the contralateral extremity
• Medical or psychological condition that would preclude functional testing (ex. moderate or severe brain injury, stroke, heart disease)
• Wounds to the calf that would prevent CDO fitting
• Fractures secondary to neuropathy or severe osteopenia
• Classification as non-ambulatory
• Previous fractures near the tibial pilon on the involved limb
• Surgery on involved limb anticipated in the next 6 months
• Requirement of a knee stabilizing device (i.e. KAFO, KO…) to perform daily activities
• Visual or hearing impairments that limit walking ability or limit the ability to comply with instructions given during testing
• BMI greater than 40
• Pregnancy- Per participant self-report. Due to the expected small number of pregnant individuals and resulting inability to account for its effect on resulting outcomes, participants will be withdrawn from the study.

Participants will be blinded to the different CDO designs and will only be introduced to each device as CDO-A or CDO-B.