Iterative Design of Custom Dynamic Orthoses to Reduce Articular Contact Stress

Study Overview
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Brief Summary
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The proposed study evaluates the effect of carbon fiber brace design on forces across the ankle joint. Research suggests that ankle arthritis develops after ankle fracture, in part, due to elevated forces on the cartilage. It is expected that carbon fiber braces can be designed to reduce forces in the ankle joint and thereby reduce the risk of developing arthritis following traumatic injury. In this study, brace geometry will be varied to determine how these changes influence the forces experienced by ankle cartilage. The proposed study will provide evidence that can be used by clinicians and researchers to design braces that most effectively reduce forces on ankle cartilage.

Detailed Description
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The primary purpose of this line of research is to investigate the effects of carbon fiber custom dynamic orthosis (CDO) design on the forces and contact stress at the ankle, with the goal of reducing the development of post traumatic osteoarthritis (PTOA) in the ankle. Research suggests that ankle arthritis develops, in part, due to increased contact stresses within the ankle joint following fracture. It is expected that reducing articular contact stress at the ankle has the potential to delay or prevent the development of PTOA. CDOs have been shown to significantly improve function following extremity injury, and show promise for offloading the injured limb after severe lower extremity injuries. Therefore, the proposed effort is designed to evaluate how different CDO design factors influence offloading and therefore the reduction of forces and articular contact stress at the ankle. Adult participants will be evaluated while wearing carbon fiber braces of varied geometry. The primary dependent measure is ankle joint contact stress. Following consent and enrollment computerized tomography (CT) images will be used to determine the geometry of the joint articular surfaces. Ankle contact stress will be calculated using discrete element analysis and biomechanical data collected in subsequent data collection. Participants will be cast and fit for three CDOs with varied geometry. Participants will be blinded to the design variation of each device and will only know them as CDO-A, CDO-B, or CDO-C. Testing will be completed under 4 conditions: No-CDO, CDO-A, CDO-B, CDO-C, with each bracing condition (A/B/C) representing a CDO design variant. Physical performance measures will incorporate tests of agility, speed, and lower limb power to ensure that changes to device design do not negatively affect physical function. Questionnaires will be used to evaluate participants' current and desired activity level, pain with and without CDO use, satisfaction with the devices, perception of comfort and smoothness between devices, and preference between CDOs. Semi-structured interviews will be completed to fully capture the participant's perspective. Lower limb forces and motion will be assessed using a computerized motion capture system and force plates in the floor. Forces between the foot and CDO will be measured using force sensing insoles, and muscle activity data will be collected using surface electromyography. Devices will be mechanically tested, and participant demographic and anthropometric data will be recorded.

Official Title
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Iterative Design of Custom Dynamic Orthoses to Reduce Articular Contact Stress

Conditions
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Ankle Fractures, Post-traumatic Osteoarthritis, Osteoarthritis Ankle

Intervention / Treatment
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* Device: Custom Carbon Fiber Dynamic Orthosis (CDO)


Participation Criteria
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Eligibility Criteria
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TIBIAL PILON FRACTURE PARTICIPANTS: Inclusion Criteria: Ages: 18-65 Sustained unilateral fracture of the tibial pilon within the preceding 5 years 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 13 Ability to read and write in English and provide written informed consent Individuals with elevated contact stress according to model generated using PedCAT 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. HEALTHY ABLE-BODIED PARTICIPANTS: Patient Inclusion Criteria Between the ages of 18 and 65 Shoe size between women's 8 and 13.5 or men's 6.5 and 13 Healthy individuals without a current complaint of lower extremity pain, spine pain, or medical or neuromusculoskeletal disorders that have limited participation in work or exercise in the last 6 months Full active range of motion of the bilateral lower extremities and spine Ability to hop without pain Ability to perform a full squat without pain Ability to read and write in English and provide written informed consent Patient Exclusion Criteria Diagnosed moderate or severe brain injury Prior lower extremity injury resulting in surgery or limiting function for greater than 6 weeks Diagnosis of a physical or psychological condition that would preclude testing (e.g. cardiac condition, clotting disorder, pulmonary condition) Visual or hearing impairment that would interfere with instructions given during testing Require an assistive device Wounds to the foot or calf that would prevent CDO use 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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: All participants will be cast and fit with three carbon fiber custom dynamic orthoses (CDOs). Each CDO will differ from the others in design and will be labeled as CDO-A, CDO-B and CDO-C. Participants will be randomly assigned to one of six CDO testing sequences (ABC, ACB, BCA, BAC, CAB, CBA) to prevent testing order from influencing study results. Multiple rounds of evaluation ( 5 rounds) with small groups of participants in each round (n= 6) will be used.
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: No Device<br>Participants will be evaluated without a CDO. | |
| Experimental: CDO-A<br>The first design variant will be designated CDO-A | Device: Custom Carbon Fiber Dynamic Orthosis (CDO)<br>* The custom carbon fiber dynamic orthoses will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff below the knee.<br>* Other names: Ankle Foot Orthosis;|
| Experimental: CDO-B<br>The second design variant will be designated CDO-B | Device: Custom Carbon Fiber Dynamic Orthosis (CDO)<br>* The custom carbon fiber dynamic orthoses will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff below the knee.<br>* Other names: Ankle Foot Orthosis;|
| Experimental: CDO-C<br>The third design variant will be designated CDO-C | Device: Custom Carbon Fiber Dynamic Orthosis (CDO)<br>* The custom carbon fiber dynamic orthoses will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff below the knee.<br>* Other names: Ankle Foot Orthosis;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Joint Contact Stress Time Exposure (Model estimated) | Joint contact stress time exposure (MPA-s/gait cycle) will be estimated using a participant specific musculoskeletal model. | Baseline | 
| Peak Plantar Force (Total Foot) | Plantar forces (N) will be measured across the forefoot (100% of sensor) as participants walk without a CDO and with each CDO. | Baseline | 
| Plantar Force Impulse (Total Foot) | Plantar force impulse (Ns) across the forefoot (100% of sensor) will be calculated using the integral of the force over the stance phase as participants walk without a CDO and with each CDO. | Baseline | 
| Peak Plantar Force (Forefoot) | Plantar forces (N) will be measured across the forefoot (distal 40% of sensor) as participants walk without a CDO and with each CDO. | Baseline | 
| Plantar Force Impulse (Forefoot) | Plantar force impulse (Ns) across the forefoot (distal 40% of sensor) will be calculated using the integral of the force over the stance phase as participants walk without a CDO and with each CDO. | Baseline | 
| Peak Plantar Force (Midfoot) | Plantar forces (N) will be measured across the forefoot (middle 30% of sensor) as participants walk without a CDO and with each CDO. | Baseline | 
| Plantar Force Impulse (Midfoot) | Plantar force impulse (Ns) across the forefoot (middle 30% of sensor) will be calculated using the integral of the force over the stance phase as participants walk without a CDO and with each CDO. | Baseline | 
| Peak Plantar Force (Hindfoot) | Plantar forces (N) will be measured across the forefoot (proximal 30% of sensor) as participants walk without a CDO and with each CDO. | Baseline | 
| Plantar Force Impulse (Hindfoot) | Plantar force impulse (Ns) across the forefoot (proximal 30% of sensor) will be calculated using the integral of the force over the stance phase as participants walk without a CDO and with each CDO. | Baseline | 
| Numerical Pain Rating Scale | Pain will be assessed using a standard 11-point numerical pain rating scale, in which 0 = no pain and 10 = worst pain imaginable. | Baseline | 
| Participant Device Preference | The participant will rank order their preference for their standard of care device (if applicable), No Device, CDO-A, CDO-B, CDO-C on a questionnaire. | After completing other study activities | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Peak Soleus Muscle Force (model estimated) | Peak soleus muscle force (N) during gait will be estimated using a participant specific musculoskeletal model. | Baseline | 
| Peak Gastrocnemius Muscle Force (model estimated) | Peak gastrocnemius muscle force (N) during gait will be estimated using a participant specific musculoskeletal model. | Baseline | 
| Ankle Range of Motion | Peak ankle dorsiflexion (degrees) during gait. | Baseline | 
| Peak Ankle Moment | Peak ankle moment (Nm/kg) during gait. | Baseline | 
| Peak Ankle Power | Peak ankle power (W/kg) during gait. | Baseline | 
| Four Square Step Test (4SST) | The 4SST (s) is a standardized timed test of balance and agility. | Baseline | 
| Sit to Stand 5 Times (STS5) | STS5 (s) is a well-established timed measure of lower limb muscle strength and power. Participants are instructed to stand up and sit down 5 times as fast as possible. | Baseline | 
| The Orthotics Prosthetics Users' Survey (OPUS) | Satisfaction with device will be assessed using the Orthotics Prosthetics Users' Survey Satisfaction With Device Score (11-55). Lower scores indicate a better outcome. | Baseline | 
| Modified Socket Comfort Score (Comfort and Smoothness) | Comfort scores range from 0 = most uncomfortable to 10 = most comfortable, and from 0 = least smooth to 10 = most smooth. | Baseline | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Carbon Fiber, Gait Analysis, Ankle Foot Orthosis, Arthritis, Biomechanics, Ankle, Adult