Iterative Design of Custom Dynamic Orthoses to Reduce Articular Contact Stress

Not Applicable

Completed

Conditions: Post-traumatic Osteoarthritis
Ankle Fractures
Osteoarthritis Ankle

Interventions: Device: Custom Carbon Fiber Dynamic Orthosis (CDO)

Registration Number: NCT04562896

Lead Sponsor: University of Iowa

Brief Summary: 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: 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.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 22

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
CDO-C	Custom Carbon Fiber Dynamic Orthosis (CDO)	The third design variant will be designated CDO-C
CDO-A	Custom Carbon Fiber Dynamic Orthosis (CDO)	The first design variant will be designated CDO-A
CDO-B	Custom Carbon Fiber Dynamic Orthosis (CDO)	The second design variant will be designated CDO-B

Primary Outcome Measures

Name	Time	Method
Peak Plantar Force (Midfoot)	Baseline	Plantar forces normalized to body weight (N/kg) will be measured across the forefoot (middle 30% of sensor) as participants walk without a CDO and with each CDO.
Peak Plantar Force (Forefoot)	Baseline	Plantar forces normalized to body weight (N/kg) will be measured across the forefoot (distal 40% of sensor) as participants walk without a CDO and with each CDO.
Participant Device Preference (Rank Order NoCDO, CDOA, CDOB, CDOC)	Baseline	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.
Participant Device Preference (First Preferred Condition)	Baseline	Participants were asked to rank order their preference for NoCDO, CDO-A, CDO-B, CDO-C on a questionnaire.
Joint Contact Stress Time Exposure (Model Estimated)	Baseline	Joint contact stress time exposure (MPA-s/gait cycle) was estimated using a participant specific musculoskeletal model. Peak joint contact stress time exposure (MPA-s/gait cycle) acting on the tibia during the gait cycle were reported. Lower peak contact stress time exposure is considered a better outcome.
Peak Plantar Force (Total Foot)	Baseline	Plantar forces normalized to body weight (N/kg) will be measured across the forefoot (100% of sensor) and normalized to participant body weight as they walk.
Peak Plantar Force (Hindfoot)	Baseline	Plantar forces normalized to body weight (N/kg) will be measured across the forefoot (proximal 30% of sensor) as participants walk without a CDO and with each CDO.
Plantar Force Impulse (Total Foot)	Baseline	Plantar force impulse normalized to body weight (Ns/kg) across the forefoot (100% of sensor) will be calculated using the integral of the force over the stance phase and normalized to participant body weight as they walk.
Plantar Force Impulse (Hindfoot)	Baseline	Plantar force impulse normalized to body weight (Ns/kg) 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.
Plantar Force Impulse (Midfoot)	Baseline	Plantar force impulse normalized to body weight (Ns/kg) 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.
Plantar Force Impulse (Forefoot)	Baseline	Plantar force impulse normalized to body weight (Ns/kg) 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.
Numerical Pain Rating Scale (Before Performance Measures - 4SST, 5STS)	Baseline	Pain will be assessed using a standard 11-point numerical pain rating scale, in which 0 = no pain and 10 = worst pain imaginable. Lower values are better as they indicate less pain.
Numerical Pain Rating Scale (After Performance Measures - 4SST, 5STS)	Baseline	Pain will be assessed using a standard 11-point numerical pain rating scale, in which 0 = no pain and 10 = worst pain imaginable. Lower values are better as they indicate less pain
Participant Device Preference (Second Preferred Condition)	Baseline	Participants were asked to rank order the testing conditions from the condition they would most prefer to walk in everyday (first preferred) to the condition they would least prefer to walk in everyday (fourth preferred).
Participant Device Preference (Third Preferred Condition)	Baseline	Participants were asked to rank order the testing conditions from the condition they would most prefer to walk in everyday (first preferred) to the condition they would least prefer to walk in everyday (fourth preferred).
Participant Device Preference (Fourth Preferred Condition)	Baseline	Participants were asked to rank order the testing conditions from the condition they would most prefer to walk in everyday (first preferred) to the condition they would least prefer to walk in everyday (fourth preferred).

Secondary Outcome Measures

Name	Time	Method
Peak Soleus Muscle Force (Model Estimated)	Baseline	Peak soleus muscle force (N) during gait was estimated using a participant specific musculoskeletal model.
Peak Gastrocnemius Muscle Force (Model Estimated)	Baseline	Peak gastrocnemius muscle force (N) during gait was estimated using a participant specific musculoskeletal model.
Ankle Range of Motion	Baseline	Peak ankle dorsiflexion (degrees) during gait.
Peak Ankle Moment	Baseline	Peak ankle plantarflexion moment (Nm/kg) during gait.
Peak Ankle Power	Baseline	Peak ankle push-off power (W/kg) during gait.
Four Square Step Test (4SST)	Baseline	The 4SST (s) is a standardized timed test of balance and agility. One inch pipe is placed on the floor in the shape of a Maltese cross and participants are instructed to begin in the back left quadrant then to move 1) forward, 2) sideways right, 3) backward, then 4) sideways left, then to move in the reverse direction back to the original square.
Sit to Stand 5 Times (STS5)	Baseline	STS5 (s) is a well-established timed measure of lower limb muscle strength and power. Participants are instructed to start the test sitting with their arms folded across their chest and with their back against a standard chair. Patients are then instructed to stand up and sit down 5 times as fast as possible, avoiding touching their back to the chair during each repetition. The time to complete all five continuous repetitions is reported.
The Orthotics Prosthetics Users' Survey (OPUS)	Baseline	Satisfaction with device will be assessed using the Orthotics Prosthetics Users' Survey Satisfaction With Device Score (11-55). Lower scores indicate a better outcome.
Modified Socket Comfort Score (Comfort)	Baseline	Comfort scores range from 0 = most uncomfortable to 10 = most comfortable. Higher scores are better as they indicate a more comfortable device.
Modified Socket Comfort Score (Smoothness)	Baseline	Comfort scores range from 0 = least smooth to 10 = most smooth. Higher scores are better as they indicate a smoother rollover with the device.