Comparative Effect of Carbon Fiber Orthosis Cuff Design on Preference, Comfort, and Mechanics (AFOCUFF)

Carbon fiber custom dynamic orthoses (CDOs) consist of a proximal cuff that wraps around the leg just below the knee, a posterior carbon fiber strut that stores and returns energy during gait, and a carbon fiber foot plate that supports the foot and allows bending of the posterior strut. The proximal cuff is a primary interface between the patient and the CDO and may influence comfort, preference, limb mechanics and loading, and effective stiffness of the CDO. The important role of the proximal cuff has not been examined. The purpose of this study is to determine the effects of CDO proximal cuff design on patient reported outcomes, limb mechanics and loading, and CDO mechanical characteristics.

Study Overview

• Status: Completed
• Conditions: Healthy; Lower Limb Injury; Post-Traumatic Osteoarthritis
• Intervention / Treatment: Device: Carbon Fiber Custom Dynamic Orthosis (CDO)

Detailed Description

Traumatic lower limb injuries often result in poor functional outcomes with long-term negative effects. Carbon fiber custom dynamic orthoses (CDOs) can improve outcomes by reducing pain, supporting the limb, and transferring forces around the limb through the CDO. CDOs consist of a proximal cuff that wraps around the leg just below the knee, a posterior carbon fiber strut that stores and returns energy during gait, and a carbon fiber foot plate that supports the foot and allows bending of the posterior strut. The proximal cuff is a primary interface between the patient and the CDO and may influence comfort, preference, limb mechanics and loading, and effective stiffness of the CDO. Although CDOs are becoming more commonly prescribed following injury the evidence available to guide clinical practice remains limited. The important role of the proximal cuff has not been systematically examined.

The purpose of this study is to determine the effects of CDO proximal cuff design on patient reported outcomes, limb mechanics and loading, and CDO mechanical characteristics. Two groups of individuals will participate: individuals with post-traumatic osteoarthritis in the ankle and healthy individuals. Testing will occur without an orthosis and while wearing orthoses with four proximal cuff designs representative of currently available devices: 1) a rigid patellar tendon bearing (PTB) clamshell cuff secured using a mechanical ratcheting system, 2) a PTB shell with a fixed pivot point secured with Velcro, 3) a rigid clamshell cuff secured with Velcro, and 4) a semi-rigid cuff with a flexible outer layer secured with Velcro.

• Study Type: Interventional
• Enrollment (Actual): 35
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Iowa
    • Iowa City, Iowa, United States, 52241
      • University of Iowa

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 50 years (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

PARTICIPANTS WITH PTOA:

Inclusion Criteria:

1. Ages 18-65.
2. Diagnosis of ankle PTOA.
3. Ability to walk 50 feet at a slow to moderate pace.
4. Ability to walk without a cane or crutch.
5. Ability to read and write in English and provide written informed consent.

Exclusion Criteria:

1. Diagnosis with a moderate or severe brain injury.
2. Diagnosis with a physical or psychological condition that would preclude functional testing (e.g. cardiac condition, clotting disorder, pulmonary condition…).
3. Ankle weakness as a result of spinal cord injury or nervous system pathology.
4. Nerve, muscle, bone, or other condition limiting function in the contralateral extremity.
5. Rheumatoid or inflammatory arthritis.
6. Necrosis of any bones in the foot or ankle.
7. Pain of 8/10 or greater during walking.
8. Surgery on study limb anticipated in the next 6 months.
9. Uncorrected visual or hearing impairments.
10. Require use of a stabilizing device (i.e. Ankle Foot Orthosis or Knee Orthosis…) to perform daily activities.
11. Pregnancy
12. Body mass index greater than 40.

HEALTHY ABLE-BODIED PARTICIPANTS:

Inclusion Criteria:

1. Ages 18-65.
2. Without current complaint of lower extremity pain, spine pain, open wounds or active infection.
3. Ability to hop without pain.
4. Ability to perform a full squat without pain.
5. Ability to read and write in English and provide written informed consent.

Exclusion Criteria:

1. Diagnosis with a moderate or severe brain injury.
2. Diagnosis with a physical or psychological condition that would preclude functional testing (e.g. cardiac condition, clotting disorder, pulmonary condition).
3. Medical conditions or injuries that have limited participation in work or exercise in the last 6 months.
4. Medical conditions of injuries limiting function for greater than 6 weeks.
5. Uncorrected visual or hearing impairments.
6. Use of an assistive device.
7. Pregnancy
8. Body mass index greater than 35.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: NoCDO; Participants will be tested with no CDO
Experimental: CUFF-A; The first study CDO will be designated CUFF-A	Device: Carbon Fiber Custom Dynamic Orthosis (CDO); The carbon fiber custom dynamic orthosis will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff that wraps around the leg below the knee. The design of the proximal cuff will differ between CUFF-A, CUFF-B, CUFF-C, CUFF-D.; Other Names: Ankle Foot Orthosis (AFO)
Experimental: CUFF-B; The first study CDO will be designated CUFF-B	Device: Carbon Fiber Custom Dynamic Orthosis (CDO); The carbon fiber custom dynamic orthosis will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff that wraps around the leg below the knee. The design of the proximal cuff will differ between CUFF-A, CUFF-B, CUFF-C, CUFF-D.; Other Names: Ankle Foot Orthosis (AFO)
Experimental: CUFF-C; The first study CDO will be designated CUFF-C	Device: Carbon Fiber Custom Dynamic Orthosis (CDO); The carbon fiber custom dynamic orthosis will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff that wraps around the leg below the knee. The design of the proximal cuff will differ between CUFF-A, CUFF-B, CUFF-C, CUFF-D.; Other Names: Ankle Foot Orthosis (AFO)
Experimental: CUFF-D; The first study CDO will be designated CUFF-D	Device: Carbon Fiber Custom Dynamic Orthosis (CDO); The carbon fiber custom dynamic orthosis will consist of a semi-rigid foot plate, a posterior carbon fiber strut, and a proximal cuff that wraps around the leg below the knee. The design of the proximal cuff will differ between CUFF-A, CUFF-B, CUFF-C, CUFF-D.; Other Names: Ankle Foot Orthosis (AFO)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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), NoCDO, CUFF-A, CUFF-B, CUFF-C, CUFF-D on a questionnaire.	Baseline
PROMIS Patient Reported Outcomes for Physical Function	The Patient Reported Outcome Information System (PROMIS) physical function Computer Adaptive Test (CAT) is a computerized assessment measuring physical function. It is scored using a T-score in which 50 is the mean of a relevant reference population and 10 is the standard deviation (SD) of that population. In a given PROMIS domain, a T-score above 50 represents more of the measured variable than the population average.	Baseline
PROMIS Patient Reported Outcomes for Pain Interference	The Patient Reported Outcome Information System (PROMIS) pain interference Computer Adaptive Test (CAT) is a computerized assessment measuring pain interference. It is scored using a T-score in which 50 is the mean of a relevant reference population and 10 is the standard deviation (SD) of that population. In a given PROMIS domain, a T-score above 50 represents more of the measured variable than the population average.	Baseline
Peak Plantar Force (total foot)	Force data (N) collected from the total foot (100% of sensor), measured between the foot and orthosis during gait.	Baseline
Plantar Force Impulse (total foot)	Plantar force impulse (Ns) across the total foot (100% of sensor) will be calculated using the integral of the force over the stance phase as participants walk in each study condition.	Baseline
Peak Plantar Force (forefoot)	Force data (N) collected from the total foot (distal 40% of sensor), measured between the foot and orthosis during gait.	Baseline
Plantar Force Impulse (forefoot)	Plantar force impulse (Ns) across the total foot (distal 40% of sensor) will be calculated using the integral of the force over the stance phase as participants walk in each study condition.	Baseline
Peak Plantar Force (midfoot)	Force data (N) collected from the total foot (middle 30% of sensor), measured between the foot and orthosis during gait.	Baseline
Plantar Force Impulse (midfoot)	Plantar force impulse (Ns) across the total foot (middle 30% of sensor) will be calculated using the integral of the force over the stance phase as participants walk in each study condition.	Baseline
Peak Plantar Force (hindfoot)	Force data (N) collected from the total foot (proximal 30% of sensor), measured between the foot and orthosis during gait.	Baseline
Plantar Force Impulse (hindfoot)	Plantar force impulse (Ns) across the total foot (proximal 30% of sensor) will be calculated using the integral of the force over the stance phase as participants walk in each study condition.	Baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Peak Ankle Moment	Peak ankle moment (Nm/kg) during gait.	Baseline
Peak Ankle Power	Peak ankle power (W/kg) during gait.	Baseline
Ankle Range of Motion	Peak ankle dorsiflexion (degrees) during gait.	Baseline
Modified Socket Comfort Score (Comfort)	Comfort scores range from 0 = most uncomfortable to 10 = most comfortable.	Baseline
Modified Socket Comfort Score (Smoothness)	Comfort scores range from 0 = least smooth to 10 = most smooth.	Baseline

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Semi-Structured Interview	Semi-structured interviews will also be used to fully capture the patients' perspectives, experience, and opinions associated with the device options they experienced as part of the study.	Baseline
Center of Pressure Velocity Timing	Timing of peak center of pressure velocity (percent stance) during gait.	Baseline
Center of Pressure Velocity Magnitude	Magnitude of peak center of pressure velocity (m/s) during gait.	Baseline
Soleus Muscle Activity	Electromyography (EMG, % Maximum) of the soleus during gait.	Baseline
Medial Gastrocnemius Muscle Activity	Electromyography (EMG, % Maximum) of the medial gastrocnemius during gait.	Baseline
Tibialis Anterior Muscle Activity	Electromyography (EMG, % Maximum) of the tibialis anterior during gait.	Baseline
Peroneus Longus Muscle Activity	Electromyography (EMG, % Maximum) of the peroneus longus during gait.	Baseline

Collaborators and Investigators

• Sponsor: University of Iowa
• Collaborators: Fabtech Systems
• Investigators: Principal Investigator: Jason M Wilken, PT, PhD, University of Iowa

Study record dates

Study Major Dates

• Study Start (Actual): May 17, 2023
• Primary Completion (Actual): September 29, 2025
• Study Completion (Actual): September 29, 2025

Study Registration Dates

• First Submitted: June 20, 2022
• First Submitted That Met QC Criteria: July 8, 2022
• First Posted (Actual): July 13, 2022

Study Record Updates

• Last Update Posted (Actual): January 15, 2026
• Last Update Submitted That Met QC Criteria: January 13, 2026
• Last Verified: December 1, 2025

More Information

Terms related to this study

• Keywords: Arthritis; Healthy; Adult; Biomechanics; Gait Analysis; Carbon Fiber; Ankle Foot Orthosis
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Wounds and Injuries; Joint Diseases; Arthritis; Leg Injuries; Anti-Infective Agents; Anti-Infective Agents, Local; Carbon Fiber
• Other Study ID Numbers: 202202450; CDMRP-OP210037 (Other Grant/Funding Number: Department of Defense)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No