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

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.

PARTICIPANTS WITH PTOA:

Inclusion criteria

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

Exclusion criteria

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

HEALTHY ABLE-BODIED PARTICIPANTS:

Inclusion criteria

• Ages 18-65.
• Without current complaint of lower extremity pain, spine pain, open wounds or active infection.
• 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.

Exclusion criteria

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