Effects of Malleo-Lok Stiffness on Lower Limb Mechanics

University of Iowa20 enrolled

Overview

The primary purpose of this research study is to determine if the stiffness of a commercially available ankle foot orthosis (Malleo-Lok, Bio-Mechanical Composites, Des Moines IA) impacts gait biomechanics and overall joint level stiffness. Previously published research suggests that AFO stiffness can affect gait biomechanics and patient preference. However, previous studies have focused on traditional posterior strut devices with the strut aligned in the frontal plane to allow sagittal plane deflection. The Malleo-Lok is a novel, low-profile carbon fiber device with two laterally positioned struts aligned in the sagittal plane. The proposed study will provide insight that can be used by certified prosthetists orthotists (CPOs), physical therapists, and physicians to select the device that bests meets their patients' needs.

Healthy adult individuals will be invited to participate in this study, at the University of Iowa, that involves one visit lasting 3-4 hours. The primary purpose of this work is to determine the effects of Malleo-Lok stiffness on gait biomechanics and ankle joint stiffness. Previous work has highlighted the effects of ankle foot orthosis stiffness on gait using devices with a traditional single posterior strut opposed to the Malleo-Lok, which has two laterally positioned struts. Orthosis stiffness is an important factor to consider during device prescription and manufacturing. The ability to tune overall joint level stiffness by determining the combined effects of biological limb stiffness and orthosis stiffness will enhance precision medicine when treating individuals who require an orthosis for daily activities. The secondary purpose of this research study is to determine the within session repeatability of a novel approach for in-vivo AFO stiffness testing. AFO stiffness testing is typically performed using mechanical testing systems without accounting for the interaction of the individual and the device. During the visit to the University of Iowa campus participants will review a list of inclusion and exclusion criteria to determine their eligibility for this study. Eligible participants will review an informed consent document and have the chance to ask any questions they may have. Study staff will thoroughly explain the informed consent document and answer all questions. Upon signing the informed consent document study activities will begin. Participants will complete all study activities wearing no brace and two braces of differing stiffness's. Anthropometric and demographic information will be collected from each participant. The investigators will also use a motion capture system to evaluate gait biomechanics and ankle joint stiffness. Participants will walk at a self-selected and a controlled speed to evaluate gait biomechanics, and will stand in the motion capture system and bring their knee forward over the foot to evaluate ankle joint stiffness. Participants will be provided visual feedback of muscle activity to minimize lower limb muscle activity during ankle stiffness testing. Results from the proposed study will provide information about the effects of orthosis stiffness on gait biomechanics and ankle joint stiffness. Study results will be made available to clinicians to use when prescribing and fitting individuals with ankle foot orthoses.

Eligibility

Sex: ALLMin age: 18 YearsMax age: 45 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Between the ages of 18 and 45 * Healthy without current complaint of lower extremity pain, spine pain, open wounds or active infections, or medical or neuromusculoskeletal disorders that have limited their participation in work or exercise in the last 6 months * Able to hop without pain * Able to perform a full squat without pain * Ability to speak and understand English Exclusion Criteria: * Diagnosed with a moderate or severe brain injury * Lower extremity injury resulting in surgery or limiting function for greater than 6 weeks * Injuries that would limit performance in this study * History of recurrent ankle sprains or chronic ankle instability * Diagnosed with a physical or psychological condition that would preclude functional testing (e.g. cardiac condition, clotting disorder, pulmonary condition) * Uncorrected visual or hearing impairment(s) * Require use of an assistive device * Unhealed wounds (cuts/abrasions) that would prevent AFO use * BMI \> 35 * Pregnancy

Outcomes

Primary Outcomes

Ankle Joint Stiffness

Ground reaction force and ankle motion data were collected simultaneously using the force measurement and motion capture systems as participants wore no brace (NoCDO), a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order. The ankle motion data was plotted against the ankle moment data and the slope of the corresponding line was the resulting ankle joint stiffness (Nm/degree).

Time frame: In-vivo ankle joint stiffness was measured for each condition before and after short bouts of walking (~15-20 minutes).

Ankle Joint Power

Peak ankle joint push-off power (W/kg) was calculated during gait and normalized to participant body weight as participants wore no brace (NoCDO), a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order.

Time frame: Ankle joint power was measured for each condition during short bouts of walking (~15-20 minutes).

Ankle Joint Moment

Peak ankle plantarflexion moment (Nm/kg) was calculated during gait and normalized to participant body weight as participants wore no brace (NoCDO), a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order.

Time frame: Ankle joint moment was measured for each condition during short bouts of walking (~15-20 minutes).

Secondary Outcomes

Numerical Pain Rating Scale

Participants were asked to rate their pain on a standard 11-point numerical pain rating scale, in which 0 = no pain and 10 = worst pain imaginable. Participants were asked to rate their pain after completing testing in no brace (NoCDO), a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order.

Time frame: Participants were asked to rate their pain after completing in-vivo ankle stiffness testing and walking trials in all conditions.

Modified Socket Comfort Score: Comfort

Study participants were asked to rank the smoothness of each orthosis on a scale from 0-10 where 0 = least smooth and 10 = most smooth orthosis. Participants were asked to rate the comfort of each orthosis after completing testing in a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order.

Time frame: Participants were asked to rate their comfort after completing in-vivo ankle stiffness testing and walking trials in Compliant and Stiff conditions.

Modified Socket Comfort Score: Smoothness

Study participants were asked to rank the smoothness of each orthosis on a scale from 0-10 where 0 = least smooth and 10 = most smooth orthosis. Participants were asked to rate the smoothness of each orthosis after completing testing in a moderate stiffness orthosis (Compliant) and a stiff orthosis (Stiff) in a randomized order.

Time frame: Participants were asked to rate the orthosis smoothness after completing in-vivo ankle stiffness testing and walking trials in Compliant and Stiff conditions.

Effects of Malleo-Lok Stiffness on Lower Limb Mechanics

Overview

Conditions

Interventions

Eligibility

Locations (1)

Outcomes

Primary Outcomes

Secondary Outcomes