# Development and evaluation of a knee brace for joint stress modulation -A literature review

Léa Boillereaux, Simon Le Floc'h, Abderrahmane Kheddar, Franck Jourdan

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Léa Boillereaux, Simon Le Floc'h, Abderrahmane Kheddar, Franck Jourdan. Development and evaluation of a knee brace for joint stress modulation -A literature review. GDR Mecabio Santé, Nov 2022, Paris, France. **hal-04054171**

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Submitted on 31 Mar 2023

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# Development and evaluation of a knee brace for joint stress modulation – A literature review

Léa Boillereaux, Simon Le Floc'h, Abderrahmane Kheddar, Franck Jourdan

In order to relieve the patients suffering osteoarthritis or other cartilage diseases and to facilitate the rehabilitation after an operation, it is necessary to unload the knee during daily living activities. Doctors usually prescribe the wearing of an unloading orthosis. But are they really efficient ? What are their impact on the tibiofemoral contact forces ?

## Evaluation criteria for braces in the literature :

<table><caption>Fig 1 : Quantitative and qualitative orthosis evaluation methods (1)</caption><thead><tr><th>Symptoms</th><th>Measures outcomes</th><th>Evaluation methods and instruments</th></tr></thead><tbody><tr><td>Clinical symptoms</td><td>Knee pain, joint stiffness and function, quality of life, physical activity</td><td>VAS, WOMAC, QoL, KOOS-QoL, IPAQ, UCLA Scale, IKDC</td></tr><tr><td>Functional effects</td><td>Knee proprioception, stability, posture control</td><td>KOOS, KSS, IPAQ, VAS, Lequesne index, Safety and observance</td></tr><tr><td>Morphological effect</td><td>JSW, JSN, tibio-femoral Angle, hip-knee-ankle angle, condylar separation, angle condylar separation distance</td><td>Weight-bearing lower limb radiographs, ultrasound, fluoroscopy, gait analysis, loaded MRI, morphological MRI, WORMS, BLOCKS grading</td></tr><tr><td>Gait effects</td><td>Frontal plane kinematics, sagittal plane kinematics, lower limb malalignment, knee adduction flexion angles, knee forces and moments</td><td>3D motion analysis, dynamic simulations, gait analysis</td></tr><tr><td>Muscle strength</td><td>Muscle co-contraction, medial/lateral, flexors/extensors co-contraction ratios</td><td>Electromyograms (EMG), muscle MRI</td></tr></tbody></table>

* WOMAC : Western Ontario McCaster Arthritis index
* KOOS : Knee injury and Osteoarthritis Outcome Score
* KSS: Knee society score

* IPAQ: International Physical Activity Questionnaire

The contact force is not measurable in vivo. Therefore, its reduction by an orthosis cannot be directly evaluated.

However, several researchers have demonstrated a correlation between contact stress and muscle activity.

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<figure><img src="image_4.png" /><figcaption>Fig 2 : Muscle's contribution on the tibiofemoral contact force during the stance phase of the gait cycle (2)</figcaption></figure>

Possibility to estimate the contact stress : underfoot force sensors + Electromyography + Numerical model (inverse dynamics, musculoskeletetic model)

<figure><img src="image_5.png" /><figcaption>Fig 3 : Evaluation of muscular and ligament forces with different orthosis (3)</figcaption></figure>

Decreasing the contact force by recreating the flexion-extension torque via the orthosis, a promising solution ?

<figure><img src="image_6.png" /><figcaption>Fig 4 : Unloading brace during stance phase of the gait cycle and evaluation of the device with different stiffnesses (K in N/m) (4)</figcaption></figure>

<figure><img src="image_7.png" /></figure>

Take into account the size of the device and the pressure applied on skin during the conception.

Our objective : Designing a brace decreasing the muscular forces during squat movement with two secondary objectives :

(i) Consideration of the shear stresses on skin and the sliding of the muscles on the bones
(ii) Validation of the orthosis with the most quantitative tools possible to show the tibiofemoral contact stress reduction

(1) Methods for evaluating effects of unloader knee braces on joint health : a review – Rizuwana Parween and Al. – Korean Society of Medical and Biological Engineering, 2019

(2) Individual Muscle contributions to tibiofemoral compressive articular loading during walking, running and sidestepping – B.A. Killena

(3) Biomechanical Study of a Tricompartmental Unloader Brace for Patellofemoral or Multicompartment Knee Osteoarthritis – Chris A. McGibbon – Frontiers in Bioengineering and Biotechnology, 2021

(4) Development and Functionnal testing of an unloading concept for Knee Osteoarthritis Patients : A pilot study – Stoltze and Al – Journal of Biomedical Engineering, 2022

<figure><img src="image_8.png" /></figure>