Biomechanical interventions in the management of knee osteoarthritis: the role of orthosis (braces)

Martin van der Esch, PhD

An orthosis is an external device used to modify the structural or functional characteristics of the neuromuscular system

Splints, calipers, supports, trusses, casts and …. braces

(International Standards Organisation)

Focus on braces!

Definition of an orthosis

Introduction

Knee bracesare ‘‘medical devices added to a person’s body tosupport, align, position, immobilize, prevent orcorrect deformity, assist weak muscles, or improvefunction’’ The general purpose of knee braces in OA is to decrease

pain, improve physical function, and possibly, slow disease progression

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Raja K et al, 2011

Bracing an option in OA management?

• Osteoarthritis (OA) management guidelines (EULAR/OARSI) highlight knee bracing as a treatment with unknown effect sizes and inconsistent or absent recommendations (McAlindon 2014, Nelson 2013, Zhang 2008, Jordan 2003, Hochberg 2012)

• Relatively low cost intervention• Supporting evidence is inconclusive (Hochberg 2012, Moyer 2014)

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OARSI guideline on braces

A 2011 SR and three recent RCTs evaluated the effectiveness of knee braces, knee sleeves, and foot orthoses in conservative management of knee OA. One review suggested that knee braces and foot orthoses were effective in decreasing pain, joint stiffness, and drug dosage and also improved physical function, with insignificant adverse events (Raja 2011)

The conclusions were limited due to the heterogeneity and poor quality of available evidence

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Brace type

Braces: Unloader braces (reduce malalignment, unloading medial/lateral compartment, effect on cartilage, long run, low adherence) (Brouwer 2005, 2006)

Soft braces (mechanical stability not be expected) - effective in decreasing kneepain and improving balance

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(Hassan 2002, Raja 2011)

Unloader brace and medial knee OA

Patients with OA of the medial compartment often have progressive loss of cartilage and joint space in this compartment, typically resulting in varus malalignment, which causes the mechanical axis/ground reaction force vector to pass more medially to the knee joint center during gait

This results in increased loads across the medial compartment, as indicated by the external knee adduction moment (KAM) measured during gait

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Raja K et al, 2011

Unoader brace and lateral knee OA

Patients with OA of the lateral compartmentgenerally have a valgus alignment, and the mechanicalaxis and load bearing pass through thelateral compartment Malalignment increases risk and progression of knee OA

and results in decline in physical function

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Raja K et al, 2011

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Soft brace and knee OA

Source of skin sensitivity - proprioceptive input• Positive effect on pain, proprioceptive acuity and

postural balance/sway • Not explained by reduction of painNo information on:• Impact on knee joint instability• Functioning during daily lifeEffects to be expected in a short time (experts opinion)

Hassan, 2002 a, b

Hassan, 2002 a, b

Biomechanical characteristics knee OA

Biomechanical characteristics: muscle weakness and inaccuate propriocption - instability

i. Muscle weakness (Fransen 2015, Segal 2010)

ii. Proprioceptive inaccuracy (Knoop 2014)

iii. Perceived instability: highly prevalent in knee OA 63 % (Fitzgerald 200.) and 65% (van der Esch 2012)

Impact of instability on activity limitations (van der Esch 2012)

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Instability of the joint in knee OA

Inability to maintain a position or to control movements under external load

Highly prevalent in knee OA •6

3 % •6

5 % Strong impact on activity limitations van der Esch, 2012

van der Esch, 2007; Dekker, 2014; Knoop, 2014

Fitzgerald, 2004

van der Esch, 2012

Suggested underlying mechanism soft braces?

It has been suggested that the sensorial input of cutaneous receptors contributes for the sense of articular position and that the central nervous system can use the tactile information of skin stretch to elaborate descending motor strategies (Pegoretti 2014, Raja 2011)

Bandage on the skin may influence proprioceptive acuity and subsequently results in improvement in stability

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(Raja K 2011)

Theoretical background

Spinal cord Brain

Proprioception1.Articular2.Muscle (muscle spindle)3.Cutaneous Knee

stability

Neuromuscular reflexesMuscle activity (strength)Control of movement

Sensorimotor system (Riemann 2002)

Theoretical background

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Spinal cord Brain

Proprioception1.Articular2.Muscle (muscle spindle)3.Cutaneous (nociception) Knee

(in)stability

Neuromuscular reflexesMuscle activity (strength)Control of movement

Sensorimotor system (Riemann 2002)

Deep/superficial pain

Thijs 2010

Pain in knee OA: sensitivity

Peripheral and central sensitization (Arendt-Nielsen 2010, Imamura 2008)

Skin (superficial) sensitization (peripheral hyperalgesia) (Kosek 2013)

Deep sensitization ( Goode 2014)

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Does soft braces infuence knee stability and indirectly activity limitations?

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Theoretical model

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Soft brace

Proprioception

Nociceptionperipheral and central sensitization

Knee joint stability

Muscle strength

Activity limitations

Spinal and supra-spinal nervous syetem+

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Objectives

(i) to assess the effect of soft braces on pain, knee stability and activity limitations,

(ii) to assess the difference in effect of two knee soft braces(i.e., non-tight and tight) on pain, knee stability and activity limitations,

(iii) to explore underlying mechanisms of the therapeutic effect of soft braces and

(iv) to assess the late effects of two weeks application of a soft brace on pain, knee stability and activity limitations in patients with knee osteoarthritis (OA)

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Questions

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