1. Biomechanical interventions in the management of knee osteoarthritis: the role of orthosis (braces) Martin van der Esch, PhD

2. 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

3. Introduction Knee braces are ‘‘medical devices added to a person’s body to support, align, position, immobilize, prevent or correct deformity, assist weak muscles, or improve function’’ The general purpose of knee braces in OA is to decrease pain, improve physical function, and possibly, slow disease progression 2 Raja K et al, 2011

4. 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) 3

5. 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 4

6. 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 knee pain and improving balance 5 (Hassan 2002, Raja 2011)

7. 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 6 Raja K et al, 2011

8. Unoader brace and lateral knee OA Patients with OA of the lateral compartment generally have a valgus alignment, and the mechanical axis and load bearing pass through the lateral compartment Malalignment increases risk and progression of knee OA and results in decline in physical function 7 Raja K et al, 2011

9. 8 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 pain No information on: Impact on knee joint instability Functioning during daily life Effects to be expected in a short time (experts opinion) Hassan, 2002 a, b

10. 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)

11. 10 Instability of the joint in knee OA Inability to maintain a position or to control movements under external load Highly prevalent in knee OA 63 % 65 % Strong impact on activity limitations van der Esch, 2012 van der Esch, 2007; Dekker, 2014; Knoop, 2014 Fitzgerald, 2004 van der Esch, 2012

12. 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 11 (Raja K 2011)

13. Theoretical background Spinal cord Brain Proprioception 1.Articular 2.Muscle (muscle spindle) 3.Cutaneous Knee stability Neuromuscular reflexes Muscle activity (strength) Control of movement Sensorimotor system (Riemann 2002)

14. Theoretical background 13 Spinal cord Brain Proprioception 1.Articular 2.Muscle (muscle spindle) 3.Cutaneous (nociception) Knee (in)stability Neuromuscular reflexes Muscle activity (strength) Control of movement Sensorimotor system (Riemann 2002) Deep/superficial pain Thijs 2010

15. 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) 14

16. Does soft braces infuence knee stability and indirectly activity limitations? 15

17. Theoretical model 16 Soft brace Proprioception Nociception peripheral and central sensitization Knee joint stability Muscle strength Activity limitations Spinal and supra-spinal nervous syetem + _

18. 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) 17

19. Questions 18