The optimization of footwear choices in the management of knee osteoarthritis

Background: An estimated 4.71 million people aged 45 and over have sought treatment for knee osteoarthritis (OA) in the UK, with this number predicted to grow to 6.5 million people by 2020. Structural changes of knee OA are the most common cause of disability in the UK; symptoms include pain, stiffness, crepitus, swelling and giving way, increasing the risk factor for falls. Medial compartment osteoarthritis (MCOA) has been found to be the most common form of OA and dynamic joint loading has been implicated in disease progression. It has been postulated that various load-bearing conditions alter kinematics and kinetic load and this has the potential to unevenly distribute load across articular cartilage surfaces. NICE guidelines have stipulated that conservative treatment methods, such as footwear for long-term self-management of knee osteoarthritis are a priority for research due to the prevalence of OA and the growing population. The objective of therapeutic footwear is to distribute load evenly across the knee joint by reducing the peak external knee adduction moment (EKAM) and knee adduction angular impulse (KAAI) by manipulating the vertical ground reaction force vector laterally to the knee joint centre and preventing exaggerated adduction of the tibia. The purpose of this review was to explore the literature in relation to footwear that have specific design features, aimed at providing symptom relief and reducing EKAM and KAAI in individuals living with MCOA. Additionally taking in consideration the needs, expectations and perspectives of the at risk population.Methods: Systematic searches were carried out in July 2016, using the EBSCOhost research database (SPORTDiscus, Medline, CINAHL and Academic search premier), Pubmed and Web of Science. Critical appraisal was performed using the validated Downs and Black appraisal tool.Results: Fifteen articles satisfied the inclusion criteria. Overall, articles appraised were scored fair to moderate methodological quality. All footwear revealed variable reductions of first peak EKAM and KAAI when compared to control shoes that were selected due to their stable and supportive nature. All research that compared shod conditions to barefoot walking found that shoes increased first and second peak EKAM and KAAI. Minimalist footwear reflected the kinetic and kinematic components of barefoot walking. Natural movement patterns and increased lower limb muscular activity are evidenced to be biomechanically and symptomatically beneficial.Conclusion: Biomechanical adaptations exhibited through use of conventional and offloading shoes increase EKAM and KAAI significantly when compared to the barefoot walking condition, this significantly increases the risk of disease progression. Minimalist footwear closely mimics the significantly lower knee loading and kinematic characteristics of barefoot walking. A therapeutic effect could be induced by providing a less supportive platform, thereby facilitating improved neuromuscular control, joint stability and alleviating abnormal joint loading