Associate Professor Gwyn Lewis
Neurophysiologist, Department of Physiotherapy, Auckland University of Technology, Auckland, NZ
Associate Professor Gwyn Lewis works in the Department of Physiotherapy at the Auckland University of Technology, New Zealand. She obtained a PhD in 2003 and then had an extended post-doctoral experience undertaking research in motor control, rehabilitation, and neurophysiology. Her current research focus is in acute and chronic pain, particularly around pain neurophysiology and the development of persistent pain. She has undertaken specific research projects examining neural plasticity associated with pain and pain modulation, cognitive and psychosocial influences on pain, and predictors of chronic pain development.
Persistent Pain following Total Knee Arthroplasty
Total knee arthroplasty (TKA), or knee joint replacement, is one of the most common orthopaedic surgeries performed. TKA is usually undertaken in patients with end-stage osteoarthritis of the knee when non-surgical management is no longer effective. One of the primary reasons that TKA is performed is to reduce pain associated with the joint. However, 20% or more of patients report ongoing pain in the affected joint 1-2 years after surgery. A meta-analysis we conducted found that pain catastrophising, poor mental health, high preoperative knee pain, and pain at other sites were the strongest predictors of persistent pain after TKA, although the associated effect sizes were small. A subsequent prospective study of 300 people undergoing TKA examined clinical, psychological, physiological, and genetic predictors of persistent pain. Similar to the review, we found that preoperative pain, expected pain, and anxiety were the strongest predictors of pain outcomes. Again, the predictive ability was only fair, but the findings give insight into areas that may be targeted in future interventions. Clinical implications and future directions will be discussed.