Virtual Reality for Post Operative Pain Management After Total Knee Arthroplasty: a Randomized, Controlled, Multi-center, Double Blind, Parallel Group, Superiority Trail to Evaluate VR as a Component of a Multi-modal Pain Treatment

Introduction: Postoperative pain frequently occurs after total knee arthroplasty. The IASP defines pain as "an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage". Pain is a major cause of post-operative distress and has a variety of side effects and complications. Chronic post surgical pain is probably the most feared complication of acute pain. Therefore, adequate pain control after surgery is mandatory.

In modern western healthcare, multi-modal pain treatment is the standard of care. This means that a variety of drugs, acting on different receptors, are used alongside non-pharmacological interventions, to decrease pain. Such an approach enables the physician to use a lower concentration of a specific drug, in order to avoid adverse effects that can occur when giving higher doses of one individual drug. These drugs are based on the analgesic ladder of the WHO to relief cancer pain. From the different drugs that are used, the major concern will be with the opioids, as they are known to have major complications. Especially today in the USA there is an epidemic of opioid related deaths. Very often these drugs have been prescribed in a post-operative setting. The search for a different non-pharmacological analgesic treatment is today, more than ever, a pressing need.

Virtual reality (VR) is a non-pharmacological way to decrease pain in a number of different situations. It has been around for some years, some articles describing VR in medicine are 25 years old but it only recently became a popular medical treatment since the introduction of the Oculus Rift in 2014. Before that HMDs (head-mounted display) were expensive and very bulky devices. Since the introduction of the Oculus Rift HMD the availability and usability of VR has increased dramatically.

In the post-operative period pain at rest is generally reported to be acceptable by our patients (VAS<3), but if movements are involved the pain increases to unacceptable levels. Postoperative physiotherapy generally involves the use of a continuous passive motion (CPM), a machine used for passive bending of the knee. This postoperative mobilization is one of the major causes of pain in the aftermath of a total knee arthroplasty.

Available evidence: Virtual Reality (VR) has been shown to reduce pain in different situations. From experimental pain in healthy subjects to changing dressing of burn patients, several studies have shown the use of immersive VR therapy as an adjunct for pain treatment.