People with chronic pain present a special risk for surgeons, anaesthetists, nurses and the rehabilitation team working with them after surgery. Surgery is, after all, “planned trauma”, and a sensitive nervous system is going to be even more sensitive after a surgical insult – even when that surgery is intended to reduce pain.
One of the most cost-effective, and clinically-effective treatments for osteoarthritic hips and knees is to simply replace the offending joint with a shiny new one.
In one major New Zealand hospital, people are referred to the Orthopaedic Department by their GP or family doctor. The referral is screened for suitability, the individual is asked to see a physiotherapist for a physical performance test and to complete a set of questionnaires about function and pain. The results from this testing is returned to the Orthopaedic Surgery triage team who review the findings, and, depending on the level of disability, determine whether the person should then proceed to see a surgeon. Once a surgeon has reviewed the person in a face-to-face clinical consultation, if suitable for surgery, they may be placed on a waiting list and eventually have their surgery.
Surgeons like to be successful, and they try to identify those people who will do well with a joint replacement, but despite this, every year there are a good number of people who don’t get the result they’d hoped for. For some, the result might be a very slow recovery, some may do well then end up with a “squeaky” or “clunky” joint, some have an infection or the prosthesis doesn’t sit correctly or something goes awry and they need to have a revision of the joint.
In the case of knee joint replacements, the number one reason for surgical revision is ongoing pain. Now there are a number of reasons for this: the joint capsule is pulled and pushed around to get the replacement joint into place; there are a good many muscles to manipulate, the joint must be moved consistently after surgery so that range of movement is maintained, and so on.
But one reason could be because a group of patients receiving a joint replacement have additional risk factors for post-operative pain that remains unrecognised.
In a large study in Michigan, people about to undergo hip or knee replacement surgery were asked to complete a range of questionnaires – in this study, one of the items included in the questionnaires was the Michigan Body Map. This is a one-sided body map in which the respondent is asked to tick as many boxes as needed (up to 35) to identify where pain that has lasted longer than 3 months is experienced. The researchers used the responses from this questionnaire to calculate a Widespread Pain Index from the 19 specific body areas identified by the 2011 ACR suvey criteria for fibromyalgia. Additionally, they used the scores from a Symptom Severity Scale, added to the WPI and identified those with a score of 13 or more, which is thought to denote those with fibromyalgia from those without. Purists will note that this is not a typical methodology for diagnosing fibromyalgia, but it seems a pragmatic way to identify those with a greater potential for having this diagnosis than not.
Because people with fibromyalgia paradoxically have more endogenous opioids in their body, therefore fewer opioid receptors available to bind to any additional prescribed opioids, people with fibromyalgia need considerably greater doses of opioid than those without this diagnosis. In this study, therefore, the researchers monitored the use of opioids pre and post-operatively.
After some serious statistical work, the group found that younger people, anaesthetic technique, having a total knee replacement (as opposed to a total hip replacement), and longer stays were more likely to use a greater amount of opioid. And, more importantly, the scores obtained for fibromyalgia corresponded the most – an increased opioid consumption of 9.1mg for every 1-point increase on the 0 – 31 point scale.
What does this mean for nonmedical clinicians working with people in that important post-operative period?
Along with factors we already know about, such as the tendency to catastrophise or “think the worst”, it means this group of people need extra special care. Maybe we need to be very certain that these people have good pain relief on board before we start getting them to move. Maybe we need to carefully grade the amount of movement we ask from them in those early hours and days. Maybe we need to follow them up with very precise and careful prescribed exercises, and review these “at risk” people earlier than we need to for others.
Pre-operatively too, we might have some good things to suggest.
Watching our language – being cautious about emotive or alarmist language. Giving people visualisation and mindfulness training so they can use all that wonderful descending inhibition to reduce the sensitivity of their nervous system. Good relaxation, mindfulness, visualisation and diaphragmatic breathing is something people need to learn and be confident with well in advance of needing it. Letting people know that surgeons put the knee through its paces while they’re anaesthetised, so they know that the range of movement limitation they feel is due to post-operative healing rather than the joint not being properly seated in the joint. Giving people a guideline of the expectations we have for them to be able to get up and about despite pain – and that if they need pain relief, we will ensure they have it, irrespective of whether they seem to need “more” than we would expect.
Most importantly, I think allied health need to assess for the increased risk for having a sensitive nervous system before surgery, so we can take far greater care to reassure them and help them settle their nervous system down themselves.
Brummett CM, Janda AM, Schueller CM, Tsodikov A, Morris M, Williams DA, & Clauw DJ (2013). Survey criteria for fibromyalgia independently predict increased postoperative opioid consumption after lower-extremity joint arthroplasty: a prospective, observational cohort study. Anesthesiology, 119 (6), 1434-43 PMID: 24343289
This is from NOIJam – a great example of how it might work