Pain is often moderate to severe following knee arthroscopy, and the addictive nature of opioids in its management is well documented. Currently, the British National Formulary (BNF, 2022a) states that opioid analgesics can be given to patients with moderate-to-severe postoperative pain, with the dose given as soon as the patient can eat and drink. The dosage is then reduced or adjusted as soon as possible so as to aid functional recovery. Morphine, if not administered orally, can be given via patient-controlled analgesia (PCA).
The National Institute for Health and Care Excellence (NICE, 2016) recommends caution when prescribing controlled drugs such as morphine. Both the benefits and risks should be considered, such as the dangers of over-prescribing, dependency, overdose and diversion. In addition, all medications currently being taken by the patient must be carefully considered, along with the possibility that the patient might be opioid-naïve (NICE, 2016).
Use of dexamethasone
In a recently published study, Gasbjerg et al (2022) explored dexamethasone as an analgesic adjuvant in multimodal pain management following total knee arthroplasty; the authors examined the effects of single and double doses of intravenous dexamethasone. They concluded that two doses of dexamethasone was able to reduce morphine consumption within 48 hours following a total knee arthroplasty, as well as reduce postoperative pain.
Dexamethasone is currently restricted to various conditions and not recommended as an adjunct for pain relief (BNF, 2022b). The only situation where dexamethasone is currently licensed for pain is in palliative care, where there is pain secondary to nerve compression (BNF, 2022b).
Systemic cautions advised for the use of dexamethasone include congestive heart failure, diabetes, diverticulitis, epilepsy, glaucoma, hypertension, hyperthyroidism, infection, psychiatric reactions, peptic ulcer, myocardial infarction, steroid-induced psychosis, thromboembolic disorders and ulcerative colitis (BNF, 2022b).
Implementation of this drug is not normally encouraged, as it is either common or very common for someone who has received dexamethasone to experience the following: anxiety, abnormal behaviour, cataracts, cognitive impairment, Cushing's syndrome, electrolyte imbalance, fatigue, fluid retention, gastrointestinal discomfort, headache, impaired healing, hypertension, menstrual irregularities, weight gain, nausea, osteoporosis, psychotic disorder, skin reactions and sleep problems (BNF, 2022b). While dexamethasone may reduce pain (BNF, 2022b), the question whether this outweighs its risks must still be posed.
Worldwide, there are over 1 million total knee arthroplasties a year, with this number set to increase as the population increasingly ages (Gasbjerg et al, 2022). The researchers note that multimodal pain management is required for the moderate-to-severe pain this procedure causes postoperatively (Gasbjerg et al, 2022).
A look at the research
Even with dexamethasone as an adjuvant to three non-opioid analgesic interventions, the researchers (Gasjberg et al, 2022) noted the reduction in morphine consumption of patients receiving dexamethasone corresponds to almost 25%. The authors were careful, however, to point out that there should not be an overemphasis on statistics such as this, given the use of dexamethasone is not always appropriate or deemed safe. Gasjberg et al (2022) gave participants a multimodal non-opioid treatment, and the reduction in morphine use with dexamethasone should therefore be considered in this context.
At 48 hours, only the group receiving a second dose of dexamethasone displayed reductions in pain and morphine use. The differences in morphine application can be used to reference the analgesic efficacy between intervention and placebo groups. Gasbjerg et al (2022) suggested that this can be considered a valid surrogate outcome mirroring patients' total pain. In addition, reducing morphine consumption can help patients avoid the adverse effects associated with the opioid.
Despite the well-documented history of adverse effects from dexamethasone in the BNF (2022b), Gasbjerg et al (2022) detected no differences in patient-reported adverse events within 0 to 48 hours between the groups, and found fewer serious adverse events within 90 days for patients who had two doses of dexamethasone rather than one. However, the researchers could not ascertain the reasoning for this. Interestingly, dexamethasone appeared to reduce postoperative opioid-related adverse effects such as nausea, vomiting, sedation, and dizziness (Gasjberg et al, 2022). The team was cautious to warn that the benefits observed in the study should always be interpreted in light of the known rare, but serious, adverse events that can occur.
An earlier study by Zhou et al (2018) showed similar results. They determined that administering dexamethasone could significantly reduce the use of opioids at 12 hours following total knee arthroplasty. Similar to Gasjberg et al (2022), Zhou et al (2018) saw a decreased risk of adverse effects in dexamethasone groups. The authors concluded the use of dexamethasone could therefore result in a reduction in pain following total knee arthroplasty and that adverse events could also be minimised through its use.
Conclusion
The management of pain, which has remained a multimodal method for sometime now, cannot always achieve full pain management and at times, produces significant adverse effects. Rehabilitation can be slow for patients with severe pain, but it is important to support the patient back to mobility as they are functional. Often, it is pain that prevents the patient from wanting to fully engage with physiotherapy. If dexamethasone can reduce adverse effects and reduce the use of highly addictive morphine, it sounds like a promising pathway. However, in a small group of patients, there will be very severe adverse events, which may not be a risk worth taking. Further research can shed light on the use of this drug as an adjunct to pain management, with clearly and fully ascertained risks.