With ongoing advancements in healthcare leading to prolonged life expectancy, orthopedic
surgeries are increasingly performed in elderly patients. Total knee arthroplasty, in
particular, has been increasing with the growing demand for improved mobility and quality of
life. Total knee arthroplasty is performed on patients with advanced and painful
osteoarthritis of the knees, but it can result in moderate to severe postoperative pain
during the recovery period.
To relieve anxiety or stress during surgery under regional anesthesia, sedation can be
provided. Dexmedetomidine is a sedative-analgesic agent acting as α2-adrenergic receptor
agonist, and its analgesic effect has been well established in various procedures or
surgeries.
Magnesium has been reported to produce important analgesic effects including the suppression
of neuropathic pain, potentiation of morphine analgesia, and attenuation of morphine
tolerance. Although the exact mechanism is not yet fully understood, the analgesic properties
of magnesium are believed to stem from regulation of calcium influx into the cell and
antagonism of N-methyl-D-aspartate (NMDA) receptors in the central nervous system. In this
study, investigators will evaluate the reducing effect of magnesium on the post-total knee
arthroplasty pain in patients sedated with dexmedetomidine under spinal anesthesia.