Despite the increasing interest in postoperative pain management and development of pain control modalities, more than half of the patients who undergo surgery experience inappropriate level of postoperative pain1
. In particular, pain after orthopedic surgery has been considered especially difficult to manage4
. Approximately half of total knee arthroplasty (TKA) patients present with extreme pain immediately after surgery1
Therefore, "immediate postoperative pain" is top on the list of concerns for TKA candidates12)
, which often results in a delay or cancellation of the surgical intervention13)
Severe postoperative pain after TKA can not only be a patient suffering but also negatively affect postoperative recovery. Extensive tissue damage in major operations, such as TKA, cause immediate changes in the endocrine system and central, peripheral, and sympathetic nervous systems, and stimulate catabolic hormone release including cortisol, glucagon, growth hormone, and catecholamine, resulting in compromised immunity, increased oxygen demand, and higher strain on the cardiovascular system11)
. If severe postoperative pain is managed inadequately under these circumstances, the surgery-induced responses can be exacerbated, posing a serious danger to patients.
Specifically, severe postoperative pain has been associated with serious complications including ischemic cardiac events and myocardiac insufficiency that result from increased stress on the cardiovascular system14)
. In addition, immobilization caused by pain may increase the risk of decreased pulmonary function15)
, gastrointestinal complications, such as ileus16)
, and thrombus formation that are related to surgical stress. An increase in stress hormone and sleep disorder due to severe pain can worsen the already decreased immunity, which leads to higher risk of infection. In particular, this may affect the mental status of elderly patients, causing delirium or anxiety disorder8
. Uncontrolled severe immediate postoperative pain can develop into chronic pain due to the sensitization of the nerve system17
. Accordingly, early rehabilitation and recovery can be delayed, resulting in longer hospitalization, higher medical costs, and more burden on the health care provider1
. Pain after TKA is a particularly serious problem, considering the substantially increasing TKA use and the aging population.
Therefore, proper management of pain after TKA is not just for the humane purpose of freeing patients from suffering. Rather, it is essential for successful TKA outcome in terms of improving patient satisfaction and quality of life and prevention of complications. The most important concept of current pain management following TKA is the preemptive use of multimodal approach. "Preemptive" refers to initiate pain management before surgical stimuli. In addition, "multimodal approach" means more than 2 drugs or modalities with different mechanisms or sites for synergistic effects. These two concepts have also been known to be remarkably effective for reducing the opioid consumption that has been associated with high complication rates.