Introduction
Pain is a concern after surgery
Traditional pain protocol
Contemporary pain protocol
Local level
Peripheral nerve level
Spinal level
Cortical level
Pre-emptive analgesia
Conclusion
Introduction
Total knee replacement surgery is indicated for advanced osteoarthritis of knee. It had a poor reputation as being very painful and entailing lengthy rehabilitation. This is a review on pain management following total knee surgery and the pain management protocol.
Pain is a concern after surgery
Pain is defined as an unpleasant sensory and emotional experience associated or described with actual or potential tissue damage. Failure to control pain following total joint replacement can increase postoperative morbidity, impede rehabilitation, increase anxiety and decrease overall patient satisfaction. Postoperative wound pain can be intensified with movement and physical therapy. On the other hand, early mobilization and avoiding prolonged lying in bed are essential in order to prevent deep venous thrombosis, a complication that potentially can lead to a serious complication called pulmonary embolism.
Traditional pain protocol
Traditional method relies heavily on oral or parenteral opioids. Opioid medications provide predictable pain relief. However, if used as a sole agent for postoperative pain relief, it increases the incidence of dose related side effects including nausea, vomiting, ileus of bowel, constipation, urinary retention, excessive somnolence and even respiratory depression.
Contemporary pain protocol
The concept of pre-emptive analgesia reduces the intensification of pain stimuli and pain transmission along the pain pathway. Contemporary method relies on combination of medications, given at different levels along the pain pathway well before the surgical procedures. Pain is controlled at local, peripheral nerve, spinal and cortical levels.
Local level
At local level, a mixture of medications can be given at the soft tissue and skin around wound. This is called cocktail injection. The medications include local anaesthetics, anti-inflammatory drugs and opioids.
Peripheral nerve level
As knee is innervated by peripheral nerves, pharmaceutical blockade of the nerves can reduce pain signal transmission. Anaesthetists can give either a single shot or inserting a catheter to allow continuous infusion of medications to the related peripheral nerve.
Spinal level
Anaesthetists can insert a needle into spinal canal and give medication for spinal anaesthesia. Also, during the same procedure, they can insert a catheter into the epidural space to control the postoperative pain.
Cortical level
Patients should receive preoperative education before elective total knee surgery to prepare them for a realistic expectation about the post-operative wound pain. Contemporary protocol allows excellent pain relief but does not mean there is no pain. Patient should expect some pain especially during movement of the joint. However, the pain should not stop them undergoing physical therapy or mobilization. If so, they should contact their attending doctor.
Pre-emptive analgesia
Oral medications including anti-inflammatory drugs or opioids are given as the preemptive analgesia. It is to stop or limit pain transmission before it amplifies. Continuous use of the same medication is usually required after the operation.
Conclusion
Total knee replacement is not very painful as previously thought. The advance in pain management has allowed patient much earlier and more comfortable rehabilitation after this major orthopaedic procedure. Currently, most patients can ambulate with walking aids in 1 to 2 weeks. In three months, most patients can experience improved walking ability after this surgery
Dr. NG, Fu-yuen