Is pain after TKA better with periarticular injection or intrathecal morphine?

59 patients undergoing total knee arthroplasty (TKA) were randomized to receive either spinal anesthesia with intrathecal morphine sulfate or periarticular multimodal drug injections. The purpose of the study was to compare which method provided better pain alleviation and fewer adverse events. Following 3 months of assessment, there no significant differences between the two techniques concerning pain and function. However, the incidences of nausea, vomiting, and pruritus were significantly higher for patients who received the intrathecal morphine sulfate.