Background: Postoperative pain after TKA is a major concern to patients. The best technique to control pain is still controversial. Intrathecal morphine or periarticular multimodal drug injection are both commonly used and both appear to provide better pain control than placebo, but it is unclear whether one or the other provides better pain control.

Questions/purposes: We asked whether intrathecal morphine or periarticular multimodal drug injection provides better pain control with fewer adverse events.

Methods: In a prospective, double-blind, randomized controlled trial we randomized 57 patients with osteoarthritic knees who underwent TKAs into two groups. Group M (n = 28) received 0.2 mg intrathecal morphine while Group I (n = 29) received periarticular multimodal drug injection. Postoperative pain was managed with patient-controlled analgesia using ketorolac. The outcomes were pain levels, the amount of analgesic drug used, and drug-related side effects. Patients and evaluators were blinded. All patients were followed up to 3 months.

Results: We found no difference in postoperative pain level, analgesia drug consumption, blood loss in drain, and knee function. More patients in Group M required antiemetic (19 [69%] versus 10 [34%]) and antipruritic drugs (10 [36%] versus three [10%]) than patients in Group I.

Conclusions: The two techniques provide no different pain control capacity. The periarticular multimodal drug injection was associated with lower rates of vomiting and pruritus.