Adjunctive Muscle Relaxants and Opioid Use Following Total Knee Arthroplasty

Area of Science:

• Orthopedic Surgery
• Pain Management
• Pharmacology

Background:

• The opioid crisis is a major concern in the U.S., particularly within orthopedic practices.
• Postoperative pain management after total knee arthroplasty (TKA) frequently involves opioid prescriptions.
• Investigating non-opioid adjuncts is crucial for reducing opioid dependence.

Purpose of the Study:

• To evaluate the efficacy of skeletal muscle relaxants (SMRs) as an adjunct therapy for decreasing postoperative opioid consumption in TKA patients.
• To compare opioid use, pain scores, and length of stay between TKA patients who received SMRs and those who did not.

Main Methods:

• Retrospective cohort study of 157 patients undergoing elective TKA between July 2012 and July 2020.
• Patients receiving scheduled SMRs during hospitalization were matched 1:2 with a control group not receiving SMRs.
• Primary outcome: daily Morphine Milligram Equivalents (MME); Secondary outcomes: pain scores, length of stay, complications.

Main Results:

• Median daily MME was similar between the SMR group (n=55) and the control group (n=102) (80.2 vs 78.2, p=0.37).
• No significant differences in adverse events were observed between the groups.
• Patients receiving SMRs reported higher postoperative day 1 pain scores and had a longer length of admission.

Conclusions:

• Adjunct use of SMRs did not significantly decrease immediate postoperative opioid use in TKA patients.
• SMRs did not demonstrate a benefit in reducing opioid requirements and were associated with increased pain and admission duration.
• Further prospective research is needed to definitively assess the role of SMRs in multimodal pain management after TKA.