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Retrospective analyzing the effects of nerve block on postoperative pain management after total knee arthroplasty

Yu‑Ning Huanga, Jen‑Hung Wangb, Po‑Kai Wanga,c*

aDepartment of Anesthesiology, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan, bDepartment of Medical Research, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan, cSchool of Medicine, Tzu Chi University, Hualien, Taiwan

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Open Access funded by Buddhist Compassion Relief Tzu Chi Foundation



Objective: Total knee arthroplasty (TKA) is usually associated with moderate‑to‑severe postoperative pain. Our study investigated the possible benefits of the use of nerve blocks (NBs), including pain score reduction, the rescuing dosage of morphine, the timing of ambulation, and the length of stay (LOS) in the hospital. Materials and Methods: We included patients who underwent unilateral primary TKA due to primary knee osteoarthritis under general anesthesia with laryngeal mask airway. The control group only received
oral pain medication with rescuing morphine injections, whereas the NB group received oral pain medication with an NB and rescuing morphine injections. We collected data on the patients’ basic characteristics, postoperative visual analog scale (VAS), the dosage of
rescuing morphine over 3 days, time to ambulation, and LOS in the hospital. Results: The NB group received significantly fewer morphine dose compared with the control group during postoperative days 1 to 3. There were no statistically significant differences
between the NB and control groups on days 1 and 2 in the VAS score, and the VAS score was significantly lower in the NB group on postoperative day 3. The NB group had a significantly shorter time to ambulation compared with the control group. LOS did not differ
significantly between the NB and control groups. Conclusion: Patients, who underwent TKA under general anesthesia with laryngeal mask airway (LMAGA) receiving NB for postoperative pain, needed less dosage of morphine and had the trend of having lower
VAS. There was no association with LOS between two groups, but time to ambulation might be decreased with NB group. Some limitations might need to be further investigated in future study, such as NB regimens, knee function after TKA, muscle power, information after discharge, and NB‑related complications.


Keywords: Nerve block, Postoperative pain management, Total knee arthroplasty

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