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No Clinically Important Difference in Pain Scores After THA Between Periarticular Analgesic Injection and Placebo: A Randomized Trial

Hirasawa, Naoyuki, MD, PhD; Kurosaka, Kenji, MD; Nishino, Masahiro, MD; Nakayama, Tsutomu, PT; Matsubara, Masaaki, MD, PhD; Tsukada, Sachiyuki, MD, PhD

Clinical Orthopaedics and Related Research®: September 2018 - Volume 476 - Issue 9 - p 1837–1845
doi: 10.1097/CORR.0000000000000374
CLINICAL RESEARCH

Background Periarticular analgesic injection (PAI) is being used more commonly for pain relief after orthopaedic surgeries. However, there is conflicting evidence regarding the effectiveness of PAI for post-THA pain relief.

Questions/purposes In a double-blind, randomized, controlled trial among patients undergoing same-day bilateral THA, with each patient serving as his or her own control, we asked: (1) Did the pain score as measured on a 100-mm VAS differ between the hips that received PAI versus placebo? (2) Were there differences in complications between the treatment and control hips in these patients?

Methods Over a 1-year period at one center, 45 patients underwent same-day bilateral THA; three were excluded for prespecified reasons, and two declined participation in this randomized, controlled trial, leaving 40 patients (80 THAs) in the study. Patients randomly received PAI in one hip and placebo in the contralateral hip; patients, surgeons, and nurses were blinded in terms of which hip received the PAI and which hip received a placebo saline injection. The PAI solution included ropivacaine, morphine hydrochloride hydrate, methylprednisolone, ketoprofen, and epinephrine. The primary outcome was the VAS for pain at rest 24 hours after THA, measured using a 100-mm horizontal VAS. The VAS score was compared between two groups and assessed to reach the reported threshold values for the minimum clinically important difference (MCID) of 20 mm for the postoperative VAS score. No patients were lost to followup, and there were no missing data for the primary outcome. Complications that occurred during the trial were recorded prospectively with emphasis on infection, wound complications, nerve palsy and allergic reactions to the injections.

Results There were no clinically important differences between hips treated with the PAI and those treated with the placebo injection at any point. The hips that received PAI had less pain than those receiving placebo 24 hours after THA (16 ± 17 mm versus 22 ± 20 mm; mean difference, 6 mm; 95% confidence interval [CI], 2–9 mm; p = 0.006), but this effect size was below the MCID of 20 mm and thus is unlikely to be clinically important. The hips that received PAI also had better VAS scores in the recovery room (38 ± 29 mm versus 52 ± 33 mm; mean difference 14 mm; 95% CI, 5–23 mm; p = 0.004) and 3 hours after THA than placebo controls (28 ± 22 mm versus 37 ± 24 mm; mean difference 9 mm; 95% CI, 2–16 mm; p = 0.010). Neither of these differences exceeded the MCID and likewise were unlikely to be clinically important. No complications, including surgical site infections, were observed in either group.

Conclusions Periarticular analgesic injection for pain control after THA did not result in a clinically important reduction in pain at any point examined. Given the expense associated with this PAI mixture and the lack of effectiveness outside this timeframe, we cannot recommend its use. Other mixtures or concentrations of drugs may be helpful in short-stay admissions for THA, but this will require further research.

Level of Evidence Level I, therapeutic study.

N. Hirasawa, K. Kurosaka, M. Nishino, S. Tsukada, Department of Orthopaedic Surgery, Hokusuikai Kinen Hospital, Mito, Ibaraki, Japan

T. Nakayama, Department of Rehabilitation, Hokusuikai Kinen Hospital, Mito, Ibaraki, Japan

M. Matsubara, Department of Orthopaedic Surgery, Nissan Tamagawa Hospital, Tokyo, Japan

Each author certifies that neither he, nor any member of his immediate family, have funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.

Each author certifies that his institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

This work was performed at Hokusuikai Kinen Hospital, Ibaraki, Japan.

N. Hirasawa, Department of Orthopaedic Surgery, Hokusuikai Kinen Hospital, 3-2-1 Higashihara, Mito, Ibaraki 310-0035, Japan, email: hirari3@orion.ocn.ne.jp

Received January 30, 2018

Accepted May 22, 2018

© 2018 Lippincott Williams & Wilkins LWW
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