Comparison Ultrasound-Guided Adductor Canal Block and Surgeon-Performed Block for Pain Management After Total Knee Arthroplasty: A Prospective Randomized Controlled Study

1. Introduction In advanced stages of osteoarthritis (OA) of knee, one of major option of treatment is total knee arthroplasty (TKA). Approximately 20% of individuals who undergo TKA experience a loss of physical function, primarily due to the variable intensity of post-operative pain. The risk of thromboembolism due to ambulation limitations and immobility increases along with pain . Various approaches have been proposed to manage post-operative pain. Three distinct regimens have been developed to control pain that develops after TKA. These can be pre-operative, intraoperative, and post-operative analgesic regimens . The main component of the pre-operative regimen is opioids. Local infiltration analgesic regimens are considered in the intraoperative regime, while peripheral nerve blocks are examined in the post-operative analgesic regime .

Opioids are effective in pain management, yet they come with limited side effects . Local infiltration anesthesia administration is straightforward and carries a low risk of systemic toxicity . While various methods exist, the posterior capsule is a commonly targeted administration site. Adductor canal block (ACB) can be performed pre-operatively, intraoperatively, or post-operatively. The motor branches of the femoral nerve are preserved while blocking the saphenous nerve, and quadriceps muscle strength is minimally affected. Hospital stay is shortened. ACB is becoming increasingly popular due to these advantages. ACB is routinely performed with ultrasound (USG) pre-operatively or post-operatively. In addition, intraoperative ACB performed by the surgeon has recently been introduced. One of the techniques utilized to alleviate post-operative pain is known as posterior capsular infiltration analgesia (PCI). In PCI, local sensory nerve endings are targeted. PCI preserves muscle strength and does not negatively impact functional recovery.

The objective of this study is to compare postoperative pain among knee prosthesis patients who undergo adductor canal block (ACBa) performed by an anesthetist using ultrasound guidance, ACB (ACBs) performed intraoperatively by the surgeon, and those without ACB. 2. Materials and Methods This study has been designed in a double-blind, randomized, controlled trial format. The study included 255 participants diagnosed with knee osteoarthritis and underwent TKA surgery between May 2021 and May 2022 at our university hospital. The sample size for the study was determined through a power analysis. Based on power analysis for the F-test with a Type I error rate of 0.05, a 95% confidence interval, and a Type II error rate of 0.10, the requisite total sample size is determined to be 207 subjects (equating to 69 patients per group). Owing to the potential employment of non-parametric tests within the analyses, it is recommended to augment the sample size by 15%. Consequently, the calculated sample size necessary is established at 240 subjects (thereby requiring 80 patients per group). This study will be conducted in accordance with the principles of the Declaration of Helsinki. Ethical approval for the study was been obtained from the ethics committee of the institution where the researchers are employed (Kirsehir Ahi Evran University, Faculty of Medicine Ethics Committee, IRB approval number: 2022-08/89). Participation was voluntary. Informed consent was obtained from the participants, indicating that their information would be used in the study, but their identities would remain confidential.

Physical examinations were repeated on participants before the surgery, and pre-operative anesthesia examinations were conducted. At this stage, the acceptance criteria for the participants were evaluated. Inclusion criteria were defined as end stage (Kellgren-Lawrence grade 4) knee osteoarthritis, treated with primary TKA and willing to participate the study. The following were excluded from the study: refusal to participate, underwent revision TKA, allergy to any of the painkillers used, contraindication to regional or spinal anesthesia, use of narcotic painkillers prior to surgery, sensory or motor neuropathy, cirrhosis of the liver, chronic renal failure. The study was continued with 240 participants after excluding those who did not meet the criteria. The participants were randomly divided into three groups, one being the control group. Figure 1 shows the Consolidated Standards of Reporting Trials (CONSORT) diagram.

A computer-generated randomized list was generated from which participants were randomly allocated to one of the three study groups in a 1:1:1 allocation ratio. Adductor canal block plus posterior capsular infiltration analgesia was performed intra-operatively by the surgeon using anatomical landmarks, and no additional imaging was performed (ACBs). Adductor canal block plus posterior capsular infiltration analgesia was performed post-operatively by a specialist in anesthesiology with the help of ultrasound (ACBa). Finally, a control group underwent PCI only. Patients were evaluated postoperatively by different authors for double-blind.