Multimodal Pain Management With Adductor Canal Block Decreases Opioid Consumption Following Total Knee Arthroplasty

Ease of access to opioids in the perioperative period is a risk factor for opioid misuse and has been identified as a strong risk factor for heroin use.^1,2 Three-quarters of today’s heroin users were introduced to opioids through prescription medications.² The United States accounts for about 80% of the global opioid supply consumption, and deaths from opioid overdose are increasing: 70,630 deaths in 2019 alone.^3,4

The Centers for Disease Control and Prevention (CDC) has called for changes in opioid prescribing. The American Academy of Orthopaedic Surgeons (AAOS) also has published an information statement with strategies to decrease opioid misuse and abuse.^5,6 Arthroplasty surgeons have recently focused on decreasing use of opioids in total knee arthroplasty (TKA), a procedure traditionally associated with high levels of opioid consumption and historical reliance on opioid monotherapy for postoperative analgesia.^7,8 From a clinical perspective, prolonged postoperative opioid use contributes to poorer surgical outcomes due to increased risk of complications, including stiffness, infection, and revision TKA.⁹

Multimodal pain regimens are increasingly being used to control postoperative pain as data supports their efficacy.^10,11 Previous studies have found that simultaneous modulation of multiple pain pathways decreases narcotics consumption and improves patient outcomes.^12,13 Along with other adjuvant therapies, peripheral nerve blocks, such as adductor canal block (ACB) and femoral nerve block (FNB), have been used to decrease postoperative pain.¹⁴ Studies have shown that ACB has fewer complications and shorter functional recovery times compared with FNB.^15,16 The distribution of the ACB excludes the femoral nerve, thus preserving greater quadriceps strength while providing equivalent levels of analgesia compared with FNB.^15,17,18 The ACB has shown decreased near-fall events and improved balance scores in the immediate postoperative period.¹⁹

Our study analyzed opioid consumption patterns of TKA patients from a US Department of Veterans Affairs (VA) medical center before and after the institution of a multimodal analgesic protocol using ACB. The primary purpose of this study was to determine whether a protocol that included intraoperative spinal anesthesia with a postoperative multimodal analgesic regimen and ACB was associated with a decreased postoperative opioid requirement when compared with patients who received intraoperative general anesthesia and a traditional opioid regimen. Secondary outcomes included the effect of opioid consumption on range of motion on postoperative day (POD) 1 and number of opioid prescriptions written at the first postoperative clinic visit.

Methods

Approval for the study was obtained from the institutional review board at the Dayton Veterans Affairs Medical Center (DVAMC) in Ohio. A retrospective chart review was performed to collect data from all patients undergoing TKA at DVAMC from June 1, 2011, through December 31, 2015. Exclusion criteria included multiple surgeries in the study time frame, documented chronic pain, allergy to local anesthetics, daily preoperative use of opioids, and incomplete data in the health record.

All surgeries were performed by 2 staff arthroplasty surgeons at a single VAMC. All patients attended a preoperative visit where a history, physical, and anesthesia evaluation were performed, and watched an educational video detailing surgical indications and postoperative rehabilitation. All surgeries were performed with tourniquets and a periarticular injection was performed at the conclusion of each case. Surgeon 1 treatment of choice was 10 mL 0.5% bupivacaine, whereas surgeon 2 performed a posterior capsular injection of 30 mL 0.25% bupivacaine and a periarticular injection of 30 mg ketorolac in 10 mL 0.25% bupivacaine with epinephrine.

Prior to August 2014, general endotracheal anesthesia was used intraoperatively. A patient-controlled analgesia (PCA) pump of morphine or hydromorphone and additional oral oxycodone or hydrocodone was used for postoperative pain. PCA pumps were patient dependent. In the control group, 245 patients received the morphine PCA while 61 received the hydromorphone PCA. Morphine PCA dosing consisted of 1-mg doses every 10 minutes with potential baseline infusion rates of 0.5 to 1.0 mg/h and a 4-hour limit of 20 mg. Hydromorphone PCA dosing consisted of 0.2 to 0.4-mg doses with a potential continuous dose of 0.2 to 0.4 mg/h and a 4-hour limit of 4 mg.