Ultrasound-Guided Motor-Sparing Knee Blocks for Postoperative Analgesia Following Total Knee Arthroplasty: A Cost Analysis

Background: We recently performed a clinical trial comparing motor sparing blocks (MSB) to periarticular infiltration (PAI) following total knee arthroplasty (TKA). We found that MSBs provided longer analgesia (8.8 hours) than PAI with retention of quadriceps strength, and with similar function, satisfaction, and length hospital stay. However, its potential increased cost could serve as a barrier to its adoption. Therefore, our aim was to compare the costs of MSBs to PAI following TKA. Methods: We conducted a retrospective review of data from our previous RCT. There were 82 patients included in the RCT (n = 41 MSB group, n = 41 PAI group). We compared the mean total costs associated with each group until hospital discharge including intervention costs, health-care professional service fees, intraoperative medications, length of stay, and postoperative opioid use. Results: Seventy patients were included (n = 35 MSB group, n = 35 PAI group). The mean total costs for the MSB group were significantly higher ($1959.46 [+ or -] 755.4) compared to the PAI group ($1616.25 [+ or -] 488.33), with a mean difference of $343.21 (95% CI = $73.28 to $664.11, p = 0.03). The total perioperative intervention costs for performing the MSB was also significantly higher; however, postoperative inpatient costs including length of stay and total opioid use did not differ significantly. Conclusion: Motor sparing blocks had significantly higher mean total and perioperative costs compared to PAI with no significant difference in postoperative inpatient costs. However, its quadricep sparing nature and previously demonstrated prolonged postoperative analgesia can be used to facilitate an outpatient TKA pathway thereby offsetting its increased costs. Keywords: costs, total knee arthroplasty, outpatient arthroplasty, adductor canal blocks, periarticular infiltration, motor sparing blocks