Does Adductor Canal Block After Knee Manipulation Reduce Post-Manipulation Opioid Prescribing or Improve Range of Motion?

Introduction Manipulation under anesthesia (MUA) is a non-invasive intervention commonly performed after total knee arthroplasty (TKA) for persistent knee stiffness unresponsive to conservative measures. Adjunctive strategies, including periarticular injections and regional anesthesia, have been proposed to improve pain control and outcomes following MUA. This study evaluated whether adductor canal block (ACB) at the time of MUA reduces postoperative opioid use and improves range of motion (ROM). Methods We performed a retrospective review of 83 consecutive patients undergoing MUA after TKA between October 2021 and April 2024 at a single institution. All patients after June 28, 2023 were offered ACB per an initiative set by the institution's Department of Anesthesia. Patients receiving ACB after the initiative were compared to controls prior to the initiative. Five patients were excluded (four lost to follow-up, one due to concomitant open lysis of adhesion), leaving 78 patients: 39 received ACB and 39 served as controls. Demographic variables collected included age, sex, and relevant medical comorbidities. Clinical variables comprised of time to manipulation, pre- and post-manipulation range of motion (ROM), and postoperative opioid prescription data. Results Mean time to MUA was 76.6 days after TKA; controls underwent earlier manipulation (64.2 vs 88.9 days). Pre-manipulation ROM ranged from 4.3°–84.1° in controls and 2.8°–85.5° in the ACB group. At two weeks, ROM improved to 2.5°–102.7° and 1.2°–101.8°, respectively (p=0.821). Eighteen patients (23.1%) received opioid prescriptions within 30 days, most commonly oxycodone 5 mg. Opioids were prescribed to seven (17.9%) of controls and eleven (28.2%) of ACB patients (p=0.345). Mean morphine milligram equivalents were 43.7 (S.D. 115.9) and 70.6 (122.3), respectively (p=0.225). The remaining patients did not require opioid prescriptions during the post-manipulation period. Conclusion MUA resulted in short-term ROM improvement regardless of ACB use. Although the ACB group underwent later manipulation, both groups achieved comparable gains at two weeks. ACB was not associated with reduced opioid prescribing or improved ROM, suggesting no measurable benefit in this setting.