Rehabilitation Outcomes for Total Knee Arthroplasties: Continuous Adductor Canal Block Versus Continuous Femoral Nerve Block

Objective: To determine whether any strength, range of motion (ROM), or functional improvement exists in the adductor canal block (ACB) group after completion of inpatient rehabilitation and following the removal of the continuous block. Design: Retrospective cohort. Setting: Inpatient rehabilitation at discharge and outpatient orthopedic clinic for follow-up. Participants: Two hundred forty-six consecutive primary total knee arthroplasties (TKAs; N = 221 patients) performed by a single surgeon in a single institution between July 2013 and August 2015 for a diagnosis of osteoarthritis. Interventions: All TKA cases received a continuous femoral nerve block (FNB) from July 2013 to August 2014 for postoperative pain control. From August 2014 through August 2015, all TKAs received a continuous ACB. Main Outcome Measures: Manual muscle tests (MMTs; 0-5 scale) of the quadriceps and passive ROM of the knee were assessed at 3 time periods (hospital discharge [HD], 1-2 weeks, and 1 month). Patient-oriented outcomes and clinical knee scores were examined preoperatively and postoperatively at 3 and 6 months. Results: 63.6% of FNB cases had an MMT less than 3 at HD and 36.4% of FNB cases had an MMT of 3 or greater at HD. Conversely, 46% of ACB cases had an MMT less than 3 at HD and 54% had an MMT of 3 or greater at HD. There were no statistically significant differences in all postoperative variables at all tested time periods. Conclusions: This study showed no short-term postoperative advantages in the ACB group after catheter removal. The superior inpatient rehabilitation course in the continuous ACB group is likely not long enough to translate into any maintained benefit following catheter removal. Nevertheless, the trend toward greater strength in the ACB group in the immediate short term at HD warrants further investigation