Quadriceps Weakness After Single-Shot Adductor Canal Block: A Multivariate Analysis of 1,083 Primary Total Knee Arthroplasties.

BACKGROUND: Adductor canal blocks (ACBs) are commonly employed in multimodal pain control for total knee arthroplasty (TKA) and minimize motor blockade compared with femoral nerve blocks. Quadriceps weakness may be associated with ACBs. The purpose of this study was to quantify the prevalence of clinically relevant quadriceps weakness after a single-shot ACB and to identify the factors that are associated with its diagnosis. METHODS: The study group consisted of 1,083 retrospectively reviewed consecutive TKAs that were performed with ACBs at an academic hip and knee center. Quadriceps weakness was quantified with a standardized rating system during the initial physical therapy evaluation, and 23 potential covariates were analyzed. RESULTS: The prevalence of quadriceps weakness was 9%. Increasing the dose of the ACB anesthetic per unit of body mass index (BMI) increased the probability of quadriceps weakness by 5.0 times (95% confidence interval [CI], 1.9 to 13.3; p = 0.001). The highest probability of quadriceps weakness (52.9%) was associated with women who received the highest anesthetic dose per unit of BMI and an epinephrine extender but no corticosteroid extender. CONCLUSIONS: The optimal volume of local anesthetic in ACBs to maintain pain control while minimizing quadriceps weakness has not yet been defined. Our observation that quadriceps weakness was associated with increasing doses of ACB anesthetic per unit of BMI suggests that more than traditional structural canal-fill parameters (i.e., filling the distal aspect of the adductor canal without spreading to the femoral triangle) should be considered when choosing injectates and injectate volumes for ACBs. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Identifiable Risk Factors to Minimize Postoperative Urinary Retention in Modern Outpatient Rapid Recovery Total Joint Arthroplasty.

BACKGROUND: Postoperative urinary retention (POUR) following total joint arthroplasty (TJA) presents a significant barrier to outpatient and early discharge TJA. This study examined the incidence and risk factors for acute POUR in a modern, evidence-based, outpatient, and early discharge TJA program. METHODS: Prospectively recorded data on 685 consecutive primary unilateral TJAs discharged the day of or day after surgery were retrospectively reviewed. POUR was diagnosed by a perioperative internal medicine specialist. Univariate analysis of potential predictors was performed, followed by binary logistic regression (BLR) testing of predictors with P ≤ .25. RESULTS: After exclusions for confounds, the final analysis sample consisted of 633 procedures. The overall incidence of POUR was 5.5% (3.9% for same day discharges). Male gender, history of urinary retention, use of rocuronium, use of glycopryrrolate, use of neostigmine, fentanyl spinals, and the absence of an indwelling urethral catheter were associated with acute POUR and met criteria for entry into multivariate BLR. Seventeen additional predictors, including kidney disease and outpatient surgery were unrelated to POUR. In the final BLR model (P = .001), male patients who received glycopyrrolate with neostigmine had a 34% probability of developing POUR, which declined to 2.8% in the absence of these risk factors. CONCLUSION: Despite a relatively low incidence of 5.5%, avoidance of anticholinergics and cholinesterase inhibitors during anesthesia should be carefully considered in outpatient TJA, particularly in stand-alone ambulatory surgery centers.