Isokinetic Strength Deficit 6 Months After Adductor Canal Blockade for Anterior Cruciate Ligament Reconstruction

BACKGROUND: Recent evidence shows a delayed return to sport in children and delayed quadriceps recovery in both adults and children who have undergone anterior cruciate ligament (ACL) reconstruction with concomitant femoral nerve blockade (FNB) compared with those who had no blockade. We evaluated the use of adductor canal blockade (ACB), as an alternative to FNB, at the time of ACL reconstruction. HYPOTHESIS: Patients who receive ACB will have greater isokinetic strength at 6 months postoperative compared with patients who receive FNB at the time of ACL reconstruction. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective record review was performed at a single academic medical center to identify all patients aged ≥16 years who had undergone ACL reconstruction with blockade between January 2010 and January 2015. Exclusion criteria included (1) non–sports medicine fellowship–trained surgeon performing the procedure, (2) continuous nerve catheter or concurrent epidural used, (3) revision ACL reconstruction or multiligament reconstruction as the index procedure, (4) previous contralateral ACL reconstruction, (5) concurrent microfracture, and (6) additional surgery within the 6-month outcome period that affected recovery. Isokinetic strength testing was performed using a computerized dynamometer, measuring total work at fast speed and peak torque at slow speed at 6 months; results were evaluated as a percentage of the nonoperative side. Multivariate regression analysis was used to evaluate the effect of block type on isokinetic strength outcome variables, controlling for age, sex, body mass index, graft type, and surgeon. RESULTS: There were 230 patients receiving FNB and 30 patients receiving ACB included in the study. The multivariate regression analysis identified a greater side-to-side deficit in extension total work for the ACB group compared with the FNB group (P = .040), after controlling for age, sex, body mass index, graft type, and surgeon. CONCLUSION: Compared with FNB, ACB for ACL reconstruction is associated with a persistent fast-activation isokinetic strength deficit at 6 months after surgery. This is the first study to compare FNB to ACB, and results are concerning for patients planning an early return to sport.