Abstract
The purpose of this study was to determine if quadriceps strength and functional outcomes
were similar at 6 months following anterior cruciate ligament [ACL] reconstruction
in patients receiving a continuous 48-hour femoral nerve blockade for postoperative
analgesia (FNB group) versus patients with no FNB (control group). A retrospective
cohort was designed including athletes who underwent primary ACL reconstruction with
patellar tendon autograft between 2005 and 2010 at our institution with identical
rehabilitation protocols. The FNB group included 96 patients with an average age of
21 years and the control group included 100 patients with an average age of 20 years.
At 6 months following ACL reconstruction, isokinetic strength (slow and fast activation)
and functional tests including vertical jump, single hop, triple hop, and return to
sport were analyzed with an α value < 0.05 as significant. Multivariate regression models were used to compare
these outcomes between the FNB and control groups after adjusting for gender and competitive
athlete status. At 6 months, fast extension isokinetic strength was inferior in the
FNB group (78 vs. 85%; p < 0.01). After adjusting for gender and competitive athlete status, fast (p = 0.002) and slow extension strength (p = 0.01), vertical jump (p = 0.03) and single jump (p = 0.02) were also inferior in the FNB group. There were no significant differences
in full return to sport between the two groups (86% at 7.5 months in the FNB group
vs. 93% at 7.3 months in the control group). In this retrospective comparative study,
the hypothesis that patients treated with continuous FNB for postoperative analgesia
following ACL reconstruction with patellar tendon autograft will have inferior knee
extension (quadriceps) strength and function at 6 months follow-up was affirmed. However,
no differences were observed in return to sport, bringing into question whether these
statistical differences translate into meaningful clinical consequences after ACL
reconstruction. The level of evidence was level III, retrospective case–control series.
Keywords
ACL reconstruction - femoral nerve blockade - quadriceps strength - isokinetic strength
- functional testing