Adverse Effect of Femoral Nerve Blockade on Quadriceps Strength and Function after ACL Reconstruction

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.

Deficits in Quadriceps Strength and Patient-Oriented Outcomes at Return to Activity After ACL Reconstruction

“…Of the 37 studies included in this review, 2 , 4 - 7 , 9 - 11 , 13 , 18 - 20 , 25 - 27 , 30 - 35 , 37 , 40 , 44 - 47 , 52 - 57 , 59 - 62 only 5 studies 26 , 27 , 33 , 56 , 60 met clinical recommendations at 6 months postsurgery, indicating that patients commonly return to activity post–ACL reconstruction with side-to-side quadriceps strength deficits that exceed 10% (Appendix 1, available at http://sph.sagepub.com/content/by/supplemental-data ). Strength deficits ranged anywhere from 3% to 40% compared with the noninjured limb, with an average strength deficit of 23% ± 8% reported at 6 months postsurgery.…”

“…Strength deficits ranged anywhere from 3% to 40% compared with the noninjured limb, with an average strength deficit of 23% ± 8% reported at 6 months postsurgery. 2 , 4 , 5 , 9 - 11 , 18 , 19 , 26 , 27 , 31 , 32 , 35 , 44 - 46 , 54 , 56 , 59 , 60 , 62 Of the 5 studies that met clinical recommendations (ie, side-to-side strength deficits ≤ 10%), 26 , 27 , 33 , 56 , 60 results were not conclusive as investigators used a wide range of concentric isokinetic velocities to quantify quadriceps strength at return to activity. Notably, in these studies, investigators found that side-to-side strength deficits still persisted at lower isokinetic velocities (60 deg/s), although patients displayed less quadriceps strength asymmetry at higher velocities (120, 180, and 240 deg/s).…”

“…When studies were separated by patellar tendon (PT) and hamstring grafts (semitendinosus gracilis [STG] and semitendinosus [ST]), individuals with patellar tendon grafts had an average side-to-side strength deficit of 25% ± 8% (range, 3%-41%) at 6 months postreconstruction 2 , 4 , 5 , 10 , 11 , 26 , 27 , 31 , 35 , 37 , 40 , 59 , 60 , 62 and 16% ± 6% (range, 3%-28%) at 12 months postsurgery. 2 , 4 , 6 , 13 , 32 , 37 , 55 , 59 - 61 In comparison, individuals with STG grafts report an average strength deficit of 18% ± 9% (range, 3%-38%) at 6 months 4 , 9 , 11 , 18 , 56 , 59 and 9% ± 5% (range, 3%-17%) at 12 months postsurgery.…”

“…At 6 months postreconstruction, 5 of the 9 included studies 4 , 18 , 26 , 27 , 31 , 35 , 52 , 59 , 62 met clinical criteria defined as performance deficits ≤10% of the noninvolved limb. 4 , 18 , 27 , 35 , 52 This result improved at 12 months postsurgery, wherein all but 2 studies 26 , 31 found limb symmetries ≤10% of the contralateral noninjured limb. Specifically at 6 months postreconstruction, physical deficits ranged from 3% to 29%, with a mean performance deficit of 11% ± 7% reported in this review.…”

Ultrasound-Guided Motor-Sparing Knee Blocks for Postoperative Analgesia Following Total Knee Arthroplasty

“…Since the TKA procedure is invasive, it is often associated with intense postoperative pain and therefore a comprehensive multimodal analgesic regimen 4,11,32,33 . Pain management after a TKA is of great importance because of the high incidence for severe acute postoperative pain which can interfere with patients' ability to sleep, walk, and participate in rehabilitation activities required for hospital discharge 3,34 .…”