Should we abandon femoral nerve block?

黄建宏

Should we abandon femoral nerve block?

Femoral Nerve block has been widelyutilized for postoperative analgesia in patients underwent ACL reconstructionand total knee replacement. However, recently, more and more surgeons abandonfemoral nerve block.

One study showed subclinicalfemoral nerve palsy rates up to 24% as diagnosed by electromyogram (EMG) at 4weeks following ACL reconstruction (1).

A retrospective matched case–controlstudy was conducted by Aaron Krych, MD, Mayo Clinic. The results was publishedin 2015 Journal Knee Surgery (2). This new study created more debate whetherfemoral nerve block should be abandoned.

They collected data of all patientswith a history of primary ACL reconstruction performed between 2004 and 2010. Patients18 years of age and older undergoing primary one-incision, arthroscopically assistedpatellar tendon autograft ACL reconstruction for acute ACL tears. Competitiveathletes were defined as playing high school, college, or professionalathletics. Confirmation of block use was obtained by analyzing the anesthesiarecord of each patient.

In the FNB group, all patientsunderwent placement of a preoperative indwelling femoral nerve catheter using astimulation needle technique by an experienced anesthesiologist. The catheterinsertion was approximately 5 cm in depth with a bolus of bupivacaine 0.5% with1:200,000 epinephrine (20–30 mL) followed by an infusion of bupivacaine 0.1% (10mL/h X 40 hours) with a home-going pump.

Patients in both groups were treatedwith identical rehabilitation protocols.

At 6 months following ACLreconstruction, isokinetic strength testing, measured as maximum repetitiontotal work at both 60 degrees/s (slow activation) and 180 degrees/s (fastactivation)

for knee extension (quadriceps) andknee flexion (hamstrings) was performed with a Biodex machine.

At 6 months following ACL reconstruction,functional tests including vertical jump, single hop, and triple jump were performedand supervised by a trained physical therapist.

Results:

The patients in the FNB group weresimilar to the patients in the control group.

In a univariate analysis at 6 months,fast extension isokinetic strength was worse in the FNB group (78 vs. 85%; p <0.01).

After adjusting for gender andcompetitive athlete status in the multivariate analysis, patients in the FNB groupwere weaker in fast and slow extension strength, and also slow flexion strengththan patients in the control group (without FNB).

Patients in the FNB group did worsein the vertical jump and single hop, with triple hop approaching significance.

No significant differences in fullreturn to sport between the two groups were noted with 86% returning to sportat 7.5 months in the FNB group versus 93% returning to sport at 7.3 months inthe control group.

Conclusions:

Patients treated with continuousFNB for postoperative analgesia following ACL reconstruction with patellartendon autograft had inferior knee extension (quadriceps) strength and functionat 6 months follow-up.

Questions:

Will the evidence from the studychange your practice?

References

• AlbrechtE, Niederhauser J, Gronchi F, et al. Transient femoral neuropathy after kneeligament reconstruction and nerve stimulator-guided continuous femoral nerve block:a case series. Anaesthesia 2011;66(9):850–851
  
  

• Krych A, Arutyunyan G, Kuzma S, Levy B, Dahm D,,Stuart M: AdverseEffect of Femoral Nerve Blockade on Quadriceps Strength and Function after ACL Reconstruction.JKnee Surg 2015; 28:83–88
  
  

anescn

of course not. first, it work nicely as its indicated with high safety margin. second, combined with sciatica  nerve block, it work greatly for lower extrimtity for a patient spinal or epidural is not indicated. third, with guidance of ultrasound, it is a very efficient procedure.

黄建宏

what we concern about this article:
most patients who underwent ACL repair are athletic players. they have a dream to become professional players. If femoral nerve block can cause muscle weakness, then their dream may end. Therefore they may potentially against the healthcare providers.

anescn

it is very unlikely first of all. you job is go over benefits and risks with patients. respect patient 's autonomy and decision and provid alternatives are important steps to make anesthesia decisions. this doesn't necessarily mean you need bandond femoral block. much more important is you have more options and individualize d when you make decision. also anesthesia decision is all about benefits and risks.