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RCT
ACE Report #8824

Lateral femoral cutaneous nerve block does not demonstrate analgesic efficacy in THA


Study Type:Therapy
OE Level Evidence:2
Journal Level of Evidence:N/A

Effect of lateral femoral cutaneous nerve-block on pain after total hip arthroplasty: a randomised, blinded, placebo-controlled trial

BMC Anesthesiol. 2016 Mar 23;16(1):21

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Synopsis

120 patients scheduled for total hip arthroplasty were randomized to receive either an ultrasound-guided lateral femoral cutaneous nerve (LFNC) block or placebo, in addition to standard oral paracetamol and ibuprofen, and oxycodone for breakthrough pain. The purpose of this study was to evaluate if the use of a LFCN block significantly reduce pain scores and opioid consumption within the first 24 hours postoperative in comparison to placebo. No significant difference between groups in pain score or opioid consumption were observed.

Publication Funding Details +
Funding:
Non-Industry funded
Sponsor:
Department of Anaesthesiology, Næstved Hospital
Conflicts:
None disclosed

Risk of Bias

7.5/10

Reporting Criteria

19/20

Fragility Index

N/A

Was the allocation sequence adequately generated?

Was allocation adequately concealed?

Blinding Treatment Providers: Was knowledge of the allocated interventions adequately prevented?

Blinding Outcome Assessors: Was knowledge of the allocated interventions adequately prevented?

Blinding Patients: Was knowledge of the allocated interventions adequately prevented?

Was loss to follow-up (missing outcome data) infrequent?

Are reports of the study free of suggestion of selective outcome reporting?

Were outcomes objective, patient-important and assessed in a manner to limit bias (ie. duplicate assessors, Independent assessors)?

Was the sample size sufficiently large to assure a balance of prognosis and sufficiently large number of outcome events?

Was investigator expertise/experience with both treatment and control techniques likely the same (ie.were criteria for surgeon participation/expertise provided)?

Yes = 1

Uncertain = 0.5

Not Relevant = 0

No = 0

The Reporting Criteria Assessment evaluates the transparency with which authors report the methodological and trial characteristics of the trial within the publication. The assessment is divided into five categories which are presented below.

4/4

Randomization

3/4

Outcome Measurements

4/4

Inclusion / Exclusion

4/4

Therapy Description

4/4

Statistics

Detsky AS, Naylor CD, O'Rourke K, McGeer AJ, L'Abbé KA. J Clin Epidemiol. 1992;45:255-65

The Fragility Index is a tool that aids in the interpretation of significant findings, providing a measure of strength for a result. The Fragility Index represents the number of consecutive events that need to be added to a dichotomous outcome to make the finding no longer significant. A small number represents a weaker finding and a large number represents a stronger finding.

Why was this study needed now?

Pain management following total hip arthroplasty is an important consideration in overall patient outcome. Current strategies aim to reduce opioid use in patients, particularly among elderly, who demonstrate poor tolerance to opioids. Peripheral nerve blocks, such as a femoral nerve block and fascia iliaca block, have demonstrated efficacy in limiting postoperative pain, but face the drawback of motor deficit, which in turn can delay mobilization and recovery. A more recent nerve block approach for postoperative analgesia in THA is a lateral femoral cutaneous nerve block, though randomized controlled trials on its use in this setting are lacking.

What was the principal research question?

Does a lateral femoral cutaneous nerve block, when used in conjunction with a basic analgesic regimen of paracetamol and ibuprofen, significantly reduce pain on movement at 4 hours after total hip arthroplasty, when compared to a placebo block?

Study Characteristics -
Population:
120 patients scheduled for primary total hip arthroplasty. All cases were performed under spinal anaesthesia and through a posterior approach. Standardized oral analgesia with 1g paracetamol every 6 hours and 600mg ibuprofen every 8 hours was used. Intravenous or oral oxycodone was used in cases of break-though pain exceeding 30mm on a 100mm visual analog scale. Allocation intervention was administered within the post-anaesthesia care unit, when participants were able to move their toes but prior to spinal anaesthesia wearing off.
Intervention:
LFCN block group: Patients received an ultrasound-guided lateral femoral cutaneous nerve block, using an in-plane approach, with a bolus 8mL 7.5mg/mL ropivacaine. (n=59 randomized; 47 analyzed) (Mean age: 69 +/- 11)
Comparison:
Placebo group: Patients received ultrasound-guided bolus administration of 8mL saline using an in-plane approach. (n=61 randomized; 53 analyzed) (Mean age: 69 +/- 8)
Outcomes:
Pain was assessed at rest and during movement (30degree hip flexion) using a 100mm visual analog scale; primary outcome was the difference between groups at 4 hours. Other secondary outcomes included cumulative opioid consumption, time to first administration of opioids, length of hospital stay, time to mobilization and ability to mobilize patient.
Methods:
RCT; patient- and assessor-blind
Time:
Outcomes assessed at 0, 1, 2, 4, 8, 12, and 24 hours postoperatively.

What were the important findings?

  • At 4 hours, there was no significant difference in VAS pain score on movement between the LFCN block group and the placebo group (Mean difference: -5mm [95%CI -15, 5]) (p=0.41).
  • There were also no reported significant differences in pain at rest or pain on movement at any time point between groups (p-values not reported). Data on pain scores at 8 and 12 hour time points was excluded due to difficulty in obtaining data at those points.
  • There was no significant difference in cumulative 24-hour opioid consumption between the LFCN block group (Median: 7mg [2-13]) and the placebo group (6mg [2-9]) (p=0.12),
  • Time to first request of opioid analgesia did not significantly differ between the LFCN block group (253min [144-379]) and the placebo group (237min [155-380]) (p=1.0).
  • Ambulation score and time to ambulation did not significantly differ between groups (p=0.26 and 0.69, respectively).
  • Length of hospital stay did not significantly differ between the LFCN block group (49+/-10 hours) and the placebo group (50+/-20 hours) (p=0.53).
  • No treatment related adverse events were documented in either group.

What should I remember most?

In total hip arthroplasty, a lateral femoral cutaneous nerve block did not significantly reduce pain scores or opioid consumption over the first 24 hours postoperative in patients managed with standardized oral analgesia and opioid analgesia for breakthrough pain.

How will this affect the care of my patients?

The results of this study suggest that the use of a lateral femoral cutaneous nerve block administered postoperatively may not demonstrate analgesic efficacy for patients undergoing total hip arthroplasty.

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