Is fascia iliaca block as good as spinal morphine for hip replacement?

“Never underestimate the pain of a person, because in all honesty, everyone is struggling. Some people are just better at hiding it than others.” ― Will Smith

A randomised, controlled, double blind, non‐inferiority trial of ultrasound‐guided fascia iliaca block vs. spinal morphine for analgesia after primary hip arthroplasty. Kearns, R., et al. Anaesthesia DOI: 10.1111/anae.13620

This was a non-inferiority trial comparing spinal morphine against fascia iliaca blocks (FIB) for post- operative pain relief after total hip arthroplasty (THA). It was a single centre trial, randomised, double-blinded and controlled.

All 108 patients received spinal anaesthetic for their THA and had a morphine PCA for postoperative pain for 24 hours. Group A had 100mcg spinal morphine and a sham FIB (saline instead of levobupivicaine) and Group B had plain spinal and a FIB.

Morphine consumption in the first 24 hours post-op was the primary outcome. Other outcomes were reported, though the trial was not powered for these.

Intravenous morphine consumption in the first 24 hours was 39mg in the FIB group was and 14mg in the spinal morphine group, a difference of 25mg. This was statistically significant and the authors conclude that fascial iliaca block is inferior to spinal morphine for post-op analgaesia.

Secondary outcomes showed that morphine consumption was low after 24 hours in both groups. Complication rates were small, with one report of temporary femoral nerve palsy with FIB and no reports of respiratory depression.

It was a well-designed study. The groups were largely matched although there were differences in sex ratios, preoperative paracetamol consumption and NSAID use not reported.

Despite some limitations, the findings are compelling, and if preservative-morphine were available here, it would be my technique of choice. However, a FIB may add analgesia to spinal morphine, although whether it would be clinically meaningful I’m not convinced. Moreover, the finding of a femoral nerve palsy, albeit transient, is a significant side effect of a surgical procedure which is primarily aiming to improve mobility.

Summary by Dr Mohammed Haque

 

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