Special needle over cannula for postoperative analgesia in geriatric lower extremity joint arthroplasty.

Objective: To investigate superiorities of a special needle-over-cannula adopting different location methods for continuous femoral nerve block (CFNB) for geriatric lower extremity joint arthroplasty.
Methods: 60 elderly patients intending to receive scheduled knee or hip replacement surgery were recruited and divided into 3 groups randomly. Group 1 (n=20) adopted fascial pop for continuous femoral nerve block and postoperative analgesia with indwelling cannula. Group 2 (n=20) adopted location guided by B ultrasound, and Group 3 (n=20) adopted fascial pop combined with B ultrasound.
Results: There was significant difference in the performing time of cannula indwelling on average between each two groups (P<0.01). There was no significant difference among three groups about visual analogue scale (VAS) score, Ramsay sedation score (RSS), incidence of nausea and vomit, or patient's satisfaction at 6, 12, 24 and 48 h. Infection at the puncture site, toxic reaction of local anesthetics and respiratory depression were absent during the cannula indwelling. All the patients did not receive any other analgesic, and the indwelling time of external cannula was 45.3 hours on average. There was only one patient in group 2 who felt mild pains in front of the thigh after removing the indwelling cannula. No stolidity or other abnormal symptom was found among the remaining patients.
Conclusions: Shorter indwelling cannula time and higher success rate of single attempt placement suggest that fascial pop combined ultrasound guidance is worth for clinical recommendation.