Femoral nerve block using ropivacaine 0.025%, 0.05% and 0.1%: effects on the rehabilitation programme following total knee arthroplasty: a pilot study.

Femoral nerve blockade is recommended for analgesia following total knee arthroplasty. Following implementation of this type of postoperative analgesia in our hospital we found that active mobilization the day after surgery, may be difficult due to insufficient quadriceps muscle strength. We therefore designed a pilot study comparing the effect of ropivacaine 0.1%, 0.05% or 0.025% on the patient's postoperative rehabilitation and analgesia. Three groups of 12 patients received bolus doses of ropivacaine via their femoral nerve catheters for postoperative analgesia. The ability to actively mobilize, quadriceps muscle strength, pain VAS-scores and patient's satisfaction were measured during in the first three postoperative days. There were no significant differences in the patient's ability to actively mobilize and the pain VAS-scores. The overall satisfaction of the patients with the pain treatment was significantly better (p = 0.049) in the 0.1% compared with the 0.025% group. This pilot-study demonstrated no advantage associated with the use of a ropivacaine concentration less than 0.1%.