Negative Influence of femoral nerve block on quadriceps strength recovery following total knee replacement: A prospective randomized trial

135 patients admitted for total knee replacement were randomized to receive patient controlled analgesia with morphine with either an additional continuous femoral nerve block (FNB), an additional single-shot femoral nerve block, or control (no femoral nerve block). The primary outcome of interest was quadriceps strength recovery (QSR). Secondary outcomes of interest included pain on a Visual Analog Scale (VAS), knee range of motion, thigh diameter, the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index, the Short Form 36 (SF-36) questionnaire, opioid consumption and length of stay. Follow up was performed during inpatient stay, and at 6 weeks, 6 months and 12 months. Results revealed significantly favourable quadriceps recovery in closed chain contractions at all time points, and in open chain reactions at 6 weeks, in favour of the control group. Knee range of motion was significantly in favour of the control group. No significant differences in morphine consumption, length of stay, thigh diameter, VAS pain score, or SF-36 scores were observed among the three groups. Patients in the control group reported the best WOMAC scores.