Table 1.

Details of patient groups

	Men (n=200)			Women (n=220)
	GA+FNB (n=73)	SA+ITF (n=66)	SA+ITM (n=61)	GA+FNB (n=79)	SA+ITF (n=77)	SA+ITM (n=64)
Mean age (range)	64.4 (50–83)	65.6 (38–94)	65.3 (51–87)	66.9 (43–84)	69.3 (52–87)	69.8 (41–84)
Number of patients per surgical procedure	THR 21 TKR 52	THR 28 TKR 38	THR 24 TKR 37	THR 29 TKR 50	THR 37 TKR 40	THR 39 TKR 25
Retention	14%	9%	60%	2%	3%	5%

GA = general anaesthesia; FNB = femoral nerve block; SA = spinal anaesthesia; ITF = intrathecal fentanyl; ITM = intrathecal morphine;

THR = total hip replacement; TKR = total knee replacement