Table 1

Characteristics of the included studies

First author, year	Mean age	Gender (F/M)	N (K/P)	Doses of ketamine	Time	Type of injection	Start time of injection	Type of arthroplasty
Wong, 199624	63.7	8/8	6/10	10 mg	12, 24, 48, 72 hours	Epidural	Immediately after surgery	TKA, THA
Adam, 200513	68.5	27/13	20/20	3 µg/kg/min until the patient emerged from anaesthesia, and then 1.5 µg/kg/min maintained for 48 hours	0, 1, 4, 12, 24, 48 hours, before and after rehabilitative therapy on days 1 and 2	Intravenous	After the induction of anaesthesia	TKA
Aveline, 200912	71	30/19	25/24	0.2 mg/kg followed by a continuous infusion at 120 µg/kg/hour until the end of surgery, and then 60 µg/kg/hour until the second postoperative day	PACU, 2, 6, 12, 24, 48 hours	Intravenous	After anaesthetic induction and tracheal intubation	TKA
Perrin, 200925	62.5	5/7	5/7	0.5 mg/kg bolus followed by 4 µg/kg/min infusion	Preoperative, 4, 12, 26 weeks	Intravenous	Before surgical incision	TKA
Remerand, 200914	64.5	76/78	79/75	0.5 mg/kg bolus followed by 2 µg/kg/min infusion	PACU, 24, 48, 96, 168 hours	Intravenous	Before skin closure	THA
Guará Sobrinb, 201217	66.8	30/9	19/20	0.25 mg/kg	2, 6, 12, 24 hours	Intra-articular	Before skin closure	TKA
Cengiz, 201411	58.5	44/16	30/30	6 µg/kg/min	1, 3, 6, 12, 24 hours	Intravenous	Immediately after orotracheal intubation continuing until wound closure	TKA
Martinez, 201416	62.1	36/36	34/38	0.5 mg/kg bolus followed by 3 µg/kg/min infusion	PACU, 24, 48 hours	Intravenous	At the time of anaesthesia induction immediately	THA
Zhang, 201818	54.9	31/13	21/23	2 mg/kg	0, 2, 4, 8, 12, 24, 48 hours	Intra-articular	At the end of the surgery	TKA
Tan, 201915	67.9	53/38	48/43	6 µg/kg/min	Preoperative, 0, 24, 48, 72, 96, 120, 144, 168, 336 hours	Intravenous	Once patient was situated on the table	TKA

F, female;K, ketamine; M, male; N, number of patients per group; P, placebo; PACU, post-anaesthesia care unit; THA, total hip arthroplasty; TKA, total knee arthroplasty.