| Study ID | Allocation concealment score | Quality score | Level of evidence |
Clinical Points |
| Abdel-Salam 1995 | A | 11110:4 | 1 | |
| Adam 2005 | A | 11111:5 | 1 | |
| Adams 2002 | B | 10000:1 | 2 | High dose of intra-op fentanyl could be effective during 1st h postop |
| Ahdieh 2004 | B | 10101:3 | 1 | |
| Allen 1998 (HW) | B | 10110:3 | 1 | |
| Allen 1998 (JG) | A | 11111:5 | 1 | |
| Angulo 1990 | B | 10110:3 | 1 | |
| Axelsson 2005 | A | 11111:5 | 1 | |
| Badner 1991 | B | 10111:4 | 1 | |
| Badner 1996 | A | 11110:4 | 1 | |
| Badner 1997 | A | 11110:4 | 1 | |
| Barrack 1997 | A | 11111:5 | 1 | |
| Barrack 2001 | A | 11111:5 | 1 | |
| Barwell 1997 | A | 11110:4 | 1 | Difficult to interpret because of insufficient detail and description of methods |
| Beaupre 2004 | A | 11001:3 | 1 | No VAS scores, only WOMAC and SF36 |
| Boeckstyns 2004 | B | 10101:3 | 1 | |
| Bowrey 2005 | B | 10111:4 | 1 | |
| Browne 2004 | B | 10110:3 | 1 | |
| Burnett 2004 | A | 11111:5 | 1 | |
| Buvanendran 2003 | A | 11111:5 | 1 | |
| Can 2003 | B | 10000:1 | 2 | |
| Casati 2005 | A | 11111:5 | 1 | |
| Cheville 2001 | A | 11001:3 | 1 | |
| Cole 2000 | A | 11101:4 | 1 | |
| Confalonieri 2004 | A | 11000:2 | 1 | |
| Dahl 1994 | A | 11111:5 | 1 | |
| Dang 2005 | A | 10001:2 | 1 | |
| Davies 2004 | B | 10111:4 | 1 | |
| D’Lima 1996 | A | 11000:2 | 1 | |
| Edwards 1992 | B | 10001:2 | 1 | |
| Eggers 1999 | A | 11111:5 | 1 | |
| Esler 2003 | A | 11000:2 | 1 | |
| Farag 2005 | A | 11001:3 | 1 | |
| Fernandez-Galinski 1996 | B | 10110:3 | 1 | |
| Ferrante 1988 | B | 10000:1 | 2 | Variation in intra- and postop technique between each patient |
| Ferrante 1993 | A | 11110:4 | 1 | |
| Fisher 1998 | B | 11110:4 | 1 | |
| Frost 2002 | A | 11001:3 | 2 | < 80% follow-up |
| Ganapathy 1999 | B | 10110:3 | 1 | |
| Gibbons 2001 | B | 10000:1 | 2 | |
| Grace 1995 | A | 11111:5 | 1 | Only 12 patients’ data. Note that study was discontinued because of inadequate analgesia in tramadol group |
| Harms 1991 | B | 11000:2 | 2 | |
| Hendolin 1996 | B | 10110:3 | 1 | |
| Hilding 1997 | A | 11001:3 | 1 | |
| Himmelseher 2001 | A | 11111:5 | 1 | |
| Hirst 1996 | B | 10110:3 | 1 | |
| Holmstrom 2005 | B | 10001:2 | 1 | |
| Hubbard 2003 | A | 11101:4 | 1 | |
| Jacobson 1989 | B | 10110:3 | 1 | |
| Jenny 2001 | A | 11000:2 | 1 | |
| Kaloul 2004 | A | 11000:2 | 1 | |
| Kampe 2002 | B | 10101:3 | 1 | |
| Klasen 1999 | A | 11001:3 | 1 | |
| Kudoh 2003 | A | 11000:2 | 1 | Clinical relevance questionable because primary outcome was not pain but global recovery |
| Levy 1993 | A | 11001:3 | 1 | |
| Macalou 2004 | A | 11001:3 | 1 | |
| Mauerhan 1997 | A | 11110:4 | 1 | |
| McNamee 2001 | A | 11111:5 | 1 | |
| McNamee 2002 | A | 11111:5 | 1 | |
| McSwiney 1997 | B | 10001:2 | 1 | |
| Mitchell 2005 | A | 11001:3 | 2 | <80% follow up |
| Moffet 2004 | A | 11001:3 | 1 | |
| Moiniche 1994 | A | 11000:2 | 1 | |
| Muldoon 1998 | B | 10110:3 | 1 | |
| Nechleba 2005 | B | 10111:4 | 1 | |
| Ng 2001 | A | 10110:3 | 1 | |
| Nielsen 1989 | B | 10001:2 | 1 | |
| Niskanen 2005 | B | 10000:1 | 2 | Questionable practice for routine analgesia |
| Pang 2003 | A | 11110:4 | 1 | |
| Park 1996 | A | 10111:4 | 1 | |
| Partio 1995 | B | 10000:1 | 1 | |
| Pettine 1989 | B | 10000:1 | 2 | |
| Price 2003 | A | 11001:3 | 1 | |
| Riad 2002 | A | 11101:4 | 1 | |
| Ritter 1999 | A | 11100:3 | 1 | |
| Serpell 1991 | B | 10001:2 | 2 | |
| Sharrock 1994 | A | 11000:2 | 1 | |
| Silvanto 2002 | A | 11111:5 | 1 | |
| Silvasti 2001 | A | 11111:5 | 1 | |
| Singelyn 1998 | A | 11000:2 | 1 | |
| Singelyn 2000 | A | 11110:4 | 1 | |
| Sites 2003 | A | 11110:4 | 1 | |
| Sites 2004 | A | 11001:3 | 1 | |
| Smith 2002 | A | 11000:2 | 1 | |
| Szczukowski 2004 | A | 11110:4 | 1 | |
| Tan 2001 | B | 10101:3 | 1 | |
| Tanaka 2001 | B | 10100:2 | 2 | |
| Vandenbussche 2002 | A | 11110:4 | 1 | |
| Wakankar 1999 | A | 11001:3 | 1 | |
| Wang 2002 | B | 11100:3 | 1 | |
| Waters 2003 | A | 11110:4 | 1 | |
| Weber 2001 | A | 11111:5 | 1 | |
| Weber 2005 | A | 11111:5 | 1 | |
| Weinhardt 2004 | B | 10001:2 | 2 | |
| Weir 1998 | B | 10111:4 | 1 | |
| Weller 1991 | B | 10001:2 | 2 | |
| Wong 1997 | B | 10001:2 | 1 | |
| Wood 2002 | A | 11001:3 | 1 | |
| YaDeau 2005 | A | 11110:4 | 1 |