Table 1. Randomized controlled trials according to basis of hip implant comparison.

Basis of comparison	Study ID
Cup fixation (cemented vs. cementless)	Bjorgul 2010 [22]
	Angadi 2012 [24]
Cup liner bearing surface (XLPE vs. non-XLPE)	McCalden 2009 [25]
	Engh 2012 [26]
Cup shell design (porous-coated vs. arc-deposited HA-coated)	Capello 2008 [28]
Cup and femoral stem fixation (cemented vs. cementless)	Corten 2011 [32]
Femoral head size (36 mm vs. 28 mm)	Howie 2012 [36]
Femoral head bearing (oxinium vs. CoCr)	Lewis 2008 [37]
Femoral head-on-cup liner bearing
Ceramic-on-ceramic vs. ceramic-on-PE	Amanatullah 2011 [38]
Ceramic-on-ceramic vs. CoCr-on-PE	Capello 2008 [28]
Steel-on-PE vs. CoCr-on-PE vs. oxinium-on-PE vs. CoCr-on-XLPE vs. oxinium-on-XLPE	Kadar 2011 [39]
Ceramic-on-ceramic vs. CoCr-on-XLPE	Bascarevic 2010 [43]
Femoral stem composition (CoCr vs. titanium)	Healy 2009 [40]
Femoral stem design (short metaphyseal-fitting vs. conventional metaphyseal- and diaphyseal-filling)	Kim 2011 [41]
Femoral stem fixation (cemented vs. cementless)	Kim 2011 [42]

XLPE = cross-linked polyethylene; PE = polyethylene; HA = hydroxyapatite; CoCr = cobalt chrome.