Author (year)	Head size (mm)/type	Type/level of study	Single/multi centric study	Total no pt (hips)	Male (%)	Female (%)	Country
Wu (2012)	Durom LDH	Prospective III/IV	Multi	59 (70)	66	34	Taiwan
Saragalia (2015)	38–56	Retrospective IV	Single	146(156)	53	47	France
Lu (2015)	≥ 36	Retrospective IV	?	41 (42)	51	49	Taiwan
Hu (2017)	Durom LDH	Retrospective IV	?	80 (96)	72.5	27.5	Taiwan
Howie (2016)	36	RCT II	Single	29 (*)	52	48	Australia
Shah (2017)	36	Prospective IV	Multi	(192,275)	NA	NA	Australia
Kindsfater (2012)	36	Prospective III/IV	Single	(85)	60	40	USA
Jameson (2015)	36	Prospective IV	Multi	(1863)	58	42	UK
Zijlstra (2017)		Retrospective IV	Multi	(166,231)	NA	NA	Netherlands
Singh (2013)	36	Prospective III/IV	single	281 (317)	72.8	27.2	India
Mokka (2013)		Retrospective IV	Multi	(25,037)	54	46	Finland
Delay (2016)	38–56	Case control III/IV	Single	101 (112)	NA	NA	France
Agarwala (2014)	36–44	Retrospective IV	Single	59 (62)	NA	NA	India
Stroh-Alex (2012)	36, 40	Case control III/IV	Single	225 (248)	60.8	39.2	USA
Allen (2014)	≥ 36	Prospective III/IV	Single	(327)	63	37	New Zealand
Lachiewicz (2018)	36–40	Retrospective IV	single	93 (107)	NA	NA	USA
Hammerberg (2010)	38, 44	Prospective III/IV	?	30 (33)	NA	NA	USA
Ho (2012)	36	Retrospective IV	?	404 (421)	42	58	UK
Lombardi (2015)	≥ 38	Retrospective IV	Single	1235 (1440)	55	45	USA
Khatod (2014)	≥  36	Retrospective IV	Multi	(35,960)	42.6	57.4	USA
Sachde (2012)	36	Retrospective IV	Single	28	71	29	India
Hailer (2012)	36 (4%)	Prospective III/IV	Multi	2722 out of 61,743 pt (78,098)	40	60	Sweden
Kostensalo (2013)	36, > 36	Prospective III/IV	Multi	(13,764)	NA	NA	Finland