Table 2.

Quality assessment of the included trials.

Study	Randomized adequately*	Allocation concealed	Blinding**	Selective reporting	Similar co-factors#	(%) Loss to follow-up (VS/PLB)##	ITT analysis
Atchia 2011	Adequately	Yes	Double Blinded	No	Yes	5.3%/0	Yes
Brander 2018	Adequately	Yes	Double Blinded	No	Yes	1.7%/1.7%	Yes
Migliore 2009	Adequately	Unclear	Double Blinded	No	No	(22.7%/15%)	Unclear
Qvistgaard 2006	Inadequately	Unclear	Double Blinded	No	Yes	12%/8%	Yes
Richette 2009	Adequately	Yes	Double Blinded	No	Yes	14.3%/9.3%	Yes

VS – viscosupplementation; PLB – placebo; ITT – itention to treat.

^*Randomization schedules based on randomly permuted blocks were considered not adequately according to Cochrane Handbook 5.0.2 [2008];

^**All the studies declared double-blind intervention, adequate methods of which were decribed explictly; outcome assessors were also considered to be blinded;

^#Qvistgaard’ study added lidocaine during injection equally in all groups;

^##Less than 25% loss-to-follow-up rate was considered acceptable.