Table 2.

Summary of the meta-analysis and systematic review studies evaluated.

Study (ref#)	Level of evidence	Type of study	Parameters evaluated	Results and conclusions
22	1 A	Systematic review 5 case series and 13 RCTs High molecular weight HA	Pain	High molecular weight HA is effective for treating continuous pain in patients with knee osteoarthrosis. Its action has a slower start but longer effects than those of intra-articular steroids.
23	1 A	Systematic review 14 studies HA, placebo, sodium hyaluronate	WOMAC with pain and functional capacity	Use of HA is not recommended in patients with symptomatic knee osteoarthritis
24	1 A	Systematic review 9 RCTs Intra-articular HA versus placebo	Pain Evaluated 1, 5–7, 8–12 and 15–22 weeks after HA injection	HA has a modest effect on pain in patients with knee osteoarthritis, 5–7 and 8–10 weeks after the injection, but has no effect after 15–22 weeks.
25	1 A	Systematic review 7 RCTs, 6 case series and 1 cross-sectional study Hylan G-F 20, placebo, NSAIDS, sodium hyaluronate	Pain and functional capacity of the knee	Hylan G-F improves pain and functional capacity of knees over the short term.
26	1 A	Systematic review 67 RCTs Several classes of HA versus placebo	Pain and functional capacity of the knee	Viscosupplementation is effective in treating knee osteoarthritis; it reduces the pain and improves functional capacity.
27	1 A	Meta-analysis 29 RCTs IAHA approved in the United States	Pain and functional capacity 4–13 and 14–26 weeks after infiltration	IAHA is safe and effective in patients with symptomatic knee osteoarthritis
28	1 A	Meta-analysis 89 studies HA or derivative, placebo	Pain and functional capacity	The benefit of viscosupplementation for improving pain and functional capacity in the knee is minimal or non-existent. Its use should be discouraged given the greater local adverse effects.

RCT, randomized clinical trial; DB, double blinding; HA, hyaluronic acid; IAHA, intra-articular hyaluronic acid.