Efficacy and safety of hyaluronic acid (500-730kDa) ultrasound-guided injections on painful tendinopathies: A prospective, open label, clinical study

Background: Tendinopathies are conditions characterized by activity-induced pain, local tenderness and swelling for which a gold standard treatment is not established yet. Hyaluronic Acid (HA) is a key-molecule in several cellular activities and it is normally present in the extra-cellular matrix of tendons and ligaments. Amongst its properties, HA injections may reduce pain and determine disease-modifying effects. This study is an investigator-initiated open-label trial conducted to investigate the efficacy and safety of HA (500-730 kDa) peritendinous injections on pain reduction in patients affected by lateral elbow, Achilles or patellar tendinopathy. Methods: A total of 71 tendons (34 with Achilles tendinopathy, 26 with lateral elbow tendinopathy, 11 with patellar tendinopathy) of 62 patients with painful tendinopathy were treated with a cycle of ultrasound-guided peritendinous injections one injection per week for three consecutive weeks. Efficacy assessments included changes in pain intensity measured by Visual Analogue Scale (VAS) at follow-up evaluations were performed 7 (V2), 14 (V3) and 56 days aften first treatment. An Ultrasound (US) assessment was also performed to evaluate changes in tendon thickness and neovascularization. Adverse events were recorded for safety analysis throughout the study. All results were analyzed with descriptive statistics appropriate to the nature of the variables. Results: Significant reduction in VAS (p<0.001) from baseline was observed in Achilles (-6.16 ± 0.45 cm), patellar (-6.16 ± 0.72 cm) and lateral elbow (-5.33 ± 0.43 cm) tendinopathies. The sagittal thickness decreased significantly from baseline at each endpoint (V3 day 14 and V4 day 56) in each type of tendinopathy analyzed (p<0.05). Neovascularization decreased for each tendons at V3 and V4, except for patellar tendon at V3 V1 (p=0.125). Nevertheless, reduction at V4 compared to baseline remained significant (p=0.016). Conclusions: US-guided HA (500-730 kDa) peritendinous injections determine significant pain relief and reduction in tendon thickness and neovascularization in US evaluations. The effect of HA did not show differences regarding the site of affected tendon. The treatment proved to be safe and very well tolerated. Level of evidence: 4.