Effects of hyaluronic acid injections on pain and functioning in patients affected by tendinopathies: A narrative review

BACKGROUND: Tendinopathies are overuse tendon injuries showing load-dependant pain, stiffness, weakness of movement in the affected area, and impairment in the movements. The scientific interest on the role of Hyaluronic Acid (HA) for the management of tendinopathies has been increased due to its anti-inflammatory and lubricative properties. OBJECTIVE: To collect evidence regarding the effectiveness and safety of HA injections in reducing pain in patients affected by tendinopathies. METHODS: A scientific literature search was conducted using the PubMed, Medline and PEDro electronic databases. The databases were searched since their inception until July 2021. The search was limited to English language articles. Different combinations of the terms and MeSH terms 'tendinopathy', 'tendinosis', 'tendinitis', 'hyaluronic acid', 'hyaluronate', 'infiltration', 'hyaluronic injections', 'viscosupplementation' connected with various boolean operators were used for other electronic databases. RESULTS: One hundred and one records were identified from the selected databases plus three additional papers identified by the authors through other sources. After removing duplicated papers and title/abstract screening, 19 studies were included in our review (eight papers on shoulder, three on elbow, four on hand, one on knee, and three on ankle). CONCLUSION: The results showed that none of the studies report severe adverse effects and most of them support the use of HA injections in tendinopathies, with a special attention to pain reduction and functional assessment. Further studies are warranted to better investigate effects and methods of administration of HA in tendinopathies.