Viscosupplementation with intra-articular hyaluronic acid for hip disorders. A systematic review and meta-analysis

Background: Hip joint diseases are common in adult population and their prevalence increases with age. Osteoarthritis, rheumatoid arthritis and femoroacetabular impingement are the most common chronic diseases in the hip joint. Viscosupplementation with exogenous hyaluronic acid (HA) is one of the most widely used conservative treatment aiming to improve synovial fluid properties and to decrease pain. There is no global consensus on the type of HA, method of injection and frequency, or on its efficacy in hip joint. Methods: We selected published data in English in the PubMed and Google Scholar electronic databases up to March 2016 about hyaluronic acid injections in hip disorders. Results: 26 articles were included following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Conclusion: There is a lack of standardization of HA injections for hip conditions. Our results suggest that this is the best conservative therapy before surgery and it can act on pain relief and function however there is no evidence to prove its ability to modify the morphological structure of the pathological hip and the natural history of the disease. There are few data about the use of HA in other hip disorders rather than osteoarthritis. The most relevant evidence seems to show the utility of HA injections in improving synovial inflammation, but only a few studies have been conducted. Level of evidence: I.