Research suggests that patients with advanced subtalar osteoarthritis (OA) may benefit from intra-articular viscosupplementation.
The study, published in the Journal of Foot and Ankle Surgery, demonstrates significant improvements in function and pain in the 6 months after three sodium hyaluronate 10 mg injections over 3 weeks.
"Viscosupplementation with [hyaluronic acid] injection is a valuable addition to the current nonsurgical options for the treatment of subtalar OA," say Omer Mei-Dan (Meir University Hospital, Kfar-Sabar, Israel) and co-authors.
By week 28, American Orthopaedic Foot and Ankle Society Ankle Hindfoot scores in the 22 patients had significantly improved from a baseline score of 54.5 points to 73.7 points.
This was accompanied by significant improvements over the study on 10-point visual analog scales for pain (5.4 to 2.8), stiffness (5.8 to 3.1), and function (6.9 to 3.8), and a significant global assessment improvement in 18 of the 20 patients.
While 45% of patients reported constant pain at baseline, there was a significant decrease in pain over follow-up, and just one (5%) patient reported constant pain by week 28 of the study.
Tolerable walking distance also significantly increased, from an average of 770 m at baseline to 2075 m at 28 weeks.
The patients were aged between 22 and 72 years (mean 53 years) and trauma was the most common underlying cause of subtalar OA, with 40% of the group experiencing hindfoot fracture and 10% a recent sprain.
The researchers say that the patients had symptomatic grade II-IV Kellgren-Lawrence and grade 1-3 Paley and Hall disease, but there was no significant correlation between severity and treatment response.
Mei-Dan et al are therefore unable to say whether sodium hyaluronate is equally effective across disease severity. "Nevertheless, the favorable outcome in younger patients with more severe OA adds weight to the use of [hyaluronic acid] as treatment of OA of the subtalar joint," they write, recommending larger randomized controlled trials to confirm the findings.
The researchers note that two patients experienced mild discomfort within a few hours of treatment but this resolved spontaneously within a day. There were no reports of superficial or joint infections, or other side effects.
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