The Effect of a Single Hyaluronic Acid Injection in Ankle Arthritis: A Prospective Cohort Study.

Nonoperative measures are often used as first line treatment in ankle osteoarthritis. One of these measures consists of hyaluronic acid injections in the affected ankle joint, but efficiency of this treatment is uncertain. The purpose of the study was to evaluate the effect on Self-reported Foot and Ankle Score, visual analog scale score at rest, and visual analog scale score at activity 6 months after a single dose of hyaluronic acid in patients with ankle osteoarthritis. Patients were included from December 2017 to March 2019. A single intra-articular injection of Cingal or MonoVisc was administered. Age, gender, osteoarthritis-grade, Self-reported Foot and Ankle Score, visual analog score at activity, and at rest before injection and after 6 months was registered. A total of 33 patients were included, with 14 lost to follow-up. Four were treated with MonoVisc and were excluded to reduce confounding. The remaining 15 patients were included for analysis. Median Self-reported Foot and Ankle Score remained unchanged (p = .06), whereas visual analog score at activity went from 7 to 6 (.02) and visual analog score at rest was reduced from 4 to 3 (.02). Subgroup analysis on arthrosis grade (grade I-II and III-IV) showed no statistically significant changes for all variables even though patients with grade III-IV arthrosis seemed to benefit more from the treatment. The results indicate that a single injection of hyaluronic acid is insufficient to produce at clinically relevant response after 6 months even though there is a high risk of underpowering because of a small patient population.