Rheumatoid arthritis (RA) cause pain and inflammation in the affecting joints. The study mentioned here was performed to reveal whether hyaluronic acid (HA) injection into rheumatoid arthritis ankles and feet can achieve improvement in foot function and lessen synovial hyper-vascularization.

A total of 44 patients suffering from RA having unilateral or bilateral painful ankle and foot involvement (N = 75) were studied. All the patients were randomized to obtain HA (N = 40) or lidocaine (LI) (N = 35) injection at 2-week intervals. At baseline, 4 weeks (first evaluation) and 12 weeks (secondary evaluation), the clinical estimation was performed via a visual analog scale (VAS) and foot function index (FFItotal) including subscales of pain (FFIpain) before injection. The color Doppler ultrasound (CDUS) and synovitis scores were used for the imaging evaluation performed concurrently. At the first evaluation, HA injection improved the VAS score (p = .009), FFIpain (p = .041), and FFItotal(p = .032) considerably more than LI injections. At the first evaluation (p = .005) and secondary evaluation (p < .001), the CDUS values decreased notably compared with the base line values. The CDUS values of more than half of the joints (54%, p = .042) were reduced due to HA injections while  the control group displayed no change (20%, p = .56). Although, HA injection did not decrease the CDUS values more than LI injection did. No noteworthy difference was observed between or within the groups in the synovitis scores concerning the evaluation of synovial hypertrophy.

Improvement was observed in foot function and pain reduction due to HA injection. HA injection may have a modest consequence in reducing synovial hyper-vascularization. Further large-scale study are needed to confirm this outcome.