No conclusive evidence that histologically found granulomas and acute local reactions following hylan G-F 20 injections are related or have clinical significance.

: Osteoarthritic (OA) knee pain can be successfully treated with hylan G-F 20 (Synvisc, Sanofi Biosurgery, Cambridge, MA) with few local adverse events. However, a few studies have identified hyaluronate positive (HA+) granulomas in the synovial tissue of patients treated with hylan G-F 20 raising the question of their relationship and clinical significance. To understand the potential relationship of HA+ granulomas with the occurrence of acute local reactions (ALRs), we evaluated the synovial tissue of OA patients undergoing total knee replacement that had previously been treated with hylan G-F 20 (n = 101) or had not been treated (n = 20). Granulomas were observed in nine patients, of which eight were in the hylan G-F 20 group (7.9%); HA+ granulomas were identified in six of these eight patients (5.9%). Three of the six patients with HA+ granulomas experienced an ALR within 30 days of administering an injection. Overall, we found no consistent relationship between histologically found HA+ granulomas and the occurrence of an ALR following hylan G-F 20 treatment. These microscopic granulomas were not associated with any symptoms and likely have little clinical significance. The low occurrence of granulomas and/or ALRs should not preclude use of hylan G-F 20 for the treatment of knee pain associated with OA.