Effect of hylan G-F 20 in Achilles' tendonitis:: An experimental study in rats

Objective: To investigate the local effects of hylan G-F 20 on locally administered corticosteroid-induced experimental Achilles' tendonitis. Design: Before-after trial. Setting: Institutional practice. Animals: Convenience sample of 18 male Wistar white rats (weight range, 322-375g). Interventions: After performing Achilles' degeneration with local corticosteroid injections, the rats were divided into 4 groups. The right Achilles' tendon of the rats served as the hylan injection group and the left tendon as the control group, which was injected with saline at 5-day intervals. The tendons and paratenons were excised at the end of 60 or 75 days and evaluated histopathologically and statistically. Main Outcome Measure: Histopathologic changes, including staining affinity, nuclear appearance, fibrillar appearance for tendon and thickness, occurrence of fibrosis and edema, capillary changes, and inflammation for paratenon, were assessed according to a semiquantitative scoring system. The Mann-Whitney U test was used for statistical analysis, with a P value of .05 or less considered statistically significant. Results: Semiquantitative scoring of histopathologic changes showed that histologic appearances differed between the hylan and saline groups and between 2 hylan groups. Hylan-injected tendons and paraterions demonstrated significantly lower scores, especially after 75 days. Conclusions: Hylan G-F 20 has a promising curative effect on the tendon and paratenon and can be used in Achilles' tendonitis. This finding should be supported by biomechanical and biochemical studies.