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, 322-375 g).
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 paratenons 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.