A new device to produce a standardized experimental fracture in the rat tibia.

OBJECTIVE: To develop and introduce a new device to produce a standardized closed experimental fracture in the rat tibia. METHODS: This study took place in the Research Laboratory, Medical Faculty, Dokuz Eylul University, in the year 2003. We include 20 healthy male white Wistar rats. After pinning both tibia of the rat intramedullary with the needle of a sterile injector without any incision, we tried to produce a fracture with the pendulum of the device, which was dropped in different angles in 9 rats. The tibial diaphysis of 14 rats in the main study were fractured at 60 degrees. After the fractures were confirmed radiologically, 4 tibia underwent pathological analysis to determine the degree of soft tissue damage and 24 tibia were examined in terms of histological fracture healing. RESULTS: Radiologically, this technique resulted in a transverse or short oblique bicortical fracture in the middle of the tibial diaphysis. The healing process was well adjusted with the classification of Allen. No noticeable soft tissue damage in the fracture region was demonstrated. CONCLUSION: This method of producing an easy and reproducible fracture in a standard fashion without displacement and minimal soft tissue trauma in laboratory animals with this simple apparatus make it a useful technique for bone healing studies.

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, 322-375 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.