Solvent-dried and gamma-irradiated tendon allografts in rats

Abstract

We examined solvent-dried, gamma-irradiated (SD-R) allografts and fresh-frozen (FF) allografts mechanically and morphologically. Before transplantation, FF grafts were more than six times stronger than SD-R grafts. After four weeks, the tensile strength was about the same in both groups. At 24 weeks only collagen fibrils of small diameter were observed in the SD-R grafts while in FF grafts fibrils of small and intermediate diameter were seen. Clinically, we suggest that SD-R grafts could be used as a favourable alternative to FF grafts if care was taken regarding their initial mechanical weakness.J Bone Joint Surg [Br] 1998;80-B:731-6. Received 18 July 1997; Accepted after revision 8 January 1998 Allogeneic tendon grafts have been used successfully for ligament reconstruction. [1][2][3][4] Allografts eliminate morbidity at the harvest site and there is a shorter operating time. The disadvantages are the risk of transmission of disease and difficulties in storage and handling. The use of solventdrying and gamma irradiation could provide a solution to these problems. Solvent-dried and gamma-irradiated (SD-R) fascia lata allografts (Tutoplast Fascia lata; Biodynamics, Erlangen, Germany) have been used successfully to reconstruct collateral ligaments in the knee and ankle. 5,6We have found, however, that solvent-drying and gamma irradiation had adverse effects on their initial strength. 7Our aim was to examine the time course of the mechanical properties and the collagen fibril profile of SD-R allografts and to compare them with those of fresh-frozen (FF) allografts in a rat model of patellar tendon transplantation. Materials and MethodsWe used 16-week-old male Lewis rats (LEW/crj, Charles River, Japan) as donors and Wistar rats (Crj:Wistar, Charles River, Japan) as recipients.We harvested the medial half of the patellar tendon with a tibial bone block from both knees of 24 Lewis rats. The bone block was 4 mm wide and 8 mm long and the tendon graft 2.5 mm wide and 8 mm long. These grafts were randomly allocated to two groups, FF or SD-R. The latter were suspended in 3% hydrogen peroxide, and then dried with organic acetone followed by gamma irradiation (2.8 Mrads). This treatment has been confirmed to inactivate human immunodeficiency virus. 8 The FF grafts were stored at -80°C for two to five weeks before transplantation. At the time of transplantation FF grafts were thawed at room temperature and SD-R grafts were reconstituted in saline for 30 minutes. Each recipient rat was operated on under general anaesthesia by intravenous injection of ketamine to create defects in the medial half of the patellar tendon and the tibia of both legs which were then replaced with a graft. The tibial bone block was fixed with a 0.7 mm Kirschner wire and the proximal and lateral ends of the graft were sutured with 6-0 nylon thread. After transplantation, each animal was allowed free activity in the cage. Mechanical studies. Groups of three rats were killed at 4, 8, 12 and 24 weeks after transplantation and the transplanted patel...

The effect of cryopreservation or heating on the mechanical properties and histomorphology of rat bone-patellar tendon-bone

“…Therefore, preservation and sterilization of tendon allografts are required to prevent these problems, although this tissue processing has a potentially negative effect on the quality of the graft. Several authors have reported the effects of processing of tendon allografts on reconstruction (Maeda et al 1997(Maeda et al , 1998Noyes and Grood 1976;Woo et al 1986). …”