[Primary stability of autologous and heterologous implants for intervertebral body spondylodesis].

In this study, we tested the stability of the xenograft SURGIBONE and of human iliac crest graft depending on the donor's bone density. The mean load bearing capacity of SURGIBONE was 4816 N, the compressive strength 32.8 N/mm2. This even exceeds the values given by the producer. Yet in clinical use the material caused problems by collapses or lysis of the graft. According to our results, those failures can not be explained by missing primary stability. Perhaps there is a immunogenic reaction of the host against the remaining protein as it once was proved for the "kielspan"-graft. The iliac crest grafts of donors with normal bone density had a load bearing capacity of 3397 N. Grafts of donors with reduced bone density of less than 60 mg/ml Ca-Equivalent showed reduced load bearing capacities of 2265 N. DEXA (Dual-Energy X-Ray Absorptiometry) seems to be suitable to scan preoperatively the iliac crest graft stability in order to recognize the danger of reduced stability by osteoporosis.