Porous Titanium Granules in Rabbit Tibia Critical Size Osseous Defects

Objectives:

Porous Titanium Granules (PTG, TIGRAN AB, Malmö, Sweden) have been used in orthopaedic surgery for 15 years. So far no studies have been published assessing the regenerative potential of PTG in animal models. Our objective was to evaluate bone growth in critical size osseous defects filled with PTG.

Methods:

Three mm wide and five mm deep defects were prepared in the tibias of 24 New Zealand White rabbits. The holes penetrated through the cortical bone into the marrow space. The defects were randomized into test or control defects (sham). After treatment all defects were covered with coin shaped titanium implants and the wounds sutured and left for healing for 4 weeks.

After harvesting the defects were analyzed by histology, histomorphometry and microradiographs. Three indexes were scored; width of new cortical bone (A), new bone in the marrow space (B) and thickness of new cortical bone (C).

Results:

The results show that significantly more bone was present in the defects treated with PTG compared to sham defects (p<0.05 for index A, p<0.01 for indexes B and C). No signs of adverse effects, fibrous encapsulation or inflammation were observed in any of the animals. In the test group the morphology of the new bone looked normal and had a distribution roughly matching the distribution of the granules.

The sham defects did not close completely and did not show any bone formation in the marrow compartment, confirming that these defects are true critical size defects at least within the time frame of this experiment.

Conclusions:

Within the limitations of this study the results suggest that porous titanium granules can be used as an osteoconductive graft material in critical size osseous defects.