Prefabricated flaps for bone reconstructive surgery.

Tissue engineering of bone could help minimise donor site defects of conventional bone flaps like the fibula, iliac crest, radius and scapula. First a review is given on the literature of donor site morbidity of these flaps. Then the use of MRI is investigated for longitudinal study of ectopic bone formation in a rat model with demineralised bone matrix in a subcutaneous site. The results of this study show that in vivo MRI is well suited to assess bone formation larger than 0.5 mm in diameter and to monitor the complete three-dimensional shape of the newly formed bone in a noninvasive manner. In the third chapter it is concluded that in vivo MRI proves to be a reliable method for monitoring ectopic bone formation in a rat model with DBM in a muscle flap, while in vivo DEXA was unable to detect the implants. Furthermore, in vivo MRA proves to be a very useful technique for studying the circulation of muscle flaps in this animal model. In chapter four it is concluded that enlargement of the surface area by morsellizing DBM implants in a rat model is not an important factor in bone forming capacity. In chapter five, the aim of the study is to investigate the influence of the carrier in a cell-based bone regeneration approach, whereby we hypothesize that CaP ceramic implants will induce more bone formation than Ti-fiber implants. Our hypothesis is confirmed. In chapter six the hypothesis that a muscle recipient site could favor bone formation in a cell-based bone graft substitute compared to a subcutaneous recipient site due to the higher vascularity of muscle tissue, could not be confirmed. In the last chapter the influence of a microsurgical anastomosis on a prefabricated flap is investigated: We conclude that in a rat model viable microsurgical bone flaps can be obtained by using a cell-based tissue engineering approach