Spatial and temporal patterns of bone formation in ectopically pre-fabricated, autologous cell-based engineered bone flaps in rabbits

Biological substitutes for autologous bone flaps could be generated by combining flap pre-fabrication and bone tissue engineering concepts. Here, we investigated the pattern of neotissue formation within large pre-fabricated engineered bone flaps in rabbits. Bone marrow stromal cells from 12 New Zealand White rabbits were expanded and uniformly seeded in porous hydroxyapatite scaffolds (tapered cylinders, 10-20 mm diameter, 30 mm height) using a perfusion bioreactor. Autologous cell-scaffold constructs were wrapped in a panniculus carnosus flap, covered by a semipermeable membrane and ectopically implanted. Histological analysis, substantiated by magnetic resonance imaging (MRI) and micro-computerized tomography scans, indicated three distinct zones: an outer one, including bone tissue; a middle zone, formed by fibrous connective tissue; and a central zone, essentially necrotic. The depths of connective tissue and of bone ingrowth were consistent at different construct diameters and significantly increased from respectively 3.1 +/- 0.7 mm and 1.0 +/- 0.4 mm at 8 weeks to 3.7 +/- 0.6 mm and 1.4 +/- 0.6 mm at 12 weeks. Bone formation was found at a maximum depth of 1.8 mm after 12 weeks. Our findings indicate the feasibility of ectopic pre-fabrication of large cell-based engineered bone flaps and prompt for the implementation of strategies to improve construct vascularization, in order to possibly accelerate bone formation towards the core of the grafts

Computer Assisted Oral and Maxillofacial Reconstruction

Ablative tumor surgery, orbital and mid face reconstruction as much as skull base surgery requires detailed planning using CT or MRI. Reconstruction is depending on reliable information to choose correct type of grafts and to predict the outcome. This study evaluates the benefit and the indications of computer assisted surgery in the treatment of cranio-maxillofacial surgery.Based on a CT or MRI data set an optical navigation system was used for preoperative planning, intraoperative navigation and postoperative control. Surgery was preoperatively planned and intraoperatively navigated. Preoperatively required soft and hard tissue was measured using the mirrored data set of the unaffected side; size and location of the graft were chosen virtually. Intraoperatively contours of transplanted tissues were navigated to the preoperatively simulated reconstructive result.Computer assisted treatment was successfully completed in all cases (n=107). Preoperatively outlined safety margins could be exactly controlled during tumor resection. Reconstruction was designed and performed precisely as virtually planned. Image guided treatment improves preoperative planning by visualization of the individual anatomy, intended reconstructive outcome and by objectivation the effect of adjuvant therapy. Intraoperative navigation makes tumor and reconstructive surgery more reliable by showing the safety margins, saving vital structures and leading reconstruction to preplanned objectives