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Projektleiter:
Prof. PD Dr. med. Stefan Rammelt

Projektbearbeiter:
Dr. rer. medic. Claudia Rentsch
Dr. med. Sebastian Rehberg

Laufzeit:
01/2012 - 12/2013

Projektbeschreibung:
Large bone defects resulting from trauma or tumor resection require extensive surgical therapy. Autografts are still considered the gold standard substrate for bone defect filling. The most common site of obtaining autologous bone is the iliac crest, but the amount of bone is limited and the donor side pain is the most common cause of morbidity.
New implants like polycaprolactone-co-lactide (PCL) scaffolds are investigated for large bone defect reconstruction at different defect locations showing promising results.
However, relevant long-term animal studies with an appropriate number of large animals, with similar biomechanical conditions to the human setting, are needed before employing clinical trials for human applications. A long-term investigation of PCL-scaffold bone implants would allow a relevant follow-up analysis beyond primary healing of the defects and include the evaluation of callus remodelling to gain initial stability as well as the resorption of the implant material.
The aim of the present study is a long-term evaluation (12 months) of PCL-scaffolds implanted in sheep at two different defect locations. The intention is to use the scaffold as an implant to reconstruct large bone defects in long bones (tibia) as well as a scaffold for iliac crest reconstruction. This setup would also allow a comparison about the healing progress under load bearing (tibia defect) and unloaded (iliac crest defect) conditions.
Four groups will be compared (n=10 each group): group 1: empty defects (negative control), group 2: autologous bone grafting (gold standard), group 3: PCL uncoated, group 4: PCL coated with type I collagen (coll I) + chodroitinsulfate (cs).
A 3 cm long segmental mid-diaphysial osteotomy will be performed on the tibia of each sheep and a 3x1,5 cm defect will be created at the iliac crest. Both defects will be treated with the same implant to allow individual comparison of new bone formation.

Radiographic evaluation will be performed post operatively, every 4 weeks for the first 6 months, and then every 2 months. Bone healing will be measured by final radiographs, computed tomography scans, semi-quantitative scoring, quantification of bone volume, biomechanical testing, histological and imunohistological evaluation.