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Tissue-engineering Based Repair of a Critical Porcine Tibial Defect
Christopher Runyan MD,PhD
Wendy Chen BS
David Billmire MD
Jesse Taylor MD
University of Cincinnati
2013-02-25
Presenter: Christopher Runyan
Affidavit:
This work has not yet been published. A portion of this work was presented at the AAPS 2012, however those were preliminary findings, and this represents the complete data set presented for the first time. 100% of this is the original work of the resident.
Director Name: W John Kitzmiller
Author Category: Resident Plastic Surgery
Presentation Category: Basic Science Research
Abstract Category: General Reconstruction
We previously described generating vascularized bone in a pig model using hemi-mandible allograft, adipose-derived stem cells (ASCs), bone morphogenetic protein-2 (BMP-2) and native periosteum. This new study examines this technique, known as 'allograft revitalization', for repair of a critical tibial defect.
Methods: Juvenile pigs had 3-cm defects created in their bilateral tibial diaphyses, for repair using one of three modalities. 'Negative control' (NC) tibias were repaired with allograft tibia. To simulate repair using vascularized autograft, the ostectomized bone in 'positive control' (PC) animals was left in situ, with the posterior, native periosteum intact. 'Experimental' (EXP) animals' defects were repaired with allograft tibia containing ASCs and BMP-2, with native periosteum intact. All constructs were secured with rigid fixation. Healing was assessed using clinical exam and serial radiography. Eight weeks later, each pig received a unilateral mid-graft osteotomy to assess ability to heal. After an additional 7-weeks, explants were harvested for micro-CT and histologic analyses.
Results: At 7 weeks, no NC tibias had healed (0/6) whereas most PC (5/6) and all EXP tibias (6/6) had healed. Unilateral mid-graft osteotomies performed at 8 weeks were performed to assess grafts ability to heal. As expected, all NC tibias (3/3) had radiographic non-unions 7 weeks later. However, all PC (4/4) and EXP (6/6) tibias healed their repeat osteotomies. Micro-CT and histologic analyses confirmed healing of both PC and EXP tibias. This is the first study demonstrating allograft revitalization for repairing of critical defects, and supports this technique as an alternative to vascularized bone flaps for critical defects.
