Plastic Surgery Research Council
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Presenter: Raja Mohan, MD
Co-Authors: Brown EN; Mundinger GS; Kelamis JA; Bojovic B; Chrsity MR; Dorafshar AH; Rodriguez ED
Johns Hopkins University and University of Maryland

Introduction: The gold standard for reconstructing mandibular defects ? 6cm is vascularized bone flaps. However, this technique can result in significant donor site morbidity and requires microsurgical expertise. To explore alternative methods of mandibular reconstruction, we sought to compare the reamer-irrigator-aspirator (RIA) to osseous free fibular flap for reconstruction of a large animal critical sized mandibular defect.

Methods: Nine 3-month old Yorkshire pigs underwent 6cm full-thickness resection of the left mandible. A mandibular reconstruction plate was placed at the inferior border of the mandible prior to osteotomies and secured in place. For the free fibular group (four pigs), an 8-10cm osseous free fibula flap from the left leg was raised and anastomosed to the facial artery and secured with the reconstruction plate. For the RIA group (five pigs), a Synthes RIA Instrument Set (Fig. 1) was used on the ipsilateral femur to ream the femoral canal and harvest medullary contents. An intramedullary reamer was placed under radiographic guidance and passed 6-10 times to obtain medullary bone. RIA putty (Fig. 2) containing medullary bone marrow contents and cortical bone was placed in the mandibular defect (Fig. 3). Animals were followed with serial radiographs and evaluated for ability to masticate, ambulate, and gain weight for a six-month time period.

Results: The reconstruction of the mandibular defect was successfully performed in both experimental groups. Average operative times (p<0.05) were 144.4 minutes (RIA) and 353.3 minutes (free fibula). Biomechanical testing of reconstructed sites showed a maximum load (p=0.11) of 468N (RIA) and 689N (free fibula). Volumetric analysis of bone growth of the reconstructed sites using three-dimensional CT scans showed no significant difference (p=0.60) between both experimental groups.

Conclusion: We believe the RIA technique is acceptable for use in craniomaxillofacial surgery to reconstruct critical sized bone defects and is comparable to free fibular flaps. Future directions include histological analysis to assess osteoid formation in both groups.

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