5 research outputs found
Evaluation of human acellular dermis versus porcine acellular dermis in an in vivo model for incisional hernia repair
Incisional hernias commonly occur following abdominal wall surgery. Human acellular dermal matrices (HADM) are widely used in abdominal wall defect repair. Xenograft acellular dermal matrices, particularly those made from porcine tissues (PADM), have recently experienced increased usage. The purpose of this study was to compare the effectiveness of HADM and PADM in the repair of incisional abdominal wall hernias in a rabbit model. A review from earlier work of differences between human allograft acellular dermal matrices (HADM) and porcine xenograft acellular dermal matrices (PADM) demonstrated significant differences (P < 0.05) in mechanical properties: Tensile strength 15.7 MPa vs. 7.7 MPa for HADM and PADM, respectively. Cellular (fibroblast) infiltration was significantly greater for HADM vs. PADM (Armour). The HADM exhibited a more natural, less degraded collagen by electrophoresis as compared to PADM. The rabbit model surgically established an incisional hernia, which was repaired with one of the two acellular dermal matrices 3 weeks after the creation of the abdominal hernia. The animals were euthanized at 4 and 20 weeks and the wounds evaluated. Tissue ingrowth into the implant was significantly faster for the HADM as compared to PADM, 54 vs. 16% at 4 weeks, and 58 vs. 20% for HADM and PADM, respectively at 20 weeks. The original, induced hernia defect (6 cm2) was healed to a greater extent for HADM vs. PADM: 2.7 cm2 unremodeled area for PADM vs. 1.0 cm² for HADM at 20 weeks. The inherent uniformity of tissue ingrowth and remodeling over time was very different for the HADM relative to the PADM. No differences were observed at the 4-week end point. However, the 20-week data exhibited a statistically different level of variability in the remodeling rate with the mean standard deviation of 0.96 for HADM as contrasted to a mean standard deviation of 2.69 for PADM. This was significant with P < 0.05 using a one tail F test for the inherent variability of the standard deviation. No significant differences between the PADM and HADM for adhesion, inflammation, fibrous tissue or neovascularization were noted
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Improved osseointeraction of calcium phosphate-coated external fixation pins: Studies in calves
We investigated osseointeraction of solution-precipitated calcium phosphate (SPCP)-coated transfix-ation pins used in external skeletal fixation of a calf stable fracture model. One group (SPCP) received centrally-threaded transfixation pins which had SPCP coating; the other group (control) received identical, but not coated, pins. Radiographs were obtained 1 and 40 days after surgery and examined for evidence of osteolysis. Bone phase 99rnTc-MDP studies were performed 6 and 28 days after surgery. Calves were killed 40 days after surgery and mechanical tests performed. Dual-energy x-ray absorptiometry (DEXA) and histomorphometric analyses were done. A smaller proportion of SPCP pins (5/24) had evidence of discharge during the study compared with control pins (21/24). A smaller proportion of SPCP pins (4%) had radiographic evidence of osteolysis compared with control pins (42%). Uptake of 99mTc-MDP was similar for SPCP and control calves. Uptake was significantly greater in bone segments showing radiographic evidence of osteolysis than in bone segments not having osteolysis. Yield stress (MPa) for axial displacement was similar in the treatment groups. Bone mineral density was less in SPCP pins. Affinity index and interface histologic score were greater and osteoclastic index less in SPCP calves. Coating of transfixation pins with solution-precipitated calcium phosphate improved the osseointeraction of pin and bone during this 40-day study