Osteogenic ability of free periosteal autografts in tibial fractures with severe soft tissue damage: An experimental study

Objective: The present study was undertaken to assess whether free nonvascu larized autologous periosteum transplants enhance bone healing in a rabbit fracture model designed to resemble a tibial fracture with severe soft tiss ue damage. Design: Transplantation of free autologous periosteal grafts on the anterom edial site of the tibia (experimental group) was compared with nontransplan tation on the contralateral tibia (control group). We produced a standardiz ed transverse osteotomy of both tibial diaphyses in white male adult New Ze aland rabbits. The endomedullary cavity was reamed and nailed, and then a o ne-centimeter segment of periosteum was excised from either side of the ost eotomy. To prevent periosteal and extraosseous ingrowth at the osteotomy si te, a silastic sheet was wrapped around two-thirds of the circumference of the tibia. In the first group, on the silastic-free bone window, we then sp anned the osteotomy with a free, nonvascularized, longitudinally oriented a utologous periosteum and sewed it to the adjacent periosteum both proximall y and distally. In the second group, the periosteum was placed transversely , leaving a gap between it and the adjacent periosteum proximally and dista lly. Revascularization of the graft was determined with the colored microsp here technique. Main Outcome Measurements: Histomorphometric analysis of the periosteal cal lus was done on a transparent grid superimposed on enlarged photographs of the histologic sections. Results: Free, nonvascularized, longitudinally placed autologous periosteum in contact with intact periosteum produced significantly more periosteal c allus than was seen in the control group, in which no periosteal graft was used. However, when transversely placed periosteal grafts were set in the s ilastic-free bone window and there was no contact with surrounding remnants of intact periosteum, no significant difference in callus production was n oted when compared with the control. Revascularization of these grafts was seen within one week after transplantation. Bone healing occurred mainly th rough endochondral ossification Conclusion: Our data suggest that orthotopically placed autologous nonvascu larized periosteum retains its osteogenic potential in a poorly vascularize d environment such as a tibial fracture with severe soft tissue damage. The effect is enhanced if the graft is in contact with intact periosteum. Hist ologically, callus formation after periosteal grafting resembles endochondr al and intramembranous ossification.