Comparison of open osteotomy model and closed fracture model in the rat femur

Chang SHE; Qirong DONG; Xiaozhong ZHOU

ABSTRACT

BACKGROUND:

There is no doubt that animal model of fracture is the basis of fracture healing research.The fracture animal mode is divided into open osteotomy model and closed fracture model.There is no research about the difference between two kinds of fracture rat models.

OBJECTIVE:

To compare the modeling process between open osteotomy model and closed fracture model in rats,and to compare fracture healing using radiograph.DESIGN,TIME AND

SETTING:

The randomized,controlled animal experiment was performed at the Laboratory of Department of Orthopaedics,Second Affiliated Hospital,Soochow University from January to May 2007.MATERIALSA total of 40 SPF male Sprague Dawley rats,weighing(220?30) g,were randomly divided into an open osteotomy model group and a closed fracture model group,with 20 rats for each group.Electric swing saw was a kind of self-made percussion device for closed fracture models.

METHODS:

All rats in the open osteotomy model group received open osteotomy to create transverse fracture of the middle femur,and fixed using Kirschner wire.Rats in the closed fracture model group received retrograde Kirschner wire fixation,and midshaft femoral closed fracture induced by model establishment stent.MAIN OUTCOME

MEASURES:

Mean model establishment time;Successful rate of model establishment;Radiography of fracture healing at 2,3,4 and 8 weeks after surgery.

RESULTS:

Success rate of open osteotomy model establishment was 90%.Average modeling time was 17 minutes.Rate of malunion and nonunion was 40%.Successful rate of each closed fracture models was 85%,with average modeling time was 12 minutes.There was no malunion and nonunion.At 2,3 and 4 weeks after surgery,X-ray score was lower in the open osteotomy model group compared with the closed fracture model group(P 0.05).

CONCLUSION:

Model establishment of open osteotomy takes a longer time,with a high rate of malunion and nonunion.In near future or medium-term,fracture healing is significantly lagged.Thus,open osteotomy is not suitable for the study of early or medium-term fracture healing.