ABSTRACT
BACKGROUND: Establishment of a standard experimental animal model of atrophic nonunion is necessary for experimental study and related treatment of atrophic nonunion. However, the common modeling methods cannot accurately simulate atrophic nonunion in the clinical practice. OBJECTIVE: To construct a standard animal model of atrophic nonunion. METHODS: Thirty male Sprague-Dawley rats were randomly divided into experimental and control groups. All animals were subjected to bone cutting at the middle-lower segment of the right tibia and the circular external fixator was applied to keep a 4 mm defect interval. The animals in the experimental group were subjected to an additional cauterization of the periosteum at the fracture end of the tibia with a length of 1 mm. The periosteum was not treated in the control group. The study protocol was approved by the Experimental Animal Ethics Committee of the First Affiliated Hospital of Guangzhou University of Chinese Medicine on January 01, 2018, with approval No. TCMF1-2018002. RESULTS AND CONCLUSION: After modeling, there was one case of loose external fixation in each group, and no infection occurred in both groups. Imaging examination showed no bone connection and no sign of healing between the fractures of the tibia in the two groups at 6 weeks after modeling. Imaging and histological findings showed no healing at the end of fracture but typical atrophic nonunion in the experimental group at 12 weeks after modeling. By contrast, six animals had atrophic nonunion, and eight had hypertrophic nonunion in the control group. Overall, the animal model of atrophic tibial nonunion can be successfully constructed using circular external fixator combined with periosteal cauterization at the fracture end.
ABSTRACT
The purpose of this study was to evaluate the results and complications in difficult periarticular fractures of the knee treated with a circular(Ilizarov) external fixator. The mean follow-up period was 34 months(range: 12-55 months). Of the 27 cases, 12 cases involved fractures of distal femur (two M ller type A3, four type C2, six type C3) and 15 cases involved fractures of the proximal tibia (one Schatzker type V, eight type VI, two segmental, four metaphyseal comminuted fractures). Twenty-two cases(81%) were open fractures and most of the cases were open intra-articular comminuted fractures. The average duration of external fixation was 7.7 months (9.8 months for the distal femur cases, 6.5 months for the proximal tibia cases and 11.5 months for the cases which required lengthening, and 6 months in the non-lengthening group). In 8 cases, in which bone lenthening was done, no leg length discrepancy occurred after lengthening. The mean length gained was 5.9 cm and the mean healing index was 1.8 months/cm (1.8months/cm in distal femur cases and 1.9 months/cm in proximal tibia cases). According to Neers criteria, the treatment results for cases involving distal femur fracture were as follows: six satisfactory, three unsatisfactory, three failures; cases with proximal tibia fractures had these results: nine excellent, three satisfactory, three unsatisfactory. Average range of motion was 67 degrees in distal femur fracture cases and 114 degrees in proximal tibia fracture cases. According to Paleys complication grading system, six problems, six obstacles, and eight com- plications occurred. In conclusion, the Ilizarov external fixator can be a useful treatment method in periarticular fractures of the knee with severe intra-articular or metaphyseal comminution, bone loss, severe soft tissue injury, or multiple associated injury. Its use can reduce the associated complications such as leg length discrepancy, infection, and nonunion.