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Characterization of a rat osteotomy model with impaired healing.

Kratzel C, Bergmann C, Duda G, Greiner S, Schmidmaier G, Wildemann B - BMC Musculoskelet Disord (2008)

Bottom Line: The healing progress of the osteotomy model was compared to a previously described closed fracture model.The dimensions of whole reactive callus and the amounts of vessels in defined regions of the callus differed significantly between osteotomized and fractured animals at 10 d post surgery.Moreover, the osteotomy technique is associated with cellular and vascular signs of persistent inflammation within the first 10 d after bone defect and may be a contributory factor to impaired healing.

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Affiliation: Julius Wolff Institut, BCRT, CMSC Charité-Universitätsmedizin Berlin Augustenburger Platz 1, 13353 Berlin, Germany. chris.kratzel@web.de

ABSTRACT

Background: Delayed union or nonunion are frequent and feared complications in fracture treatment. Animal models of impaired bone healing are rare. Moreover, specific descriptions are limited although understanding of the biological course of pathogenesis of fracture nonunion is essential for therapeutic approaches.

Methods: A rat tibial osteotomy model with subsequent intramedullary stabilization was performed. The healing progress of the osteotomy model was compared to a previously described closed fracture model. Histological analyses, biomechanical testing and radiological screening were undertaken during the observation period of 84 days (d) to verify the status of the healing process. In this context, particular attention was paid to a comparison of bone slices by histological and immunohistological (IHC) methods at early points in time, i.e. at 5 and 10 d post bone defect.

Results: In contrast to the closed fracture technique osteotomy led to delayed union or nonunion until 84 d post intervention. The dimensions of whole reactive callus and the amounts of vessels in defined regions of the callus differed significantly between osteotomized and fractured animals at 10 d post surgery. A lower fraction of newly formed bone and cartilaginous tissue was obvious during this period in osteotomized animals and more inflammatory cells were observed in the callus. Newly formed bone tissue accumulated slowly on the anterior tibial side with both techniques. New formation of reparative cartilage was obviously inhibited on the anterior side, the surgical approach side, in osteotomized animals only.

Conclusion: Tibial osteotomy with intramedullary stabilisation in rats leads to pronounced delayed union and nonunion until 84 d post intervention. The early onset of this delay can already be detected histologically within 10 d post surgery. Moreover, the osteotomy technique is associated with cellular and vascular signs of persistent inflammation within the first 10 d after bone defect and may be a contributory factor to impaired healing. The model would be excellent to test agents to promote fracture healing.

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(a and b). Histological preparation of comparable osteotomized (a) and fractured (b) tibial areas 10 days after surgery. Movat Pentachrome staining for detection of newly formed trabecular bone (arrows). Cavities correspond to the 1 mm wire diameter. Diamonds indicate the proximal and anterior tibial side.
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Figure 6: (a and b). Histological preparation of comparable osteotomized (a) and fractured (b) tibial areas 10 days after surgery. Movat Pentachrome staining for detection of newly formed trabecular bone (arrows). Cavities correspond to the 1 mm wire diameter. Diamonds indicate the proximal and anterior tibial side.

Mentions: Significantly more newly arranged bone was found in fractured animals at 10 d post operation than in the osteomized group (p = 0.0087). Moreover, in nearly all individuals in both groups, lower amounts of this tissue were observed on the anterior tibial side. This was not only the side with a minor soft tissue envelope but also the side of surgery (Figs. 6a and 6b; Table 4). More newly formed cartilage was found in the fractured animals 5 and 10 d post surgery (p = 0.026). Only osteotomized animals accumulated lower amounts of differentiated cartilaginous cells on the anterior tibial side (Figs. 7a and 7b; Table 5).


Characterization of a rat osteotomy model with impaired healing.

Kratzel C, Bergmann C, Duda G, Greiner S, Schmidmaier G, Wildemann B - BMC Musculoskelet Disord (2008)

(a and b). Histological preparation of comparable osteotomized (a) and fractured (b) tibial areas 10 days after surgery. Movat Pentachrome staining for detection of newly formed trabecular bone (arrows). Cavities correspond to the 1 mm wire diameter. Diamonds indicate the proximal and anterior tibial side.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2571093&req=5

Figure 6: (a and b). Histological preparation of comparable osteotomized (a) and fractured (b) tibial areas 10 days after surgery. Movat Pentachrome staining for detection of newly formed trabecular bone (arrows). Cavities correspond to the 1 mm wire diameter. Diamonds indicate the proximal and anterior tibial side.
Mentions: Significantly more newly arranged bone was found in fractured animals at 10 d post operation than in the osteomized group (p = 0.0087). Moreover, in nearly all individuals in both groups, lower amounts of this tissue were observed on the anterior tibial side. This was not only the side with a minor soft tissue envelope but also the side of surgery (Figs. 6a and 6b; Table 4). More newly formed cartilage was found in the fractured animals 5 and 10 d post surgery (p = 0.026). Only osteotomized animals accumulated lower amounts of differentiated cartilaginous cells on the anterior tibial side (Figs. 7a and 7b; Table 5).

Bottom Line: The healing progress of the osteotomy model was compared to a previously described closed fracture model.The dimensions of whole reactive callus and the amounts of vessels in defined regions of the callus differed significantly between osteotomized and fractured animals at 10 d post surgery.Moreover, the osteotomy technique is associated with cellular and vascular signs of persistent inflammation within the first 10 d after bone defect and may be a contributory factor to impaired healing.

View Article: PubMed Central - HTML - PubMed

Affiliation: Julius Wolff Institut, BCRT, CMSC Charité-Universitätsmedizin Berlin Augustenburger Platz 1, 13353 Berlin, Germany. chris.kratzel@web.de

ABSTRACT

Background: Delayed union or nonunion are frequent and feared complications in fracture treatment. Animal models of impaired bone healing are rare. Moreover, specific descriptions are limited although understanding of the biological course of pathogenesis of fracture nonunion is essential for therapeutic approaches.

Methods: A rat tibial osteotomy model with subsequent intramedullary stabilization was performed. The healing progress of the osteotomy model was compared to a previously described closed fracture model. Histological analyses, biomechanical testing and radiological screening were undertaken during the observation period of 84 days (d) to verify the status of the healing process. In this context, particular attention was paid to a comparison of bone slices by histological and immunohistological (IHC) methods at early points in time, i.e. at 5 and 10 d post bone defect.

Results: In contrast to the closed fracture technique osteotomy led to delayed union or nonunion until 84 d post intervention. The dimensions of whole reactive callus and the amounts of vessels in defined regions of the callus differed significantly between osteotomized and fractured animals at 10 d post surgery. A lower fraction of newly formed bone and cartilaginous tissue was obvious during this period in osteotomized animals and more inflammatory cells were observed in the callus. Newly formed bone tissue accumulated slowly on the anterior tibial side with both techniques. New formation of reparative cartilage was obviously inhibited on the anterior side, the surgical approach side, in osteotomized animals only.

Conclusion: Tibial osteotomy with intramedullary stabilisation in rats leads to pronounced delayed union and nonunion until 84 d post intervention. The early onset of this delay can already be detected histologically within 10 d post surgery. Moreover, the osteotomy technique is associated with cellular and vascular signs of persistent inflammation within the first 10 d after bone defect and may be a contributory factor to impaired healing. The model would be excellent to test agents to promote fracture healing.

Show MeSH
Related in: MedlinePlus