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. 2023 Mar 7;10(3):338.
doi: 10.3390/bioengineering10030338.

Development of a Metaphyseal Non-Union Model in the Osteoporotic Rat Femur

Amelie Deluca  1   2 , Andrea Wagner  1   3 , Bettina Faustini  1   3 , Nadja Weissenbacher  1   3 , Christian Deininger  1   4 , Florian Wichlas  4 , Herbert Tempfer  1   3 , Ernst J Mueller  2 , Andreas Traweger  1   3
Affiliations

Development of a Metaphyseal Non-Union Model in the Osteoporotic Rat Femur

Amelie Deluca et al. Bioengineering (Basel). .

Abstract

The aim of this current study was to establish a metaphyseal femoral non-union model in osteoporotic rats by comparing a power tool versus a manual tool for fracture creation. Twelve adult female Sprague Dawley rats were ovariectomized (OVX) and received a special diet for 6 weeks. Biweekly pQCT measurements confirmed a significant reduction in the cancellous and total bone mineral density in OVX rats compared to control (CTRL) animals. After 6 weeks, OVX rats underwent surgery creating a distal metaphyseal osteotomy, either using a piezoelectric- (n = 6) or a manual Gigli wire (n = 6) saw. Fractures were stabilized with a Y-shaped mini-locking plate. Within each group, three rats received Alginate directly into the fracture gap. OVX animals gained more weight over 8 weeks compared to CTRL animals. pQCT analysis showed a significant difference in the volumetric cancellous bone mineral density between OVX and CTRL rats. A histological examination of the osteoporotic phenotype was completed. Radiographic evaluation and Masson-Goldner trichrome staining with the piezoelectric saw failed to demonstrate bony bridging or a callus formation. New bone formation and complete healing were seen after 6 weeks in the Gigli group. For the creation of a metaphyseal atrophic non-union in the osteoporotic bone, a piezoelectric saw should be used.

Keywords: metaphyseal fracture; osteoporosis; pseudoarthrosis; rat models for fracture healing.

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Conflict of interest statement

The authors declare no conflict of interest and the funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Distal right metaphyseal osteotomy model. (A) Macroscopic plate fixation and (B,C) application of alginate into the fracture gap.
Figure 2
Figure 2
Osteoporotic induction. (A) pQCT analysis of the left proximal tibia metaphysis after 8 weeks of non-OVX and (B) OVX rats. (C) Volumetric cancellous bone mineral density and (D) volumetric total bone mineral density in CTRL and OVX rats over 8 weeks (n = 3 per group).
Figure 3
Figure 3
Representative distal metaphyseal femur with H&E staining (top) and Masson–Goldner staining (bottom) confirming the induced osteoporotic bone phenomenon in the OVX group compared to the CTRL group using reduced trabecular density (arrows). CTRL (A) and OVX (B) animals with H&E staining, compared to CTRL (C) and OVX (D) rats with Masson-Goldner staining.
Figure 4
Figure 4
(A) Comparison of X-rays left to right from the time of surgery until 6 weeks post-surgery. The top row shows samples without the implantation of an alginate clot, whereas the bottom samples were treated with alginate. (B) A close-up of the non-union fracture induced with the piezoelectric saw at 6 weeks post-surgery is shown (representative image of the alginate-treated group).
Figure 5
Figure 5
(A) Fracture consolidation over a time period of 6 weeks post-surgery after performing a complete osteotomy using a Gigli saw. The top row shows samples without the implantation of an alginate clot, whereas the bottom samples were treated with alginate. (B) The fracture gap showed full bridging 6 weeks post-surgery for all animals investigated (representative image of the alginate-treated group).
Figure 6
Figure 6
Representative histological sections of the fracture defect area for all treatment groups stained either with Masson–Goldner (bottom) stain. (A) Fracture creation with the piezoelectric saw and the (B) Gigli saw. The bottom row shows enlarged sections (box) of the fracture defect area.
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