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Characterization of a Pre-Clinical Mini-Pig Model of Scaphoid Non-Union.

Behrends DA, Khendek L, Gao C, Zayed N, Henderson JE, Martineau PA - J Funct Biomater (2015)

Bottom Line: A 3 mm osteotomy of the radiocarpal bone was generated and treated with immediate fixation or filled with a dense collagen gel followed by delayed fixation.With immediate fixation, the osteotomy site was filled with new bone across its whole length resulting in complete bridging.The dense collagen gel, previously shown to impede neo-vascularization, followed by delayed fixation resulted in impaired bridging with less bone of lower quality.

View Article: PubMed Central - PubMed

Affiliation: Bone Engineering Labs, Research Institute-McGill University Health Centre, Montreal General Hospital, 1650 Cedar Ave, Montreal, Quebec H3G 1A4, Canada. domi.behrends@gmail.com.

ABSTRACT
A fractured scaphoid is a common disabling injury that is frequently complicated by non-union. The treatment of non-union remains challenging because of the scaphoid's small size and delicate blood supply. Large animal models are the most reliable method to evaluate the efficacy of new treatment modalities before their translation into clinical practice. The goal of this study was to model a human scaphoid fracture complicated by non-union in Yucatan mini-pigs. Imaging and perfusion studies were used to confirm that the anatomy and blood supply of the radiocarpal bone in mini-pigs were similar to the human scaphoid. A 3 mm osteotomy of the radiocarpal bone was generated and treated with immediate fixation or filled with a dense collagen gel followed by delayed fixation. Bone healing was assessed using quantitative micro computed tomography and histology. With immediate fixation, the osteotomy site was filled with new bone across its whole length resulting in complete bridging. The dense collagen gel, previously shown to impede neo-vascularization, followed by delayed fixation resulted in impaired bridging with less bone of lower quality. This model is an appropriate, easily reproducible model for the evaluation of novel approaches for the repair of human scaphoid fractures.

No MeSH data available.


Related in: MedlinePlus

Repair after immediate (LEFT) and delayed (RIGHT) fixation: 2D micro CT images are shown in the sagittal plane (A,A’) indicating the position along the screw (arrows) at which transaxial 2D images are shown for the volar (V,B,B’), osteotomy site (O,C,C’) and dorsal (D,D,D’) aspects of the radiocarpal bones. Corresponding histological sections from the same levels (E–G,E’–G’) were stained with Alizarin red and Methylene blue to distinguish mineralized (red) from soft (blue) tissue. Complete bridging occurred with immediate fixation (A,C) whereas little bone was seen in the osteotomy site (A’,C’) with delayed fixation. Histological sections confirmed the presence of bone in the osteotomy site with immediate fixation (F) and its absence with delayed fixation (F’). Arrow (B) points to ROI used for quantitative micro CT analyses and scale bars (B,E) represents 2 mm.
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jfb-06-00407-f003: Repair after immediate (LEFT) and delayed (RIGHT) fixation: 2D micro CT images are shown in the sagittal plane (A,A’) indicating the position along the screw (arrows) at which transaxial 2D images are shown for the volar (V,B,B’), osteotomy site (O,C,C’) and dorsal (D,D,D’) aspects of the radiocarpal bones. Corresponding histological sections from the same levels (E–G,E’–G’) were stained with Alizarin red and Methylene blue to distinguish mineralized (red) from soft (blue) tissue. Complete bridging occurred with immediate fixation (A,C) whereas little bone was seen in the osteotomy site (A’,C’) with delayed fixation. Histological sections confirmed the presence of bone in the osteotomy site with immediate fixation (F) and its absence with delayed fixation (F’). Arrow (B) points to ROI used for quantitative micro CT analyses and scale bars (B,E) represents 2 mm.

Mentions: The time taken to anesthetize the animals and perform bilateral surgical interventions on each of three mini-pigs varied between 80 min and 110 min. Surgeries were uneventful except for a partial fracture of the volar aspect of the left radiocarpal at the time of screw insertion in the first animal operated. This bone was subsequently excluded from all post-mortem analyses leaving only two animals for direct comparison of bone repair after immediate fixation (IF) and three for delayed fixation (DF). All mini-pigs were fully ambulatory within 48 hours post-operation and had no visible signs of infection or other complications after one week. Micro CT and un-decalcified histological analyses (Figure 3) clearly demonstrated mal-union of the right radiocarpal bone at 19 weeks post-operative. The dorsal and volar segments were rigidly fixed at seven weeks after removal of the dense collagen spacer.


Characterization of a Pre-Clinical Mini-Pig Model of Scaphoid Non-Union.

Behrends DA, Khendek L, Gao C, Zayed N, Henderson JE, Martineau PA - J Funct Biomater (2015)

Repair after immediate (LEFT) and delayed (RIGHT) fixation: 2D micro CT images are shown in the sagittal plane (A,A’) indicating the position along the screw (arrows) at which transaxial 2D images are shown for the volar (V,B,B’), osteotomy site (O,C,C’) and dorsal (D,D,D’) aspects of the radiocarpal bones. Corresponding histological sections from the same levels (E–G,E’–G’) were stained with Alizarin red and Methylene blue to distinguish mineralized (red) from soft (blue) tissue. Complete bridging occurred with immediate fixation (A,C) whereas little bone was seen in the osteotomy site (A’,C’) with delayed fixation. Histological sections confirmed the presence of bone in the osteotomy site with immediate fixation (F) and its absence with delayed fixation (F’). Arrow (B) points to ROI used for quantitative micro CT analyses and scale bars (B,E) represents 2 mm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493521&req=5

jfb-06-00407-f003: Repair after immediate (LEFT) and delayed (RIGHT) fixation: 2D micro CT images are shown in the sagittal plane (A,A’) indicating the position along the screw (arrows) at which transaxial 2D images are shown for the volar (V,B,B’), osteotomy site (O,C,C’) and dorsal (D,D,D’) aspects of the radiocarpal bones. Corresponding histological sections from the same levels (E–G,E’–G’) were stained with Alizarin red and Methylene blue to distinguish mineralized (red) from soft (blue) tissue. Complete bridging occurred with immediate fixation (A,C) whereas little bone was seen in the osteotomy site (A’,C’) with delayed fixation. Histological sections confirmed the presence of bone in the osteotomy site with immediate fixation (F) and its absence with delayed fixation (F’). Arrow (B) points to ROI used for quantitative micro CT analyses and scale bars (B,E) represents 2 mm.
Mentions: The time taken to anesthetize the animals and perform bilateral surgical interventions on each of three mini-pigs varied between 80 min and 110 min. Surgeries were uneventful except for a partial fracture of the volar aspect of the left radiocarpal at the time of screw insertion in the first animal operated. This bone was subsequently excluded from all post-mortem analyses leaving only two animals for direct comparison of bone repair after immediate fixation (IF) and three for delayed fixation (DF). All mini-pigs were fully ambulatory within 48 hours post-operation and had no visible signs of infection or other complications after one week. Micro CT and un-decalcified histological analyses (Figure 3) clearly demonstrated mal-union of the right radiocarpal bone at 19 weeks post-operative. The dorsal and volar segments were rigidly fixed at seven weeks after removal of the dense collagen spacer.

Bottom Line: A 3 mm osteotomy of the radiocarpal bone was generated and treated with immediate fixation or filled with a dense collagen gel followed by delayed fixation.With immediate fixation, the osteotomy site was filled with new bone across its whole length resulting in complete bridging.The dense collagen gel, previously shown to impede neo-vascularization, followed by delayed fixation resulted in impaired bridging with less bone of lower quality.

View Article: PubMed Central - PubMed

Affiliation: Bone Engineering Labs, Research Institute-McGill University Health Centre, Montreal General Hospital, 1650 Cedar Ave, Montreal, Quebec H3G 1A4, Canada. domi.behrends@gmail.com.

ABSTRACT
A fractured scaphoid is a common disabling injury that is frequently complicated by non-union. The treatment of non-union remains challenging because of the scaphoid's small size and delicate blood supply. Large animal models are the most reliable method to evaluate the efficacy of new treatment modalities before their translation into clinical practice. The goal of this study was to model a human scaphoid fracture complicated by non-union in Yucatan mini-pigs. Imaging and perfusion studies were used to confirm that the anatomy and blood supply of the radiocarpal bone in mini-pigs were similar to the human scaphoid. A 3 mm osteotomy of the radiocarpal bone was generated and treated with immediate fixation or filled with a dense collagen gel followed by delayed fixation. Bone healing was assessed using quantitative micro computed tomography and histology. With immediate fixation, the osteotomy site was filled with new bone across its whole length resulting in complete bridging. The dense collagen gel, previously shown to impede neo-vascularization, followed by delayed fixation resulted in impaired bridging with less bone of lower quality. This model is an appropriate, easily reproducible model for the evaluation of novel approaches for the repair of human scaphoid fractures.

No MeSH data available.


Related in: MedlinePlus