Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing
Aims: The “2 to 10% strain rule” for fracture healing has been widely interpreted to mean that interfragmentary strain greater than 10% predisposes a fracture to nonunion. This interpretation focuses on the gap-closing strain (axial micromotion divided by gap size), ignoring the region around the g...
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The British Editorial Society of Bone & Joint Surgery
2025-01-01
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| Series: | Bone & Joint Research |
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| Online Access: | https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.141.BJR-2024-0191.R2 |
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| author | Maham Tanveer Karina Klein Brigitte von Rechenberg Salim Darwiche Hannah L. Dailey |
| author_facet | Maham Tanveer Karina Klein Brigitte von Rechenberg Salim Darwiche Hannah L. Dailey |
| author_sort | Maham Tanveer |
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| description | Aims: The “2 to 10% strain rule” for fracture healing has been widely interpreted to mean that interfragmentary strain greater than 10% predisposes a fracture to nonunion. This interpretation focuses on the gap-closing strain (axial micromotion divided by gap size), ignoring the region around the gap where osteogenesis typically initiates. The aim of this study was to measure gap-closing and 3D interfragmentary strains in plated ovine osteotomies and associate local strain conditions with callus mineralization. Methods: MicroCT scans of eight female sheep with plated mid-shaft tibial osteotomies were used to create image-based finite element models. Virtual mechanical testing was used to compute postoperative gap-closing and 3D continuum strains representing compression (volumetric strain) and shear deformation (distortional strain). Callus mineralization was measured in zones in and around the osteotomy gap. Results: Gap-closing strains averaged 51% (mean) at the far cortex. Peak compressive volumetric strain averaged 32% and only a small tissue volume (average 0.3 cm3) within the gap experienced compressive strains > 10%. Distortional strains were much higher and more widespread, peaking at a mean of 115%, with a mean of 3.3 cm3 of tissue in and around the osteotomy experiencing distortional strains > 10%. Callus mineralization initiated outside the high-strain gap and was significantly lower within the fracture gap compared to around it at nine weeks. Conclusion: Ovine osteotomies can heal with high gap strains (> 10%) dominated by shear conditions. High gap strain appears to be a transient local limiter of osteogenesis, not a global inhibitor of secondary fracture repair. Cite this article: Bone Joint Res 2025;14(1):5–15. |
| format | Article |
| id | doaj-art-d890bfde26f9469dac3fc6f243e74254 |
| institution | Kabale University |
| issn | 2046-3758 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | The British Editorial Society of Bone & Joint Surgery |
| record_format | Article |
| series | Bone & Joint Research |
| spelling | doaj-art-d890bfde26f9469dac3fc6f243e742542025-01-28T06:54:24ZengThe British Editorial Society of Bone & Joint SurgeryBone & Joint Research2046-37582025-01-0114151510.1302/2046-3758.141.BJR-2024-0191.R2Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testingMaham Tanveer0https://orcid.org/0009-0002-9581-4455Karina Klein1Brigitte von Rechenberg2Salim Darwiche3https://orcid.org/0000-0001-5116-4564Hannah L. Dailey4https://orcid.org/0000-0002-4574-800XDepartment of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, Pennsylvania, USAMusculoskeletal Research Unit (MSRU), Vetsuisse Faculty, University of Zurich, Zurich, SwitzerlandMusculoskeletal Research Unit (MSRU), Vetsuisse Faculty, University of Zurich, Zurich, SwitzerlandMusculoskeletal Research Unit (MSRU), Vetsuisse Faculty, University of Zurich, Zurich, SwitzerlandDepartment of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, Pennsylvania, USAAims: The “2 to 10% strain rule” for fracture healing has been widely interpreted to mean that interfragmentary strain greater than 10% predisposes a fracture to nonunion. This interpretation focuses on the gap-closing strain (axial micromotion divided by gap size), ignoring the region around the gap where osteogenesis typically initiates. The aim of this study was to measure gap-closing and 3D interfragmentary strains in plated ovine osteotomies and associate local strain conditions with callus mineralization. Methods: MicroCT scans of eight female sheep with plated mid-shaft tibial osteotomies were used to create image-based finite element models. Virtual mechanical testing was used to compute postoperative gap-closing and 3D continuum strains representing compression (volumetric strain) and shear deformation (distortional strain). Callus mineralization was measured in zones in and around the osteotomy gap. Results: Gap-closing strains averaged 51% (mean) at the far cortex. Peak compressive volumetric strain averaged 32% and only a small tissue volume (average 0.3 cm3) within the gap experienced compressive strains > 10%. Distortional strains were much higher and more widespread, peaking at a mean of 115%, with a mean of 3.3 cm3 of tissue in and around the osteotomy experiencing distortional strains > 10%. Callus mineralization initiated outside the high-strain gap and was significantly lower within the fracture gap compared to around it at nine weeks. Conclusion: Ovine osteotomies can heal with high gap strains (> 10%) dominated by shear conditions. High gap strain appears to be a transient local limiter of osteogenesis, not a global inhibitor of secondary fracture repair. Cite this article: Bone Joint Res 2025;14(1):5–15.https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.141.BJR-2024-0191.R2secondary fracture healinginterfragmentary motionbone repairimage-based modellingfracture healingstrainsosteotomiesnonunionosteogenesissheeptibial osteotomiesfinite element modelssecondary fracturecompressive strains |
| spellingShingle | Maham Tanveer Karina Klein Brigitte von Rechenberg Salim Darwiche Hannah L. Dailey Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing Bone & Joint Research secondary fracture healing interfragmentary motion bone repair image-based modelling fracture healing strains osteotomies nonunion osteogenesis sheep tibial osteotomies finite element models secondary fracture compressive strains |
| title | Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing |
| title_full | Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing |
| title_fullStr | Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing |
| title_full_unstemmed | Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing |
| title_short | Don’t mind the gap: reframing the Perren strain rule for fracture healing using insights from virtual mechanical testing |
| title_sort | don t mind the gap reframing the perren strain rule for fracture healing using insights from virtual mechanical testing |
| topic | secondary fracture healing interfragmentary motion bone repair image-based modelling fracture healing strains osteotomies nonunion osteogenesis sheep tibial osteotomies finite element models secondary fracture compressive strains |
| url | https://online.boneandjoint.org.uk/doi/epdf/10.1302/2046-3758.141.BJR-2024-0191.R2 |
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