Lateral drill holes decrease strength of the femur: An observational study using finite element and experimental analyses

Melanie J. Fox, Jennie SCARVELL, Paul N. Smith, Shankar Kalyanasundaram, Zbigniew H. Stachurski

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Background: Internal fixation of femoral fractures requires drilling holes through the cortical bone of the shaft of the femur. Intramedullary suction reduces the fat emboli produced by reaming and nailing femoral fractures but requires four suction portals to be drilled into the femoral shaft. This work investigated the effect of these additional holes on the strength of the femur.

Methods: Finite element analysis (FEA) was used to calculate compression, tension and load limits which were then compared to the results from mechanical testing. Models of intact femora and fractured femora internally fixed with intramedullary nailing were generated. In addition, four suction portals, lateral, anterior and posterior, were modelled. Stresses were used to calculate safety factors and predict fatigue. Physical testing on synthetic femora was carried out on a universal mechanical testing machine.

Results: The FEA model for stresses generated during walking showed tensile stresses in the lateral femur and compression stresses in the medial femur with a maximum sheer stress through the neck of the femur. The lateral suction portals produced tensile stresses up to over 300% greater than in the femur without suction portals. The anterior and posterior portals did not significantly increase stresses. The lateral suction portals had a safety factor of 0.7, while the anterior and posterior posts had safety factors of 2.4 times walking loads. Synthetic bone subjected to cyclical loading and load to failure showed similar results. On mechanical testing, all constructs failed at the neck of the femur.

Conclusions: The anterior suction portals produced minimal increases in stress to loading so are the preferred site should a femur require such drill holes for suction or internal fixation
Original languageEnglish
Pages (from-to)1-8
Number of pages8
JournalJournal of Orthopaedic Surgery and Research
Volume8
Issue number29
DOIs
Publication statusPublished - 2013

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Finite Element Analysis
Suction
Femur
Observational Studies
Femoral Fractures
Femur Neck
Safety
Walking
Intramedullary Fracture Fixation
Thigh
Embolism
Fatigue
Fats
Bone and Bones

Cite this

Fox, Melanie J. ; SCARVELL, Jennie ; Smith, Paul N. ; Kalyanasundaram, Shankar ; Stachurski, Zbigniew H. / Lateral drill holes decrease strength of the femur: An observational study using finite element and experimental analyses. In: Journal of Orthopaedic Surgery and Research. 2013 ; Vol. 8, No. 29. pp. 1-8.
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abstract = "Background: Internal fixation of femoral fractures requires drilling holes through the cortical bone of the shaft of the femur. Intramedullary suction reduces the fat emboli produced by reaming and nailing femoral fractures but requires four suction portals to be drilled into the femoral shaft. This work investigated the effect of these additional holes on the strength of the femur. Methods: Finite element analysis (FEA) was used to calculate compression, tension and load limits which were then compared to the results from mechanical testing. Models of intact femora and fractured femora internally fixed with intramedullary nailing were generated. In addition, four suction portals, lateral, anterior and posterior, were modelled. Stresses were used to calculate safety factors and predict fatigue. Physical testing on synthetic femora was carried out on a universal mechanical testing machine. Results: The FEA model for stresses generated during walking showed tensile stresses in the lateral femur and compression stresses in the medial femur with a maximum sheer stress through the neck of the femur. The lateral suction portals produced tensile stresses up to over 300{\%} greater than in the femur without suction portals. The anterior and posterior portals did not significantly increase stresses. The lateral suction portals had a safety factor of 0.7, while the anterior and posterior posts had safety factors of 2.4 times walking loads. Synthetic bone subjected to cyclical loading and load to failure showed similar results. On mechanical testing, all constructs failed at the neck of the femur. Conclusions: The anterior suction portals produced minimal increases in stress to loading so are the preferred site should a femur require such drill holes for suction or internal fixation",
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Lateral drill holes decrease strength of the femur: An observational study using finite element and experimental analyses. / Fox, Melanie J.; SCARVELL, Jennie; Smith, Paul N.; Kalyanasundaram, Shankar; Stachurski, Zbigniew H.

In: Journal of Orthopaedic Surgery and Research, Vol. 8, No. 29, 2013, p. 1-8.

Research output: Contribution to journalArticle

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T1 - Lateral drill holes decrease strength of the femur: An observational study using finite element and experimental analyses

AU - Fox, Melanie J.

AU - SCARVELL, Jennie

AU - Smith, Paul N.

AU - Kalyanasundaram, Shankar

AU - Stachurski, Zbigniew H.

PY - 2013

Y1 - 2013

N2 - Background: Internal fixation of femoral fractures requires drilling holes through the cortical bone of the shaft of the femur. Intramedullary suction reduces the fat emboli produced by reaming and nailing femoral fractures but requires four suction portals to be drilled into the femoral shaft. This work investigated the effect of these additional holes on the strength of the femur. Methods: Finite element analysis (FEA) was used to calculate compression, tension and load limits which were then compared to the results from mechanical testing. Models of intact femora and fractured femora internally fixed with intramedullary nailing were generated. In addition, four suction portals, lateral, anterior and posterior, were modelled. Stresses were used to calculate safety factors and predict fatigue. Physical testing on synthetic femora was carried out on a universal mechanical testing machine. Results: The FEA model for stresses generated during walking showed tensile stresses in the lateral femur and compression stresses in the medial femur with a maximum sheer stress through the neck of the femur. The lateral suction portals produced tensile stresses up to over 300% greater than in the femur without suction portals. The anterior and posterior portals did not significantly increase stresses. The lateral suction portals had a safety factor of 0.7, while the anterior and posterior posts had safety factors of 2.4 times walking loads. Synthetic bone subjected to cyclical loading and load to failure showed similar results. On mechanical testing, all constructs failed at the neck of the femur. Conclusions: The anterior suction portals produced minimal increases in stress to loading so are the preferred site should a femur require such drill holes for suction or internal fixation

AB - Background: Internal fixation of femoral fractures requires drilling holes through the cortical bone of the shaft of the femur. Intramedullary suction reduces the fat emboli produced by reaming and nailing femoral fractures but requires four suction portals to be drilled into the femoral shaft. This work investigated the effect of these additional holes on the strength of the femur. Methods: Finite element analysis (FEA) was used to calculate compression, tension and load limits which were then compared to the results from mechanical testing. Models of intact femora and fractured femora internally fixed with intramedullary nailing were generated. In addition, four suction portals, lateral, anterior and posterior, were modelled. Stresses were used to calculate safety factors and predict fatigue. Physical testing on synthetic femora was carried out on a universal mechanical testing machine. Results: The FEA model for stresses generated during walking showed tensile stresses in the lateral femur and compression stresses in the medial femur with a maximum sheer stress through the neck of the femur. The lateral suction portals produced tensile stresses up to over 300% greater than in the femur without suction portals. The anterior and posterior portals did not significantly increase stresses. The lateral suction portals had a safety factor of 0.7, while the anterior and posterior posts had safety factors of 2.4 times walking loads. Synthetic bone subjected to cyclical loading and load to failure showed similar results. On mechanical testing, all constructs failed at the neck of the femur. Conclusions: The anterior suction portals produced minimal increases in stress to loading so are the preferred site should a femur require such drill holes for suction or internal fixation

KW - Femur fracture

KW - Finite element analysis

KW - Internal fracture fixation

KW - Intramedullary fixation

KW - Materials testing

KW - Mechanical

KW - Stress

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DO - 10.1186/1749-799X-8-29

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JO - Journal of Orthopaedic Surgery and Research

JF - Journal of Orthopaedic Surgery and Research

SN - 1749-799X

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