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Home / Equine Research Bank / Vet Surg / The failure mode of a mechanically loaded equine medial femo...
Veterinary surgery : VS2022; 51(3); 474-481; doi: 10.1111/vsu.13765

The failure mode of a mechanically loaded equine medial femoral condyle analog with a void and the impact of lag and neutral screw placement.

Abstract: To determine the failure method of simulated equine medial femoral condyle (MFC) subchondral bone defects under compression and the influence of screw placement on failure resistance. Methods: In vitro study. Methods: Composite disks (CD) simulating the moduli of yearling bone in the MFC. Methods: Four CD conditions were tested, all with a 12.7 mm void (n = 6 per condition): intact (no void), void only, void with a 4.5 mm screw placed in neutral fashion, and void with a 4.5 mm screw placed in lag fashion. Composite disks of each condition were tested under monotonic compression to 6000 N and cyclic compression to 10 000 cycles. Observable failure, load at first observable failure, and displacement at peak 2000 N load were compared among conditions. Results: Specimens failed by cracking at the superior aspect of the void or the screw exit hole. After monotonic loading, cracks were observed 6/6 CD with a void, 6/6 CD with a void/lag screw, and 5/6 CD with a void/neutral screw. After cyclical testing, cracks were noted only on the superior aspect of 6/6 CD with a void and 3/6 CD with a void/lag screw. Displacement at peak load was 0.06 mm (intact), 0.32 mm (void), 0.24 mm (void/lag screw), and 0.11 mm (void/neutral screw). Conclusions: Model MFC voids failed by superior cracking that was resisted by lag and neutral screw placement. Conclusions: Neutral screws may be an acceptable treatment for subchondral lucencies in the MFC.
© 2022 American College of Veterinary Surgeons.
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Publication Date: 2022-01-31 PubMed ID: 35102588DOI: 10.1111/vsu.13765Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study examines how simulated horse thigh bone defects behave under various types of stress and the potential effect of screw placement in reinforcing these defects. The research found that specific placements of screws might represent a beneficial treatment method for defects in this kind of bone tissue.

Research Parameters

  • The research was performed as an in vitro study, meaning it was conducted in a controlled, non-living environment such as a test tube or petri dish.
  • The researchers created composite disks which simulated the properties of equine medial femoral condyle (MFC), a part of a horse’s thigh bone, specifically simulating the characteristics of yearling bone age.

Test Conditions and Procedures

  • Four different conditions of these simulated bone disks were studied, each group having six samples. The conditions encompassed a disk with no void, a disk with a void (an empty space or defect), a disk with a void and a screw placed neutrally, and a disk with a void and a screw inserted in a lag fashion.
  • Two types of compression testing were conducted on the disks – monotonic compression (steady stress increase until failure) and cyclic compression (repeated, fluctuating stress).

Results and Observations

  • The predominant failure mode of the disks was cracking, either at the superior aspect (top) of the void or at the screw exit hole.
  • Performance varied depending on the scenario: in monotonic loading, all disks with voids showed cracking, whereas in cyclic testing, only the disks with voids and voids with lag screw showed superior cracking.
  • The amount of movement (displacement) at maximum load varied depending on the setup: the intact disks showed minimal displacement, while the voided disks exhibited more, and those with ca void and screws moved the least.

Conclusions

  • Defective areas in model MFCs primarily failed due to superior cracking. However, the presence of screws, regardless of placement, was observed to resist and minimize this failure.
  • The results indicate that the use of neutral screws may be a viable treatment for subchondral lucencies (bony defects) in equine medial femoral condyles.

Cite This Article

APA
Moreno CR, Santschi EM, Younkin JT, Larson RL, Litsky AS. (2022). The failure mode of a mechanically loaded equine medial femoral condyle analog with a void and the impact of lag and neutral screw placement. Vet Surg, 51(3), 474-481. https://doi.org/10.1111/vsu.13765

Publication

Veterinary surgery : VS
ISSN: 1532-950X
NlmUniqueID: 8113214
Country: United States
Language: English
Volume: 51
Issue: 3
Pages: 474-481

Researcher Affiliations

Moreno, Caitlin R
  • Department of Clinical Sciences, Kansas State University, Manhattan, Kansas, USA.
Santschi, Elizabeth M
  • Department of Clinical Sciences, Kansas State University, Manhattan, Kansas, USA.
Younkin, Jarrod T
  • Department of Clinical Sciences, Kansas State University, Manhattan, Kansas, USA.
Larson, Robert L
  • Department of Clinical Sciences, Kansas State University, Manhattan, Kansas, USA.
Litsky, Alan S
  • Departments of Orthopaedics and Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA.
  • Orthopaedic BioMaterials Laboratory, The Ohio State University, Columbus, Ohio, USA.

MeSH Terms

  • Animals
  • Biomechanical Phenomena
  • Bone Screws / veterinary
  • Epiphyses
  • Femur / surgery
  • Fracture Fixation, Internal / methods
  • Fracture Fixation, Internal / veterinary
  • Horses / surgery

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This article includes 21 references
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Citations

This article has been cited 1 times.
  1. Moreno CR, Santschi EM, Janes J, Liu J, Kim DG, Litsky AS. Compression generated by cortical screws in an artificial bone model of an equine medial femoral condylar cyst.. Vet Surg 2022 Jul;51(5):833-842.
    doi: 10.1111/vsu.13814pubmed: 35394080google scholar: lookup
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