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Joint Diseases and
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Original Article · Open access

Effects of Schanz screw location on reduction efficiency in distal femur fractures: A finite element analysis

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Shou-I Chen

Department of Mechanical Design Engineering, National Formosa University, Huwei Township, Yunlin County, Taiwan

ORCID: 0009-0008-5064-4855

Wei-Sheng Hong

Department of Mechanical Design Engineering, National Formosa University, Huwei Township, Yunlin County, Taiwan

ORCID: 0009-0001-7164-3981

Chia-Che Lee

Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei City, Taiwan

ORCID: 0000-0002-1616-0178

Hung-Kuan Yen

Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei City, Taiwan

ORCID: 0000-0003-4381-2220

Tzu-Hao Tseng

Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei City, Taiwan

ORCID: 0000-0002-8564-3149

Shau-Huai Fu

Department of Orthopaedic Surgery, National Taiwan University Hospital, Taipei City, Taiwan Department of Orthopedics, National Taiwan University Hospital Yun-Lin Branch, Douliu City, Yunlin County, Taiwan

ORCID: 0000-0001-9853-872X

Abstract

Objectives: The aim of this study was to evaluate the biomechanical efficiency of different Schanz screw positions for indirect reduction of distal femur fractures using finite element analysis.

Materials and methods: A three-dimensional finite element model of a comminuted distal femur fracture was constructed, incorporating relevant anatomical structures including ligaments, menisci, and the gastrocnemius muscle. A 30 N posterior force simulated gastrocnemius-induced deformity, followed by a 15 N horizontal traction force applied through Schanz screws inserted at six positions (hole 1 to 6) on a standard distal femur locking plate. Residual displacement and reduction ratios were measured to assess reduction efficiency.

Results: The model successfully replicated the characteristic posterior displacement (~15 mm) caused by gastrocnemius contraction. Among the six pin positions, hole 6 (most anterior and distal position) achieved the greatest reduction (12.90 mm) with an 86.83% correction ratio, while hole 4 (most posterior and distal position) performed the worst (26.88%). More anterior and distal pin locations provided superior reduction outcomes due to improved mechanical advantage and alignment with the deforming force vector.

Conclusion: Schanz screw placement significantly influences the effectiveness of traction-assisted reduction in distal femur fractures. Hole position 6 yielded the most optimal biomechanical performance and may serve as a practical reference for optimizing intraoperative pin placement, potentially improving surgical efficiency and outcomes.

Declarations

Author Contributions

Were responsible for the study design and conceptualization: S.I.C., T.H.T., S.H.F.; Conducted the study: S.I.C., W.S.H.; Jointly performed the data analysis: S.I.C., W.S.H., T.H.T., S.H.F.; Prepared the manuscript: S.I.C., T.H.T., S.H.F. All authors participated in the revision of the manuscript and responded to the reviewers’ comments.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

This study was supported by the Research Assistantships funded by the National Science and Technology Council, Taiwan (grant number NSTC 113-2221-E-150-001 to Shou-I Chen).

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

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