Biomechanical Analysis of the Proximal Femoral Locking Compression Plate: Do Quality of Reduction and Screw Orientation Influence Construct Stability?

Ivan Zderic, Jong Keon Oh, Karl Stoffel, Christoph Sommer, Tobias Helfen, Gaston Camino, Geoff Richards, Sean E. Nork, Boyko Gueorguiev

    Research output: Contribution to journalArticlepeer-review

    16 Citations (Scopus)


    Objectives: To investigate biomechanically in a human cadaveric model the failure modes of the proximal femoral locking compression plate and explore the underlying mechanism. Methods: Twenty-four fresh-frozen paired human cadaveric femora with simulated unstable intertrochanteric fractures (AO/OTA 31-A3.3) were assigned to 4 groups with 6 specimens each for plating with proximal femoral locking compression plate. The groups differed in the quality of fracture reduction and plating fashion of the first and second proximal screws as follows: (1) anatomic reduction with on-axis screw placement; (2) anatomic reduction with off-axis screw placement; (3) malreduction with on-axis screw placement; (4) malreduction with off-axis screw placement. The specimens were tested until failure using a protocol with combined axial and torsional loading. Mechanical failure was defined as abrupt change in machine load-displacement data. Clinical failure was defined as 5 degrees varus tilting of the femoral head as captured with optical motion tracking. Results: Initial axial stiffness (in N/mm) in groups 1 to 4 was 213.6 ± 65.0, 209.5 ± 134.0, 128.3 ± 16.6, and 106.3 ± 47.4, respectively. Numbers of cycles to clinical and mechanical failure were 16,642 ± 10,468 and 8695 ± 1462 in group 1, 14,076 ± 3032 and 7449 ± 5663 in group 2, 8800 ± 8584 and 4497 ± 2336 in group 3, and 9709 ± 3894 and 5279 ± 4119 in group 4. Significantly higher stiffness and numbers of cycles to both clinical and mechanical failure were detected in group 1 in comparison with group 3, P ≤ 0.044. Conclusions: Generally, malreduction led to significantly earlier construct failure. The observed failures were cut-out of the proximal screws in the femoral head, followed by either screw bending, screw loosening, or screw fracture. Proper placement of the proximal screws in anatomically reduced fractures led to significantly higher construct stability. Our data also indicate that once the screws are placed off-axis (>5 degrees), the benefit of an anatomic reduction is lost.

    Original languageEnglish
    Pages (from-to)67-74
    Number of pages8
    JournalJournal of orthopaedic trauma
    Issue number2
    Publication statusPublished - 2018 Feb 1

    Bibliographical note

    Funding Information:
    This investigation was performed with the assistance of the AO Foundation via the AOTK System and supported by a grant from DePuy Synthes, Zuchwil, Switzerland.

    Publisher Copyright:
    Copyright © 2017 Wolters Kluwer Health, Inc. All rights reserved.


    • biomechanics
    • proximal femoral locking compression plate
    • reduction
    • screw placement
    • unstable intertrochanteric fracture

    ASJC Scopus subject areas

    • Surgery
    • Orthopedics and Sports Medicine


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