Examining the novel use of continuous compression implants in clavicle reconstruction: A biomechanical study


      • Low-profile shape-memory staples may hold promise for clavicle fracture fixation.
      • Shape-memory staples were more compliant than traditional plate constructs.
      • Traditional plates outperformed shape-memory staples in cyclic loading.
      • Synthetic bones and osteopenic cadaveric bo nes yielded different failure modes.
      • Plate and staple repair constructs may be a viable option for larger bones.



      Current implants for clavicle fractures are known to cause poor cosmesis and irritation, which may require implant removal. Low-profile shape-memory staples provide an attractive alternative, but their biomechanical utility in clavicle reconstruction is unknown. We hypothesized that shape-memory reconstructions would be more compliant compared to traditional constructs but would also outperform conventional plates during cyclic loading to failure.


      This study was performed with 36 synthetic clavicles and 12 matched pairs of cadaveric specimens. The synthetic study tested four reconstructions: a single superiorly placed staple (n = 6), a single anteroinferiorly-placed staple (n = 6), a 3.5 mm reconstruction plate (n = 12), and two orthogonally placed staples (n = 12). The cadaveric study tested three constructs: reconstruction plate (n = 8), two orthogonal staples (n = 8), and a 2.7 mm reconstruction plate combined with a superior staple (n = 8). Non-destructive 4-point bending, compression, and torsion assays were performed prior to destructive cantilever bending and cyclic torsion tests.


      The single staple and double staple groups demonstrated significantly decreased resistance to bending (p < 0.001) and torsion (p ≤ 0.027) when compared to reconstruction plate groups. The double staple group sustained significantly fewer cycles to failure than the reconstruction plate group in cyclic torsional tests (p = 0.012). The synthetic models produced higher stiffness and failure mechanisms that were completely different from cadaveric specimens.


      Shape memory alloy implants provided inadequate stiffness for clavicle fixation but may have utility in other orthopaedic applications when used as a supplementary compression device in conjunction with traditional plated constructs. Synthetic bones have limited capacity for modeling fragility fractures.



      CCI (Continuous compression implant), SS (Superior staple group), AS (Anterior staple group), PLT (Plate group), 2S (2-staple group), PLT + SS (Plate and single staple group), PMMA (poly(methyl methacrylate)), SI (superior-inferior), AP (anterior-posterior)
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