The Biomechanical Behavior of Selected Achilles Tendon Revision Constructs: An Exploratory Cadaveric Study

Background: Achilles tendon re-rupture following operative repair remains a challenging complication, and biomechanical evidence guiding revision strategies is limited. The mechanical behavior of commonly used revision constructs has not been well characterized. The objective of this exploratory study was to provide a descriptive biomechanical characterization of commonly used Achilles tendon revision constructs, focusing on viscoelastic behavior, load-to-failure properties, and failure mechanisms under standardized loading conditions. Although limited by the absence of construct replication, this study provides hypothesis-generating biomechanical insight into the failure mechanisms of revision constructs, which may inform future comparative studies and surgical strategy selection. Methods: Four fresh-frozen human cadaveric lower limbs underwent standardized Achilles tendon transection with segmental excision to simulate revision conditions. Five revision techniques were evaluated: tensioned cross-lock Bunnell, Krakow, posterior tibial tendon (PTT) augmentation with Bunnell repair, double Kessler with circumferential running suture, and V–Y advancement combined with three simple sutures and double Kessler. All repairs were performed using No. 2 high-strength suturing by a single surgeon. Constructs underwent stress relaxation testing under a constant 100 N load followed by uniaxial load-to-failure testing. Mechanical parameters and failure modes were recorded. Results: All constructs demonstrated time-dependent stress relaxation. The tensioned cross-lock Bunnell repair retained the highest residual force during sustained loading. The PTT-augmented construct exhibited the highest load to failure among the constructs tested and failed at the tendon substance, whereas non-augmented repairs failed predominantly at the suture–tendon interface. The V–Y advancement construct failed at relatively low applied loads under the applied testing protocol. Conclusions: Achilles tendon revision constructs demonstrate distinct biomechanical behaviors. Augmented constructs exhibited higher resistance to tensile loading in this experimental setting and shifted failure away from the repair site, while non-augmented repairs were limited by suture–tendon interface strength. Given that each construct was tested only once and that one specimen was used sequentially for two repairs, the findings should be interpreted strictly as descriptive and hypothesis-generating, without any basis for comparative or inferential conclusions.