Comparison of load-to-failure in pre-shaped versus surgeon-shaped Achilles tendon allograft bone blocks

Traditional bone-plug allografts in reconstruction of anterior cruciate ligament (ACL) tears require shaping of the bone plug by surgeons, yielding inconsistent results, greater costs, and increased operative time. We compare the load-to-failure between pre-shaped and surgeon-shaped Achilles allografts with calcaneal bone blocks to assess their use in ACL reconstruction.

Six pre-shaped Achilles allograft tendons with calcaneus bone grafts were compared to 6 surgeon-shaped allografts. Calcaneal grafts were inserted into artificial saw bone while the opposite ends were fixed to a linear-torsion dynamic test machine for cyclic and load-to-failure testing. Loading began with a preconditioning phase, followed by uniaxial cycles. Failure load was and mechanism of failure for each graft was identified.

Of the 6 pre-shaped bone grafts, 3 (50 %) experienced a failure at the sawbone/screw interface, 2 (33 %) experienced a bone graft fracture, and 1 (17 %) a tendon avulsion during cycling. Of the 6 surgeon-shaped bone grafts, 3 (50 %) experienced failure at the sawbone screw interface, and 3 (50 %) experienced a bone block fracture. No significant differences in biomechanical properties measured during load-to-failure testing or failure modes were detected between the two graft types.

Pre-shaped grafts exhibited a trend towards higher load and displacement at failure, although this was not statistically significant. These findings, along with potential cost and time savings, warrant further study on their impact on surgical efficiency and outcomes.