Nathan D Schilaty1, R Kyle Martin2, Ryo Ueno3, Luca Rigamonti4, Nathaniel A Bates5. 1. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA; Sports Medicine Center, Mayo Clinic, Rochester, MN, USA; Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN, USA. 2. Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN, USA; Department of Orthopedic Surgery, CentraCare, Saint Cloud, MN, USA. 3. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA. 4. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy. 5. Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Biomedical Engineering and Physiology, Mayo Clinic, Rochester, MN, USA; Sports Medicine Center, Mayo Clinic, Rochester, MN, USA. Electronic address: batesna@gmail.com.
Abstract
BACKGROUND: Around half of anterior cruciate ligament (ACL) injuries are treated through reconstruction, but the literature lacks mechanical investigation of reconstructions in a dynamic athletic task and rupture environment. The current objective was to ascertain the feasibility of investigating ACL reconstructions in a rupture environment during simulated landing tasks in a validated mechanical impact simulator. METHODS: Four cadaveric lower extremities were subjected to simulated landing in a mechanical impact simulator. External joint loads that mimicked magnitudes recorded from an in vivo population were applied to each joint in a stepwise manner. Simulations were repeated until ACL failure was achieved. Repeated measures design was used to test each specimen in the native ACL and hamstrings, quadriceps, and patellar tendon reconstructed states. FINDINGS: ACL injuries were generated in 100% of specimens. Graft substance damage occurred in 58% of ACLRs, and in 75% of bone tendon bone grafts. Bone tendon bone and quadriceps grafts survived greater simulated loading than hamstrings grafts, but smaller simulated loading than the native ACL. Median peak strain prior to failure was 20.3% (11.6, 24.5) for the native ACL and 17.4% (9.5, 23.3) across all graft types. INTERPRETATION: The simulator was a viable construct for mechanical examination of ACLR grafts in rupture environments. Post-surgery, ACL reconstruction complexes are weaker than the native ACL when subjected to equivalent loading. Bone tendon bone grafts most closely resembled the native ligament and provided the most consistently relevant rupture results. This model advocated reconstruction graft capacity to sustain forces generated from immediate gait and weightbearing during rehabilitation from an ACL injury.
BACKGROUND: Around half of anterior cruciate ligament (ACL) injuries are treated through reconstruction, but the literature lacks mechanical investigation of reconstructions in a dynamic athletic task and rupture environment. The current objective was to ascertain the feasibility of investigating ACL reconstructions in a rupture environment during simulated landing tasks in a validated mechanical impact simulator. METHODS: Four cadaveric lower extremities were subjected to simulated landing in a mechanical impact simulator. External joint loads that mimicked magnitudes recorded from an in vivo population were applied to each joint in a stepwise manner. Simulations were repeated until ACL failure was achieved. Repeated measures design was used to test each specimen in the native ACL and hamstrings, quadriceps, and patellar tendon reconstructed states. FINDINGS: ACL injuries were generated in 100% of specimens. Graft substance damage occurred in 58% of ACLRs, and in 75% of bone tendon bone grafts. Bone tendon bone and quadriceps grafts survived greater simulated loading than hamstrings grafts, but smaller simulated loading than the native ACL. Median peak strain prior to failure was 20.3% (11.6, 24.5) for the native ACL and 17.4% (9.5, 23.3) across all graft types. INTERPRETATION: The simulator was a viable construct for mechanical examination of ACLR grafts in rupture environments. Post-surgery, ACL reconstruction complexes are weaker than the native ACL when subjected to equivalent loading. Bone tendon bone grafts most closely resembled the native ligament and provided the most consistently relevant rupture results. This model advocated reconstruction graft capacity to sustain forces generated from immediate gait and weightbearing during rehabilitation from an ACL injury.
Authors: Nathaniel A Bates; Gregory D Myer; Jason T Shearn; Timothy E Hewett Journal: Clin Biomech (Bristol, Avon) Date: 2014-12-20 Impact factor: 2.063