2015 ISAKOS Biennial Congress ePoster #421

Biomechanic Testing of the Porcine Triple Bundle Anterior Cruciate Ligament

Maurício Pedro Pinto, MD, Pittsburgh, PA UNITED STATES
Thiago R. Protta, MD, Sao Paulo, Sao Paulo BRAZIL
Gof Tantisricharoenkul, MD, Bangkok THAILAND
Paulo Araujo, MD, Pittsburgh, PA UNITED STATES
Monica A. Linde, MSIE, RN, Pittsburgh, PA UNITED STATES
Patrick J. Smolinski, PhD, Pittsburgh, PA UNITED STATES
James J. Irrgang, PT, PhD, FAPTA, Pittsburgh, Pennsylvania UNITED STATES
Freddie H. Fu, MD, Pittsburgh, PA UNITED STATES
University of Pittsburgh, Pittsburgh, PA, USA

FDA Status Not Applicable

Summary: The purpose of this study is to investigate the biomechanics of the antero-medial (AM), intermediate (IM) and postero-lateral (PL) bundles in porcine anterior cruciate ligament (ACL).

Abstract:

Animal models are used to develop and to evaluate new surgical techniques such as the anatomic double-bundle anterior cruciate ligament (ACL) reconstruction. Several species of animals, including pig, bear, lion, monkey, gazelle and goat have three bundles in the ACL: antero-medial (AM), intermediate (IM) and postero-lateral (PL). Biomechanical analysis of three bundles has been recently done in the porcine ACL and showed that IM bundle has a supplementary role of AM and PL bundles and is not important restrain to anterior tibial translation (ATT) and to internal tibial rotation (IR). However, IM bundle diameter is not small and it is more than a half of AM bundle diameter size. Also, it attachs at important position wich prevent ATT at high knee flexion.
The purpose of this study is to investigate the biomechanics of the antero-medial (AM), intermediate (IM) and postero-lateral (PL) bundles in porcine anterior cruciate ligament (ACL).
Twenty four mature porcine knees were tested using a robotic/universal force moment sensor (UFS) system. This system applied an anterior loading of 89N at 30, 60 and 90 degree of knee flexion to
measure anterior tibial translation (ATT) before and after each bundle was selectively cut.
The testing protocol was divided into 3 differents groups according to the sequence of bundles sectioned: group 1 – AM sectioned, IM sectioned and PL sectioned; group 2 – AM sectioned, PL sectioned and IM sectioned; group 3 – IM sectioned, PL sectioned and AM sectioned.
The AM bundle stabilized the porcine knee against anterior tibial translation (ATT) and rotatory loads. At high knee flexion angles, the IM bundle supports the AM bundle in preventing ATT. Also, at low knee flexion angles, the IM bundle supports the PL bundle in preventing ATT. The role of the IM bundle supports both the AM and PL bundles through all flexion angles, especially at 30 degree which is the full extension in the porcine knee. The PL bundle stabilized the porcine knee against rotatory load especially near full extension. The IM bundle has an important role in porcine knee stability.
There were some limitations of this study. One of them, dissection of the three bundles and surgical skills depended on human evaluation and was prone to error and difference. To minimize these, the same experienced surgeon performed all the procedures.
Knowledge of functions of the different ACL bundles will help improve ACL reconstruction techniques and patients outcomes to enable restoration of normal knee function.