Effect of Anterior Translation on Anterior Knee Force in a Porcine Model

The knee is a complex load-bearing joint that is subjected to compound loading patterns that often lead to injury. The most common traumatic injury occurs in the anterior cruciate ligament; with approximately 80,000 ACL injuries annually in the United States and 50,000 of these requiring reconstructions [1]. The role of the ACL is critical in knee joint stability. It prevents excess movement accounting for over 80% of the total restraining force for anterior tibial translation [2]. ACL reconstruction has been found to have a 10–25% failure rate [3]. These failures could be attributed to our limited understanding of the forces in the ACL during daily activities [3]. ACL measurements have been taken with invasive methods using strain gauges and other types of transducers surgically implanted within the ACL [4]. Noninvasive methods have used ultrasound and MRI to measure strains, or ground reaction forces, motion tracking systems, and biomechanical models to interpolate the in vivo forces [1,4,5]. Recently the use of robotic technology has offered the possibility of simulating in vivo motion paths to determine the force and moments in the knee [3,6,7]. This method has the ability to accurately and precisely control motions and allows for testing one specimen under different experimental conditions (e.g. ACL-intact versus ACL-deficient) [7]. It is important to use this robotics technology with an appropriate animal model taking into consideration joint size and anatomical structure to ensure the results are relevant [8]. The objectives of this study were to examine how anterior translation affected anterior knee force, to determine if right-left differences exist, and to determine if the porcine knee is ACL dependent.