Method for establishing and measuring in vivo forces in an anterior cruciate ligament composite graft: Response to differing levels of load sharing in a goat model

Abstract

In order to determine the appropriate load history for optimal remodeling of an anterior cruciate ligament graft, methods for establishing and measuring the graft force due to an external load could be set to a preselected value in in vivo are required. Our objectives with this study were to (a) develop a method in which the graft force due to an external load could be set to a preselected value in a living animal, (b) show that this force could be maintained after fixation, and (c) determine what happens to the forces after the animal has functioned for as long as 2 weeks postoperatively, when differing levels of load sharing between the segments had been set at surgery. The anterior cruciate ligament was reconstructed in 12 goats with use of a bone-patellar tendon-bone graft and a synthetic augmentation device. The forces in the graft segments were established, at the time of surgical fixation, with use of a force-setting technique. In five animals, the tendon segment was set to carry 90% of the total graft force; in the remaining seven animals, the augmentation segment was set to share 90% of the total graft force. Graft forces were measured, with the use of buckle transducers mounted extra-articularly over the anterior tibia, under a 67 N anterior tibial load at 60 degrees of knee flexion before and after fixation and at 2 weeks postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Can suture repair of ACL transection restore normal anteroposterior laxity of the knee? An ex vivo study

“…In the past, large stents, such as the carbon fiber graft or Ligament Augmentation Device (LAD), and even the middle third of the patellar tendon, have been used to protect repair of the ACL,14-16 however, these procedures all involved placement of a relatively large amount of material in the same space as the ACL, thus leaving less room for formation of a hypertrophic scar and also resulting in extensive disruption to the native ACL insertion sites. The technique proposed here could possibly provide a means to modulate load and protect the healing ACL, particularly during initial healing17,18, while still allowing preservation of the insertion sites and scar volume. An additional advantage with this technique is that the sutures could be selected or designed to support the repair for a specified period of time and then release or resorb, to minimize any potential complication of stress shielding by the suture-stent.…”

In vivo forces during remodeling of a two‐segment anterior cruciate ligament graft in a goat model

“…The anterior cruciate ligament was surgically reconstructed in 12 skeletally maturc French Alpine, Nubian Cross, or Sonnen goats (40-60 kg) with use of an autogenous graft and a synthetic augmentation segment (3M, Minneapolis, MN, U.S.A.). Buckle transducers were used to measure forces in the graft segments in vivo (12). A force-setting technique (10) was used to establish graft segment forces at surgical fixation.…”

“…In vivo graft forces were also measured during level walking at 6 weeks. The details of the model have been previously reported (12). Briefly, after removal of the central third patellar tendon graft, a lateral arthrotomy was made and then the native anterior cruciate ligament was excised.…”

Estimation of ACL forces by reproducing knee kinematics between sets of knees: A novel non-invasive methodology

“…During the last decade, a number of studies have been performed to estimate the in situ forces in the ACL in vivo (Holden et al, 1994;Lewis et al, 1994;Lundberg et al, 1997;Zacharias et al, 2001Zacharias et al, ,2000. While providing valuable information, each methodology requires measurements that are difficult to obtain using human subjects.…”

“…While providing valuable information, each methodology requires measurements that are difficult to obtain using human subjects. In animals, buckle and pressure transducers were surgically implanted within the ACL and the in situ force in the ligament was determined using an in vitro calibration of the transducer (Holden et al, 1994;Lewis et al, 1994). Analytical models have also been used with human subject data to estimate in vivo force in the ACL with data from force plates and motion tracking systems Morrison, 1970;Toutoungi et al, 2000;Zheng et al, 1998).…”