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Comparable in vivo graft motion after ACL reconstruction found with BTB vs hamstring autograft
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ORLANDO, Fla. — In a study analyzing in vivo human ACL graft motion during activities of daily living, researchers found no significant differences at 6 weeks and 1 year postoperatively between reconstructions performed with either bone-tendon-bone or hamstring autograft with respect to graft motion within bone tunnels.
“At 6 weeks and 1 year, BTB [bone-tendon-bone] and hamstring grafts demonstrated similar motion in both the tibial and femoral tunnels. The [next] question is, ‘Do BTB grafts heal to bone tunnels more quickly than hamstrings?’” study author Christopher D. Harner, MD, said, noting that future studies will investigate whether such healing could justify quicker return to play.
To determine whether differences in knee kinematics and graft behavior existed in vivo during functional activities, Harner and colleagues studied six patients who underwent ACL reconstruction with a BTB graft and six patients who had the procedure done with a hamstring autograft. All procedures were performed by a single surgeon using a similar single-bundle ACL reconstruction technique.
Christopher D. Harner
Each graft used had six 0.8-mm tantalum beads embedded within them before implantation, with bead pairs located within each bone tunnel and in the mid-substance region. Intraoperative fluoroscopy was used to confirm bead placement.
The patients were tested in a biodynamics lab, where the researchers evaluated graft behavior and knee kinematics at 6 weeks for walking and stair descent, and at 1 year for walking, stair descent and running. Patients completed three trials for each activity.
The researchers used a DSX system to track the beads within the tunnels, and 3-D CT scans were obtained and transposed on the DSX bone models. Additionally, the maximum displacement of the beads within the tunnels was assessed, and the researchers examined bone tunnel graft motion, kinematics and anterior tibial translation and rotation.
“Bone-tendon-bone compared to hamstrings at 6 weeks shows no difference in graft motion [and] no difference in knee kinematics. With walking and stair descent, both were less than 2 mm,” Harner said. “At 1 year, [there was] no difference in graft motion. No change from 6 weeks. No difference in knee kinematics,” he said, noting both groups showed anterior tibial translation between 1 mm to 2 mm with walking and between 2 mm and 4 mm of graft tunnel motion during running. – by Gina Brockenbrough, MA
Reference:
Arner JW, et al. Paper #8. Presented at: American Orthopaedic Society for Sports Medicine Annual Meeting; July 9-12, 2015; Orlando, Fla.
Disclosure: Harner reports no relevant financial disclosures. The study was funded by the Orthopaedic Research Foundation.