New Implant Likely to Stabilize Spine After Facetectomy

Auxiliary Facet System stabilization of axial rotation due to presence of a cross-link connector

THURSDAY, May 5 (HealthDay News) -- Following medial facetectomy, use of Auxiliary Facet System (AFS) instrumentation has a minor influence on flexion/extension and lateral bending, stabilizes axial rotation, and reduces intradiscal pressure (IDP), according to a study published in the April 20 issue of Spine.

Yann Philippe Charles, M.D., from the Arts et Métiers ParisTech, and colleagues analyzed the influence of AFS on lumbar intersegmental motion after medial facetectomy, and on the intact segment in six human cadaver specimens. Using a load of 1 to 10 Nm, they conducted flexion/extension, lateral bending, and axial rotation tests on the intact segment, instrumented segment, instrumented plus medial facetectomy, and facetectomy alone between L3 and S1. They measured the IDPs in flexion/extension and calculated the sagittal mean center of rotation (MCR).

The investigators found that the intact segment had a range of motion (ROM) of 10.9 degrees in flexion/extension, 9.5 degrees in lateral bending, and 4.7 degrees in axial rotation. ROM decreased by 6 percent in flexion/extension and increased by 1 percent in lateral bending after medial facetectomy and instrumentation. Axial rotation increased by 106 percent following medial facetectomy without implant, and instrumentation reduced it by 38 percent, mainly due to the presence of the cross-link. In intact and instrumented specimens, MCR was located around the middle of the superior L5 endplate, which moved cranially after facetectomy without instrumentation. Maximal IDP during flexion/extension was decreased by 17 percent by the implant.

"This new kind of device would be clinically useful for younger patients, where segmental stabilization could be performed without fusion, to avoid accelerated adjacent level degeneration," the authors write.

One or more of the study authors disclosed financial ties to the pharmaceutical and medical device industries. Clariance Spine supported this study.

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