The use of an interspinous implant in conjunction with a graded facetectomy procedure.

STUDY DESIGN: The range of motion (ROM) of lumbar cadaver spines was measured during flexion, extension, axial rotation, and lateral bending following graded facetectomies and implantation of an X STOP interspinous spacer implant.

OBJECTIVE: The study was performed undertaken to understand better the influence of the interspinous spacer implant on the kinematics of the lumbar spine following graded facetectomies.

SUMMARY OF THE BACKGROUND DATA: Lateral lumbar spinal stenosis is often treated with a unilateral or bilateral facetectomy procedure. Previous biomechanical research has shown that a facetectomy may increase the ROM during flexion and axial rotation.

METHODS: Seven cadaver spines (L2-L5) were tested in flexion, extension, axial rotation, and lateral bending, and the individual ROM of each motion segment was measured. Specimens were tested intact and following 3 graded facetectomies (i.e., unilateral medial facetectomy [UMF], unilateral total facetectomy [UTF], and bilateral total facetectomy [BTF]), with and without the X STOP.

RESULTS: A BTF caused a significant increase in ROM during flexion and axial rotation but not extension and lateral bending. The UMF and UTF did not affect the ROM during any of the 4 motions. The interspinous implant: (1) significantly decreased the flexion ROM for the intact, UMF, UTF, and BTF treatments; (2) significantly decreased the extension ROM for the intact, UMF, and BTF treatments but not the UTF (P < 0.13); (3) had no significant effect on the axial rotation ROM; and (4) significantly increased the lateral bending ROM for the UMF, UTF, and BTF treatments.

CONCLUSIONS: The results suggest that the implant may be used in conjunction with a UMF or UTF. However, the X STOP should not be used in conjunction with BTF.