The Journal of Bone and Joint Surgery, Vol 76, Issue 12 1847-1853, Copyright © 1994 by Journal of Bone and Joint Surgery, Inc
Increase of motion between lumbar vertebrae after excision of the capsule and cartilage of the facets. A cadaver study
SD Boden, C Martin, R Rudolph, JS Kirkpatrick, SM Moeini and WC Hutton
Department of Orthopaedic Surgery, Emory University School of Medicine, Atlanta, Georgia.
Seventeen fresh segments of cadaveric lumbar spines were tested in flexion,
extension, and axial rotation. The resulting angular rotations were
measured with the use of a goniometer and a three-dimensional system of
video analysis. Measurements of flexibility were made, in order, in the
intact spine; after decompression (bilateral total laminectomies, partial
medial facetectomies, and foraminotomies); after excision of the capsule
and cartilage of the facets; and after cancellous bone had been packed into
the facet defects. Decompression resulted in a slight increase in the
sagittal and axial ranges of motion. Subsequent excision of the capsule and
cartilage of the facets, as in preparation for an arthrodesis of the
facets, resulted in a significant increase in both the sagittal (5.7 +/-
2.9 degrees, mean and standard deviation) (p < 0.001) and the axial (1.4
+/- 0.9 degrees) (p < 0.01) ranges of motion compared with the motion in
the intact specimen and with the motion in the specimen after only
decompression had been done (p < 0.01 and p < 0.05, respectively).
Packing of bone in the facets did not significantly reduce motion. It was
calculated that the increase in the sagittal range of motion after excision
of the capsule and cartilage of the facets would increase the tensile
strain in a graft between the transverse processes of the fourth and fifth
lumbar vertebrae (18 +/- 1 per cent tensile strain [mean and 95 per cent
confidence interval] for the intact vertebrae and 25 +/- 1 per cent for the
vertebrae in which the facets had been excised).
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