Study Design. The risk factors of patients with and without radiculopa
thy after laminoplasty of the cervical spine were compared retrospecti
vely. Objectives. To study the association between risk variables and
postlaminoplastic radiculopathy to clarify the pathogenesis of radicul
opathy and to devise preventive measures, Summary of Background Data.
Radiculopathy after cervical laminoplasty on the expanded side has bee
n attributed mainly to traumatic surgical techniques, whereas radiculo
pathy on the hinged side has been attributed to traction, tethering, o
r kinking of the nerve root that has resulted from posterior shift of
the spinal cord from the preoperative position. There is still much di
vergence of opinion concerning the risk factors for the outbreak as we
ll as the prevention. Methods. Of 365 patients who had undergone lamin
oplasty, 20 patients (5.5%) developed postoperative radiculopathy. Usi
ng data from postoperative computed tomography scans and other sources
, these patients were compared with 211 patients with no radiculopathy
, who had undergone laminoplasty during the same period, to identify r
isk factors related to patient characteristics and surgical techniques
. Results, Of Various risk factors studied, the narrowest level of the
spinal canal, preoperative symptomatic severity, flatness of the spin
al cord assessed by computed tomography myelography at C4-C5, cervical
curvature, anterior protrusion of the superior articular process as a
ssessed by computed tomography scan, laterality of the osteophytes, an
d ossification of the posterior longitudinal ligament could not signif
icantly discriminate between patients with and without postoperative r
adiculopathy. The angle of lamina as measured by using computed tomogr
aphy scans obtained after expansion in the patients with radiculopathy
was greater than 68 degrees on the opened and hinged sides and was si
gnificantly greater than the angle in patients without radiculopathy (
P < 0.05). The incidence of radiculopathy on both the opened and hinge
d sides was significantly higher in patients in whom the bony gutter h
ad been cut on the lateral side of the medial aspect of the zygapophys
eal joint. Conclusion. Any one of patients' characteristics could not
be correlated with postoperative cervical radiculopathy in this study.
To prevent postoperative radiculopathy, it may be important during su
rgery to place the bony gutter on the medial side of the zygapophyseal
joint and to keep the slope of the opened lamina within 60 degrees.