Abstract:
OBJECTIVE : To evaluate the accuracy of end-on fluoroscopy in predicting
implant position in relation to the vertebral canal in the canine thoracolumbar
vertebral column.
STUDY DESIGN : In vitro imaging and anatomic study.
ANIMALS : Canine cadaveric thoracolumbar vertebral columns (n = 5).
METHODS : Smooth Steinmann pins were inserted bicortically into the
thoracolumbar vertebral columns between T10 and L7 using recommended
insertion angles. Penetration of the spinal canal was not strictly avoided. After
pin placement, end-on fluoroscopy images were obtained of each pin. Pin
position was subsequently assessed by four evaluators and determined to
either being out of the vertebral canal or in, with the latter being additionally
divided into partially or completely penetrating the canal. To assess potential
differences in modalities, fluoroscopy images were gray-scale inverted and
evaluated again later by the same four individuals. Correct identification of pin
position in relationship to the vertebral canal was assessed for both fluoroscopy
images. Anatomic preparation of the spines was used for verification of pin
position in relation to the spinal canal. Some data from this study were
compared with historical data on accuracy using orthogonal radiography and
computed tomography (CT).
RESULTS : Overall sensitivity and specificity of F to detect vertebral canal
penetration was 98.8 % (95% confidence interval (CI), 96.0–99.6) and 98.0%
(95% CI, 77.0–99.9), respectively. For Fi, sensitivity and specificity were 97.0%
(95% CI, 91.5–99.0) and 98.5% (95% CI, 81.5–99.9) respectively. F exceeded
Fi for the sensitivity of detecting pin penetration into the vertebral canal
(p = 0.039) but specificities were not different (p = 0.585). When comparing to historical data, the overall accuracy of end-on fluoroscopy (F) and
inverted fluoroscopy (Fi) was statistical better than conventional radiographic
assessment (p < 0.001).
CONCLUSION : End-on fluoroscopy is a highly accurate
method for the assessment of pin position in relationship
to the thoracolumbar spinal canal in cadaveric dogs.
CLINICAL SIGNIFICANCE : End-on fluoroscopy, with or without inversion,
is accurate in identifying vertebral canal violation by bicortically placed
Steinmann pins. When CT is not available, end-on fluoroscopy might
be a valuable imaging modality to determine pin position in the canine
vertebral column.
