Assessment of Navigated Pedicle Screws From Intraoperative Imaging: A Prospective Study of Accuracy and Agreement

Josefin Åkerstedt; Anders Berglund; Przemyslaw Kolakowski; Piotr Sliwinski; Marcin Jablonski; Lukas Bobinski

doi:10.14444/8550

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Figure 1
Flowchart of patient and screw inclusion.
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Figure 2
Example of screws rated as optimal (left; Group 1) or suboptimal (right; Group 2).

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Table 1
The Gertzbein and Robbins classification system for pedicle screw accuracy.3
Group Grade Breach Distance, mm
1 A 0
B <2
2 C <4
D <6
E ≥6

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Table 2

Overview of demographic distribution of study sample: gender and age distribution and indication for surgery (N = 70).^{^a}

Demographics	n (%)
Sex
Men	49 (79)
Women	21 (30)
Age, y
18–29^{^a}	4 (6)
30–49	9 (13)
50–64	24 (34)
65+	33 (47)
Indication for surgery
Thoracic traumatic fracture	22 (31)
Lumbar traumatic fracture	17 (24)
Thoracic degenerative disease	5 (7)
Lumbar degenerative disease	5 (7)
Thoracic adjacent segment disease	1 (2)
Lumbar adjacent segment disease	1 (2)
Thoracic tumor/metastasis	11 (16)
Lumbar tumor/metastasis	8 (11)

↵a Inclusion criteria: Patient aged >18 y; American Society of Anesthesiologists score ≤3; able to understand oral and written information; signed the written consent to participate in the study.

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Table 3

Data distribution between optimal (Group 1) and suboptimal (Group 2) screw placement and accuracy (95% CI) of each surgeon reviewer’s assessment of IO (O-arm) and PO (CT) images.

	PO Images, Reviewer 1			PO Images, Reviewer 2			PO Images, Reviewer 3
IO Images	Group 1	Group 2	Total	Group 1	Group 2	Total	Group 1	Group 2	Total
Group 1	405	4	409	415	4	419	410	7	417
Group 2	4	9	13	2	1	3	4	1	5
Total	409	13	422	417	5	422	414	8	422
Accuracy (95% CI)	0.98 (0.96–0.99)			0.99 (0.97–0.99)			0.95 (0.97–0.99)

Abbreviations: CT, computed tomography; IO, intraoperative; PO, postoperative.

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Table 4

Analysis of agreement using AC1 between surgeon reviewers from IO and PO images and between individual surgeon reviewers and the neuroradiologists rating the PO images.

Comparisons	AC1	95% CI
All raters	0.95	0.93–0.97
Reviewer 1 and Reviewer 2	0.97	0.96–0.99
Reviewer 1 and Reviewer 3	0.96	0.94–0.98
Reviewer 2 and Reviewer 3	0.98	0.97–1.00
Reviewer 1 and neuroradiologist	0.93	0.90–0.96
Reviewer 2 and neuroradiologist	0.93	0.90–0.96
Reviewer 3 and neuroradiologist	0.92	0.90–0.95