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Inter- and intra-observer reliability of measurement of pedicle screw breach assessed by postoperative CT scans.

Lavelle WF, Ranade A, Samdani AF, Gaughan JP, D'Andrea LP, Betz RR - Int J Spine Surg (2014)

Bottom Line: Underlying spinal pathology, screw type, and patient age did not seem to impact the reliability of our CT assessments.Our results indicate the evaluation of pedicle screw breach on CT by a single surgeon is highly variable, and care should be taken when using individual CT evaluations of millimeters of breach as a basis for screw removal.This was a Level III study.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, State University of New York Upstate Medical University, Syracuse, NY.

ABSTRACT

Background: Pedicle screws are used increasingly in spine surgery. Concerns of complications associated with screw breach necessitates accurate pedicle screw placement. Postoperative CT imaging helps to detect screw malposition and assess its severity. However, accuracy is dependent on the reading of the CT scans. Inter- and intra-observer variability could affect the reliability of CT scans to assess multiple screw types and sites. The purpose of this study was to assess the reliability of multi-observer analysis of CT scans for determining pedicle screw breach for various screw types and sites in patients with spinal deformity or degenerative pathologies.

Methods: Axial CT scan images of 23 patients (286 screws) were read by four experienced spine surgeons. Pedicle screw placement was considered 'In' when the screw was fully contained and/or the pedicle wall breach was ≤2 mm. 'Out' was defined as a breach in the medial or lateral pedicle wall >2 mm. Intra-class coefficients (ICC) were calculated to assess the inter- and intra-observer reliability.

Results: Marked inter- and intra-observer variability was noticed. The overall inter-observer ICC was 0.45 (95% confidence limits 0.25 to 0.65). The intra-observer ICC was 0.49 (95% confidence limits 0.29 to 0.69). Underlying spinal pathology, screw type, and patient age did not seem to impact the reliability of our CT assessments.

Conclusion: Our results indicate the evaluation of pedicle screw breach on CT by a single surgeon is highly variable, and care should be taken when using individual CT evaluations of millimeters of breach as a basis for screw removal. This was a Level III study.

No MeSH data available.


Related in: MedlinePlus

Example demonstrating a greater than 2 mm breach representative of worst agreement.
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Figure 0002: Example demonstrating a greater than 2 mm breach representative of worst agreement.

Mentions: Of the twenty-three patients, fifteen were diagnosed with degenerative spine pathology and eight patients were diagnosed with spinal deformity. Twelve patients received 193 stainless steel pedicle screws and eleven patients received 93 titanium pedicle screws. (Table 1) Standard CT sequences were utilized. We optimized pedicle screw visualization with respect to the pedicle using 3mm fine axial cut CT images with bone windows. It was also determined that our ability to discern a pedicle breach was 2 mm, and this became our aforementioned criterion for our categorization of “in” and “out” breaches. Figure 1 and Figure 2 demonstrate breaches of greater than and less than 2 mm respectively. In addition, previous studies utilized a similar 2 mm incitement in their analysis. Two millimeters is often considered a critical breach as described by Belmont et al.14 Further, Reynolds et al. previously demonstrated radiographic evidence of a 2 mm of lateral epidural space from T7 to L4.15 This was confirmed by Gertzbein and Robbins who examined 71 thoracic screws (T8–T12) with a 26% incidence of medial cortical breaches.16 These authors again noted a 2 mm epidural space and the 2 mm subarachnoid space. All of these studies consider screws with a 2 mm breach as clinically acceptably and believed to be accompanied by cortical expansion and benign pedicle wall fracture.


Inter- and intra-observer reliability of measurement of pedicle screw breach assessed by postoperative CT scans.

Lavelle WF, Ranade A, Samdani AF, Gaughan JP, D'Andrea LP, Betz RR - Int J Spine Surg (2014)

Example demonstrating a greater than 2 mm breach representative of worst agreement.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4325493&req=5

Figure 0002: Example demonstrating a greater than 2 mm breach representative of worst agreement.
Mentions: Of the twenty-three patients, fifteen were diagnosed with degenerative spine pathology and eight patients were diagnosed with spinal deformity. Twelve patients received 193 stainless steel pedicle screws and eleven patients received 93 titanium pedicle screws. (Table 1) Standard CT sequences were utilized. We optimized pedicle screw visualization with respect to the pedicle using 3mm fine axial cut CT images with bone windows. It was also determined that our ability to discern a pedicle breach was 2 mm, and this became our aforementioned criterion for our categorization of “in” and “out” breaches. Figure 1 and Figure 2 demonstrate breaches of greater than and less than 2 mm respectively. In addition, previous studies utilized a similar 2 mm incitement in their analysis. Two millimeters is often considered a critical breach as described by Belmont et al.14 Further, Reynolds et al. previously demonstrated radiographic evidence of a 2 mm of lateral epidural space from T7 to L4.15 This was confirmed by Gertzbein and Robbins who examined 71 thoracic screws (T8–T12) with a 26% incidence of medial cortical breaches.16 These authors again noted a 2 mm epidural space and the 2 mm subarachnoid space. All of these studies consider screws with a 2 mm breach as clinically acceptably and believed to be accompanied by cortical expansion and benign pedicle wall fracture.

Bottom Line: Underlying spinal pathology, screw type, and patient age did not seem to impact the reliability of our CT assessments.Our results indicate the evaluation of pedicle screw breach on CT by a single surgeon is highly variable, and care should be taken when using individual CT evaluations of millimeters of breach as a basis for screw removal.This was a Level III study.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, State University of New York Upstate Medical University, Syracuse, NY.

ABSTRACT

Background: Pedicle screws are used increasingly in spine surgery. Concerns of complications associated with screw breach necessitates accurate pedicle screw placement. Postoperative CT imaging helps to detect screw malposition and assess its severity. However, accuracy is dependent on the reading of the CT scans. Inter- and intra-observer variability could affect the reliability of CT scans to assess multiple screw types and sites. The purpose of this study was to assess the reliability of multi-observer analysis of CT scans for determining pedicle screw breach for various screw types and sites in patients with spinal deformity or degenerative pathologies.

Methods: Axial CT scan images of 23 patients (286 screws) were read by four experienced spine surgeons. Pedicle screw placement was considered 'In' when the screw was fully contained and/or the pedicle wall breach was ≤2 mm. 'Out' was defined as a breach in the medial or lateral pedicle wall >2 mm. Intra-class coefficients (ICC) were calculated to assess the inter- and intra-observer reliability.

Results: Marked inter- and intra-observer variability was noticed. The overall inter-observer ICC was 0.45 (95% confidence limits 0.25 to 0.65). The intra-observer ICC was 0.49 (95% confidence limits 0.29 to 0.69). Underlying spinal pathology, screw type, and patient age did not seem to impact the reliability of our CT assessments.

Conclusion: Our results indicate the evaluation of pedicle screw breach on CT by a single surgeon is highly variable, and care should be taken when using individual CT evaluations of millimeters of breach as a basis for screw removal. This was a Level III study.

No MeSH data available.


Related in: MedlinePlus