Is the two-dimensional computed tomography scan analysis reliable for coracoid graft positioning in Latarjet procedures?

Abstract

Background: The aim of the study was to develop a computed tomography (CT)-based measurement protocol for coracoid graft (CG) placement in both axial and sagittal planes after a Latarjet procedure and to test its intraobserver and interobserver reliability.

Methods: Fifteen postoperative CT scans were included to assess the intraobserver and interobserver reproducibility of a standardized protocol among 3 senior and 3 junior shoulder surgeons. The evaluation sequence included CG positioning, its contact area with the glenoid, and the angle of its screws in the axial plane. The percentage of CG positioned under the glenoid equator was also analyzed in the sagittal plane. The intraobserver and interobserver agreement was measured by the intraclass correlation coefficient (ICC), and the values were interpreted according to the Landis and Koch classification.

Results: The ICC was substantial to almost perfect for intraobserver agreement and fair to almost perfect for interobserver agreement in measuring the angle of screws in the axial plane. The intraobserver agreement was slight to almost perfect and the interobserver agreement slight to substantial regarding CG positioning in the same plane. The intraobserver agreement and interobserver agreement were both fair to almost perfect concerning the contact area. The ICC was moderate to almost perfect for intraobserver agreement and slight to almost perfect for interobserver agreement in analyzing the percentage of CG under the glenoid equator.

Conclusion: The variability of ICC values observed implies that caution should be taken in interpreting results regarding the CG position on 2-dimensional CT scans. This discrepancy is mainly explained by the difficulty in orienting the glenoid in the sagittal plane before any other parameter is measured.

Keywords: 2D CT scan; Latarjet; Shoulder instability; graft positioning; imaging protocol; reliability test.