Quantitative Evaluation of Articular Involvement of Posterior Malleolus Associated with Operative Indication: A Comparative Study of Six Methods Based on Radiography and CT

Abstract

The aim of this study was to compare the values of six methods in measuring the involvement of posterior malleolus and to demonstrate the reliability and reproducibility of each method. Three independent orthopaedic surgeons, retrospectively, measured 106 cases. The difference between the six methods was analyzed using Bonferroni-corrected paired t-tests after one-way ANOVA. The agreement between the six methods was analyzed using Bland–Altman analysis. The intraclass correlation coefficient (ICC) was used to assess intraobserver reproducibility and interobserver reliability. Significant differences were observed between values of any two of the six measurement methods (P<0.0033), except between any two of the plane radiograph linear, axial CT linear, sagittal CT linear, and 3D CT linear. The Bland–Altman plots demonstrated poor agreement between values of any two of the six methods. The lowest intraobserver reproducibility was 0.46 (moderate) for resident surgeon using plain radiographs. The intraobserver reproducibility for three surgeons using two-dimensional (2D) and 3D images was almost perfect (ICC, 0.82–0.96). The lowest interobserver reliability was 0.41 (moderate) between chief and attending surgeon using plain radiographs, and it improved to almost perfect (ICC, 0.81–0.95) with the use of 3D CT images. The standard error of measurement showed almost the same results as ICC values. The existing operative indications which were determined based on plain radiography are neither reliable nor suitable for other measurement methods. Both 3D linear and 3D surface measurement methods are reliable and reproducible in measuring posterior fragment involvement, and experience is not so crucial. Operative indications for posterior malleolar fractures need to be redefined based on the 3D measurement method.

Effect of Posterior Malleolar Fixation on Syndesmotic Stability

“…However, fragment size on axial CT scans, calculated as a percentage of fragment involvement in relation to the fibular incisura, has been demonstrated to be in poor agreement with fragment size on lateral plain radiographs. 39 This implies that the size of the PMFs in the present study was not directly transferable to lateral plain radiographs. Yet, based on the low inter- and intraobserver reproducibility reported on lateral plain radiographs, 39 other measurements for determining surgical indication should be considered in the future.…”

“…39 This implies that the size of the PMFs in the present study was not directly transferable to lateral plain radiographs. Yet, based on the low inter- and intraobserver reproducibility reported on lateral plain radiographs, 39 other measurements for determining surgical indication should be considered in the future. Furthermore, the present study was designed to examine how to best stabilize the syndesmosis with the presence of a PMF.…”

Importance of computed tomography in posterior malleolar fractures: Added information to preoperative X-ray studies

“…There is controversy regarding the best way of measuring PM size in lateral X-ray images; moreover, interobserver agreement shows variable results[ 22 ]. Currently, many authors consider CT essential for an adequate understanding of PM fractures due to the limitations of X-ray images and because CT aids in surgical planning by providing information on PM size and morphology and on its relationship with other malleoli and with the syndesmosis[ 20 - 22 , 32 , 33 ].…”

“…The distribution of PM fractures among the three CT categories was satisfactory. However, there was a significant sample loss, and the distribution was based solely on 2D CT images, when some studies also used 3D images to evaluate PM[ 22 , 33 ]. Finally, the present findings add new information to the topic of articular involvement in PM fractures, which will hopefully aid the analysis of the clinical results of patients with PM fractures in future studies.…”