Novel Measurement Technique of the Tibial Slope on Conventional MRI

Abstract

Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Is Noncontact ACL Injury Associated with the Posterior Tibial and Meniscal Slope?

“…Patients with implants, fractures, and tumors were excluded from further investigation. An a priori sample size power analysis was conducted based on the data from a prior study on the method for PTS measurement technique on MRI [23]. A sample size of 54 individuals for both groups was calculated to detect a 1.5°difference with a power of 0.94 at an a-error of 0.05.…”

“…The targeted primary outcome variable was set to 1.5°b ecause PTS differences reported in the literature range from 0.9°-3.4° [8,46,47]. The typical errors for interobserver and intraobserver variability related to the method used herein are 1.4°and 1.2°, respectively [23].…”

“…Therefore, we used conventional MRI scans of the knee, because they allow simple assessment of each plateau separately and provide the possibility to assess the MS reliably following a newly described method [23]. MRI scans were obtained on a 1.5 Tesla MRI scanner (Symphony, Siemens Medical Solutions, Erlangen, Germany) using the following parameters: T1, coronal plane, slice thickness: 3 mm for 170 9 138 mm, TE: 14-16 ms, TR: 450 ms; intermediate weighted sagittal plane, slice thickness: 3 mm for 180 9 143 mm, TE: 15, TR: 2700).…”

“…One of us (RH) made all measurements on the MRI as previously described [23]. In this previous study, the reliability of the measure was described with the typical error (TE) suggested by Hopkins [22].…”

“…The advantage of the TE is its simple conversion to a variance and its self-explanatory appearance because it shows the variation in the values of repeated measurements. The intraobserver and interobserver TEs were 1.2°(confidence interval (CI), 1.2°-1.6°) and 1.4°(CI, 1.1°-1.4°), respectively [23]. All images were retrieved from our PACS system.…”