Summary

The study aimed to evaluate MRI-based methods for assessing patella height, finding that a cross-sectional MRI technique correlated better with traditional X-Ray assessments, especially in patients with elevated TT-TG distances, compared to the single-slice MRI method.

Abstract

Objectives
The radiographical assessment of patella height has historically been performed using X-Ray. The aim of this study was to evaluate a new method for the assessment of patella height using MRI and to assess the correlation with the X-Ray based assessment.

Methods

159 patients who had both lateral radiographs and MRI images were included. Parameters measured included traditional radiographical CDI, MRI-based CDI, and TT-TG distance. On the basis of the TT-TG, the patients were divided into 2 groups. Two different methods were used to assess CDI using MRI: using a single slice image, and an alternative technique using two different cross-sectional images. The correlation of the two measurement methods was assessed using Pearson's correlation coefficient. The intraclass correlation coefficient (ICC) was determined from the measurements of the two investigators.

Results

The average TT-TG distance was 11.6mm (±4.6). In patients with a TT-TG <15mm, both measurement methods showed comparable correlation with measurements on X-Ray. In patients with a TT-TG of >15 the the new cross-sectional imaging method showed higher correlation with traditional X-Ray assessment compared to CDI assessment using the traditional single slice method (r = 0.594, p < 0.001 vs. r = 0.302, p = 0.055).

Conclusions

The assessment of CDI on MRI using a cross-sectional imaging method has a better correlation with traditional X-Ray assessment of CDI than single-slice assessment. This is particularly true in patients with elevated TT-TG and as such should be preferentially used in the assessment of Patellar height in this cohort.