2017 ISAKOS Biennial Congress ePoster #401

 

Ultrasonography is More Effective than MRI for Evaluating the Instability of Osteochondritis Dissecans of the Elbow

Jun Takeba, MD, PhD, Toon, Ehime JAPAN
Toshiaki Takahashi, MD, PhD, Prof., Matsuyama, Ehime JAPAN
Seiji Watanabe, MD, Toon, Ehime JAPAN
Hiroshi Imai, MD, PhD, Toon, Ehime JAPAN
Hiromasa Miura, MD, PhD, Prof., Toon, Ehime JAPAN
Mayuki Aibiki, MD, PhD, Toon JAPAN

Department of Emergency Medicine Ehime University Graduate School of Medicine, Toon, Ehime , JAPAN

FDA Status Not Applicable

Summary

Ultrasonography is more effective than MRI for evaluating instability in OCD, particularly instability of osteochondral fragments, as it accurately identifies irregularities in the articular cartilage and the subchondral bone.

Abstract

Purpose

We carried out a retrospective study to determine whether preoperative ultrasonography (US) or magnetic resonance imaging (MRI) enabled more accurate evaluation of the instability of lesions in osteochondritis dissecans (OCD) of the elbow, by comparing the results of these preoperative scans with intraoperative determination of the instability of the lesion area by arthroscopy.
Subjects and Methods: Thirty adolescent baseball players with OCD of the elbow underwent preoperative MRI and US scans, and their International Cartilage Repair Society (ICRS) grade was determined during surgery. The presence of an area of hyperintensity between the osteochondral fragment and the underlying bone on T2-weighted fat-suppressed MRI scans in the sagittal section was regarded as indicating instability. In US, the assessment of the cortical line in the subchondral bone and the nature of the cancellous bone are both important, and the formation of a step in this line and of a displaced bulge, crack, or depression in the bone beneath the cartilage was regarded as indicating instability. On arthroscopy, ICRS Grade II was considered as stable and ICRS Grade III–IV as unstable. A Chi-squared test was used to compare the accuracy of the results of the instability assessments based on US and MRI findings.

Results

All 30 patients were assessed as having unstable lesions on the basis of MRI. Among these patients, 23 elbows were detected as ICRS Grade III–IV, with an accuracy of 76.7%. Of the 23 elbows with unstable lesions, 22 were classified as unstable on the basis of US findings, with a sensitivity of 95.7%. Seven elbows were ICRS Grade II, all of which exhibited only cracks or flattening of the subchondral bone on US and were thus assessed as stable; US thus had a specificity of 100% and accuracy of 96.7%. A comparison of the accuracy of the assessment of lesions as unstable on the basis of US and MRI findings found that US was significantly more accurate than MRI (p < 0.0001).

Conclusion

US accurately visualizes irregularities in the surface of the articular cartilage and the subchondral bone, and is therefore more appropriate than MRI for assessing instability in OCD of the elbow.