Journal of Ultrasound in Medicine, Vol 17, Issue 1 41-48, Copyright © 1998 by American Institute of Ultrasound in Medicine
Triangular fibrocartilage of wrist: presentation on high resolution ultrasonography
H. J. Chiou, C. Y. Chang, Y. H. Chou, C. C. Hsu, Y. F. Jim, C. M. Tiu and M. M. Teng
Department of Radiology, Veterans General Hospital-Taipei, National Yang Ming University, College of Medicine, Taiwan.
This study consisted of two parts. Part I is for detection of the normal
triangular fibrocartilage by high resolution ultrasonography and Part II is
a preliminary study to evaluate high resolution ultrasonography in the
diagnosis of tears of the triangular fibrocartilage. Normally, the
triangular fibrocartilage was seen in all cases in Part I as an inverse
triangular structure of homogeneous hyperechogenicity on transverse and
oblique sagittal scans at the level of the distal radioulnar joint. At its
waist it measured from 2.3 to 4.2 mm (mean, 3.0 +/- 0.5 mm) on oblique
sagittal scan and from 2.5 to 3.7 mm (mean, 3.2 +/- 0.4 mm) on transverse
scan. Under normal conditions, the triangular fibrocartilage is thicker
than 2.5 mm on both transverse and oblique sagittal sections with a
confidence level of 95%. In Part II, eight of the 47 wrists were found to
be hypoechoic in the triangular fibrocartilage region, which proved to be
tears by arthrography. Six cases showed a homogeneous hyperchoic triangular
fibrocartilage measuring from 1.8 to 2.8 mm (mean, 2.3 +/- 0.5 mm) in
transverse section and from 0 to 2.2 mm (mean 1.2 +/- 1.1 mm) in oblique
sagittal section; five of these proved to be tears by arthrography. In
contrast, 33 wrists had a homogeneous hyperechoic triangular fibrocartilage
measuring from 2.5 to 4 mm (mean, 3.1 +/- 0.4 mm) and 2.5 to 4.2 mm (mean,
3.1 +/- 0.6 mm) on transverse and oblique sagittal sections, respectively;
27 proved to be normal triangular fibrocartilage by arthrography. The
sensitivity, specificity, positive predictive value, negative predictive
value, and accuracy were 68.4%, 96.4%, 92.9%, 81.8%, and 85.1%,
respectively. HRUS can display the normal triangular fibrocartilage as a
homogeneous hyperechoic and inverted triangular structure. The torn
triangular fibrocartilage appears as a hypoechoic region or as thinning
(< 2.5 mm) of the hyperechoic structure on either transverse or oblique
sagittal section. HRUS has an acceptable accuracy in the diagnosis of
triangular fibrocartilage tear.
