Mateusz Gładysz FESSH prep

FESSH prep Imaging Ulnar variance and its dynamic change, MRI of ulnar impaction, MRI versus MR arthrography for TFCC tears, arthroscopic hook and trampoline tests

Imaging of ulnar-sided wrist pain

Last reviewed v1.0

FESSH-038Imaging●●○ intermediate

Regarding imaging and arthroscopic assessment of ulnar-sided wrist pain:

  1. 1.Ulnar variance measured on a standard neutral-rotation posteroanterior radiograph is a fixed anatomical value that is not influenced by forearm rotation or grip.

  2. 2.In ulnar impaction syndrome, MRI characteristically shows focal signal change in the ulnar aspect of the lunate, low on T1-weighted images, and this signal can return to normal after ulnar unloading surgery.

  3. 3.In meta-analysis with arthroscopy as the reference standard, MR arthrography has higher pooled sensitivity and specificity than conventional MRI for full-thickness tears of the triangular fibrocartilage complex.

  4. 4.A normal wrist MRI reliably excludes a clinically relevant tear of the triangular fibrocartilage complex, so arthroscopy is unnecessary when the MRI is negative.

  5. 5.At arthroscopy the hook test is more accurate than the trampoline test for detecting a foveal (proximal) tear of the triangular fibrocartilage complex, whereas the trampoline test, not the hook test, detects an isolated distal peripheral tear.

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Question ID
FESSH-038
First published
Last reviewed
Version
v1.0
Answer key and explanations — open after answering

  1. 1. Ulnar variance measured on a standard neutral-rotation posteroanterior radiograph is a fixed anatomical value that is not influenced by forearm rotation or grip.

    False

    Ulnar variance is dynamic. Epner showed that supination increases the measurement of negative variance and pronation decreases it, and that wrist deviation and beam angle also alter the value, hence the standardised view with the shoulder abducted, the elbow flexed to 90 degrees and the forearm in neutral. Friedman recorded a mean increase of 1.27–1.95 mm with grip alone on zero-rotation films, with every wrist increasing, and Jung found a mean dynamic range of 1.34 mm in normal wrists between relaxed supination (+0.19 mm) and pronated grip (+1.52 mm). Tomaino therefore recommended both neutral and pronated-grip radiographs before choosing treatment for ulnar impaction.

    • Epner RA, Bowers WH, Guilford WB. Ulnar variance--the effect of wrist positioning and roentgen filming technique. J Hand Surg Am. 1982;7(3):298-305. PMID 7086100
    • Friedman SL, Palmer AK, Short WH, Levinsohn EM, Halperin LS. The change in ulnar variance with grip. J Hand Surg Am. 1993;18(4):713-6. PMID 8349988
    • Jung JM, Baek GH, Kim JH, Lee YH, Chung MS. Changes in ulnar variance in relation to forearm rotation and grip. J Bone Joint Surg Br. 2001;83(7):1029-33. PMID 11603517
    • Tomaino MM. The importance of the pronated grip x-ray view in evaluating ulnar variance. J Hand Surg Am. 2000;25(2):352-7. PMID 10722828

  2. 2. In ulnar impaction syndrome, MRI characteristically shows focal signal change in the ulnar aspect of the lunate, low on T1-weighted images, and this signal can return to normal after ulnar unloading surgery.

    True

    Imaeda's MRI–arthroscopy series of 30 wrists found focal abnormal signal in the ulnar aspect of the lunate in 87%, the radial aspect of the triquetrum in 43% and the ulnar head in 10%; the signal was decreased on T1-weighted images and decreased or increased on T2-weighted images. After ulnar recession the lunate signal shifted from low through slightly low to normal. Baek's series of ulnar shortening osteotomies likewise found that pre-operative cystic changes in the carpal bones were no longer evident one to two years after unloading. Marrow change is therefore an early, reversible marker of overload rather than established arthrosis.

    • Imaeda T, Nakamura R, Shionoya K, Makino N. Ulnar impaction syndrome: MR imaging findings. Radiology. 1996;201(2):495-500. PMID 8888248
    • Baek GH, Chung MS, Lee YH, Gong HS, Lee S, Kim HH. Ulnar shortening osteotomy in idiopathic ulnar impaction syndrome. J Bone Joint Surg Am. 2005;87(12):2649-2654. PMID 16322614

  3. 3. In meta-analysis with arthroscopy as the reference standard, MR arthrography has higher pooled sensitivity and specificity than conventional MRI for full-thickness tears of the triangular fibrocartilage complex.

    True

    Smith's systematic review of 21 studies (982 wrists) pooled a sensitivity of 0.75 and specificity of 0.81 for MRI against 0.84 and 0.95 for MR arthrography, with higher field strength improving both, and recommended arthrography when the diagnosis is in doubt; data were insufficient for partial-thickness tears. Treiser's later meta-analysis of 28 studies found MRI 0.76/0.82, MR arthrography 0.78/0.85 and CT arthrography 0.89/0.89, with CT and MR arthrography statistically equivalent, and accuracy highest for central rather than peripheral tears across every modality.

    • Smith TO, Drew B, Toms AP, Jerosch-Herold C, Chojnowski AJ. Diagnostic accuracy of magnetic resonance imaging and magnetic resonance arthrography for triangular fibrocartilaginous complex injury: a systematic review and meta-analysis. J Bone Joint Surg Am. 2012;94(9):824-32. PMID 22552672
    • Treiser MD, Crawford K, Iorio ML. TFCC Injuries: Meta-Analysis and Comparison of Diagnostic Imaging Modalities. J Wrist Surg. 2018;7(3):267-272. PMID 29922507

  4. 4. A normal wrist MRI reliably excludes a clinically relevant tear of the triangular fibrocartilage complex, so arthroscopy is unnecessary when the MRI is negative.

    False

    Andersson's systematic review of studies using arthroscopy as the gold standard found negative predictive values for MRI of only 37% to 90% for the TFCC, below the 95% threshold set for clinical relevance, and concluded that a negative MRI is unable to rule out a clinically relevant injury to the TFCC, scapholunate or lunotriquetral ligaments. Peripheral and foveal tears are the ones most often missed, because they are small, obliquely oriented and frequently non-communicating; accuracy is consistently highest for central tears. Wrist arthroscopy remains the reference standard when symptoms persist.

    • Andersson JK, Andernord D, Karlsson J, Fridén J. Efficacy of Magnetic Resonance Imaging and Clinical Tests in Diagnostics of Wrist Ligament Injuries: A Systematic Review. Arthroscopy. 2015;31(10):2014-20.e2. PMID 26095820
    • Treiser MD, Crawford K, Iorio ML. TFCC Injuries: Meta-Analysis and Comparison of Diagnostic Imaging Modalities. J Wrist Surg. 2018;7(3):267-272. PMID 29922507

  5. 5. At arthroscopy the hook test is more accurate than the trampoline test for detecting a foveal (proximal) tear of the triangular fibrocartilage complex, whereas the trampoline test, not the hook test, detects an isolated distal peripheral tear.

    True

    In Atzei's series of 135 patients assessed against radiocarpal and distal radioulnar joint arthroscopy, overall accuracy was 70% for the trampoline test and 87% for the hook test; the hook test reached 97% accuracy for proximal and 98% for complete tears but had 0% sensitivity for isolated distal tears, which the trampoline test detected with 75% sensitivity, while specificity was 67% for the trampoline test and 96% for the hook test. Trehan's blinded cadaver study found hook-test sensitivity and specificity of 90% for foveal detachment with good reliability, and judged the trampoline test insufficiently reliable for that purpose. The two tests are complementary; Ecker, using direct dry-arthroscopic inspection of the fovea as the reference, found the hook test 100% sensitive but only 7% specific for foveal detachment, so a positive hook test is not pathognomonic of a foveal tear.

    • Atzei A, Luchetti R, Carletti D, Marcovici LL, Cazzoletti L, Barbon S. The Hook Test Is More Accurate Than the Trampoline Test to Detect Foveal Tears of the Triangular Fibrocartilage Complex of the Wrist. Arthroscopy. 2021;37(6):1800-1807. PMID 33745938
    • Trehan SK, Wall LB, Calfee RP, Shen TS, Dy CJ, Yannascoli SM, et al.. Arthroscopic Diagnosis of the Triangular Fibrocartilage Complex Foveal Tear: A Cadaver Assessment. J Hand Surg Am. 2018;43(7):680.e1-680.e5. PMID 29395584
    • Ecker J, Pavleski K, Andrijich C. The Hook Test Is Not Pathognomonic for Foveal Detachment of the Triangular Fibrocartilage. J Wrist Surg. 2023;13(1):44-48. PMID 38264126