The ECU Synergy Test: An Aid to Diagnose ECU Tendonitis

doi:10.1016/j.jhsa.2008.08.018

The Journal of Hand Surgery

Volume 33, Issue 10, December 2008, Pages 1777-1782

https://doi.org/10.1016/j.jhsa.2008.08.018 Get rights and content

Purpose

Chronic dorsal ulnar-sided wrist pain challenges even the most experienced physicians. The close anatomic proximity and the possibility of coexistent injuries can render physical examination maneuvers ambiguous, making it difficult to discern between intra-articular and extra-articular pathology. Using the principle of synergism, we describe the extensor carpi ulnaris (ECU) synergy test as a novel means for diagnosing ECU tendonitis and document its benefit in the clinical setting.

Methods

A retrospective chart review was performed, identifying adult patients experiencing greater than 4 months of dorsal ulnar-sided wrist pain. Physical examination findings, results of magnetic resonance imaging (MRI) and/or wrist arthroscopy, and clinical outcomes were compiled.

Results

Fifty-five patients met inclusion criteria. Twenty-one patients (group 1) had no pain with the synergy test but had exams suggesting ulnar-sided intra-articular pathology. All had ulnar-sided intra-articular pathology on MRI and/or arthroscopy. Eleven patients (group 2) had positive synergy tests and no pain with the remainder of the exam. All had greater than 90% pain relief after ECU tendon sheath injection; 5 patients remained pain free. Six patients experienced temporary improvement and had MRI evaluation, confirming the diagnosis of isolated ECU tendonitis in 5 of the 6 patients. The remaining 22 patients (group 3) had positive synergy tests and exams that suggested concomitant ulnar-sided intra-articular pathology. After ECU sheath injection, 5 patients had persistent discomfort with either lunotriquetral ballottement or triangular fibrocartilage complex compression. All 5 patients had ulnar-sided intra-articular pathology confirmed by MRI and/or arthroscopy. Seventeen patients had greater than 90% pain relief after injection. Of these, 7 patients remained asymptomatic at latest follow-up, confirming the diagnosis of ECU tendonitis. Ten patients had recurrent symptoms, of which 6 patients demonstrated ulnocarpal pathology by MRI and/or wrist arthroscopy.

Conclusions

By differentiating between intra-articular and extra-articular pathology, the ECU synergy test composes part of a clinical algorithm that minimizes the need for wrist MRI and diagnostic arthroscopy.

Type of study/level of evidence

Diagnostic II.

Section snippets

Materials and Methods

The ECU synergy test is performed by having the patient rest his or her arm on the examining table with the elbow flexed 90° and the forearm in full supination. The wrist is held in neutral position with the fingers in full extension (Fig. 1). Facing the patient, the examiner grasps the patient's thumb and long finger with one hand and palpates the ECU tendon with the other hand. The patient then radially abducts the thumb against resistance. The presence of both flexor carpi ulnaris (FCU) and

Results

EMG evaluation of both of the authors during the synergy test demonstrated active muscle contractions of both the ECU and FCU muscles.

Scrutiny of the data revealed 3 groups of patients. Group 1 (n = 21) had no pain with the ECU synergy test but had reproduction of pain with exam maneuvers that stressed intra-articular structures. Group 2 (n = 11) had their dorsal ulnar-sided wrist pain reproduced by the ECU synergy test and denied any discomfort with exam maneuvers that stressed intra-articular

Discussion

Chronic dorsal ulnar-sided wrist pain has been described as the low back pain of the wrist because of the elusiveness of a specific diagnosis and the refractory nature of the pain. With an extremely broad differential diagnosis—lunotriquetral instability, arthritic changes at the DRUJ or lunotriquetral articulation, DRUJ instability, tears of the triangular fibrocartilage, stylocarpal impingement, and ECU tendonitis or instability—deciphering the etiology of the pain, at times, challenges even

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Citation Excerpt :
In the chronic setting, tendon snapping and wrist instability may be present. The ECU synergy and subluxation tests are helpful diagnostic maneuvers.6,7 To perform the ECU synergy test, the patient supinates the wrist, and the examiner applies resistance at the radial side of the hand.
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Citation Excerpt :
However, tautness of the distal extension of the ECU subsheath changed during forearm motion, because the fibers attach to the dorsal radioulnar ligament and ulnar styloid process. This variation in the length of the fibers of the distal extension may explain why the ECU tendon is loose in forearm supination and subluxes by overriding the ulnar styloid process, which is clinically observed during a provocative test for patients with painful ECU subluxation.20 The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis of the ECU tendon.
The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis in the upper extremity, but the exact location of stenosis is not fully understood. The objective of this study was to investigate the detailed anatomy of structures surrounding the extensor carpi ulnaris (ECU) tendon around the wrist.
Fifty fresh human cadaveric wrists were used for gross observation and morphology measurements of the sixth dorsal compartment and the ECU subsheath. An additional 13 wrists were used for histological examination. We evaluated the morphology of supporting structures in 3 regions: the ulnar groove (zone I), the ulnar styloid process (zone II), and the triquetrum (zone III).
The fibro-osseous tunnel comprising the ulnar groove and the overlying subsheath (zone I) stabilized the ECU tendon, and the subsheath had thin membranous collagen fibers attached to the periosteum. We consistently found the distal extension of ECU subsheath (zone II), which connected the ulnar styloid process and the dorsal radioulnar ligament. Variations in the length of the distal extension increased with the forearm in pronation. Collagen fiber thickness around the ECU tendon in zone II was greater than that of zone I. In zone III, the overlying extensor retinaculum and septa, which were composed of thick circumferential collagen structures, supported the ECU tendon by attaching to the triquetrum on both sides of the ECU tendon. We found the presence of an ulnar septum of the sixth compartment attached to the triquetrum in 84% of dissected wrists.
The ECU tendon was supported by the ECU subsheath, which had thin and elastic collagen fibers over the ulnar groove. Distal extension of the subsheath and surrounding radial and ulnar extensor retinaculum septa attached to the triquetrum provided thicker supporting structures.
Stenosing ECU tenosynovitis may occur not only in the ulnar groove but also in the more distal ulnar styloid process and triquetrum areas.

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: The Chief, Navy Bureau of Medicine and Surgery, Washington, D.C., Clinical Investigation Program sponsored this study (CIP no. P05-018). No financial or other support was received for this project. R.T.R. and C.J.H. are military service members (or employees of the U.S. Government). This work was prepared as part of their official duties. Title 17 U.S.C. 105 provides that ‘Copyright protection under this title is not available for any work of the United States Government.' Title 17 U.S.C. 101 defines a United States Government work as a work prepared by a military service member or employee of the United States Government as part of that person's official duties.

: The views expressed in this article are those of the authors and do not reflect the official policy of the Department of the Navy, the Department of Defense, or the United States Government.

: No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.

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Scientific articleThe ECU Synergy Test: An Aid to Diagnose ECU Tendonitis

Purpose

Methods

Results

Conclusions

Type of study/level of evidence

Section snippets

Materials and Methods

Results

Discussion

Hand Clin

J Hand Surg

J Hand Surg

J Hand Surg

Scientific article
The ECU Synergy Test: An Aid to Diagnose ECU Tendonitis