Sonographic Appearance of Trigger Fingers

Size: px

Start display at page:

Download "Sonographic Appearance of Trigger Fingers"

Ira Briggs
5 years ago
Views:

1 Article Sonographic Appearance of Trigger Fingers Henri Guerini, MD, Eric Pessis, MD, Nicolas Theumann, MD, Janine-Sophie Le Quintrec, MD, Raphaël Campagna, MD, PhD, Alain Chevrot, MD, PhD, Antoine Feydy, MD, Jean-Luc Drapé, MD Objective. The purpose of this study was to describe the sonographic appearance of the first annular (A1) pulley flexor tendon complex in patients with trigger fingers. Methods. Thirty-three trigger fingers in 33 patients were examined with a 7- to 15-MHz probe. A control group consisted of 20 patients without trigger fingers. The study included systematic measurement of the thickness of the A1 pulley and a power Doppler assessment of the pulleys, tendons, and tendon sheaths. Results. Thickening and hypoechogenicity of the A1 pulley were found in all patients with trigger fingers. Measurements of A1 pulley thickness were significantly different (P <.0001) between the groups without trigger fingers (mean, 0.5 mm; range, mm) and with trigger fingers (mean, 1.8 mm; range, mm). Hypervascularization of the A1 pulley on power Doppler imaging was found in 91% of the trigger fingers but was never found in the healthy control group. Flexor tendinosis was found in 48% of the trigger fingers; tenosynovitis was found in 55%; and both were found in 39%. In the control group, tenosynovitis and tendinosis were not found. Conclusions. Thickening and hypervascularization of the A1 pulley are the hallmarks of trigger fingers on sonography. Other frequently observed features include distal flexor tendinosis and tenosynovitis. Key words: finger; power Doppler sonography; sonography. Abbreviations A1, first annular; MCP, metacarpophalangeal; P1, proximal phalanx Received March 1, 2008, from the Departments of Radiology B (H.G., E.P., R.C., A.C., A.F., J.-L.D.) and Rheumatology (J.-S.L.Q.), Hôpital Cochin, Assistance Publique Hôpitaux de Paris, Université Paris Descartes, Paris, France; and Department of Radiology, Centre Hospitalier Universitaire Vaudois Lausanne, Lausanne, Switzerland (N.T.). Revision requested March 24, Revised manuscript accepted for publication June 10, Address correspondence to Henri Guerini, MD, Department of Radiology B, Hôpital Cochin, Assistance Publique Hôpitaux de Paris, 27 rue du Faubourg Saint Jacques, Paris, France. henri.guerini@cch.aphp.fr A trigger finger is a common condition and is generally diagnosed clinically. It is either blockage or triggering of the finger from flexion to extension and in most cases involves the metacarpophalangeal (MCP) joint. The pathophysiologic mechanism of trigger fingers is controversial. The main hypothesis is that it is caused by stenosing tenosynovitis at the level of the first annular (A1) pulley. 1 Treatment is most often by corticosteroid injections near the palpable nodule or in the area of the A1 pulley. 2 Surgery may also be indicated. 3 Imaging of trigger fingers is not often performed and thus is not well documented. Sonography allows direct visualization of the A1 pulley flexor tendon complex. 4 At our institution, the development of sonographically guided injections allowed a preliminary study of the imaging appearance of trigger fingers. Consequently, our purpose was to describe the sonographic appearance of the A1 pulley flexor tendon complex in patients with trigger fingers by the American Institute of Ultrasound in Medicine J Ultrasound Med 2008; 27: /08/$3.50

2 Sonographic Appearance of Trigger Fingers Materials and Methods Over a 1-year period, 33 consecutive patients (20 male and 13 female; mean age, 67 years) with a clinical diagnosis of trigger finger were examined by a single investigator with 6 years of experience in musculoskeletal ultrasound. The patients were referred from rheumatologists and orthopedic surgeons for therapeutic purposes. All patients had typical symptoms of painful triggering: locking of the digit in a flexed position and triggering on extension. A control group consisted of 20 patients without trigger fingers (11 male and 9 female; mean age, 56 years) who were suspected of having rotator cuff lesions but had no history of finger trauma or surgery. Institutional Review Board approval and oral informed consent were obtained before sonography. A dedicated 7- to 15-MHz probe (Aplio, Toshiba Medical Systems Co, Ltd, Tokyo, Japan) was used. The sonographic analysis was focused on the A1 pulley and the flexor tendon of the involved finger. The B-mode study included measurement of the thickness of the A1 pulley in the axial and sagittal planes at the maximum thickness. Measurements were made directly on the image at the time of the examination. Power Doppler imaging was performed (Doppler frequency, 8 MHz; velocity, 5 cm/s) for evaluating pulleys, tendons, and tendon sheaths. Normal and Abnormal Sonographic Anatomy The A1 pulley is an annular structure situated at the level of the MCP joint. It consists of a strap surrounding the flexor tendon sheath. It is a very thin structure, and a high-frequency linear probe is needed to visualize it (Figure 1). With this probe, a normal thin A1 pulley appears as a hypoechoic band superficial to the flexor tendon sheath (Figure 1d). 4 In the axial plane, lateral expansions are oblique and appear very hypo - echoic because of anisotropy. Inclination of the probe eliminated this anisotropic artifact and thus allows visualization of the A1 pulley with a more echogenic band. This anisotropic artifact is useful because it can be used to find the pulley while sweeping the finger in the axial plane. Tendinopathy was defined as segmental swelling of the flexor tendons, which may have a focal hypoechoic region, and was assessed by comparison with other segments of the tendon away from the A1 pulley. Tenosynovitis was defined as hypoechoic or anechoic thickened tissue with or without fluid within the tendon sheath, which is seen in 2 perpendicular planes and may show a Doppler signal. Statistical Analysis Data are given as numbers and percentages. Trigger finger and control group results were compared by a nonparametric Mann-Whitney U test and a Fisher exact test. P <.05 was considered significant. Results In the control group with 20 normal fingers, the thickness of the A1 pulley varied from 0.4 to 0.6 mm with an average of 0.5 mm. Flexor tenosynovitis, tendinopathy, and hypervascularization on power Doppler imaging were not found in any of these cases. In the group with clinically diagnosed trigger fingers, there were 17 thumbs, 4 second fingers, 9 third fingers, 2 fourth fingers, and 1 fifth finger. The right hand was involved in 23 cases and the left hand in 10. None of the patients had underlying diseases. In this group, 3 main patterns were noted (Figure 2): 1. The thickness of the A1 pulley in the trigger fingers varied from 1.1 to 2.9 mm with an average of 1.8 mm. This finding was statistically significant when compared with the control group (P <.0001). The thickening was found to be either global or nodular and was also occasionally found in the lateral or medial expansions of the A1 pulley (Figures 3 5). In 4 cases, the A1 pulley surface had a notch in the flexor tendon (Figures 2a and 3b). 2. Hypervascularization of the A1 pulley (Figure 3d) on power Doppler imaging was found in 91% (30 of 33) of the cases. 3. Tendinosis or tenosynovitis of the flexor tendon was found in 63% (21 of 33) of the trigger fingers. Tendinosis of the flexor tendon (Figure 6) was found in 48% (16 of 33). For the second, third, fourth, and fifth fingers, tendinosis involved the distal part of the tendon opposite the proximal phalanx (P1) with the finger in extension in all cases. For the thumb, tendinosis was located 1408 J Ultrasound Med 2008; 27:

Guerini et al proximal to the A1 pulley because the normal position of rest for the thumb is in semiflexion. Tenosynovitis of the flexor tendon was found in 55% (18 of 33) of the trigger fingers.

Other ancillary findings included a diverticular cystic appearance of the synovial sheath in the absence of tenosynovitis in 24% (8 cases).

Its incidence is increased in patients with rheumatoid arthritis, diabetes mellitus, De Quervain tenosynovitis, osteoarthritis, carpal tunnel syndrome, mucopolysaccharidoses, and hypothyroidism.

However, the development of sonographically guided injections allows the sonographic appearance of trigger fingers to be depicted. Figure 1.

3 Guerini et al proximal to the A1 pulley because the normal position of rest for the thumb is in semiflexion. Tenosynovitis of the flexor tendon was found in 55% (18 of 33) of the trigger fingers. Both tenosynovitis and tendinosis were found in 39% (13 of 33). Intratendinous fissures that complicated the flexor tendinopathy were found in 6% (2 cases). Other ancillary findings included a diverticular cystic appearance of the synovial sheath in the absence of tenosynovitis in 24% (8 cases). One case with this cystic appearance was found in the control group. Discussion In most cases, the cause of trigger fingers is idiopathic, although a number of congenital forms have been noted. Its incidence is increased in patients with rheumatoid arthritis, diabetes mellitus, De Quervain tenosynovitis, osteoarthritis, carpal tunnel syndrome, mucopolysaccharidoses, and hypothyroidism. 5 7 The diagnosis is made clinically, and generally no imaging is necessary. However, the development of sonographically guided injections allows the sonographic appearance of trigger fingers to be depicted. Figure 1. Normal appearance of the volar aspect of the finger opposite the MCP. a, Schematic drawing of an axial view of the volar aspect at the level of the MCP. Note the A1 pulley, flexor tendon (FL), volar plate (pp), metacarpal head (M), and volar interdigital artery (Art). b, Corresponding sonographic view. The A1 pulley (arrow) corresponds to a hypoechoic linear structure. The thickness is submillimetric. The A1 pulley is easily recognized in an axial sweeping because of the lateral oblique expansions (arrowheads) contrasting with the vertical artifacts of the tendon in the absence of the pulley. c, Schematic drawing of a sagittal view of the volar aspect at the level of the MCP joint. P indicates proximal phalanx. d, Corresponding sonographic view. The A1 pulley is easily identified superficial to the flexor tendon and opposite the MCP joint. The A2 pulley is downstream opposite P1; syn indicates synovial membrane. J Ultrasound Med 2008; 27:

Sonographic Appearance of Trigger Fingers The pathophysiologic mechanism of trigger fingers is not well understood. In some cases, the tendinopathy itself is the origin of the blockage.

Sampson et al 1 showed that the A1 pulley was the site of fibrocartilagenous thickening, although its cause was difficult to determine.

On the other hand, the thickening may have been secondary to tendinopathy via a conflict between the pulley and the tendon during movements of flexion and extension.

This result seems to favor the hypothesis that thickening of the A1 pulley is primary.

Comparison of a healthy thumb and a trigger thumb at the level of the MCP joint in a 56-year-old man. a, Sagittal view of the healthy thumb.

The A1 pulley is thickened and causes narrowing with a fingerprint on the flexor tendon (asterisk).

4 Sonographic Appearance of Trigger Fingers The pathophysiologic mechanism of trigger fingers is not well understood. In some cases, the tendinopathy itself is the origin of the blockage. In others, stenosing thickening of the A1 pulley causes secondary tendinopathy. Sampson et al 1 showed that the A1 pulley was the site of fibrocartilagenous thickening, although its cause was difficult to determine. This study suggested that primary thickening of the A1 pulley may have been responsible for the blockage and tendon inflammation. On the other hand, the thickening may have been secondary to tendinopathy via a conflict between the pulley and the tendon during movements of flexion and extension. In our study, tendinopathy of the flexor tendon was found in only 48% of the trigger fingers, whereas thickening of the A1 pulley was found in all cases. This result seems to favor the hypothesis that thickening of the A1 pulley is primary. In our study, the pulley thickening was sometimes associated with a cystic lesion of the pulley (Figure 2b); this feature was previously considered a ganglion cyst. 8 Figure 3. Comparison of a healthy thumb and a trigger thumb at the level of the MCP joint in a 56-year-old man. a, Sagittal view of the healthy thumb. The A1 pulley has normal thickness; m indicates metacarpal head; and p, proximal phalanx. b, Sagittal view of the trigger thumb. The A1 pulley is thickened and causes narrowing with a fingerprint on the flexor tendon (asterisk). c, Axial B-mode view showing hypoechoic thickening of the A1 pulley, which is predominant on the ulnar side. d, Axial power Doppler view. The thickened area is clearly hypervascular. Figure 2. Different lesions found in trigger fingers. a, Sagittal sonographic view of a trigger finger showing thickening of the A1 pulley (white arrows) associated with stenosis (asterisk), tenosynovitis (black arrowhead), and tendinosis (white arrowhead) of the flexor superficialis tendon; m indicates metacarpal head; and p, proximal phalanx. b, Sagittal power Doppler view of another trigger finger. The A1 pulley is thickened with a cystic lesion (arrowhead), and the thickening is clearly hypervascular (arrow) J Ultrasound Med 2008; 27:

Guerini et al Our results suggest that treatment by percutaneous local corticosteroid injections should be administered at the A1 pulley rather than within the tendon sheath because inflammation was

This result is consistent with the findings of Taras et al, 2 who showed that corticosteroid injections in the soft tissue near the A1 pulley were more effective (70% good results) than within the

As a consequence, the added value of sonography for performing trigger finger injections could not be assessed in our study.

5 Guerini et al Our results suggest that treatment by percutaneous local corticosteroid injections should be administered at the A1 pulley rather than within the tendon sheath because inflammation was found in the A1 pulley in all cases. This result is consistent with the findings of Taras et al, 2 who showed that corticosteroid injections in the soft tissue near the A1 pulley were more effective (70% good results) than within the tendon sheath (47% good results). However, differences in imaging findings between patients who responded to conservative treatment and those who did not were not evaluated in our study. As a consequence, the added value of sonography for performing trigger finger injections could not be assessed in our study. A limitation of our study was the absence of a systematic dynamic evaluation. The extra information that may have been gained did not seem necessary because the static mode is adequate for diagnosis of primitive trigger fingers and for sonographically guided injections. It could be interesting to perform a dynamic study to evaluate postoperative outcomes or secondary atypical cases of triggering, such as fibrous scars occurring after rupture of a tendon, exostoses, foreign bodies, and giant cell tumors However, a dynamic study is difficult to perform in this area because flexion of P1 is hampered by the size of the linear 7- to 15-MHz probe. In some rare cases, a Figure 4. Axial images of a trigger finger in a 67-year-old woman. a, Global thickening of the A1 pulley (arrows), which is predominant on the radial side. b, Marked hypervascularization on power Doppler imaging. c, Proximally, a small amount of fluid in the synovial sheath is shown (asterisk), which is easily distinguished from the pulley (fluid is deeper and encircles the tendon). Note that contrary to Figure 1b, the artifact of reinforcement of the borders is vertical (arrowhead) because of the absence of the pulley at this level. J Ultrasound Med 2008; 27:

Sonographic Appearance of Trigger Fingers Figure 5. Comparison of sonography and magnetic resonance imaging (axial views at the level of the MCP) of a trigger finger in a 62-year-old woman.

b, Axial power Doppler view at the level of the MCP showing marked hypervascularization of the A1 pulley (arrows).

sheath (black arrow) that appears very distinct from the A1 pulley, which is more superficial (white arrow).

Very intense enhancement of the pulley is shown, which extends into the lateral expansions (white arrows) and is clearly separated from the fluid in the sheath, which appears as relatively low signal

A second limit of our study was the absence of systematic measurements of the thickness of the contralateral A1 pulley for a comparative study.

6 Sonographic Appearance of Trigger Fingers Figure 5. Comparison of sonography and magnetic resonance imaging (axial views at the level of the MCP) of a trigger finger in a 62-year-old woman. a, Axial B-mode view at the level of the MCP showing global thickening of the A1 pulley (arrows). FL indicates flexor tendon. b, Axial power Doppler view at the level of the MCP showing marked hypervascularization of the A1 pulley (arrows). c, Axial T1-weighted fat-suppressed spin echo magnetic resonance image after intravenous gadolinium injection showing a small amount of fluid in the synovial sheath with enhancement of the synovial sheath (black arrow) that appears very distinct from the A1 pulley, which is more superficial (white arrow). d, Axial T1-weighted fat-suppressed spin echo magnetic resonance image after intravenous gadolinium injection at the level of A1 pulley. Very intense enhancement of the pulley is shown, which extends into the lateral expansions (white arrows) and is clearly separated from the fluid in the sheath, which appears as relatively low signal intensity (black arrow). direct conflict between the A1 pulley and the nodular tendinosis could be observed (Figure 7). A second limit of our study was the absence of systematic measurements of the thickness of the contralateral A1 pulley for a comparative study. In conclusion, this study describes the sonographic characteristics of trigger fingers, which include thickening of the A1 pulley and the quasiconstant finding of hypervascularization of the A1 pulley on power Doppler imaging. Associations with distal flexor tendinosis and tenosynovitis are frequent although not always present. Figure 6. Tendinosis of the superficial flexor tendon of the major finger in a 72-year-old man. Axial B-mode imaging shows hypertrophy of the superficial flexor tendon with a very heterogeneous appearance (arrowheads). These areas of tendinosis are found immediately after the A1 pulley in complete finger extension, opposite P1, which explains the blockage and jamming during flexion J Ultrasound Med 2008; 27:

Guerini et al References 1. Sampson SP, Badalamente MA, Hurst LC, Seidman J. Pathobiology of the human A1 pulley in trigger finger. J Hand Surg [Am] 1991; 16:714 721. 2.

Benson LS, Ptaszek AJ. Injection versus surgery in the treatment of trigger finger. J Hand Surg [Am] 1997; 22:138 144. 4. Boutry N, Titecat M, Demondion X, Glaude E, Fontaine C, Cotten A.

7 Guerini et al References 1. Sampson SP, Badalamente MA, Hurst LC, Seidman J. Pathobiology of the human A1 pulley in trigger finger. J Hand Surg [Am] 1991; 16: Taras JS, Raphael JS, Pan WT, Movagharnia F, Sotereanos DG. Corticosteroid injections for trigger digits: is intrasheath injection necessary? J Hand Surg [Am] 1998; 23: Benson LS, Ptaszek AJ. Injection versus surgery in the treatment of trigger finger. J Hand Surg [Am] 1997; 22: Boutry N, Titecat M, Demondion X, Glaude E, Fontaine C, Cotten A. High-frequency ultrasonographic examination of the finger pulley system. J Ultrasound Med 2005; 24: Freiberg A, Mulholland RS, Levine R. Nonoperative treatment of trigger fingers and thumbs. J Hand Surg [Am] 1989; 14: Murphy D, Failla JM, Koniuch MP. Steroid versus placebo injection for trigger finger. J Hand Surg [Am] 1995; 20: Figure 7. Sagittal views at different degrees of extension of a trigger thumb (a c) in a 65-year-old man. There is a direct conflict (c) between nodular tendinosis (arrowheads) and the thickened A1 pulley (arrows) in extension. M indicates metacarpal head; and P, proximal phalanx. 7. Rhoades CE, Gelberman RH, Manjarris JF. Stenosing tenosynovitis of the fingers and thumb: results of a prospective trial of steroid injection and splinting. Clin Orthop Relat Res 1984; 190: Abe Y, Watson HK, Renaud S. Flexor tendon sheath ganglion: analysis of 128 cases. Hand Surg 2004; 9: Lee SJ, Pho RW. Report of an unusual case of trigger finger secondary to phalangeal exostosis. Hand Surg 2005; 10: Suematsu N, Hirayama T, Takemitsu Y. Trigger wrist caused by a giant cell tumour of tendon sheath. J Hand Surg [Br] 1985; 10: Tohyama M, Tsujio T, Yanagida I. Trigger finger caused by an old partial flexor tendon laceration: a case report. Hand Surg 2005; 10: J Ultrasound Med 2008; 27:

Definition: This problem generally is caused by a size mismatch between the flexor tendon and the first annular (A-1) pulley.

TRIGGER DIGITS Definition: This problem generally is caused by a size mismatch between the flexor tendon and the first annular (A-1) pulley. Abstract Primary stenosing tenosynovitis is usually idiopathic