Case Presentation 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
Combined Flexor Carpi Radialis Tear and Flexor Carpi Radialis Brevis Tendinopathy Identified by Ultrasound: A Case Report Q6
Jay Smith, MD, Sanjeev Kakar, MD A 63-year-old right-handed office worker presented with acute right wrist pain after lifting a heavy file at work. Results of a clinical examination suggested flexor carpi radialis tendinopathy. Diagnostic ultrasound (US) not only detected a complete flexor carpi radialis tear but also revealed the presence of a concomitant flexor carpi radialis brevis (FCRB) tendon with associated tenosynovitis. The ability of US to correctly identify the FCRB has not been previously reported. Furthermore, the US appearance of FCRB tendinopathy and tenosynovitis has not been described. High-resolution US can identify the FCRB muscletendon in the wrist region. Sonologists and sonographers should be aware of the US appearance of the FCRB as well as the potential for the FCRB to contribute to radial wrist pain syndromes. PM R 2014;-:1-4
INTRODUCTION Ultrasound (US) has emerged as a powerful diagnostic tool in the wrist region due to its submillimetric resolution and dynamic imaging capabilities [1-3]. In certain clinical scenarios, US may be considered as a first-line soft tissue imaging modality for detection of suspected tendon disorders around the wrist [1,2]. The flexor carpi radialis brevis (FCRB) muscle is an uncommon anomalous muscle that typically arises from the distal volar radius and attaches to the carpal or metacarpal bones [4-8]. FCRB pathology is rare and, to date, has not been documented by US in published reports [6,8]. Herein we report a case of a complete flexor carpi radialis (FCR) tear combined with clinically unsuspected FCRB tendinopathy and tenosynovitis as detected on US.
CASE PRESENTATION A 63-year-old right-hand dominant otherwise healthy office worker presented with a 3-week history of right volar wrist pain after an acute injury. While lifting a file at work, he experienced a “pop” with immediate volar-radial wrist pain followed by swelling and ecchymosis. He did not have any prodromal symptoms. Despite interim improvement, due to persistent weakness and pain, he presented for evaluation. Results of an examination was remarkable for resolving ecchymosis over the volar-radial wrist crease, a nonpalpable FCR tendon, and tenderness to palpation in the region of the scaphoid tubercle and scaphotrapeziotrapezoidal joint. He had slightly limited active and passive wrist dorsiflexion accompanied by pain and painful resisted wrist palmar flexion. Sensory examination results were normal, and results of thumb and finger flexor manual muscle testing were normal and nonprovocative. Radiographs revealed scaphotrapeziotrapezoidal and basilar thumb arthritis. An acute FCR tear was suspected, and diagnostic US was ordered. US revealed a complete FCR tear with proximal retraction to the radioscaphoid joint. In addition, a second tendon was visualized paralleling the course of the FCR sheath but lying deep to it (Figure 1A). Further scanning along the anomalous tendon both proximally and distally revealed a muscular origin from the distal-volar radius, formation of the tendon at the radioscaphoid joint, with a course through the FCR tunnel, and insertion onto the PM&R 1934-1482/14/$36.00 Printed in U.S.A.
J.S. Departments of Physical Medicine and Rehabilitation, Radiology, and Anatomy, Mayo Clinic College of Medicine, Mayo Clinic Sports Medicine Center, Mayo Clinic, Rochester, MN. Address correspondence to: J.S.; e-mail: [email protected] Disclosures outside this publication: consultancy, Tenex Health (money to author and institution); employment, Tenex Health; payment for lectures, including service on speakers bureaus, Andrews Institute Gulf Coast Ultrasound Institute; patents, Tenex Health (money to author and institution); royalties, Tenex Health (money to author and institution); stock/stock options, Tenex Health (money to author and institution) S.K. Department of Orthopedic Surgery, Mayo, Mayo Clinic Sports Medicine Center, Rochester, MN Disclosures outside this publication: consultancy, Arthrex & Skeletal Dynamics (money to institution); grants/grants pending, Arthrex (money to institution); royalties, Arthrex (money to institution); payment for development of educational presentations, Arthrex (money to institution) Submitted for publication February 9, 2014; accepted April 12, 2014.
ª 2014 by the American Academy of Physical Medicine and Rehabilitation Vol. -, 1-4, - 2014 http://dx.doi.org/10.1016/j.pmrj.2014.04.005
SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
1
56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Q1 101 102 103 104 105 106 107 108 109 110
111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165
Smith and Kakar
FLEXOR CARPI RADIALIS BREVIS ULTRASOUND
print & web 4C=FPO
2
Figure 1. (A) LG ultrasound of the RT VOL wrist, demonstrating the distal stump of the torn and retracted FCRt (yellow arrows) lying palmar to the radioscaphoid joint. Deep and parallel to the FCR sheath, and separated from the FCR by a fibrous septum (green asterisk), lies a second muscle tendon unit, which consists of the anomalous FCRBm and FCRBt. Compare with magnetic resonance image in (B). (B) Correlative T2-weighted sagittal magnetic resonance image with a larger field of view compared with (A). The complete, retracted FCR tear was confirmed; note the presence of the large FCRBm arising from the volar distal RAD; the sagittal image selected to demonstrate distal FCRBt (orange arrows) insertion into the MC2. Top ¼ volar-palmar; bottom ¼ dorsal; left ¼ proximal; right ¼ distal. LG ¼ longitudinal; RT VOL ¼ right volar; FCRt ¼ flexor carpi radialis tendon; FCR ¼ flexor carpi radialis; FCRBm ¼ flexor carpi radialis brevis muscle; FCRBt ¼ flexor carpi radialis brevis tendon; RAD ¼ radius; MC2 ¼ second metacarpal base; PQ ¼ pronator quadratus; SCPH ¼ scaphoid.
second metacarpal base (Figure 1B). The tendon was clearly distinct from the torn FCR, was located radial to the flexor pollicis longus and carpal tunnel contents, and moved with wrist palmar flexion and dorsiflexion (Figures 2 and 3). The anatomic position and course were consistent with an FCRB
muscle [6-9]. The FCRB coursed in its own fibro-osseous tunnel, and, on US, appeared as a thick, heterogenous, and hypoechoic (ie, dark) ovoid structure surrounded by a small amount of fluid (Figure 3) [1-3]. No Doppler flow was seen. The overall US appearance was consistent with a complete
Figure 2. (A) TR (ie, axial) ultrasound of the RT VOL wrist at the level of the distal RAD, demonstrating a large, anomalous FCRBm bordered dorsally by the volar RAD and PQ, volarly and radially by the radial artery (A), volarly by an abnormally dark and thickened FCRt (proximal to the tear), and ulnarly by the CT lying deep to the PL; the FCRBt (T) is forming centrally within the muscle belly, a common finding for the musculotendinous junction of the FCRB. (B) Correlative T2-weighted axial magnetic resonance imaging oriented to coincide with ultrasound image; note the large FCRBm with its central tendon forming. Top ¼ volar; bottom ¼ dorsal; left ¼ radial; right ¼ ulnar. TR ¼ transverse; RT VOL ¼ right volar; RAD ¼ radius; FCRBm ¼ flexor carpi radialis brevis muscle; PQ ¼ pronator quadratus; FCRt ¼ flexor carpi radialis tendon; CT ¼ carpal tunnel contents; PL ¼ palmaris longus; FCRBt ¼ flexor carpi radialis brevis tendon; FCRB ¼ flexor carpi radialis brevis; FPL ¼ flexor pollicis longus; ULN ¼ ulna.
SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 Q3 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220
PM&R
print & web 4C=FPO
221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268Q2 269 270 271 272 273 274 275
Vol.
-,
Iss.
-,
2014
3
276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 Figure 3. (A) TR (ie, axial) US of the RT VOL wrist at the level of the distal RAD, demonstrating a slightly heterogenous FCRB tendon entering its own fibro-osseous groove dorsal to the abnormally dark and thickened FCR tendon (just proximal to the tear site). The FCRB 293 is surrounded by fluid, particularly on its radial side (white asterisk), a finding consistent with tenosynovitis. Note the thick horizontal 294 septum (green asterisks) separating the FCR and FCRB tendons, the septum blending ulnarly with the flexor retinaculum overlying the 295 carpal tunnel (yellow arrows); this septum also is demonstrated in (A). (B) Correlative T2-weighted axial MRI oriented to coincide with 296 the US image but taken at a slightly more distal position; MRI, demonstrating the absence of the FCR, and a heterogenous FCRBt with 297 moderate peritendinous increased T2 signal; complete FCR tear with FCRB tendinosis and tenosynovitis was confirmed. Note that the horizontal septum separating the FCR sheath from the underlying FCRB is also visible on MRI (yellow arrows), although to a lesser extent 298 compared with US. Top ¼ volar; bottom ¼ dorsal; left ¼ radial; right ¼ ulnar. TR ¼ transverse; US ¼ ultrasound; RT VOL ¼ right volar; RAD ¼ 299 radius; FCRB ¼ flexor carpi radialis brevis; FCR ¼ flexor carpi radialis; FPL ¼ flexor pollicis longus; MN ¼ median nerve; FT ¼ finger flexor Q4 300 tendons; MRI ¼ magnetic resonance imaging; FCRBt ¼ flexor carpi radialis brevis tendon; CT ¼ carpal tunnel contents. 301 302 retracted FCR tear accompanied by FCRB tendinosis and incidental finding during cadaveric dissection or operative 303 tendon sheath effusion versus tenosynovitis [1-3]. Magnetic treatment of distal radius fractures [4,5,7,9]. The FCRB 304 resonance imaging (MRI) was subsequently performed, typically arises from the distal-volar radius as a large muscle, 305 which confirmed the FCR tear and FCRB tendinosis with then courses between the radial artery and pronator quad- 306 associated tenosynovitis (Figures 1 to 3). ratus radial to the FCR tendon, transitions to a central 307 After discussion of operative and nonoperative managetendon at the wrist, courses through the FCR tunnel, and 308 ment options, the patient elected nonoperative treatment, attaches to either the second metacarpal (as in our case) or 309 which consisted of splinting, ice, and a home exercise prothe trapezium (Figures 1 to 3) [4,7,8]. Alternative attach- 310 311 gram. Over the subsequent months, his pain was reduced to ments include the third metacarpal and capitate [4]. a nonfunctionally limiting intermittent “achiness,” and he The FCRB is rarely symptomatic, and only 2 case reports 312 regained full motion. At the 6-month follow-up, he that attribute symptoms to the FCRB have been published 313 continued to be satisfied with his care and was discharged. [6,8]. In 2008, Peers and Kaplan [6] reported an anomalous 314 course of an FCRB, which crossed superficially to the FCR 315 and presented as a painful wrist mass secondary to an 316 DISCUSSION intersection-type phenomenon. Preoperative MRI correctly 317 identified the FCRB, but no US was performed [6]. More 318 This case presentation gives an example of the emerging role recently, Kosiyatrakul et al [8] presented the first published 319 of US in the diagnosis and evaluation of tendon disorders case of FCRB tenosynovitis of a patient clinically suspected 320 around the wrist [1,2]. The US examination diagnosed the of having a volar ganglion cyst or FCR tendinopathy. No 321 complete FCR tear and also identified and characterized an preoperative imaging was performed. During planned sur- 322 unsuspected anatomic variation, the FCRB muscle. There are gical decompression of the FCR tunnel, an FCRB tendon was 323 no previously published reports that document the ability of encountered traversing within its own fibro-osseous tunnel 324 US to identify the FCRB or its potential associated patholadjacent to a relatively normal FCR. Results of an exami- 325 ogies. Due to the lack of prior literature and experience that nation demonstrated FCRB tenosynovitis, which was treated 326 pertains to the US evaluation of the FCRB, MRI was ordered via FCRB-tunnel decompression and tenosynovectomy. 327 in this case to confirm the unusual combination of findings. Before this report, the existence of a separate fibro-osseous 328 The FCRB is a well-described anomalous muscle-tendon tunnel for the FCRB had not been documented [8]. As 329 with a prevalence of 2.6%-8.6%, depending on the method demonstrated on both US and to a lesser extent, MRI, the 330 of documentation [4,5,7-9]. It usually is encountered as an SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
4
331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385
Smith and Kakar
FLEXOR CARPI RADIALIS BREVIS ULTRASOUND
386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 Figure 4. (A) TR (ie, axial) ultrasound of the asymptomatic LT VOL forearm at the distal RAD, demonstrating a large FCRBm, with an evolving central tendon (T), bordered dorsally by the radius and the PQ, volarly and radially by the radial artery (A), volarly by a 403 normal FCR tendon, and ulnarly by the carpal tunnel (FPL). Compare with Figure 3A. Note that the FCRB, similar to the contralateral 404 symptomatic side, is the only muscle with a proximal-distal orientation at the wrist. The PQ is horizontally oriented, and all other volar 405 muscles have transitioned to their tendons. (B) Ultrasound image taken just distal to (A), demonstrating reduction in the FCRBm and more robust formation of the FCRB tendon. The ultrasound appearance of the normal FCR at this level should be contrasted with Q5 406 407 Figures 2A and 3A. Just distal to this scan, the FCRB entered its own fibro-osseous tunnel, similar to the symptomatic right side. Orientation and labels similar to Figure 4B. Top ¼ volar; bottom ¼ dorsal; left ¼ ulnar; right ¼ radial. TR ¼ transverse; LT VOL ¼ left volar; 408 RAD ¼ radius; FCRBm ¼ flexor carpi radialis muscle; PQ ¼ pronator quadratus; FCR ¼ flexor carpi radialis tendon; FPL ¼ flexor pollicis 409 longus; FCRB ¼ flexor carpi radialis brevis. 410 411 patient presented herein also had a separate fibro-osseous aware of the US appearance of the FCRB as well as the po- 412 tunnel for the FCRB (Figure 3). Incidentally, our patient also tential for the FCRB to contribute to radial wrist pain 413 414 had a contralateral, asymptomatic FCRB with a fibro-osseous syndromes. 415 tunnel (Figure 4). Because the potential presence of a sepa416 rate FCRB fibro-osseous tunnel has only recently been 417 documented, it is unknown whether separate FCR and REFERENCES 418 FCRB tunnels are a common finding in the presence of an 1. Bajaj S, Pattamapaspong N, Middleton W, Teefey S. Ultrasound of the 419 FCRB. Furthermore, whether the presence of a separate hand and wrist. J Hand Surg Am 2009;34A:759-760. 420 FCRB fibro-osseous tunnel represents a risk factor for FCRB 2. Olubaniyi BO, Bhatanagar G, Vardhanabhuti V, Brown SE, 421 tendinosis or tenosynovitis remains indeterminate and warGafoor A, Suresh PS. Comprehensive musculoskeletal sonographic 422 rants further investigation [8]. evaluation of the hand and wrist. J Ultrasound Med 2013;32: 423 901-914. The current case represents the first published case of 3. Smith J, Finnoff JT. Diagnostic and interventional musculoskeletal ul424 concomitant complete FCR tear and FCRB tendinosis, and trasound: Part 2. Clinical applications. PM R 2009;1:162-167. 425 tenosynovitis as documented by US. Although our patient 4. Ho SYM, Yeo CJ. The flexor carpi radialis brevis muscle—An anomaly 426 improved markedly during the 6-month follow-up, he in forearm musculature: A review article. Hand Surg 2011;16: 427 continued to have some symptomatology consistent with 245-249. 428 5. Kang L, Carter T, Wolfe SW. The flexor carpi radialis brevis muscle: An “FCR tendinosis” but refused further intervention. In the anomalous flexor of the wrist and hand. A case report. J Hand Surg Am 429 setting of a complete FCR tear and minimal radiographic 2006;31A:1511-1513. 430 scaphotrapeziotrapezoidal arthritis, it is reasonable to assume 6. Peers SC, Kaplan FTD. Flexor carpi radialis brevis muscle presenting 431 that our patient’s residual symptoms may be arising from the as a painful forearm mass: Case report. J Hand Surg Am 2008;33A: 432 FCRB. However, one potential explanation for the patient’s 1878-1881. 433 7. Chong SJ, Al-Ani S, Pinto C, Peat B. Bilateral flexor carpi radialis brevis excellent functional recovery may be the existence of a robust and unilateral flexor carpi ulnaris brevis muscle: case report. J Hand Surg 434 and intact FCRB to substitute for lost FCR function. Am 2009;34A:1868-1871. 435 8. Kosiyatrakul A, Leunam S, Prachaporn S. Symptomatic flexor carpi 436 radialis brevis: Case report. J Hand Surg Am 2010;35A:633-635. CONCLUSION 437 9. Mantovani G, Lino W, Fukushima WY, Cho AB, Aita MA. Anomalous High-resolution US can identify the FCRB muscle-tendon in 438 presentation of flexor carpi radialis brevis: A report of six cases. J Hand Surg Eur 2010;35E:234-235. the wrist region. Sonologists and sonographers should be 439 440 SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
Combined Flexor Carpi Radialis Tear and Flexor Carpi Radialis Brevis Tendinopathy Identified by Ultrasound: A Case Report Q6
Jay Smith, MD, Sanjeev Kakar, MD A 63-year-old right-handed office worker presented with acute right wrist pain after lifting a heavy file at work. Results of a clinical examination suggested flexor carpi radialis tendinopathy. Diagnostic ultrasound (US) not only detected a complete flexor carpi radialis tear but also revealed the presence of a concomitant flexor carpi radialis brevis (FCRB) tendon with associated tenosynovitis. The ability of US to correctly identify the FCRB has not been previously reported. Furthermore, the US appearance of FCRB tendinopathy and tenosynovitis has not been described. High-resolution US can identify the FCRB muscletendon in the wrist region. Sonologists and sonographers should be aware of the US appearance of the FCRB as well as the potential for the FCRB to contribute to radial wrist pain syndromes. PM R 2014;-:1-4
INTRODUCTION Ultrasound (US) has emerged as a powerful diagnostic tool in the wrist region due to its submillimetric resolution and dynamic imaging capabilities [1-3]. In certain clinical scenarios, US may be considered as a first-line soft tissue imaging modality for detection of suspected tendon disorders around the wrist [1,2]. The flexor carpi radialis brevis (FCRB) muscle is an uncommon anomalous muscle that typically arises from the distal volar radius and attaches to the carpal or metacarpal bones [4-8]. FCRB pathology is rare and, to date, has not been documented by US in published reports [6,8]. Herein we report a case of a complete flexor carpi radialis (FCR) tear combined with clinically unsuspected FCRB tendinopathy and tenosynovitis as detected on US.
CASE PRESENTATION A 63-year-old right-hand dominant otherwise healthy office worker presented with a 3-week history of right volar wrist pain after an acute injury. While lifting a file at work, he experienced a “pop” with immediate volar-radial wrist pain followed by swelling and ecchymosis. He did not have any prodromal symptoms. Despite interim improvement, due to persistent weakness and pain, he presented for evaluation. Results of an examination was remarkable for resolving ecchymosis over the volar-radial wrist crease, a nonpalpable FCR tendon, and tenderness to palpation in the region of the scaphoid tubercle and scaphotrapeziotrapezoidal joint. He had slightly limited active and passive wrist dorsiflexion accompanied by pain and painful resisted wrist palmar flexion. Sensory examination results were normal, and results of thumb and finger flexor manual muscle testing were normal and nonprovocative. Radiographs revealed scaphotrapeziotrapezoidal and basilar thumb arthritis. An acute FCR tear was suspected, and diagnostic US was ordered. US revealed a complete FCR tear with proximal retraction to the radioscaphoid joint. In addition, a second tendon was visualized paralleling the course of the FCR sheath but lying deep to it (Figure 1A). Further scanning along the anomalous tendon both proximally and distally revealed a muscular origin from the distal-volar radius, formation of the tendon at the radioscaphoid joint, with a course through the FCR tunnel, and insertion onto the PM&R 1934-1482/14/$36.00 Printed in U.S.A.
J.S. Departments of Physical Medicine and Rehabilitation, Radiology, and Anatomy, Mayo Clinic College of Medicine, Mayo Clinic Sports Medicine Center, Mayo Clinic, Rochester, MN. Address correspondence to: J.S.; e-mail: [email protected] Disclosures outside this publication: consultancy, Tenex Health (money to author and institution); employment, Tenex Health; payment for lectures, including service on speakers bureaus, Andrews Institute Gulf Coast Ultrasound Institute; patents, Tenex Health (money to author and institution); royalties, Tenex Health (money to author and institution); stock/stock options, Tenex Health (money to author and institution) S.K. Department of Orthopedic Surgery, Mayo, Mayo Clinic Sports Medicine Center, Rochester, MN Disclosures outside this publication: consultancy, Arthrex & Skeletal Dynamics (money to institution); grants/grants pending, Arthrex (money to institution); royalties, Arthrex (money to institution); payment for development of educational presentations, Arthrex (money to institution) Submitted for publication February 9, 2014; accepted April 12, 2014.
ª 2014 by the American Academy of Physical Medicine and Rehabilitation Vol. -, 1-4, - 2014 http://dx.doi.org/10.1016/j.pmrj.2014.04.005
SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
1
56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Q1 101 102 103 104 105 106 107 108 109 110
111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165
Smith and Kakar
FLEXOR CARPI RADIALIS BREVIS ULTRASOUND
print & web 4C=FPO
2
Figure 1. (A) LG ultrasound of the RT VOL wrist, demonstrating the distal stump of the torn and retracted FCRt (yellow arrows) lying palmar to the radioscaphoid joint. Deep and parallel to the FCR sheath, and separated from the FCR by a fibrous septum (green asterisk), lies a second muscle tendon unit, which consists of the anomalous FCRBm and FCRBt. Compare with magnetic resonance image in (B). (B) Correlative T2-weighted sagittal magnetic resonance image with a larger field of view compared with (A). The complete, retracted FCR tear was confirmed; note the presence of the large FCRBm arising from the volar distal RAD; the sagittal image selected to demonstrate distal FCRBt (orange arrows) insertion into the MC2. Top ¼ volar-palmar; bottom ¼ dorsal; left ¼ proximal; right ¼ distal. LG ¼ longitudinal; RT VOL ¼ right volar; FCRt ¼ flexor carpi radialis tendon; FCR ¼ flexor carpi radialis; FCRBm ¼ flexor carpi radialis brevis muscle; FCRBt ¼ flexor carpi radialis brevis tendon; RAD ¼ radius; MC2 ¼ second metacarpal base; PQ ¼ pronator quadratus; SCPH ¼ scaphoid.
second metacarpal base (Figure 1B). The tendon was clearly distinct from the torn FCR, was located radial to the flexor pollicis longus and carpal tunnel contents, and moved with wrist palmar flexion and dorsiflexion (Figures 2 and 3). The anatomic position and course were consistent with an FCRB
muscle [6-9]. The FCRB coursed in its own fibro-osseous tunnel, and, on US, appeared as a thick, heterogenous, and hypoechoic (ie, dark) ovoid structure surrounded by a small amount of fluid (Figure 3) [1-3]. No Doppler flow was seen. The overall US appearance was consistent with a complete
Figure 2. (A) TR (ie, axial) ultrasound of the RT VOL wrist at the level of the distal RAD, demonstrating a large, anomalous FCRBm bordered dorsally by the volar RAD and PQ, volarly and radially by the radial artery (A), volarly by an abnormally dark and thickened FCRt (proximal to the tear), and ulnarly by the CT lying deep to the PL; the FCRBt (T) is forming centrally within the muscle belly, a common finding for the musculotendinous junction of the FCRB. (B) Correlative T2-weighted axial magnetic resonance imaging oriented to coincide with ultrasound image; note the large FCRBm with its central tendon forming. Top ¼ volar; bottom ¼ dorsal; left ¼ radial; right ¼ ulnar. TR ¼ transverse; RT VOL ¼ right volar; RAD ¼ radius; FCRBm ¼ flexor carpi radialis brevis muscle; PQ ¼ pronator quadratus; FCRt ¼ flexor carpi radialis tendon; CT ¼ carpal tunnel contents; PL ¼ palmaris longus; FCRBt ¼ flexor carpi radialis brevis tendon; FCRB ¼ flexor carpi radialis brevis; FPL ¼ flexor pollicis longus; ULN ¼ ulna.
SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 Q3 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220
PM&R
print & web 4C=FPO
221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268Q2 269 270 271 272 273 274 275
Vol.
-,
Iss.
-,
2014
3
276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 Figure 3. (A) TR (ie, axial) US of the RT VOL wrist at the level of the distal RAD, demonstrating a slightly heterogenous FCRB tendon entering its own fibro-osseous groove dorsal to the abnormally dark and thickened FCR tendon (just proximal to the tear site). The FCRB 293 is surrounded by fluid, particularly on its radial side (white asterisk), a finding consistent with tenosynovitis. Note the thick horizontal 294 septum (green asterisks) separating the FCR and FCRB tendons, the septum blending ulnarly with the flexor retinaculum overlying the 295 carpal tunnel (yellow arrows); this septum also is demonstrated in (A). (B) Correlative T2-weighted axial MRI oriented to coincide with 296 the US image but taken at a slightly more distal position; MRI, demonstrating the absence of the FCR, and a heterogenous FCRBt with 297 moderate peritendinous increased T2 signal; complete FCR tear with FCRB tendinosis and tenosynovitis was confirmed. Note that the horizontal septum separating the FCR sheath from the underlying FCRB is also visible on MRI (yellow arrows), although to a lesser extent 298 compared with US. Top ¼ volar; bottom ¼ dorsal; left ¼ radial; right ¼ ulnar. TR ¼ transverse; US ¼ ultrasound; RT VOL ¼ right volar; RAD ¼ 299 radius; FCRB ¼ flexor carpi radialis brevis; FCR ¼ flexor carpi radialis; FPL ¼ flexor pollicis longus; MN ¼ median nerve; FT ¼ finger flexor Q4 300 tendons; MRI ¼ magnetic resonance imaging; FCRBt ¼ flexor carpi radialis brevis tendon; CT ¼ carpal tunnel contents. 301 302 retracted FCR tear accompanied by FCRB tendinosis and incidental finding during cadaveric dissection or operative 303 tendon sheath effusion versus tenosynovitis [1-3]. Magnetic treatment of distal radius fractures [4,5,7,9]. The FCRB 304 resonance imaging (MRI) was subsequently performed, typically arises from the distal-volar radius as a large muscle, 305 which confirmed the FCR tear and FCRB tendinosis with then courses between the radial artery and pronator quad- 306 associated tenosynovitis (Figures 1 to 3). ratus radial to the FCR tendon, transitions to a central 307 After discussion of operative and nonoperative managetendon at the wrist, courses through the FCR tunnel, and 308 ment options, the patient elected nonoperative treatment, attaches to either the second metacarpal (as in our case) or 309 which consisted of splinting, ice, and a home exercise prothe trapezium (Figures 1 to 3) [4,7,8]. Alternative attach- 310 311 gram. Over the subsequent months, his pain was reduced to ments include the third metacarpal and capitate [4]. a nonfunctionally limiting intermittent “achiness,” and he The FCRB is rarely symptomatic, and only 2 case reports 312 regained full motion. At the 6-month follow-up, he that attribute symptoms to the FCRB have been published 313 continued to be satisfied with his care and was discharged. [6,8]. In 2008, Peers and Kaplan [6] reported an anomalous 314 course of an FCRB, which crossed superficially to the FCR 315 and presented as a painful wrist mass secondary to an 316 DISCUSSION intersection-type phenomenon. Preoperative MRI correctly 317 identified the FCRB, but no US was performed [6]. More 318 This case presentation gives an example of the emerging role recently, Kosiyatrakul et al [8] presented the first published 319 of US in the diagnosis and evaluation of tendon disorders case of FCRB tenosynovitis of a patient clinically suspected 320 around the wrist [1,2]. The US examination diagnosed the of having a volar ganglion cyst or FCR tendinopathy. No 321 complete FCR tear and also identified and characterized an preoperative imaging was performed. During planned sur- 322 unsuspected anatomic variation, the FCRB muscle. There are gical decompression of the FCR tunnel, an FCRB tendon was 323 no previously published reports that document the ability of encountered traversing within its own fibro-osseous tunnel 324 US to identify the FCRB or its potential associated patholadjacent to a relatively normal FCR. Results of an exami- 325 ogies. Due to the lack of prior literature and experience that nation demonstrated FCRB tenosynovitis, which was treated 326 pertains to the US evaluation of the FCRB, MRI was ordered via FCRB-tunnel decompression and tenosynovectomy. 327 in this case to confirm the unusual combination of findings. Before this report, the existence of a separate fibro-osseous 328 The FCRB is a well-described anomalous muscle-tendon tunnel for the FCRB had not been documented [8]. As 329 with a prevalence of 2.6%-8.6%, depending on the method demonstrated on both US and to a lesser extent, MRI, the 330 of documentation [4,5,7-9]. It usually is encountered as an SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
4
331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385
Smith and Kakar
FLEXOR CARPI RADIALIS BREVIS ULTRASOUND
386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 Figure 4. (A) TR (ie, axial) ultrasound of the asymptomatic LT VOL forearm at the distal RAD, demonstrating a large FCRBm, with an evolving central tendon (T), bordered dorsally by the radius and the PQ, volarly and radially by the radial artery (A), volarly by a 403 normal FCR tendon, and ulnarly by the carpal tunnel (FPL). Compare with Figure 3A. Note that the FCRB, similar to the contralateral 404 symptomatic side, is the only muscle with a proximal-distal orientation at the wrist. The PQ is horizontally oriented, and all other volar 405 muscles have transitioned to their tendons. (B) Ultrasound image taken just distal to (A), demonstrating reduction in the FCRBm and more robust formation of the FCRB tendon. The ultrasound appearance of the normal FCR at this level should be contrasted with Q5 406 407 Figures 2A and 3A. Just distal to this scan, the FCRB entered its own fibro-osseous tunnel, similar to the symptomatic right side. Orientation and labels similar to Figure 4B. Top ¼ volar; bottom ¼ dorsal; left ¼ ulnar; right ¼ radial. TR ¼ transverse; LT VOL ¼ left volar; 408 RAD ¼ radius; FCRBm ¼ flexor carpi radialis muscle; PQ ¼ pronator quadratus; FCR ¼ flexor carpi radialis tendon; FPL ¼ flexor pollicis 409 longus; FCRB ¼ flexor carpi radialis brevis. 410 411 patient presented herein also had a separate fibro-osseous aware of the US appearance of the FCRB as well as the po- 412 tunnel for the FCRB (Figure 3). Incidentally, our patient also tential for the FCRB to contribute to radial wrist pain 413 414 had a contralateral, asymptomatic FCRB with a fibro-osseous syndromes. 415 tunnel (Figure 4). Because the potential presence of a sepa416 rate FCRB fibro-osseous tunnel has only recently been 417 documented, it is unknown whether separate FCR and REFERENCES 418 FCRB tunnels are a common finding in the presence of an 1. Bajaj S, Pattamapaspong N, Middleton W, Teefey S. Ultrasound of the 419 FCRB. Furthermore, whether the presence of a separate hand and wrist. J Hand Surg Am 2009;34A:759-760. 420 FCRB fibro-osseous tunnel represents a risk factor for FCRB 2. Olubaniyi BO, Bhatanagar G, Vardhanabhuti V, Brown SE, 421 tendinosis or tenosynovitis remains indeterminate and warGafoor A, Suresh PS. Comprehensive musculoskeletal sonographic 422 rants further investigation [8]. evaluation of the hand and wrist. J Ultrasound Med 2013;32: 423 901-914. The current case represents the first published case of 3. Smith J, Finnoff JT. Diagnostic and interventional musculoskeletal ul424 concomitant complete FCR tear and FCRB tendinosis, and trasound: Part 2. Clinical applications. PM R 2009;1:162-167. 425 tenosynovitis as documented by US. Although our patient 4. Ho SYM, Yeo CJ. The flexor carpi radialis brevis muscle—An anomaly 426 improved markedly during the 6-month follow-up, he in forearm musculature: A review article. Hand Surg 2011;16: 427 continued to have some symptomatology consistent with 245-249. 428 5. Kang L, Carter T, Wolfe SW. The flexor carpi radialis brevis muscle: An “FCR tendinosis” but refused further intervention. In the anomalous flexor of the wrist and hand. A case report. J Hand Surg Am 429 setting of a complete FCR tear and minimal radiographic 2006;31A:1511-1513. 430 scaphotrapeziotrapezoidal arthritis, it is reasonable to assume 6. Peers SC, Kaplan FTD. Flexor carpi radialis brevis muscle presenting 431 that our patient’s residual symptoms may be arising from the as a painful forearm mass: Case report. J Hand Surg Am 2008;33A: 432 FCRB. However, one potential explanation for the patient’s 1878-1881. 433 7. Chong SJ, Al-Ani S, Pinto C, Peat B. Bilateral flexor carpi radialis brevis excellent functional recovery may be the existence of a robust and unilateral flexor carpi ulnaris brevis muscle: case report. J Hand Surg 434 and intact FCRB to substitute for lost FCR function. Am 2009;34A:1868-1871. 435 8. Kosiyatrakul A, Leunam S, Prachaporn S. Symptomatic flexor carpi 436 radialis brevis: Case report. J Hand Surg Am 2010;35A:633-635. CONCLUSION 437 9. Mantovani G, Lino W, Fukushima WY, Cho AB, Aita MA. Anomalous High-resolution US can identify the FCRB muscle-tendon in 438 presentation of flexor carpi radialis brevis: A report of six cases. J Hand Surg Eur 2010;35E:234-235. the wrist region. Sonologists and sonographers should be 439 440 SCO 5.2.0 DTD PMRJ1240_proof 3 May 2014 3:22 pm ce
