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Supernumerary extensor pollicis longus tendon: a case report1
Supernumerary Extensor Pollicis Longus Tendon: A Case Report Takuya Sawaizumi, MD, Mitsuhiko Nanno, MD, Hiromoto Ito, MD, Tokyo, Japan
We report a rare case in which the extensor pollicis longus (EPL) tendon was separated into 2 slips at the site of origin, ran an abnormal course across the wrist, and combined in the vicinity of the metacarpophalangeal (MCP) joint; the tendon on the radial side passed through another tendon sheath between the first and second compartments and the tendon on the ulnar side passed over the extensor retinaculum. (J Hand Surg 2003;28A:1014 –1017. Copyright © 2003 by the American Society for Surgery of the Hand.) Key words: Anomaly, extensor pollicis longus tendon, tenosynovitis.
There are many reports of anomalies in the extensor tendon of the hand.1– 8 There have been only 6 clinical reports of one case each of supernumerary extensor pollicis longus (EPL) tendon,9 –14 most of which are based on cadaver dissection.1,2 Therefore it is considered that anomalies in this region exist asymptomatically. We report a rare case in which the EPL tendon was separated into 2 slips at the site of origin, ran an abnormal course across the wrist, and combined in the vicinity of the metacarpophalangeal (MCP) joint.
Case Report A 40-year-old right-handed male office worker felt discomfort on the radial side of his right wrist joint after a bowling game and found difficulty in extending his thumb the next day. Because the symptom did
From the Department of Orthopaedic Surgery, Nippon Medical School, Tokyo, Japan. Received for publication February 25, 2003; accepted in revised form July 15, 2003. No benefits in any form have been received or will be received by a commercial party related directly or indirectly to the subject of this article. Reprint requests: Takuya Sawaizumi, MD, Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan. Copyright © 2003 by the American Society for Surgery of the Hand 0363-5023/03/28A06-0019$30.00/0 doi:10.1016/S0363-5023(03)00382-4
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The Journal of Hand Surgery
not improve, approximately 2 months later he visited our hospital. He had no particular past personal or familial history of limb abnormalities. On first examination a painful swelling was observed on the 1-cm dorsal side of the first extensor compartment. Flexion of the right thumb was normal, however, extension movements of the interphalangeal (IP) and MCP joints were limited to ⫺5° and ⫺20°, respectively, and strength of thumb flexion was decreased. On the dorsal side of the wrist joint slight pain on movement was observed. No skin contours of the EPL tendon of the right thumb were present, while in the normal left thumb skin contours running along the location of the EPL tendon was detected by ocular inspection or palpation (Fig. 1). No bone injury or hypoplastic Lister’s tubercle was observed on radiography, and on the blood examination neither an inflammatory reaction nor rheumatoid factor were detected. The patient was diagnosed as having either subcutaneous rupture of the EPL tendon or stenosing tenosynovitis; therefore surgery was performed. An approximately 5-cm-long skin incision was made on the dorsal side of the hand and wrist that was extended to about 7 cm intraoperatively starting from the right thumb to the dorsal side of the forearm. The EPL tendon was not separated at the muscle belly but was found separated into 2 slips at the site of origin, and both of the separated tendons were extremely thin. The 2 slips combined distally in the vicinity of
Sawaizumi, Nanno, and Ito / Supernumerary EPL Tendon
Figure 1. Based on preoperative clinical examinations, extension movements of the IP and MCP joints of the right thumb were limited. The EPL tendon was not detected on the affected side either by inspection or by palpation.
1015
the MCP joint and then continued independently to the distal phalanx. The tendon on the radial side passed through another tunnel between the first and second compartments. The tendon on the ulnar side did not pass through a compartment but passed over the extensor retinaculum approximately 5 mm on the radial side of Lister’s tubercle; the third extensor compartment did not exist. In addition, the extensor pollicis brevis (EPB) tendon did not exist. The sheath of the tendon on the radial side was extremely thick and the excursion of the tendon was impossible (Fig. 2A). Based on these findings the patient was diagnosed as having stenosing tenosynovitis. After the tendon sheath was dissected the excursion of the tendon became possible. Considering the excursion of the tendon the position of the tendon was not
Figure 2. (A) Surgical findings. The EPL tendon was not separated at the muscle belly but was separated into 2 slips at the site of origin; both of the separated tendons were extremely thin. The tendon on the radial side passed through another tunnel between the first and second compartments. The tendon on the ulnar side passed over the extensor retinaculum on the radial side of Lister’s tubercle. In addition, the abductor pollicis longus tendon was present, however, the extensor pollicis brevis tendon was absent. The arrows indicate the tendon sheath through which the tendon on the radial side passed and the constricted region. (B) Arrangement of the extensor tendons. REPL, radial slip of extensor pollicis longus; UEPL, ulnar slip of extensor pollicis longus tendon; APL, abductor pollicis longus tendon; ECR, extensor carpi radialis tendon; LT, Lister’s tubercle.
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The Journal of Hand Surgery / Vol. 28A No. 6 November 2003
Figure 3. Although some degree of dysfunction in extension remained in the right thumb of the patient 6 months after the surgery the patient has no difficulty in his daily activities.
changed. Figure 2B shows the abnormal arrangement of the extensor tendons. After the surgery the patient was able to extend the IP and MCP joints of his thumb. Six months after the surgery, although extension remained slightly limited, no tendon dislocation was observed and the strength of the EPL muscle on the operated side improved to the same level as that of the normal side. The contour of the EPL tendon, however, was not detected either by inspection or by palpation (Fig. 3).
Discussion There have been reports on anomalies of the extensor tendons of the hand based on cadaver dissection.1,2 It is known that anomalies in the hand occur at a relatively high frequency. It was reported, however, that the incidence of the anomaly of the EPL tendon is less than that of other finger extensor tendons because it is embryologically stable.1 Cauldwell et al2 reported that an anomaly in the extensor indicis proprius tendon was observed in 41 cadavers (15.6%), whereas an anomaly in the EPL tendon was observed only in 1% of the 263 total cadavers. In these anomalies the EPL tendon separated into 2 slips; 1 slip was attached to the index finger and the other slip was attached to the thumb; they were named extensor pollicis and
indicis communis, respectively. Culver9 also found similar anomalies during synovectomy. Beatty et al10 reported a case in which the patient complained of pain on the dorsal side of the wrist joint; an accessory tendon arising from the EPL tendon in the third compartment was observed. In addition, Kaplan and Nathan,11 Chiu,12 and Cohen and Haber13 reported that they found an accessory tendon of the EPL tendon arising from another muscle located between the normal EPL muscle and the extensor indicis proprius muscle, and that the accessory tendon passed through the fourth compartment. In these reports the presence or absence of the abductor pollicis longus tendon or EPB tendon was not mentioned clearly. Our case was different from the previous reports in the following points: (1) the 2 EPL tendons originated from the same muscle belly and they combined to form one tendon in the vicinity of the MCP joint, then attached to the distal phalanx; (2) neither of the separated EPL tendons passed through the compartment where the tendon usually passes through; and (3) the EPB tendon did not exist, thus it was considered that the tendon on the radial side compensated for the functions of the EPB tendon. Based on these findings this is a rare case. In many cases it is difficult to diagnose tenosynovitis of the EPL tendon on the first examination. It has been reported that patients complain of pain on the dorsal side of the wrist joint and hardly can limit the painful area, and that symptoms such as swelling, pain, and crepitation in Lister’s tubercle are important diagnostic factors.10 In our case, however, the excursion of the EPL tendon was absent on the first examination of the patient owing to severe stenosis, and specific clinical findings were absent. Because it was very difficult to diagnose the case at the initial examination, surgery was performed considering the possibility of both subcutaneous rupture of the EPL tendon and stenosing tenosynovitis. As a result the anatomic anomaly of the EPL tendon and its resulting stenosing tenosynovitis were confirmed during the surgery.
References 1. Straus WL Jr. The phylogeny of the human forearm extensors (concluded). Hum Biol 1941;13:203–238. 2. Cauldwell EW, Anson BJ, Wright RR. The extensor indicis proprius muscle. A study of 263 consecutive specimens. Bull Northwestern Univ Med School 1943;17:267–279. 3. Schenck RR. Variations of the extensor tendons of the fingers. Surgical significance. J Bone Joint Surg 1964;46A: 103–110.
Sawaizumi, Nanno, and Ito / Supernumerary EPL Tendon 4. Gschwend N. Anatomic variants of the muscles and tendons of the hand. Handchir Microchir Plast Chir 1987;19:244 – 247. 5. von Schroeder HP, Botte MJ. Anatomy of the extensor tendons of the fingers: variations and multiplicity. J Hand Surg 1995;20A:27–34. 6. El-Badawi MGY, Butt MM, Al-Zuhair AGH, Fadel RA. Extensor tendons of the fingers: arrangement and variations– II. Clin Anat 1995;8:391–398. 7. Tan ST, Smith PJ. Anomalous extensor muscles of the hand: a review. J Hand Surg 1999;24A:449 – 455. 8. Hirai Y, Yoshida K, Yamanaka K, Inoue A, Yamaki K, Yoshizuka M. An anatomic study of the extensor tendons of the human hand. J Hand Surg 2001;26A:1009 –1015. 9. Culver JE Jr. Extensor pollicis and indicis communis tendon:
10.
11. 12.
13. 14.
1017
a rare anatomic variation revisited. J Hand Surg 1980;5: 548 –549. Beatty JD, Remedios D, McCullough CJ. An accessory extensor tendon of the thumb as a cause of dorsal wrist pain. J Hand Surg 2000;25B:110 –111. Kaplan EB, Nathan P. Accessory extensor pollicis longus. Bull Hosp Joint Dis 1969;30:202–207. Chiu DTW. Supernumerary extensor tendon to the thumb: a report on a rare anatomic variation. Plast Reconstr Surg 1981;68:937–939. Cohen BE, Haber JL. Supernumerary extensor tendon to the thumb: a case report. Ann Plast Surg 1996;36:105–107. Abu-Hijleh MF. Extensor pollicis tertius: an additional extensor muscle to the thumb. Plast Reconstr Surg 1993;92: 340 –343.
We report a rare case in which the extensor pollicis longus (EPL) tendon was separated into 2 slips at the site of origin, ran an abnormal course across the wrist, and combined in the vicinity of the metacarpophalangeal (MCP) joint; the tendon on the radial side passed through another tendon sheath between the first and second compartments and the tendon on the ulnar side passed over the extensor retinaculum. (J Hand Surg 2003;28A:1014 –1017. Copyright © 2003 by the American Society for Surgery of the Hand.) Key words: Anomaly, extensor pollicis longus tendon, tenosynovitis.
There are many reports of anomalies in the extensor tendon of the hand.1– 8 There have been only 6 clinical reports of one case each of supernumerary extensor pollicis longus (EPL) tendon,9 –14 most of which are based on cadaver dissection.1,2 Therefore it is considered that anomalies in this region exist asymptomatically. We report a rare case in which the EPL tendon was separated into 2 slips at the site of origin, ran an abnormal course across the wrist, and combined in the vicinity of the metacarpophalangeal (MCP) joint.
Case Report A 40-year-old right-handed male office worker felt discomfort on the radial side of his right wrist joint after a bowling game and found difficulty in extending his thumb the next day. Because the symptom did
From the Department of Orthopaedic Surgery, Nippon Medical School, Tokyo, Japan. Received for publication February 25, 2003; accepted in revised form July 15, 2003. No benefits in any form have been received or will be received by a commercial party related directly or indirectly to the subject of this article. Reprint requests: Takuya Sawaizumi, MD, Department of Orthopaedic Surgery, Nippon Medical School, 1-1-5 Sendagi, Bunkyo-ku, Tokyo 113-8603, Japan. Copyright © 2003 by the American Society for Surgery of the Hand 0363-5023/03/28A06-0019$30.00/0 doi:10.1016/S0363-5023(03)00382-4
1014
The Journal of Hand Surgery
not improve, approximately 2 months later he visited our hospital. He had no particular past personal or familial history of limb abnormalities. On first examination a painful swelling was observed on the 1-cm dorsal side of the first extensor compartment. Flexion of the right thumb was normal, however, extension movements of the interphalangeal (IP) and MCP joints were limited to ⫺5° and ⫺20°, respectively, and strength of thumb flexion was decreased. On the dorsal side of the wrist joint slight pain on movement was observed. No skin contours of the EPL tendon of the right thumb were present, while in the normal left thumb skin contours running along the location of the EPL tendon was detected by ocular inspection or palpation (Fig. 1). No bone injury or hypoplastic Lister’s tubercle was observed on radiography, and on the blood examination neither an inflammatory reaction nor rheumatoid factor were detected. The patient was diagnosed as having either subcutaneous rupture of the EPL tendon or stenosing tenosynovitis; therefore surgery was performed. An approximately 5-cm-long skin incision was made on the dorsal side of the hand and wrist that was extended to about 7 cm intraoperatively starting from the right thumb to the dorsal side of the forearm. The EPL tendon was not separated at the muscle belly but was found separated into 2 slips at the site of origin, and both of the separated tendons were extremely thin. The 2 slips combined distally in the vicinity of
Sawaizumi, Nanno, and Ito / Supernumerary EPL Tendon
Figure 1. Based on preoperative clinical examinations, extension movements of the IP and MCP joints of the right thumb were limited. The EPL tendon was not detected on the affected side either by inspection or by palpation.
1015
the MCP joint and then continued independently to the distal phalanx. The tendon on the radial side passed through another tunnel between the first and second compartments. The tendon on the ulnar side did not pass through a compartment but passed over the extensor retinaculum approximately 5 mm on the radial side of Lister’s tubercle; the third extensor compartment did not exist. In addition, the extensor pollicis brevis (EPB) tendon did not exist. The sheath of the tendon on the radial side was extremely thick and the excursion of the tendon was impossible (Fig. 2A). Based on these findings the patient was diagnosed as having stenosing tenosynovitis. After the tendon sheath was dissected the excursion of the tendon became possible. Considering the excursion of the tendon the position of the tendon was not
Figure 2. (A) Surgical findings. The EPL tendon was not separated at the muscle belly but was separated into 2 slips at the site of origin; both of the separated tendons were extremely thin. The tendon on the radial side passed through another tunnel between the first and second compartments. The tendon on the ulnar side passed over the extensor retinaculum on the radial side of Lister’s tubercle. In addition, the abductor pollicis longus tendon was present, however, the extensor pollicis brevis tendon was absent. The arrows indicate the tendon sheath through which the tendon on the radial side passed and the constricted region. (B) Arrangement of the extensor tendons. REPL, radial slip of extensor pollicis longus; UEPL, ulnar slip of extensor pollicis longus tendon; APL, abductor pollicis longus tendon; ECR, extensor carpi radialis tendon; LT, Lister’s tubercle.
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The Journal of Hand Surgery / Vol. 28A No. 6 November 2003
Figure 3. Although some degree of dysfunction in extension remained in the right thumb of the patient 6 months after the surgery the patient has no difficulty in his daily activities.
changed. Figure 2B shows the abnormal arrangement of the extensor tendons. After the surgery the patient was able to extend the IP and MCP joints of his thumb. Six months after the surgery, although extension remained slightly limited, no tendon dislocation was observed and the strength of the EPL muscle on the operated side improved to the same level as that of the normal side. The contour of the EPL tendon, however, was not detected either by inspection or by palpation (Fig. 3).
Discussion There have been reports on anomalies of the extensor tendons of the hand based on cadaver dissection.1,2 It is known that anomalies in the hand occur at a relatively high frequency. It was reported, however, that the incidence of the anomaly of the EPL tendon is less than that of other finger extensor tendons because it is embryologically stable.1 Cauldwell et al2 reported that an anomaly in the extensor indicis proprius tendon was observed in 41 cadavers (15.6%), whereas an anomaly in the EPL tendon was observed only in 1% of the 263 total cadavers. In these anomalies the EPL tendon separated into 2 slips; 1 slip was attached to the index finger and the other slip was attached to the thumb; they were named extensor pollicis and
indicis communis, respectively. Culver9 also found similar anomalies during synovectomy. Beatty et al10 reported a case in which the patient complained of pain on the dorsal side of the wrist joint; an accessory tendon arising from the EPL tendon in the third compartment was observed. In addition, Kaplan and Nathan,11 Chiu,12 and Cohen and Haber13 reported that they found an accessory tendon of the EPL tendon arising from another muscle located between the normal EPL muscle and the extensor indicis proprius muscle, and that the accessory tendon passed through the fourth compartment. In these reports the presence or absence of the abductor pollicis longus tendon or EPB tendon was not mentioned clearly. Our case was different from the previous reports in the following points: (1) the 2 EPL tendons originated from the same muscle belly and they combined to form one tendon in the vicinity of the MCP joint, then attached to the distal phalanx; (2) neither of the separated EPL tendons passed through the compartment where the tendon usually passes through; and (3) the EPB tendon did not exist, thus it was considered that the tendon on the radial side compensated for the functions of the EPB tendon. Based on these findings this is a rare case. In many cases it is difficult to diagnose tenosynovitis of the EPL tendon on the first examination. It has been reported that patients complain of pain on the dorsal side of the wrist joint and hardly can limit the painful area, and that symptoms such as swelling, pain, and crepitation in Lister’s tubercle are important diagnostic factors.10 In our case, however, the excursion of the EPL tendon was absent on the first examination of the patient owing to severe stenosis, and specific clinical findings were absent. Because it was very difficult to diagnose the case at the initial examination, surgery was performed considering the possibility of both subcutaneous rupture of the EPL tendon and stenosing tenosynovitis. As a result the anatomic anomaly of the EPL tendon and its resulting stenosing tenosynovitis were confirmed during the surgery.
References 1. Straus WL Jr. The phylogeny of the human forearm extensors (concluded). Hum Biol 1941;13:203–238. 2. Cauldwell EW, Anson BJ, Wright RR. The extensor indicis proprius muscle. A study of 263 consecutive specimens. Bull Northwestern Univ Med School 1943;17:267–279. 3. Schenck RR. Variations of the extensor tendons of the fingers. Surgical significance. J Bone Joint Surg 1964;46A: 103–110.
Sawaizumi, Nanno, and Ito / Supernumerary EPL Tendon 4. Gschwend N. Anatomic variants of the muscles and tendons of the hand. Handchir Microchir Plast Chir 1987;19:244 – 247. 5. von Schroeder HP, Botte MJ. Anatomy of the extensor tendons of the fingers: variations and multiplicity. J Hand Surg 1995;20A:27–34. 6. El-Badawi MGY, Butt MM, Al-Zuhair AGH, Fadel RA. Extensor tendons of the fingers: arrangement and variations– II. Clin Anat 1995;8:391–398. 7. Tan ST, Smith PJ. Anomalous extensor muscles of the hand: a review. J Hand Surg 1999;24A:449 – 455. 8. Hirai Y, Yoshida K, Yamanaka K, Inoue A, Yamaki K, Yoshizuka M. An anatomic study of the extensor tendons of the human hand. J Hand Surg 2001;26A:1009 –1015. 9. Culver JE Jr. Extensor pollicis and indicis communis tendon:
10.
11. 12.
13. 14.
1017
a rare anatomic variation revisited. J Hand Surg 1980;5: 548 –549. Beatty JD, Remedios D, McCullough CJ. An accessory extensor tendon of the thumb as a cause of dorsal wrist pain. J Hand Surg 2000;25B:110 –111. Kaplan EB, Nathan P. Accessory extensor pollicis longus. Bull Hosp Joint Dis 1969;30:202–207. Chiu DTW. Supernumerary extensor tendon to the thumb: a report on a rare anatomic variation. Plast Reconstr Surg 1981;68:937–939. Cohen BE, Haber JL. Supernumerary extensor tendon to the thumb: a case report. Ann Plast Surg 1996;36:105–107. Abu-Hijleh MF. Extensor pollicis tertius: an additional extensor muscle to the thumb. Plast Reconstr Surg 1993;92: 340 –343.