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Extensor Indicis Proprius Transfer for the Abducted Small Finger
SCIENTIFIC ARTICLE
Extensor Indicis Proprius Transfer for the Abducted Small Finger Moon Sang Chung, MD, PhD, Goo Hyun Baek, MD, PhD, Joo Han Oh, MD, PhD, Young Ho Lee, MD, PhD, Hoyune Esther Cho, Hyun Sik Gong, MD, PhD Purpose Persistent abduction of the small finger has usually been treated by transfer of the extensor digiti minimi muscle. However, anatomic variations of the extensor system may limit the potential for a successful extensor digiti minimi transfer. Therefore, we evaluated the outcomes of an alternative reconstruction method for the abducted small finger using an extensor indicis proprius (EIP) transfer. Methods We performed 8 EIP transfers in 8 patients with persistent, flexible abduction posturing of the small finger. The primary etiology of the deformity was incomplete motor reinnervation after surgeries for ulnar neuropathy in 6 patients, rupture of the third palmar interosseous musculotendinous unit in 1 patient, and intrinsic muscle fibrosis in 1 patient. The EIP was elongated by splitting the tendinous portion and was transferred to the distal and radial part of the extensor hood. Surgical outcomes were assessed by comparing preoperative and postoperative active adduction and abduction motion of the 2 ulnar digits. Results At the mean follow-up of 23 months, the average adduction angle improved from 19° to 1° postoperatively. In terms of active finger motion, 6 patients showed excellent results, 1 good, and 1 fair, without loss of flexion and extension. No patient had an extension lag or complained of functional deficits of the donor index finger. There was not adverse change to digital function or range of motion for the middle and ring fingers that are crossed by the EIP. Conclusions Extensor indicis proprius transfer can be a reliable option for correction of abduction deformity of the small finger, maintaining active abduction and full flexion and extension. (J Hand Surg 2008;33A:392–397. Copyright © 2008 by the American Society for Surgery of the Hand.) Type of study/level of evidence Therapeutic IV. Key words Abducted small finger, ulnar neuropathy, extensor indicis proprius transfer.
P
ERSISTENT ABDUCTION OF THE SMALL finger was first described by Wartenberg in 1930.1 The abducted position of the extended small finger can be troublesome when the finger becomes caught while trying to insert the hand into a pocket or coat sleeve or during any movement that requires adducted and extended fingers.2,3 This condition can recover spontaneously after ulnar nerve
From the Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Korea. Received for publication August 31, 2007; accepted in revised form December 31, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Hyun Sik Gong, MD, PhD, Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-707, Korea; e-mail: [email protected]. 0363-5023/08/33A03-0016$34.00/0 doi:10.1016/j.jhsa.2007.12.019
392 䉬 © ASSH 䉬 Published by Elsevier, Inc.
recovery and motor reinnervation in patients with ulnar nerve palsy. However, when motor recovery of the ulnar nerve is incomplete or when persisting small finger abduction is the result of musculotendinous deficit, such as rupture or scarring of the third palmar interosseous muscle,4,5 correction of the deformity may be indicated. Several authors have suggested methods for surgical correction of the abducted small finger. Often, the procedures use the extensor digiti minimi (EDM) in part or total.2,6 – 8 Although the results reported by the authors of these techniques have been satisfactory, there have been concerns about loss of active extension of the small finger after using the EDM, because of the anatomic variations of the extensor system.3,9 –11 Gonzalez et al11 recommended caution in reconstructive planning when using the EDM, as their anatomic study demonstrated the absence of both the fifth extensor digitorum communis and juncturae in 6% of hands, making transfer of the EDM impossible. Instead of using the EDM, Dos Remedios et al10 suggested a tenodesis technique, and Voche and Merle3 suggested using a slip of the extensor digitorum communis from the ring finger. For independent adduction of the small finger, Hoch12 described extensor indicis proprius (EIP) transfer in 1993,
EIP TRANSFER FOR ABDUCTED SMALL FINGER
without details of the clinical results. We report the results of EIP transfer in selected patients with neurologic or musculotendinous etiology for a persisting flexible abducted small finger. Our hypothesis was that EIP transfer, with a larger excursion and mechanically advantageous direction of pull, will correct this deformity without appreciable loss of active abduction and extension of the small finger. MATERIALS AND METHODS Between May 2004 and July 2006, we performed EIP transfer in 8 patients with persistent abduction of the small finger (Table 1). There were 7 male and 1 female patients, and the mean age at operation was 28 years (range, 14 – 47 y). The causes of the abducted small finger were ulnar neuropathies in 6 patients, third palmar interosseous muscle rupture occurring 2 months prior to surgery in 1 patient (Fig. 1), and fibrosis of the third palmar interosseous muscle and other intrinsic muscles as the result of a remote compression injury in 1 patient. The ulnar neuropathies included 3 high and 3 low ulnar nerve injuries, with persisting ulnar motor deficit despite surgical interventions. Prior surgical procedures included 1 patient having neurorrhaphy in the distal forearm, 2 patients having ulnar nerve decompressions in Guyon’s canal, and 3 patients requiring ulnar decompressions at the elbow. All patients with ulnar neuropathies had functional thumb adduction and index abduction, without marked clawing of the fingers, except 4 patients who had mild flexible clawing of the small finger. The indication of the surgery included persistent, flexible abduction of the small finger causing daily functional loss in patients with an injury of the third palmar interosseous muscle or an ulnar nerve palsy. In cases of ulnar nerve palsy, the EIP transfer was performed when recovery of the third palmar interosseous muscle was incomplete after at least 3 years of observation after a nerve surgery. The EIP transfer was done for a patient with functional thumb adduction and index abduction. Surgical Technique A small transverse incision was made over the index metacarpal head, the EIP was detached, and its distal stump was sutured to the index extensor digitorum communis (EDC) tendon in order to prevent a radial subluxation of the EDC. In his original description, Hoch12 detached the EIP from distal to the extensor tendon hood to maximize the length of the tendon transfer and transposed it to the small finger palmar to the EDC tendons of the long and ring fingers. Instead, we detached the EIP from proximal to the metacarpal head to minimize the risk of subluxation of the index EDC and pulled the EIP proximally through a separate small transverse incision just distal to the wrist crease. The tendinous portion of the EIP was elongated by using a technique similar to Baek et al.13 The tendon was split longitudinally into 2 parts except for the most distal 1 cm, where a stay suture was placed to prevent splitting. One of the 2 parts was cut at the musculotendinous junction and turned distally to double the length of the transferred
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tendon. The junction of the split tendon limb was reinforced with multiple sutures (Fig. 2). A longitudinal incision was made along the dorsoradial side of the small finger. The elongated EIP tendon was passed dorsal to the EDC tendons of the middle and ring fingers and then passed palmar to the superficial transverse metacarpal ligament and dorsal to the deep transverse metacarpal ligament. The tendon was attached to the normal tendinous insertion of the third palmar interosseous muscle, or to the distal and radial part of the extensor hood when the muscle has ruptured, rather than the bony insertion that Hoch12 used in his original description (Fig. 3). This distal insertion increases the adduction moment arm, as the distance between the tendon insertion and the joint increases. The tendon was sutured under slight tension with the wrist, metacarpophalangeal and proximal interphalangeal joints in full flexion. A short-arm splint was applied with the wrist in 30° of extension and all metacarpophalangeal joints in 70° of flexion. After 2 weeks of immobilization, active abduction and adduction exercise was allowed for the small finger. Outcome Assessment We measured preoperative and postoperative abduction and adduction angles between the fourth and fifth fingers in their maximal active abduction and adduction state with the wrist in neutral extension and analyzed them using the Wilcoxon signed rank test (SPSS version 12.0; SPSS Inc., Chicago, IL). The outcome in terms of maintaining active abduction and full flexion and extension of the small finger was assessed according to the criteria we modified after that of Voche and Merle3 (Table 2). We observed any changes of the extension lag at the proximal interphalangeal joint in case of combined clawing deformity. Patients were asked their opinion regarding use of the index finger in daily activities and if they would choose to have the same operation again. RESULTS The patients were reviewed at the mean follow-up of 23 months (range, 12–36 months). All patients obtained active adduction of the small finger without any loss of flexion and extension (Table 1). The mean adduction angle improved from 19° to 1° postoperatively (p ⬍ .05). In 4 patients with concomitant clawing of the small finger, the deformity improved after surgery, as identified by the decrease of the extension lag at the proximal interphalangeal joint. The outcome using the scale we modified after that of Voche and Merle3 was excellent in 6 patients, good in 1 patient, and fair in 1 patient. One patient with a good rating had 5° of loss of active abduction, and 1 patient with a fair rating had 5° of inadequate adduction. There were no wound complications or tendon ruptures. One patient complained of bulkiness of the junction of the split tendon limb under the thin dorsal hand skin, which the patient described became less prominent with time. We did not note any adverse changes to digital function or range of motion for the middle and ring fingers that are crossed by the EIP.
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TABLE 1: Summary of Patients Adduction† (°)
Abduction* (°)
PIP Joint Extension Lag (°)
Side
Cause
Preoperative
Postoperative
Preoperative
Postoperative
Preoperative
Postoperative
FollowUp (mo)
Outcome‡
1
M
15
L
30
30
15
0
20
0
36
Excellent
2
F
14
R
25
25
15
0
0
0
30
Excellent
3
M
22
R
25
25
20
0
0
0
28
Excellent
4
M
37
R
35
30
25
0
25
10
24
Good
5
M
47
L
35
35
20
5
15
5
22
Fair
6
M
24
R
30
30
15
0
20
5
18
Excellent
7
M
28
L
35
30
20
0
0
0
16
Excellent
8
M
33
R
Third PI muscle fibrosis Low ulnar nerve palsy Low ulnar nerve palsy High ulnar nerve palsy High ulnar nerve palsy Low ulnar nerve palsy Third PI muscle rupture High ulnar nerve palsy
30
30
20
0
0
0
12
Excellent
31
30
19
1
Case
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Mean
28
PIP, proximal interphalangeal; PI, palmar interosseous. *Abduction was defined as the angle between the fourth and fifth finger with maximal active abduction of all fingers in extension. †Adduction was defined as the angle between the fourth and fifth finger with maximal active adduction of all fingers in extension. ‡Outcome was assessed by using the scale in Table 2.
23
EIP TRANSFER FOR ABDUCTED SMALL FINGER
Gender
Age (y)
EIP TRANSFER FOR ABDUCTED SMALL FINGER
FIGURE 1: Intraoperative photograph of a patient (case 7) with subacute third palmar interosseous muscle rupture (arrow) of the left hand.
FIGURE 2: The EIP tendon was split longitudinally into 2 parts except for the most distal 1 cm, where a stay suture was placed to prevent splitting. One of the 2 parts was cut at the musculotendinous junction and turned distally to double the length of the transferred tendon. The junction of the split tendon limb was reinforced with multiple sutures. The vector of its pull (arrow) is almost parallel to the third palmar interosseous muscle (vessel loop).
All patients showed independent extension of the index metacarpophalangeal joint without any extension lag or tendon subluxation but reported subjective weakness of the extension strength. However, no patient reported any discomfort with use of the index finger in his or her activities of daily living. All patients said they would choose to have the operation again for treatment of their condition. DISCUSSION Wartenberg ascribed the abducted small finger to the imbalance between the functioning extrinsic extensor and the weak intrinsic muscles.14 Blacker et al2 showed in 12 cadaver dissections a discrete attachment of the EDM tendon to the abductor tubercle on the ulnar side of the proximal phalanx. They postulated that the pull of this
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FIGURE 3: The tendon was passed palmar to the superficial transverse metacarpal ligament and dorsal to the deep transverse metacarpal ligament and attached to the normal tendinous insertion of the third palmar interosseous muscle. Sufficient tendon length provided improved the security of the tendon repair by increasing the available length for side-to-side sutures, and distal insertion increased the adduction moment arm.
ulnarly inserted tendon, as well as the axis of the extensor tendons oblique to the axis of fingers, causes abduction of the small finger, unopposed by paralyzed third palmar interosseous muscle. Voche and Merle3 suggested that delayed reinnervation of the third palmar interosseous muscle in comparison with the more proximally innervated abductor digiti minimi muscle can result in the persistence or exacerbation of Wartenberg’s sign after good nerve regeneration. Causes other than neurogenic origin have been reported, such as traumatic palmar interosseous muscle rupture,4 closed ligament injury, and necrosis and contracture of hypothenar muscles after compression injury.5 Therefore, the primary goal in correcting the deformity is to restore the function of the third palmar interosseous muscle. Several authors have suggested methods for surgical correction of the abducted small finger. Goldner6 suggested transfer of the EDM to the dorsal side of the proximal phalanx of the small finger after rerouting it around the tendon of the extensor carpi radialis longus as a pulley. Bellan et al8 rerouted the EDM through the extensor retinaculum. Blacker et al2 reported a transfer of the EDM through the intermetacarpal space into the flexor sheath slip when the abduction deformity was associated with clawing and insertion of the EDM to the radial collateral ligament of the metacarpophalangeal joint when there was no clawing. They obtained satisfactory results in 7 of 8 patients, but in 1 patient, a flexion deformity resulted from too much tension on the insertion of the transfer. Dellon7 modified this technique and inserted the EDM to the extensor hood at the metacarpophalangeal level and reported that all of his 10 patients could fully extend the small finger without abduction deformity. However, it was not mentioned how much active abduction was preserved.
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EIP TRANSFER FOR ABDUCTED SMALL FINGER
TABLE 2: Outcome Measurement After Correction of Abducted Little Finger Excellent Good Fair Poor
Full active adduction and abduction, full flexion and extension. Full active adduction, with less than 10° loss of abduction or flexion/extension. Incomplete active adduction, with less than 10° loss of abduction or flexion/extension. Persistent abduction of more than 20°, or more than 10° loss of abduction or flexion/extension.
Although the results of EDM transfer have been satisfactory, there are some concerns in using the EDM, because of the anatomic variability of the extensor system.3,9 –11 The most common distribution pattern of finger extensors is a single EIP; a single EDC to the index finger; a single EDC to the middle finger; a double EDC to the ring finger; an absent EDC to the small finger (50% to 60%); and a double EDM to the small finger.15–17 The difference in the results by various authors with respect to the absence of EDC to the small finger was because many of them regarded the tendinous expansion (juncturae tendinum) arising from the distal part of the tendon of the ring finger as an EDC to the small finger.17 Although a double EDM was the most common pattern, the incidence of a single EDM to the small finger was 15% in a total of 1,022 hands from 6 studies.17 Thus, the chance of a single EDM with an absent EDC to the small finger can be assumed to be 7% to 9% (50% to 60% ⫻ 15%). If EDM is used in this situation, the sole extensor for the small finger will be the tendinous expansion (juncturae tendinum) from the ring finger. If preoperative small finger abduction was done by the sole extrinsic EDM with paralysis of abductor digiti minimi, active abduction may be lost after using the EDM, as the vector of this tendinous expansion is adduction and extension. Furthermore, in a study by Gonzalez et al,11 6% of hands had both an absent small finger EDC and juncturae, making transfer of the EDM and maintaining small finger extension very difficult. In order to avoid possible loss of active extension or abduction, Dos Remedios et al10 suggested a tenodesis technique using a tendon graft. The tenodesis has a more favorable orientation to increase the adduction force without use of a tendon transfer. However, it has the risk of limiting abduction of the small finger when the tension is too tight. As any tenodesis reconstruction can stretch out over time, the loss of adduction power may result in the recurrence of dysfunction or deformity. Voche and Merle3 used a slip of the EDC of the ring finger in 6 patients. They obtained 3 excellent, 2 good, and 1 average result, and all patients were able to abduct the small finger actively through the action of the EDM. However, because the slip of the ring finger is not an independent muscle, adduction of the small finger can occur only when the ring finger is fully extended. In this study, EIP transfer produced consistently reliable results for persistent abduction deformity of the small finger, with no extension loss in all patients and loss of 5° of active abduction in 1 patient. Our modification of extending the tendon length improved the security of the tendon repair by
increasing the available length for side-to-side sutures. The distal and radial insertion to the extensor hood demonstrated some additional benefits in reducing the clawing and did not result in the swan-neck deformity that Dellon7 has proposed may occur with a more distal insertion of the transferred tendon. Detachment of the EIP proximal to the extensor hood, as was recommended by Noorda et al,18 resulted in no extension lag of the index finger. The advantage of this procedure is that the EIP will independently function as an adductor. The vector of its pull is straight from the origin and more anatomic in view of the function of the third palmar interosseous muscle and increases the moment arm (distance from the joint), which the non-rerouted EDM transfer cannot do. Additionally, the EIP has a relatively large amplitude of excursion of 5.5 cm,19 allowing a greater margin of error when setting the transfer’s tension; thus limitation of motion toward abduction or flexion is unlikely to occur. However, any surgeon who favors EDM transfer and wants to save the EIP may look at the EDM first and then proceed to take the EIP on encountering the anatomic variations. The disadvantage of this procedure is the sacrifice of the EIP muscle-tendon unit and the potential for index finger dysfunction. Previous literature indicates that index finger extension strength is reduced to half or two thirds of the normal finger after the EIP transfer.18,20,21 Although generally no functional deficits are noted after EIP transfer, preservation of the EIP may be preferable in some patients who require a strong extension of the index finger in their profession.22 There is also an 0.5% possibility that EIP may be absent, which would make its use impossible.17 Also, rare variations of the EIP anatomy, such as radial insertion of the EIP,23 supernumerary muscles or tendons, and intertendinous connections,24 would require careful dissection of the tendon. Our study limitation included a small study population and a lack of objective strength measurement of the small finger adduction, no validated functional outcome assessments, and no comparative groups. Despite these limitations, this study supports use of EIP transfer in selected patients with persistent, flexible abduction deformity of the small finger as a reliable procedure for restoring digital adduction without substantial risk of loss of extension or abduction. REFERENCES 1.Wartenberg R. Kleine hiffsmittel der neurologichen Diagnostik. Nervenarzt 1930;3:594 –597.
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2.Blacker GJ, Lister GD, Kleinert HE. The abducted little finger in low ulnar nerve palsy. J Hand Surg 1976;1A:190 – 196. 3.Voche P, Merle M. Wartenberg’s sign. A new method of surgical correction. J Hand Surg 1995;20B:49 –52. 4.Freeland AE, Barrett GR, Wheeless GS. Correction of abduction. Deformity of the small finger caused by avulsion of the insertion of the third volar interosseous muscle. Am J Sports Med 1985;13:273–276. 5.Kilgus M, Burg D, Loss M, Weishaupt D, Meyer VE. Wartenberg’s sign of ulnar nerve lesion. A contribution to pathophysiology and to the differential diagnosis. Handchir Mikrochir Plast Chir 2003;35:251–258. 6.Goldner JL. Tendon transfers for irreparable peripheral nerve injuries of the upper extremity. Orthop Clin North Am 1974;5:343–375. 7.Dellon AL. Extensor digiti minimi tendon transfer to correct abducted small finger in ulnar dysfunction. J Hand Surg 1991;16A:819 – 823. 8.Bellan N, Belkhiria F, Touam C, Asfazadourian H, Oberlin C. Extensor digiti minimi tendon “rerouting” transfer in permanent abduction of the little finger. Chir Main 1998;17: 325–333. 9.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. 10.Dos Remedios C, Chantelot C, Prud’homme M, Genestet M, Le Nen D, Fontaine C. Surgical correction of fifth finger permanent abduction by tenodesis. Preliminary cadaver study. Chir Main 2003;22:166 –171. 11.Gonzalez MH, Gray T, Ortinau E, Weinzweig N. The extensor tendons to the little finger: an anatomic study. J Hand Surg 1995;20A:844 – 847. 12.Hoch J. Correction of post-traumatic adduction insufficiency of the small finger by transposition of the tendon of the extensor indicis muscle. Handchir Mikrochir Plast Chir 1993;25:179 –183.
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13.Baek GH, Jung JM, Yoo WJ, Chung MS. Transfer of extensor carpi radialis longus or brevis for opponensplasy. J Hand Surg 1999;24B:50 –53. 14.Wartenberg R. A sign of ulnar palsy. JAMA 1939;112:1688. 15.von Schroeder HP, Botte MJ. Anatomy of the extensor tendons of the fingers: variations and multiplicity. J Hand Surg 1995;20A:27–34. 16.Doyle JR. Hand. In: Doyle JR, Botte MJ, eds. Surgical anatomy of the hand and upper extremity. Philadelphia: Lippincott Williams & Wilkins, 2003:642– 666. 17.Zilber S, Oberlin C. Anatomical variations of the extensor tendons to the fingers over the dorsum of the hand: a study of 50 hands and a review of the literature. Plast Reconstr Surg 2004;113:214 –221. 18.Noorda RJ, Hage JJ, de Groot PJ, Bloem JJ. Index finger extension and strength after extensor indicis proprius transfer. J Hand Surg 1994;19A:844 – 849. 19.Brand PW. Tendon transfers for median and ulnar nerve paralysis. Orthop Clin North Am 1970;1:447– 454. 20.Magnussen PA, Harvey FJ, Tonkin MA. Extensor indicis proprius transfer for rupture of the extensor pollicis longus tendon. J Bone Joint Surg 1990;72B:881– 883. 21.Lemmen MH, Schreuders TA, Stam HJ, Hovius SE. Evaluation of restoration of extensor pollicis function by transfer of the extensor indicis. J Hand Surg 1999;24B:46 – 49. 22.Saur MA, Van Schoonhoven J, Kall S, Lanz U. Reconstruction of the ruptured extensor pollicis longus tendon using a tendon interposition graft. Handchir Mikrochir Plast Chir 2003;35:377–382. 23.Yamaguchi S, Viegas SF. Extensor indicis proprius tendon: case report of a rare anatomic variation. Clin Anat 2000;13: 63– 65. 24.Komiyama M, Nwe TM, Toyota N, Shimada Y. Variations of the extensor indicis muscle and tendons. J Hand Surg 1999;24B:575–578.
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Extensor Indicis Proprius Transfer for the Abducted Small Finger Moon Sang Chung, MD, PhD, Goo Hyun Baek, MD, PhD, Joo Han Oh, MD, PhD, Young Ho Lee, MD, PhD, Hoyune Esther Cho, Hyun Sik Gong, MD, PhD Purpose Persistent abduction of the small finger has usually been treated by transfer of the extensor digiti minimi muscle. However, anatomic variations of the extensor system may limit the potential for a successful extensor digiti minimi transfer. Therefore, we evaluated the outcomes of an alternative reconstruction method for the abducted small finger using an extensor indicis proprius (EIP) transfer. Methods We performed 8 EIP transfers in 8 patients with persistent, flexible abduction posturing of the small finger. The primary etiology of the deformity was incomplete motor reinnervation after surgeries for ulnar neuropathy in 6 patients, rupture of the third palmar interosseous musculotendinous unit in 1 patient, and intrinsic muscle fibrosis in 1 patient. The EIP was elongated by splitting the tendinous portion and was transferred to the distal and radial part of the extensor hood. Surgical outcomes were assessed by comparing preoperative and postoperative active adduction and abduction motion of the 2 ulnar digits. Results At the mean follow-up of 23 months, the average adduction angle improved from 19° to 1° postoperatively. In terms of active finger motion, 6 patients showed excellent results, 1 good, and 1 fair, without loss of flexion and extension. No patient had an extension lag or complained of functional deficits of the donor index finger. There was not adverse change to digital function or range of motion for the middle and ring fingers that are crossed by the EIP. Conclusions Extensor indicis proprius transfer can be a reliable option for correction of abduction deformity of the small finger, maintaining active abduction and full flexion and extension. (J Hand Surg 2008;33A:392–397. Copyright © 2008 by the American Society for Surgery of the Hand.) Type of study/level of evidence Therapeutic IV. Key words Abducted small finger, ulnar neuropathy, extensor indicis proprius transfer.
P
ERSISTENT ABDUCTION OF THE SMALL finger was first described by Wartenberg in 1930.1 The abducted position of the extended small finger can be troublesome when the finger becomes caught while trying to insert the hand into a pocket or coat sleeve or during any movement that requires adducted and extended fingers.2,3 This condition can recover spontaneously after ulnar nerve
From the Department of Orthopedic Surgery, Seoul National University College of Medicine, Seoul, Korea. Received for publication August 31, 2007; accepted in revised form December 31, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Hyun Sik Gong, MD, PhD, Department of Orthopedic Surgery, Seoul National University Bundang Hospital, Seoul National University College of Medicine, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-707, Korea; e-mail: [email protected]. 0363-5023/08/33A03-0016$34.00/0 doi:10.1016/j.jhsa.2007.12.019
392 䉬 © ASSH 䉬 Published by Elsevier, Inc.
recovery and motor reinnervation in patients with ulnar nerve palsy. However, when motor recovery of the ulnar nerve is incomplete or when persisting small finger abduction is the result of musculotendinous deficit, such as rupture or scarring of the third palmar interosseous muscle,4,5 correction of the deformity may be indicated. Several authors have suggested methods for surgical correction of the abducted small finger. Often, the procedures use the extensor digiti minimi (EDM) in part or total.2,6 – 8 Although the results reported by the authors of these techniques have been satisfactory, there have been concerns about loss of active extension of the small finger after using the EDM, because of the anatomic variations of the extensor system.3,9 –11 Gonzalez et al11 recommended caution in reconstructive planning when using the EDM, as their anatomic study demonstrated the absence of both the fifth extensor digitorum communis and juncturae in 6% of hands, making transfer of the EDM impossible. Instead of using the EDM, Dos Remedios et al10 suggested a tenodesis technique, and Voche and Merle3 suggested using a slip of the extensor digitorum communis from the ring finger. For independent adduction of the small finger, Hoch12 described extensor indicis proprius (EIP) transfer in 1993,
EIP TRANSFER FOR ABDUCTED SMALL FINGER
without details of the clinical results. We report the results of EIP transfer in selected patients with neurologic or musculotendinous etiology for a persisting flexible abducted small finger. Our hypothesis was that EIP transfer, with a larger excursion and mechanically advantageous direction of pull, will correct this deformity without appreciable loss of active abduction and extension of the small finger. MATERIALS AND METHODS Between May 2004 and July 2006, we performed EIP transfer in 8 patients with persistent abduction of the small finger (Table 1). There were 7 male and 1 female patients, and the mean age at operation was 28 years (range, 14 – 47 y). The causes of the abducted small finger were ulnar neuropathies in 6 patients, third palmar interosseous muscle rupture occurring 2 months prior to surgery in 1 patient (Fig. 1), and fibrosis of the third palmar interosseous muscle and other intrinsic muscles as the result of a remote compression injury in 1 patient. The ulnar neuropathies included 3 high and 3 low ulnar nerve injuries, with persisting ulnar motor deficit despite surgical interventions. Prior surgical procedures included 1 patient having neurorrhaphy in the distal forearm, 2 patients having ulnar nerve decompressions in Guyon’s canal, and 3 patients requiring ulnar decompressions at the elbow. All patients with ulnar neuropathies had functional thumb adduction and index abduction, without marked clawing of the fingers, except 4 patients who had mild flexible clawing of the small finger. The indication of the surgery included persistent, flexible abduction of the small finger causing daily functional loss in patients with an injury of the third palmar interosseous muscle or an ulnar nerve palsy. In cases of ulnar nerve palsy, the EIP transfer was performed when recovery of the third palmar interosseous muscle was incomplete after at least 3 years of observation after a nerve surgery. The EIP transfer was done for a patient with functional thumb adduction and index abduction. Surgical Technique A small transverse incision was made over the index metacarpal head, the EIP was detached, and its distal stump was sutured to the index extensor digitorum communis (EDC) tendon in order to prevent a radial subluxation of the EDC. In his original description, Hoch12 detached the EIP from distal to the extensor tendon hood to maximize the length of the tendon transfer and transposed it to the small finger palmar to the EDC tendons of the long and ring fingers. Instead, we detached the EIP from proximal to the metacarpal head to minimize the risk of subluxation of the index EDC and pulled the EIP proximally through a separate small transverse incision just distal to the wrist crease. The tendinous portion of the EIP was elongated by using a technique similar to Baek et al.13 The tendon was split longitudinally into 2 parts except for the most distal 1 cm, where a stay suture was placed to prevent splitting. One of the 2 parts was cut at the musculotendinous junction and turned distally to double the length of the transferred
393
tendon. The junction of the split tendon limb was reinforced with multiple sutures (Fig. 2). A longitudinal incision was made along the dorsoradial side of the small finger. The elongated EIP tendon was passed dorsal to the EDC tendons of the middle and ring fingers and then passed palmar to the superficial transverse metacarpal ligament and dorsal to the deep transverse metacarpal ligament. The tendon was attached to the normal tendinous insertion of the third palmar interosseous muscle, or to the distal and radial part of the extensor hood when the muscle has ruptured, rather than the bony insertion that Hoch12 used in his original description (Fig. 3). This distal insertion increases the adduction moment arm, as the distance between the tendon insertion and the joint increases. The tendon was sutured under slight tension with the wrist, metacarpophalangeal and proximal interphalangeal joints in full flexion. A short-arm splint was applied with the wrist in 30° of extension and all metacarpophalangeal joints in 70° of flexion. After 2 weeks of immobilization, active abduction and adduction exercise was allowed for the small finger. Outcome Assessment We measured preoperative and postoperative abduction and adduction angles between the fourth and fifth fingers in their maximal active abduction and adduction state with the wrist in neutral extension and analyzed them using the Wilcoxon signed rank test (SPSS version 12.0; SPSS Inc., Chicago, IL). The outcome in terms of maintaining active abduction and full flexion and extension of the small finger was assessed according to the criteria we modified after that of Voche and Merle3 (Table 2). We observed any changes of the extension lag at the proximal interphalangeal joint in case of combined clawing deformity. Patients were asked their opinion regarding use of the index finger in daily activities and if they would choose to have the same operation again. RESULTS The patients were reviewed at the mean follow-up of 23 months (range, 12–36 months). All patients obtained active adduction of the small finger without any loss of flexion and extension (Table 1). The mean adduction angle improved from 19° to 1° postoperatively (p ⬍ .05). In 4 patients with concomitant clawing of the small finger, the deformity improved after surgery, as identified by the decrease of the extension lag at the proximal interphalangeal joint. The outcome using the scale we modified after that of Voche and Merle3 was excellent in 6 patients, good in 1 patient, and fair in 1 patient. One patient with a good rating had 5° of loss of active abduction, and 1 patient with a fair rating had 5° of inadequate adduction. There were no wound complications or tendon ruptures. One patient complained of bulkiness of the junction of the split tendon limb under the thin dorsal hand skin, which the patient described became less prominent with time. We did not note any adverse changes to digital function or range of motion for the middle and ring fingers that are crossed by the EIP.
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TABLE 1: Summary of Patients Adduction† (°)
Abduction* (°)
PIP Joint Extension Lag (°)
Side
Cause
Preoperative
Postoperative
Preoperative
Postoperative
Preoperative
Postoperative
FollowUp (mo)
Outcome‡
1
M
15
L
30
30
15
0
20
0
36
Excellent
2
F
14
R
25
25
15
0
0
0
30
Excellent
3
M
22
R
25
25
20
0
0
0
28
Excellent
4
M
37
R
35
30
25
0
25
10
24
Good
5
M
47
L
35
35
20
5
15
5
22
Fair
6
M
24
R
30
30
15
0
20
5
18
Excellent
7
M
28
L
35
30
20
0
0
0
16
Excellent
8
M
33
R
Third PI muscle fibrosis Low ulnar nerve palsy Low ulnar nerve palsy High ulnar nerve palsy High ulnar nerve palsy Low ulnar nerve palsy Third PI muscle rupture High ulnar nerve palsy
30
30
20
0
0
0
12
Excellent
31
30
19
1
Case
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28
PIP, proximal interphalangeal; PI, palmar interosseous. *Abduction was defined as the angle between the fourth and fifth finger with maximal active abduction of all fingers in extension. †Adduction was defined as the angle between the fourth and fifth finger with maximal active adduction of all fingers in extension. ‡Outcome was assessed by using the scale in Table 2.
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EIP TRANSFER FOR ABDUCTED SMALL FINGER
Gender
Age (y)
EIP TRANSFER FOR ABDUCTED SMALL FINGER
FIGURE 1: Intraoperative photograph of a patient (case 7) with subacute third palmar interosseous muscle rupture (arrow) of the left hand.
FIGURE 2: The EIP tendon was split longitudinally into 2 parts except for the most distal 1 cm, where a stay suture was placed to prevent splitting. One of the 2 parts was cut at the musculotendinous junction and turned distally to double the length of the transferred tendon. The junction of the split tendon limb was reinforced with multiple sutures. The vector of its pull (arrow) is almost parallel to the third palmar interosseous muscle (vessel loop).
All patients showed independent extension of the index metacarpophalangeal joint without any extension lag or tendon subluxation but reported subjective weakness of the extension strength. However, no patient reported any discomfort with use of the index finger in his or her activities of daily living. All patients said they would choose to have the operation again for treatment of their condition. DISCUSSION Wartenberg ascribed the abducted small finger to the imbalance between the functioning extrinsic extensor and the weak intrinsic muscles.14 Blacker et al2 showed in 12 cadaver dissections a discrete attachment of the EDM tendon to the abductor tubercle on the ulnar side of the proximal phalanx. They postulated that the pull of this
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FIGURE 3: The tendon was passed palmar to the superficial transverse metacarpal ligament and dorsal to the deep transverse metacarpal ligament and attached to the normal tendinous insertion of the third palmar interosseous muscle. Sufficient tendon length provided improved the security of the tendon repair by increasing the available length for side-to-side sutures, and distal insertion increased the adduction moment arm.
ulnarly inserted tendon, as well as the axis of the extensor tendons oblique to the axis of fingers, causes abduction of the small finger, unopposed by paralyzed third palmar interosseous muscle. Voche and Merle3 suggested that delayed reinnervation of the third palmar interosseous muscle in comparison with the more proximally innervated abductor digiti minimi muscle can result in the persistence or exacerbation of Wartenberg’s sign after good nerve regeneration. Causes other than neurogenic origin have been reported, such as traumatic palmar interosseous muscle rupture,4 closed ligament injury, and necrosis and contracture of hypothenar muscles after compression injury.5 Therefore, the primary goal in correcting the deformity is to restore the function of the third palmar interosseous muscle. Several authors have suggested methods for surgical correction of the abducted small finger. Goldner6 suggested transfer of the EDM to the dorsal side of the proximal phalanx of the small finger after rerouting it around the tendon of the extensor carpi radialis longus as a pulley. Bellan et al8 rerouted the EDM through the extensor retinaculum. Blacker et al2 reported a transfer of the EDM through the intermetacarpal space into the flexor sheath slip when the abduction deformity was associated with clawing and insertion of the EDM to the radial collateral ligament of the metacarpophalangeal joint when there was no clawing. They obtained satisfactory results in 7 of 8 patients, but in 1 patient, a flexion deformity resulted from too much tension on the insertion of the transfer. Dellon7 modified this technique and inserted the EDM to the extensor hood at the metacarpophalangeal level and reported that all of his 10 patients could fully extend the small finger without abduction deformity. However, it was not mentioned how much active abduction was preserved.
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EIP TRANSFER FOR ABDUCTED SMALL FINGER
TABLE 2: Outcome Measurement After Correction of Abducted Little Finger Excellent Good Fair Poor
Full active adduction and abduction, full flexion and extension. Full active adduction, with less than 10° loss of abduction or flexion/extension. Incomplete active adduction, with less than 10° loss of abduction or flexion/extension. Persistent abduction of more than 20°, or more than 10° loss of abduction or flexion/extension.
Although the results of EDM transfer have been satisfactory, there are some concerns in using the EDM, because of the anatomic variability of the extensor system.3,9 –11 The most common distribution pattern of finger extensors is a single EIP; a single EDC to the index finger; a single EDC to the middle finger; a double EDC to the ring finger; an absent EDC to the small finger (50% to 60%); and a double EDM to the small finger.15–17 The difference in the results by various authors with respect to the absence of EDC to the small finger was because many of them regarded the tendinous expansion (juncturae tendinum) arising from the distal part of the tendon of the ring finger as an EDC to the small finger.17 Although a double EDM was the most common pattern, the incidence of a single EDM to the small finger was 15% in a total of 1,022 hands from 6 studies.17 Thus, the chance of a single EDM with an absent EDC to the small finger can be assumed to be 7% to 9% (50% to 60% ⫻ 15%). If EDM is used in this situation, the sole extensor for the small finger will be the tendinous expansion (juncturae tendinum) from the ring finger. If preoperative small finger abduction was done by the sole extrinsic EDM with paralysis of abductor digiti minimi, active abduction may be lost after using the EDM, as the vector of this tendinous expansion is adduction and extension. Furthermore, in a study by Gonzalez et al,11 6% of hands had both an absent small finger EDC and juncturae, making transfer of the EDM and maintaining small finger extension very difficult. In order to avoid possible loss of active extension or abduction, Dos Remedios et al10 suggested a tenodesis technique using a tendon graft. The tenodesis has a more favorable orientation to increase the adduction force without use of a tendon transfer. However, it has the risk of limiting abduction of the small finger when the tension is too tight. As any tenodesis reconstruction can stretch out over time, the loss of adduction power may result in the recurrence of dysfunction or deformity. Voche and Merle3 used a slip of the EDC of the ring finger in 6 patients. They obtained 3 excellent, 2 good, and 1 average result, and all patients were able to abduct the small finger actively through the action of the EDM. However, because the slip of the ring finger is not an independent muscle, adduction of the small finger can occur only when the ring finger is fully extended. In this study, EIP transfer produced consistently reliable results for persistent abduction deformity of the small finger, with no extension loss in all patients and loss of 5° of active abduction in 1 patient. Our modification of extending the tendon length improved the security of the tendon repair by
increasing the available length for side-to-side sutures. The distal and radial insertion to the extensor hood demonstrated some additional benefits in reducing the clawing and did not result in the swan-neck deformity that Dellon7 has proposed may occur with a more distal insertion of the transferred tendon. Detachment of the EIP proximal to the extensor hood, as was recommended by Noorda et al,18 resulted in no extension lag of the index finger. The advantage of this procedure is that the EIP will independently function as an adductor. The vector of its pull is straight from the origin and more anatomic in view of the function of the third palmar interosseous muscle and increases the moment arm (distance from the joint), which the non-rerouted EDM transfer cannot do. Additionally, the EIP has a relatively large amplitude of excursion of 5.5 cm,19 allowing a greater margin of error when setting the transfer’s tension; thus limitation of motion toward abduction or flexion is unlikely to occur. However, any surgeon who favors EDM transfer and wants to save the EIP may look at the EDM first and then proceed to take the EIP on encountering the anatomic variations. The disadvantage of this procedure is the sacrifice of the EIP muscle-tendon unit and the potential for index finger dysfunction. Previous literature indicates that index finger extension strength is reduced to half or two thirds of the normal finger after the EIP transfer.18,20,21 Although generally no functional deficits are noted after EIP transfer, preservation of the EIP may be preferable in some patients who require a strong extension of the index finger in their profession.22 There is also an 0.5% possibility that EIP may be absent, which would make its use impossible.17 Also, rare variations of the EIP anatomy, such as radial insertion of the EIP,23 supernumerary muscles or tendons, and intertendinous connections,24 would require careful dissection of the tendon. Our study limitation included a small study population and a lack of objective strength measurement of the small finger adduction, no validated functional outcome assessments, and no comparative groups. Despite these limitations, this study supports use of EIP transfer in selected patients with persistent, flexible abduction deformity of the small finger as a reliable procedure for restoring digital adduction without substantial risk of loss of extension or abduction. REFERENCES 1.Wartenberg R. Kleine hiffsmittel der neurologichen Diagnostik. Nervenarzt 1930;3:594 –597.
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2.Blacker GJ, Lister GD, Kleinert HE. The abducted little finger in low ulnar nerve palsy. J Hand Surg 1976;1A:190 – 196. 3.Voche P, Merle M. Wartenberg’s sign. A new method of surgical correction. J Hand Surg 1995;20B:49 –52. 4.Freeland AE, Barrett GR, Wheeless GS. Correction of abduction. Deformity of the small finger caused by avulsion of the insertion of the third volar interosseous muscle. Am J Sports Med 1985;13:273–276. 5.Kilgus M, Burg D, Loss M, Weishaupt D, Meyer VE. Wartenberg’s sign of ulnar nerve lesion. A contribution to pathophysiology and to the differential diagnosis. Handchir Mikrochir Plast Chir 2003;35:251–258. 6.Goldner JL. Tendon transfers for irreparable peripheral nerve injuries of the upper extremity. Orthop Clin North Am 1974;5:343–375. 7.Dellon AL. Extensor digiti minimi tendon transfer to correct abducted small finger in ulnar dysfunction. J Hand Surg 1991;16A:819 – 823. 8.Bellan N, Belkhiria F, Touam C, Asfazadourian H, Oberlin C. Extensor digiti minimi tendon “rerouting” transfer in permanent abduction of the little finger. Chir Main 1998;17: 325–333. 9.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. 10.Dos Remedios C, Chantelot C, Prud’homme M, Genestet M, Le Nen D, Fontaine C. Surgical correction of fifth finger permanent abduction by tenodesis. Preliminary cadaver study. Chir Main 2003;22:166 –171. 11.Gonzalez MH, Gray T, Ortinau E, Weinzweig N. The extensor tendons to the little finger: an anatomic study. J Hand Surg 1995;20A:844 – 847. 12.Hoch J. Correction of post-traumatic adduction insufficiency of the small finger by transposition of the tendon of the extensor indicis muscle. Handchir Mikrochir Plast Chir 1993;25:179 –183.
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13.Baek GH, Jung JM, Yoo WJ, Chung MS. Transfer of extensor carpi radialis longus or brevis for opponensplasy. J Hand Surg 1999;24B:50 –53. 14.Wartenberg R. A sign of ulnar palsy. JAMA 1939;112:1688. 15.von Schroeder HP, Botte MJ. Anatomy of the extensor tendons of the fingers: variations and multiplicity. J Hand Surg 1995;20A:27–34. 16.Doyle JR. Hand. In: Doyle JR, Botte MJ, eds. Surgical anatomy of the hand and upper extremity. Philadelphia: Lippincott Williams & Wilkins, 2003:642– 666. 17.Zilber S, Oberlin C. Anatomical variations of the extensor tendons to the fingers over the dorsum of the hand: a study of 50 hands and a review of the literature. Plast Reconstr Surg 2004;113:214 –221. 18.Noorda RJ, Hage JJ, de Groot PJ, Bloem JJ. Index finger extension and strength after extensor indicis proprius transfer. J Hand Surg 1994;19A:844 – 849. 19.Brand PW. Tendon transfers for median and ulnar nerve paralysis. Orthop Clin North Am 1970;1:447– 454. 20.Magnussen PA, Harvey FJ, Tonkin MA. Extensor indicis proprius transfer for rupture of the extensor pollicis longus tendon. J Bone Joint Surg 1990;72B:881– 883. 21.Lemmen MH, Schreuders TA, Stam HJ, Hovius SE. Evaluation of restoration of extensor pollicis function by transfer of the extensor indicis. J Hand Surg 1999;24B:46 – 49. 22.Saur MA, Van Schoonhoven J, Kall S, Lanz U. Reconstruction of the ruptured extensor pollicis longus tendon using a tendon interposition graft. Handchir Mikrochir Plast Chir 2003;35:377–382. 23.Yamaguchi S, Viegas SF. Extensor indicis proprius tendon: case report of a rare anatomic variation. Clin Anat 2000;13: 63– 65. 24.Komiyama M, Nwe TM, Toyota N, Shimada Y. Variations of the extensor indicis muscle and tendons. J Hand Surg 1999;24B:575–578.
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