ORIGINAL ARTICLE

Sensate First Dorsal Metacarpal Artery Flap for ResurfacingExtensive Pulp Defects of the Thumb

Shun-Cheng Chang, MD, Shao-Liang Chen, MD, Tim-Mo Chen, MD, Chia-Jueng Chuang, MD,Tian-Yeu Cheng, MD, and Hsian-Jenn Wang, MD

Abstract: Finding an appropriate soft-tissue grafting material toclose a wound located over the distal phalanx of the thumb, espe-cially the pulp region, can be a difficult task. A sensate first dorsalmetacarpal artery flap, mobilized from the dorsum of the adjacentindex finger and used as an island pedicle skin flap, can be useful forthis purpose. The pedicle includes the ulnar branch of the first dorsalmetacarpal artery, the dorsal veins, and the cutaneous branch of theradial nerve. Although this tiny artery is anatomically variable, safedissection can be achieved by including the radial shaft periosteumof the secondary metacarpal bone and the ulnar head fascia of thefirst interosseous muscle.

This approach has been used for 8 individuals with extensivepulp defects of the thumb over the past 3 years. Skin defects in allpatients were combined with bone, joint, or tendon exposure. All flapssurvived completely. This 1-stage procedure is reliable and technicallysimple. It provides sensate coverage to the pulp of the thumb but alsoavoids nerve repair or more complicated microsurgery.

Key Words: first dorsal metacarpal artery flap, pulp defect ofthumb

(Ann Plast Surg 2004;53: 449–454)

Extensive pulp defects of the thumb, with the exposure oftendon or bone, are challenging reconstructive problems

because of the lack of locally available tissue. Surgicaltreatment includes the use of local, regional, and free flaps.

The use of local flaps, including transposition andadvancement flaps with random vascularity, is restricted

because of the limited range of flap mobility and the limitedamount of tissue movable from nearby areas.1 The use of askin flap mobilized from an adjacent finger, such as thecross-finger flap, requires a staged approach and has limita-tions, including a considerable period of immobilization, withthe risk of subsequent joint stiffness and a limited arc oftransposition.2

The heterodigital neurovascular island flap formedfrom the ulnar pulp of the middle finger or the radial pulp ofthe ring finger, based on the proper palmar digital artery andnerve, is another option. However, with this flap, 2 majordigital arteries are killed and extensive digital and palmardissection is needed.3 Microvascular transfer of a free flap,like free partial toe transfer, can be used to remedy theseproblems, but such a technique requires microsurgical expe-rience and prolonged operation.4

Since Foucher and Braun5 demonstrated that a sensateskin island flap created from the dorsum of the index fingercould be raised and based upon the first dorsal metacarpalartery and sensory branch of the radial nerve, similar flapshave been reported subsequently and have been shown to beappropriate for resurfacing the defects of the dorsal thumb orthe first web space.6–9 Reports seldom comment on its use forpulp loss from the thumb. Here we report 8 cases of extensivepulp loss extending to the tip of the thumb, which wereresurfaced with a sensate first dorsal metacarpal artery(FDMA) flap in a single stage procedure.

Vascular AnatomyThe FDMA is a constant vessel arising from the radial

artery just distal to the tendon of the extensor pollicis longusand proximal to the point at which the radial artery piercesbetween the radial and ulnar heads of the first dorsal in-terosseous muscle.10 The artery runs over the fascial layer ofthe first dorsal interosseous muscle and divides into the radialbranch to the thumb, the intermediate branch to the first webspace, and the ulnar branch to the index finger. The ulnarbranch usually courses distally within the musculo-osseousgroove, between the ulnar head of the first dorsal interosseousmuscle and the radial shaft of the second metacarpal bone,

Received February 9, 2004; accepted for publication March 15, 2004.From the Division of Plastic Surgery, Department of Surgery, Tri-Service

General Hospital, National Defense Medical Center, Taipei, Taiwan,R.O.C.

Presented at the Annual Meeting of the Taiwan Association of Surgery,Taipei, March 28, 2003.

Reprints: Shao-Liang Chen, Division of Plastic Surgery, Tri-Service GeneralHospital, 3F, No25, Alley 4, Lane 154, Yung-Chun Street, Taipei 100,Taiwan, R.O.C. E-mail: shaoliang1025@hotmail.com

Copyright © 2004 by Lippincott Williams & WilkinsISSN: 0148-7043/04/5305-0449DOI: 10.1097/01.sap.0000137134.15728.dd

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until it reaches the metacarpophalangeal (MP) joint. Here anutrient branch from the second palmar metacarpal arteryjoins the artery before it divides into a number of smallvessels, which supply a rich subdermal plexus over thedorsum of the proximal phalanx (Fig. 1A).11

PATIENTS AND METHODSThe FDMA flap was used to reconstruct the pulp defects

of the thumbs in 8 patients over 3 years. The patients included 6men and 2 women, ranging in age from 20 to 56 years. They allhad avulsion injury or painful scar needing reconstruction. Tis-sue grafting was contraindicated for all patients because of theexposure of tendons or bones at the wound site. The flap wasused in the acute stage for wound coverage in 7 patients, and 1was performed in the late reconstructive stage.

Operative TechniqueA skin marking, with its size determined by the defect

of the thumb, is made over the dorsum of the proximalphalanx of the adjacent index finger. The flap margins areoutlined proximally and distally to preserve the dorsal skin ofthe MP joint and the proximal interphalangeal (PIP) jointrespectively. The width of the flap is designed so that it doesnot to extend beyond the radial and ulnar midaxial lines of theproximal phalanx. The estimated pivotal point is then markedon the site of origin of the FDMA.

Operation is performed with the patient under general,axillary block, or regional anesthesia, with the aid of tourni-quet control and loupe magnification. The flap is raised fromthe distal to the proximal side and from the ulnar to the radialside. Care is taken to leave the paratenon undisturbed to

FIGURE 1. A, The first dorsal meta-carpal artery (FDMA) divides into theFDMAr to the thumb, the FDMAi tothe first web space, and the FDMAuto the index finger. The flap territoryis limited between the MP joint andthe proximal interphalangeal joint.The cutaneous branch of the radialnerve is included in the flap. Thedotted line means the radial shaftperiosteum of the secondary meta-carpal bone will be included in thepedicle. B, FDMAu usually courseswithin the musculo-osseous groove,between the ulnar head of the firstdorsal interosseous muscle and the ra-dial shaft of the secondary metacarpalbone. C, After raising the flap, theFDMAu (arrows) sticks to the fascia ofthe musculo-osseous groove. The ra-dial shaft periosteum (arrowheads)of the secondary metacarpal bone isincluded in the pedicle for safe dissec-tion of this tiny artery. FDMAi, inter-mediate branch of FDMA; FDMAr, ra-dial branch of FDMA; FDMAu, ulnarbranch of FDMA; MC I, first metacar-pal bone; MC II, second metacarpalbone; RA, radial artery; RN, radialnerve.

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ensure the “take” of a skin graft and the free gliding of thetendon. The fascia pedicle will be taken through a zigzagskin incision and subdermal dissection along the radialborder of the MP joint toward the pivot point; thus, themaximal potential length of the flap pedicle can beachieved, allowing it to reach the thumb tip withouttension. The pedicle includes the fascia of the first dorsalinterosseous muscle, the dorsal veins, and the sensorybranch of the radial nerve (Fig. 1B).

Although the ulnar branch of the FDMA is tiny andcourses deeply within the musculo-osseous groove, no at-tempt is made to visualize the artery. Instead, safe dissectioncan be achieved by including the radial shaft periosteum ofthe second metacarpal bone, continued by the ulnar headfascia of the first dorsal interosseous muscle (Fig. 1C).Another key point for successful flap dissection is near theMP joint, where the nutrient branch needs to be carefullyidentified and divided. Also, distal to this critical area, theFDMA starts to ramify into small vessels. If the fasciaoverlying the first dorsal interosseous muscle is not in-cluded, dissection will be difficult. After raising the flap,the tourniquet is released and vascular flow to the flap isascertained. A subcutaneous tunnel is made, and the flap istransferred by gentle traction into the pulp defect of thethumb. The donor site is grafted with either a split-thickness or full-thickness skin graft, depending on con-venience during surgery.

RESULTSClinical data were summarized in Table 1. The flap

sizes ranged from 3 � 1.5 cm to 5 � 3 cm, and all survivedcompletely. The eventual static 2-point discrimination ofthe flap ranged from 6 to 14 mm, and the patients needed4 to 8 months to reorient the flap in the new location. Theskin grafts applied to the donor area were satisfactory, andfull recovery of flexion and extension of the index finger

was also obtained. The only complaint from the patientswas graft discoloration.

CASE REPORTS

Case 2A 28-year-old man experienced a crushing injury with

soft tissue loss and joint exposure over the pulp of his leftthumb. A sensate FDMA flap, 3 � 1.5 cm in size, was raisedto cover the defect. The flap was completely viable followingsurgery, and its static 2-point discrimination was 8 mm, as forthe contralateral side of the dorsal index finger (Fig. 2A-D).

Case 7A 37-year-old man sustained an electric saw injury with

extensive pulp loss and bone exposure to his right thumb. Asensate FDMA flap, 5 � 3 cm in size, was raised to restorethe pulp defect. The vascular pedicle, including the radialshaft periosteum of the second metacarpal bone, was dis-sected to the origin of the FDMA. The flap survived well andthe contour of the thumb appeared to be nicely restored. Thestatic 2-point discrimination of the flap was 9 mm (Fig.3A-D).

DISCUSSIONAs an island sensory flap, the FDMA flap has a pedicle

length up to 7 cm, allowing a wide arc of rotation, and hasproved to be very useful in resurfacing pulp defects of thethumb.12 Although there are some variations of the FDMAand its ulnar branch is tiny and fragile, the vascularity of theFDMA flap can be maintained if the fascia overlying themusculo-osseous groove is included in the pedicle. Becausethe ulnar branch of the FDMA usually sticks to the fasciawithin the groove, this modified method avoids the need formeticulous dissection of the artery or raising the flap on anondominant arterial branch.

TABLE 1. Patient Data

PatientSex/age

(y) CauseFlap Size

(cm) ComplicationStatic 2-PD

(mm)Reorientation

(months)

1 M/20 Avulsion 3.5 � 3 Flap congestion 14 82 M/28 Avulsion 3 � 1.5 Nil 8 43 M/21 Avulsion 3.5 � 2 Nil 7 64 F/42 Avulsion 3.5 � 2.5 Nil 8 45 M/20 Avulsion 4 � 2 Nil 6 66 F/56 Scar contracture 4 � 2 Nil 6 47 M/37 Avulsion 5 � 3 Nil 9 58 M/40 Avulsion 4 � 2.5 Nil 7 6

F, female; M, male; 2-PD, 2-point discrimination.

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The dorsal cutaneous branch from the radial nerve isincluded in the flap for obtaining sensory restoration.13 Thenerve enters the flap lateral to the MP joint and superficial tothe extensor apparatus. It is easily identified. All cases in ourseries recovered good or excellent tactile gnosis, while theeventual static 2-point discrimination was in the order of 6 to14 mm. Although the sensation pattern of this flap in the new

location of thumb pulp was still felt as if it was at the donorsite—the dorsum of the proximal index finger—most patientsadapted it to well within 4 to 8 months.

Size limitation is a restricting factor for the FDMA flap,which can extend distally to the PIP joint and proximally tothe MP joint.14–16 There is no single artery that traverses thedorsal skin of the proximal phalanx after the ulnar branch of

FIGURE 2. A, A pulp defect of theleft thumb with joint exposure. B, Asensate FDMA flap, 3 � 1.5 cm insize, was designed on the dorsum ofthe proximal index finger. C, Imme-diately after the operation, the pulphas been nicely restored. D, View at2-year follow-up. The static 2-pointdiscrimination was 8 mm, as on thecontralateral side of the index finger.

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the FDMA ramifies into small branches distal to the MP joint,so the flap is a random flap, and its length should be confinedwithin the dorsum of the proximal phalanx. If the flap extendsbeyond the PIP joint, the viability of its distal part and scarcontracture of the donor region will be the major concerns. Inour series, there was no morbidity related to the donor area onthe dorsum of the index finger. Good take of the skin graft onpreserved paratenon and maintaining the specialized skin

over the MP and PIP joints intact were factors contributingto this.

The main goal of the plastic surgeon facing a complexsoft-tissue defect is to replace “like with like” tissue atminimal donor site cost and with maximal efficacy. TheFDMA flap, which allows the surgeon to accomplish the goalbetter, should serve as a valuable alternative for sensoryresurfacing in the thumb.

FIGURE 3. A, Extensive pulp loss ofthe right thumb with bone expo-sure. B, A large sensate first dorsalmetacarpal artery flap, 5 � 3 cm insize, was raised from the dorsum ofthe index finger. C, The flap resur-faced the pulp defect completelyand the donor site was covered withskin graft. D, View at 1-year follow-up. The contour of the pulp hasbeen restored and the static 2-pointdiscrimination was 9 mm. Free jointmotion of the index finger was alsonoted.

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2. Gaul JS. Radial-innervated cross-finger flap from index to providesensory pulp to injured thumb. J Bone Joint Surg. 1969;51A:1257–1263.

3. Littler JW. The neurovascular pedicle method of digital transposition forreconstruction of the hand. Plast Reconstr Surg. 1953;12:303–319.

4. EL-Gammal TA, Wei FC. Microvascular reconstruction of the distaldigits by partial toe transfer. Clin Plast Surg. 1997;24:49–55.

5. Foucher G, Braun JB. A new island flap transfer from the dorsum of theindex to the thumb. Plast Reconstr Surg. 1979;63:344–349.

6. Rybka FJ, Pratt FE. Thumb reconstruction with a sensory flap from thedorsum of the index finger. Plast Reconstr Surg. 1979;64:141–144.

7. Earley MG, Milner RH. Dorsal metacarpal flaps. Br J Plast Surg.1987;40:333–341.

8. Small JO, Brennen MD. The first metacarpal artery neurovascular islandflap. J Hand Surg 1988;13B:136–145.

9. Yang JY. The first dorsal metacarpal flap in first web space and thumbreconstruction. Ann Plast Surg. 1991;27:258–264.

10. Earley MJ. The arterial supply of the thumb, first web and index fingerand its surgical application. J Hand Surg. 1986;11B:163–174.

11. Sherif MM. First dorsal metacarpal artery flap in hand reconstruction, I:anatomy study. J Hand Surg. 1994;19A:26–31.

12. Sherif MM. First dorsal metacarpal artery flap in hand reconstruction, II:clinical application. J Hand Surg. 1994;19A:32–38.

13. Tubiana R, Duparc J. Restoration of sensibility in the hand by neuro-vascular skin island transfer. J Bone Joint Surg. 1961;43B:474–480.

14. Ratcliffe RJ, Regan PJ, Scerri GV. First dorsal metacarpal artery flapcover for extensive pulp defects in the normal length thumb. Br J PlastSurg. 1992;45:544–546.

15. El-Khatib HA. Clinical experiences with the extended first dorsal meta-carpal artery island flap for thumb reconstruction. J Hand Surg. 1998;23A:647–652.

16. Gebhard B, Meissl G. An extended first dorsal metacarpal artery neu-rovascular island flap. J Hand Surg. 1995;10B:529–531.

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