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Innervated Dorsal Adipofascial Turnover Flap for Fingertip Amputations

Özdemir, Ragip*; Klnç, Hdr*ıııı; Şensöz, Ömer*; Ünlü, R. Erkin; Baran, Cihat N.*

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Traumatic or thermal injury to the fingertip may result in composite tissue loss. Exposed tendon, bone, or joint surface is best treated by flap coverage. The authors present their experience with a new technique that provides coverage for fingertip defects using the innervated dorsal adipofascial turnover flap, which consists of adipofascial tissue only and relies on the arterial anastomotic network of this tissue layer to sustain its vascularization. Eight digital amputations between the distal phalanx proximal to the nail matrix and midportion of the middle phalanx were resurfaced successfully with the innervated dorsal adipofascial turnover flap. The flaps survived completely; the mean follow-up was 9 months. This technique seems to be a relatively simple way of achieving early recovery. It does not require the use of distant flap immobilization of adjacent digits, nor does it require the use of homodigital flaps, which may jeopardize an already injured finger. The main advantages of the innervated dorsal adipofascial turnover flap are its ready availability from the local tissue, its sensation, and the absence of functional and aesthetic disturbance at the donor site.

*Department of Plastic and Reconstructive Surgery, Ankara Numune Hospital; and the †Department of Plastic and Reconstructive Surgery, Dr. Muhittin Ülker Traffic and Emergency Hospital, Ankara, Turkey.

Received Mar 30, 2000, and

in revised form Aug 11, 2000.

Accepted for publication Aug 11, 2000.

Address correspondence and reprint requests to Dr Özdemir, Alidede Sokak No: 6/28, Aşagiayranci, Ankara, Turkey.

Tissue loss at the level of the fingertip, with exposure of tendons, bone, or joints, represents a challenging reconstructive problem. Skin grafts applied to a soft-tissue defect over an exposed tendon, bone, or joint surface are usually unsuccessful or nondurable. Flap coverage of such injuries is preferable. Many flaps have been described to cover composite digital defects. 1–6 We describe a technique in which a local innervated adipofascial turnover flap from the dorsal aspect of the digit is used to reconstruct fingertip defects at the distal phalanx proximal to the nail matrix and the middle part of the middle phalanx (Fig 1). This flap, which can be raised from the proximal or middle phalanx, allows coverage of a substantial loss of composite tissue at the fingertip in a single procedure.

Fig 1

Fig 1

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Surgical Anatomy

The dorsal venous and arterial networks lie in the subcutaneous plane between the dermis and the paratenon of tendons. 7 There is a well-defined longitudinal dorsal arterial network on the dorsum of the finger. 8 Proximally, this includes the dorsal digital arteries, which are the terminal branches of the dorsal metacarpal arteries, but distally from the middle of the first phalanx the network contains numerous branches from the palmar digital arteries. 9 The dorsal digital arteries terminate by subdividing further into smaller branches at the proximal third of the proximal phalanx or less often by direct anastomosis with the longitudinal dorsal arterial network. This essentially consists of plexiform anastomoses between the dorsal branches of the palmar digital arteries. 7

The dorsal branches of the digital arteries themselves are numerous and constant, and their pattern is repeated regularly in all three phalanges. 9 The largest branches are found approximately at the level of the middle and distal thirds of the proximal phalanx, in the middle of the second third, and particularly at the level of the distal interphalangeal joint. In addition, there are numerous, small bilateral branches that are connected to the well-defined longitudinal dorsal arterial network.

The dorsum of the hand is innervated by the branches of the radial and ulnar nerves (Fig 2). The superficial branch of the radial nerve usually supplies the skin of the lateral three and one-half phalanx, and a corresponding part of the dorsum of the hand. The skin over the remainder of the posterior aspect of the hand and the medial one and one-half fingers is supplied by the dorsal branches of the ulnar nerve, which arise in the anterior compartment and pass around the medial aspect of the wrist. The dorsal branch of the radial and ulnar nerves divides into multiple branches, which supply sensibility to the dorsum of the hand, fingers, and over the digits, and are located in the subcutaneous plane. 10

Fig 2

Fig 2

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Patients and Methods

Patients

Eight patients with digital amputations at levels between the distal phalanx proximal to the nail matrix and the middle of the middle phalanx, and 1 patient with a right thumb pulp defect were treated using the innervated adipofascial turnover flap. Patient details are provided in the Table. All patients had sustained acute injuries. The innervated dorsal adipofascial flap was used to cover the exposed bone and neurovascular structures in all patients. All flaps were taken from the dorsum of the proximal and middle phalanges, along with the transected dorsal digital nerves. The skin graft was harvested from the ulnar side of the hypothenar eminence of the hand. All patients were operated emergently using axillary block and local anesthesia. Patient follow-up ranged from 3 to 18 months.

Table

Table

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Operative Technique

The size of the defect and the length of the attached pedicle equal to the vertical length of the defect is measured, and the required adipofascial flap (usually twice the length of the defect) is marked. Flap width is equal to the width of the defect. Theoretically, this adipofascial flap should include the entire dorsal surface of the finger distal to the proximal phalanx along with the dorsal digital nerve. In planning the flap, intact dorsal adipofascial tissue of at least one third of the flap length, and equal to the defect length, is necessary at the base of the flap to ensure the viability of the vascular connections between the palmar and dorsal vascular networks. The lateral margins of the flap can extend from the ulnar to the radial midlateral lines, but narrower flaps are used. Local or axillary block anesthesia and tourniquet are used. Dissection is carried out with the aid of loupe magnification. The skin overlying the flap is incised carefully toward the dermal layer in a lazy-S manner (Fig 3A). The incised skin, without the adipose tissue, is undermined adequately and is held to one side with the aid of hooks. The dorsal digital nerve is identified proximal to the incised area and is transected (Figs 3B, C). The adipofascial flap, including the distal portion of the dorsal digital nerve, is then dissected free from the underlying paratenon (Fig 3D). Dissection is performed in a proximal-to-distal manner. The dissection of the flap is stopped when there is intact distal dorsal adipofascial tissue that is one third the flap length. During the entire dissection, handling of this flap must be as atraumatic as possible. On the exposed tip defect, the volar digital nerve is found, dissected, and exposed. The tourniquet is released to confirm circulation in the finger, and then flap hemostasis is carried out meticulously. The flap is turned back on its attached base to cover the defect, epineural anastomoses between the dorsal and volar nerves are accomplished, and continuity of the nerve for flap sensation is established (Figs EE, F). A split-thickness skin graft harvested from the hypothenar area is applied to the raw surface of the turnover flap after it has been fixed over the defect (Fig 3G). The skin over the donor site of the flap is returned to its original position. Excess skin can be trimmed and reapproximated with 5-0 Prolene sutures, and a drain is placed if necessary. A light tie-over dressing is applied snugly over the grafted skin. The finger is immobilized in a splint for 3 days, after which active mobilization is begun.

Fig 3

Fig 3

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Results

The innervated flap provided excellent coverage of fingertip defects and preserved finger length. The mean patient follow-up was 9 months (range, 3–18 months). The outcome was satisfactory in all patients (Fig 4). In one of the patients, this flap was used to reconstruct the pulp of the thumb successfully (Fig 5). All flaps survived completely without any loss of the overlying skin graft, and full range of motion of the affected digit was retained. There was no donor site morbidity, and donor sites were excellent in appearance and without pain in all patients. This innervated, one-step coverage provided satisfactory two-point discrimination at the tip of the finger. No complications were encountered (see the Table).

Fig 4

Fig 4

Fig 5

Fig 5

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Discussion

Reconstruction of fingertip defects with exposure of bone and joint can be a difficult problem because immediate or early closure is of paramount importance in the preservation of function and avoidance of complications. Many flaps have been described to cover composite digital defects. Kutler 11 described the advancement of V-shaped flaps with a Y closure, and Atasoy and colleagues 12 used a single volar advancement flap to repair fingertip amputations. O’Brien 13 advanced distally a volar neurovascular island pedicle flap based on both digital neurovascular bundles to cover the tip. Cross-finger flaps from the dorsal surface of an adjoining finger have been reported by many authors, as have flaps from the thenar eminence. Digital tip or dorsal avulsion injuries have been covered with distant flaps from the chest, abdomen, groin, and opposite arm. Cross-finger flaps are often the first choice for reconstruction of fingertip amputations, but they are not always possible when two or more adjacent fingers are injured simultaneously, 1,5 when there is a risk of joint stiffness, especially in older patients, or when it is preferable to limit cosmetic damage to only one finger. The use of distant flaps involves a considerable period of immobilization and always leaves donor site scars. Furthermore, these techniques require at least two procedures. Possible homodigital flaps include flag flaps, which are useful only when there are small areas of tissue loss. Lateral or palmar reverse island flaps based on a palmar digital artery may cause problems in an already injured finger. 4,14 Local transposition, rotation, and advancement flaps with random vascularity have a limited range of application. Other possible options include a local digital axial-pattern transposition flap or an arterialized lateral finger flap and homodigital subcutaneous flap, but their application is limited because there must be adequate available tissue adjacent to the defect and because they involve the sacrifice of a palmar digital artery. 6,15,16

Study of the vascular anatomy of the dorsal region of the long fingers led us to consider the possibility of using a reverse adipofascial turnover flap with a pedicle consisting of the arterial and venous networks of the dorsal adipofascial layer of the fingers based on their numerous distal connections with the palmar digital arteries. 9,14

The innervated dorsal turnover adipofascial flap, including the dorsal digital nerve, which consists of thin and pliable tissue, can be used for repairing composite tissue loss at the fingertip and total amputations at the middle or distal phalangeal levels proximal to the nail matrix. This rapid procedure is simple and maintains vascular integrity of the finger as well as its sensation. This flap depends on random-type vascularity. Theoretically, the proximal part around the defect is used as the base of the flap. For adipofascial turnover flaps on the dorsum of the finger, a width of 0.5 cm at the attached pedicle was found to be safe for flap survival. 8 For patients of all ages we used a pedicle length twice that of the defect length, and this was found to be quite safe in the current series. All flaps survived completely. There was little bleeding from the dissected surface between the fascia and the underlying intact paratenon. Undermining of the overlying skin of the donor flap is relatively safe because there is an abundant dermal plexus to ensure survival of the undermined skin flap. The gliding motion of involved tissue was restored because the paratenon was kept intact.

This flap provides a very versatile and reliable covering. It allows stump coverage without shortening the length of the finger, and restoration of sensibility can be achieved in a one-step operation. The flexor aspect of the finger is unaffected. The palmar digital artery is spared, and vascular reliability and continuity of arteries and nerves are preserved. The integrity of adjacent fingers is also preserved, and the need for a distant flap is avoided, particularly when the adjacent fingers are injured or otherwise affected. Donor site morbidity is minimized. The innervated adipofascial turnover flap allows the defect to be closed in a single outpatient procedure preformed using local anesthesia with adequate recovery of sensation. In 1 patient this flap was used to reconstruct the pulp of the thumb. This flap can be applied to defects that culminate in exposed tendon and bone.

Presented at the Turkish Society of Plastic and Reconstructive Surgery, XXII; Turkish Plastic and Reconstructive Surgery Congress; Kuşadası, Turkey; October 1–5, 1999.

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References

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12. Atasoy E, et al. Reconstruction of the amputated finger tip with a triangular volar flap—a new surgical procedure. J Bone Joint Surg Am 1970; 52A(5): 921–926.
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15. Fleegler EJ, et al. The versatile axial pattern digital transposition flap. J Hand Surg [Am] 1988; 13A: 494–500.
16. Voch P, et al. The homodigital subcutaneous flap for cover of dorsal finger defect. Br J Plast Surg 1994; 47: 435–439.
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