Operative Techniques in Hand, Wrist, and Elbow Sur 2023, Jan, 07 | 12:00 am

Soft Tissue Coverage of Fingertip Amputations

DEFINITION

A fingertip injury or amputation involves trauma to the finger distal to the distal interphalangeal (DIP) crease.

The fingertip is the most sensitive area of the hand.

Fingertip injuries are common, accounting for 45% of emergency room hand injuries.

ANATOMY

FIG 1 depicts the anatomy of the fingertip.

Eponychium: the cuticle or the thin membrane over the dorsum of the nail at the nail fold Perionychium: the skin at the lateral nail margin

Hyponychium: the skin below the distal aspect of the nail plate, consisting of a mass of keratin with a high concentration of lymphocytes and polymorphonuclear cells; serves as a barrier to infection

Nail root: portion of the nail plate proximal to the eponychial fold

Lunula: the curved white opacity representing the distal, visible portion of the germinal matrix Germinal matrix: produces 90% of the nail plate volume

Sterile matrix: contributes to nail plate adherence

Nail plate: consists of flattened sheets of anuclear keratinized epithelium

Nail bed: the floor of the nail plate, comprising proximal germinal matrix and distal sterile matrix Distal phalanx: lies deep to the nail bed

Pulp: composed of fibrous septa

FIG 1 • Cross-section of a fingertip depicting key anatomic structures.

Fingertip Amputation Classification (Tamai)

Zone I: distal to lunula Zone II: DIP joint to lunula

PATHOGENESIS

Various mechanisms of trauma

Avulsion Crush Compression Sharp

Dull

NATURAL HISTORY

Fingertip injuries with no bone exposed will ultimately heal by secondary intention.

In the setting of wounds less than 1 cm2, secondary intention healing aided by daily dressing changes actually allows for increased recovery of sensation.

The use of secondary intention healing for larger injuries involves a prolonged period of dressing changes with associated risk of infection and unfavorable scarring.

PATIENT HISTORY AND PHYSICAL FINDINGS

Full history and physical examination

Mechanism of injury Age

Handedness Occupation

Level of cooperation and understanding Injury assessment

Digit or digits involved: thumb versus finger

Transverse versus dorsal oblique-volar oblique versus radial-ulnar Damage to nail or nail bed

Exposure of bone

Static and moving two-point discrimination: There is decreased density of innervation with increased two-point discrimination.

Terminal flexion and extension: Injury to tendons will require more significant flap coverage. Vascularity: Prolonged capillary refill is suggestive of arterial injury.

IMAGING AND OTHER DIAGNOSTIC STUDIES

Plain radiographs in orthogonal planes (posteroanterior, lateral)

NONOPERATIVE MANAGEMENT

P.1251

Most fingertip amputations may be treated at the bedside using sterile technique and employing a metacarpal block, finger tourniquet, and loupe magnification.

There should be a low threshold for operative management.

If no bone is exposed, options include healing by secondary intention, primary closure, or skin grafting. Secondary intention healing aided by daily dressing changes provides the best recovery of sensation and is appropriate for wounds less than 1 cm2.

Primary closure is an option only if there is minimal skin loss.

Tight closures should be avoided. This can minimize function by causing joint contracture and distal tip tenderness due to poor soft tissue coverage of the bony prominences.

Sewing the volar skin tightly to the distal nail may result in a cosmetically displeasing hook nail.

If a nail bed laceration is suspected, the nail plate should be removed with a Freer elevator, allowing repair of the nail bed with either 6-0 or 7-0 simple interrupted absorbable sutures (chromic gut). Loupe magnification is extremely helpful.

The eponychial fold should be stented open with either trimmed and carefully cleansed nail or other material (eg, foil from a suture pack) to prevent abnormal growth of the future nail.

With amputations through the germinal matrix, any remaining unrepairable matrix should be removed to prevent formation of a painful nail remnant.

SURGICAL MANAGEMENT

The decision to take a patient with a fingertip injury to the operating room depends on the size of the defect, presence of exposed bone, angle of amputation, willingness of the patient to do dressing changes, and surgeon experience.

The goals are to preserve function and sensation and allow early return to activity.

In terms of functional outcome, healing by secondary intention provides equal or better results for defects less than 1 cm in diameter.

Full-thickness grafts are preferable to split-thickness grafts.

Split-thickness grafts should be used only on the ulnar side of the index, middle, and ring fingers.

Donor site options include the volar wrist skin (should be avoided, as it can mimic a suicide attempt laceration), antecubital skin, medial upper arm skin, and hypothenar skin.

These donor sites can be closed primarily.

If salvageable, the original skin from the amputated segment can be defatted and applied as a graft/biologic dressing.

If bone is exposed, options include bone shortening and primary closure and bone shortening and healing by secondary intention or fingertip flaps.

Preoperative Planning

Preliminary irrigation and débridement, exploration Antibiotics

Patient comorbidities

Is the patient a diabetic? smoker? recreational drug user? Is the tetanus status up-to-date?

Anesthesia assessment

Positioning

Supine with standard hand table. An arm, forearm, or digital tourniquet is used. The arm is placed in the center of the hand table for equal access by the surgeon and assistant.

Approach

Once the decision to perform a flap has been made, the angle of amputation, patient age, and patient gender determines whether an advancement or regional flap is appropriate.

TECHNIQUE

Skin Grafting

Measure the size of the defect carefully and create a template.

This template is used to draw a corresponding defect on the donor site (TECH FIG 1A).

Harvest the full-thickness graft with a no. 15 blade. Take great care to defat the graft down to dermis (TECH FIG 1B,C).

Sew the graft into place and secure it using absorbable suture (TECH FIG 1D). At four corners, the suture is left long so that later it may be tied over a bolster.

Cover the skin graft with Xeroform dressing and mineral oil-soaked sterile cotton balls.

Tie down the four long sutures over the cotton balls to create a bolster, placing gentle pressure on the graft to minimize shear.

The finger is padded with gauze and protected with a finger splint, leaving the proximal interphalangeal (PIP) joint free for 5 to 7 days.

After 5 to 7 days, the splint and dressing should be carefully removed, the graft inspected, and daily Xeroform dressing changes instituted until the graft is fully healed.

TECH FIG 1 • A. Ulnar defect of the long finger with the proposed hypothenar graft drawn out. (continued)

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**TECH FIG 1 • (continued) B. The hypothenar full-thickness skin graft is harvested, taking great care to**

defat the graft; only the dermis and epidermis are harvested. C. The hypothenar full-thickness skin graft ex vivo. Note a paucity of fat. D. The skin graft is inset using absorbable sutures. Four bolster sutures are then tied over a mineral oil-soaked cotton ball placed on top of the graft (not pictured). A dry dressing is applied. The bolster is left in place for 5 to 7 days.

Moberg Advancement Flap

Indication: thumb tip amputation less than 1.5 cm; preserves sensation and length (TECH FIG 2A,B).

Not indicated for fingertip amputations.

Make a longitudinal incision just dorsal to the neurovascular bundles, based at the metacarpophalangeal joint flexion crease (TECH FIG 2C).

Elevate a flap elevated from the flexor sheath (TECH FIG 2D).

TECH FIG 2 • A. Distal thumb defect with exposed proximal phalanx. B. Nonreplantable distal phalanx. C. Intraoperative photograph indicating planned Moberg flap, with longitudinal incisions just dorsal to neurovascular bundles and based at metacarpophalangeal joint flexion crease. D. Moberg flap elevation from flexor sheath. E. Advancement of Moberg flap was possible without creation of an island flap or use of a triangle of Burow. F. Closure of the defect after advancement of Moberg flap. (Courtesy of James Chang, MD.)

If the flap is difficult to advance, consider the following (TECH FIG 2E): Flexing the interphalangeal joint

Extending the lateral incisions toward the palm with excision of skin at base to create an island flap;

skin grafting of the secondary defect

Excise a triangle of skin at the bilateral flap base (ie, triangle of Burow). Carefully preserve bridging vessels.

Close with permanent suture under minimal tension (TECH FIG 2F).

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Lateral V-Y Advancement Flaps (Kutler)

Indication: transverse fingertip amputation with exposed bone

The apex of the V is located at the lateral distal digital crease (TECH FIG 3A-D).

TECH FIG 3 • A. Lateral view of the digit with triangular flaps raised along the midlateral line. B. Flaps raised on both the radial and ulnar neurovascular bundles. C. Adventitia is released and the flaps are advanced distally to cover the defect. D. The flaps are sewn together to cover the defect, and the donor area is closed primarily in a lateral V-Y fashion.

Adequately mobilize the flap: Only nerves and vessels need to be kept intact. Bilateral triangles are advanced and sutured together distal to the nail bed.
Volar V-Y Advancement Flap (Atasoy-Kleinert)

Indication: dorsal oblique fingertip amputation (ie, more dorsal than palmar skin loss) with exposed bone The apex of the V is at the volar midpoint of the distal digital crease (TECH FIG 4A-C).

The base of the triangle should be as wide as the nail bed. Adequately mobilize the flap.

TECH FIG 4 • A. Volar-based V is incised. B. The volar flap is advanced distally to cover the distal defect.

C. The flap is secured distally, and the donor area is closed primarily in a volar V-Y fashion.
Cross-Finger Flap

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Indication: volar fingertip defects up to 1.5 × 2.5 cm with an uninjured adjacent digit present (TECH FIG 5A-C)

The donor area is the dorsal aspect of the middle phalanx skin of the adjacent finger.

The middle finger is used for an index fingertip amputation; otherwise, the donor skin is derived from the radial digit.

Make two transverse midaxial to midaxial incisions on the donor area at roughly the DIP and PIP extension creases. Make one longitudinal midaxial incision on the side of the donor digit away from the injured digit to connect these two transverse incisions.

Dissection is carried out in the loose areolar plane above the extensor paratenon. The paratenon must not be violated.

TECH FIG 5 • A. Intraoperative photograph depicting ring finger volar fingertip avulsion with exposed flexor tendon and small finger amputation at middle phalanx level. B,C. Two weeks after successful replantation of small finger with continued problem of ring finger wound, which had been treated with daily dressing changes. D. Intraoperative photograph after elevation of cross-finger flap from dorsal aspect of middle phalanx skin of adjacent finger. E. Intraoperative photograph after cross-finger flap from middle finger for coverage of volar ring finger defect. Donor site was covered with a full-thickness skin graft. Blue background indicates preservation of sensory branch. (continued)

A dorsal cutaneous nerve may be harvested as well to create an innervated cross-finger flap. The graft is mobilized to the midaxial line adjacent to the injured digit (TECH FIG 5D).

Apply a full-thickness skin graft to the secondary defect.

The full-thickness graft should be first sewn to the hinge margin of the primary defect.

The flap and full-thickness graft are then each rotated 180 degrees, allowing the flap to cover the primary defect and the full-thickness graft to cover the secondary defect (TECH FIG 5E). If an innervated cross-finger flap is pursued, the dorsal cutaneous nerve from the donor digit (in the flap) is attached to the pulp branch from the proper digital nerve on the volar aspect of the recipient digit (TECH FIG 5F,G).

The flap is divided 2 to 3 weeks after the index procedure (TECH FIG 5H,I).

P.1255

TECH FIG 5 • (continued) F,G. Illustration of the operative method. H,I. Intraoperative photographs after cross-finger flap division at 3 weeks.
Reverse Cross-Finger Flap

Indication: dorsal fingertip injury

Raise a deepithelialized full-thickness flap from the dorsal middle phalanx skin (TECH FIG 6A,B). Elevate the subcutaneous tissues underlying the raised graft (TECH FIG 6C,D).

Cover the primary defect with the elevated deep tissue and then with a full-thickness graft (TECH FIG 6E).

Cover the secondary defect with the previously described native full-thickness flap (TECH FIG 6F). The subcutaneous flap is divided in 2 to 3 weeks (TECH FIG 6G).

TECH FIG 6 • A. Dorsal defect of the right index finger with the flap drawn out on the adjacent long finger.

(continued)

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TECH FIG 6 • (continued) B. Ulnarly based skin flap raised from the long finger. C,D. The subcutaneous tissue is elevated off the paratenon of the long finger. E. The flap is inset onto the index finger defect. F. Split-thickness skin graft placed on the recipient site. The native ulnarly based skin flap is restored onto the long finger. G. Three months postoperatively. (Courtesy of Phani Dantuluri, MD.)
Thenar Flap

Indication: Index or middle fingertip injury with exposed bone and more palmar than dorsal skin loss (defects roughly 1 × 1.5 cm in size) in patients younger than 35 years of age who are less likely to develop PIP joint contractures.

Women are better candidates for this flap than men.

Press the amputated tip against the thenar eminence with the digit in the position of least PIP flexion (TECH FIG 7A).

The position of the H flap is indicated by the bloody imprint from the amputation site (TECH FIG 7B).

TECH FIG 7 • A. The middle digit is passively flexed to the thenar eminence and the thenar H flap outlined. B. The outside pen lines reveal that the flap is widened past the bloody impression to accommodate for the contour of the pulp. Note the volar oblique fingertip amputation of the middle digit. (continued)

The designed H flap should be 50% wider than the defect to fully cover the pulp's semicircular contour.

Raise the flap at the level of the thenar muscles with as much subcutaneous tissue as possible (TECH FIG 7C).

Take care to avoid injury to the digital nerves of the thumb.

The H flaps may either be “tubed” around the defect or one flap may be advanced to fill the defect of the other flap that is sewn to the amputation site (TECH FIG 7D).

The flaps are divided at 3 weeks.

One or both H flaps can be used to close the donor defect primarily.

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TECH FIG 7 • (continued) C. Dissection of the flap is performed at the level of the thenar musculature. Note the digital nerve present in the field of dissection. D. The flap is sewn in position. (Courtesy of Thomas R. Hunt III, MD.)
Neurovascular Island Pedicle Flap (Littler)

Indication: volar distal thumb defect as well as volar radial index or volar ulnar small finger defects sufficient to produce a scarred pulp and an anesthetic tip (TECH FIG 8A,B)

Use Doppler to ensure that flow is present in the ulnar digital artery of the ring finger and the radial digital artery of the middle finger.

TECH FIG 8 • A,B. Insensate volar distal thumb after coverage of amputation site with free flap. C. Intraoperative photograph depicting neurovascular island pedicle flap (Littler) harvested from ulnar aspect of middle finger. D. Intraoperative photograph after tunneling of neurovascular island pedicle flap (Littler) to volar distal thumb, closure of wounds, full-thickness skin grafting of donor site, and application of a bolster dressing. (Courtesy of James Chang, MD.)

Create a template of the defect on the ulnar aspect of the donor digit.

Apply the pattern to the distal ulnar aspect of the middle finger with small V-shaped indentations at the DIP joint creases.

The flap may be continued posteriorly, beyond the midaxial line.

Make a Bruner incision to the distal flexor retinaculum.

Dissection is commenced in the palm to ensure normal anatomy.

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Isolate and ligate the radial digital artery to the ring finger.

Mobilize the vessel to the level of the superficial palmar arch to allow maximum pedicle length (TECH FIG 8C).

Pass the entire pedicle beneath the digital nerve if it causes tension. Create a subcutaneous tunnel to the thumb using blunt scissor dissection. The tourniquet is released and flap viability assessed.

The flap is then gently placed into a Penrose drain and secured in place with a 4-0 nylon suture to the tip of the flap skin.

The Penrose drain is used to avoid kinking and twisting of the pedicle as the flap is passed through the subcutaneous tunnel to the recipient site.

The flap is sutured in place under minimal tension and the donor site is closed primarily or with a full-thickness graft (TECH FIG 8D).
Distal Tip Replantation

Indications: amputation of the digit distal to the insertion of the extensor and flexor tendons into the distal phalanx with preserved vein(s) for anastomoses

If the Tamai zone I amputations are too small to be held by an assistant, the surgeon holds the amputated part (TECH FIG 9A).

Palmar and dorsal oblique full-thickness flaps are raised and sutured back under the microscope for thin flaps to avoid injury to the palmar veins.

The distal amputated part is stabilized, and osteosynthesis is achieved with a single axial Kirschner wire.

If in a Tamai zone II amputation, and the DIP joint is destroyed, primary arthrodesis is done with a single axial Kirschner wire for 4 to 6 weeks.

The nail plate is reinserted into the nail fold in avulsed amputations using horizontal mattress sutures. Do not repair the flexor tendon but instead insert the proximal stump into the volar plate of the DIP joint to maintain better pinch strength.

Under the microscope, visualize the nerve ends and the stumps of the arteries and veins by gently squeezing the pulp.

This can only be done once.

Subcutaneous fat is removed from the artery and vein once they are identified to make room for the clamps.

The proximal arterial stump is prepared with a tourniquet.

TECH FIG 9 • A. Positioning the amputated part between the surgeon's ring fingers of both hands. B.

Palmar vein repair.

Four to five 10-0 nylon sutures are used to repair the large central artery.

To aid the visualization and placement of the sutures, heparinized saline is used to irrigate the vessel lumen.

In zone I, following arterial repair, the clamps are released momentarily to locate the subdermal palmar vein.

Close the skin from dorsal to palmar, and then anastomose the subcutaneous palmar vein.

Palmar vein anastomosis is carried out using a 1-V double clamp. If the clamp cannot be applied, the two ends are brought together and the corner sutures are held while the others are put in (TECH FIG 9B).

A 11-0 suture with 50 μm needle is used.

Repair the nerve ends with 10-0 nylon suture.

Artery and vein clamps are removed after the repair, and skin flaps are approximated to cover the anastomosis.

The limb is kept immobilized in a short-arm cast for 2 weeks. The finger is watched for color change. Bluish coloring with hyperbrisk capillary refill indicates a venous congestion problem and a pale color with poor capillary refill and turgor indicates an arterial inflow problem. Continuous pulse oximetry may be used to monitor the oxygenation of the digit as well.

The patient is kept on intravenous (IV) antibiotics and continuous infusion of 500 mL Dextran 40 and 5000 units of Heparin for 5 days, followed by 75 mg of aspirin for 3 weeks.

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PEARLS AND PITFALLS

Fingertip injuries less than 1 cm2 can generally be treated with dressing changes with equal or better results than flap closure.

The bridging vessels should be carefully preserved when performing a Moberg flap to prevent skin necrosis.

V-Y advancement flaps may lead to scarring and hypersensitivity at the fingertip.

The radial digital nerve should be carefully preserved and protected when performing a thenar flap. Cross-finger flaps (nonglabrous skin) may lead to hair growth on the fingertip and deficiency of pulp.

Thenar flaps (glabrous skin) allow good sensibility in the flap but may be complicated by development of PIP joint contractures, especially in older male patients.

Poor sensory outcome in neurovascular island flaps can be minimized by use of the most distal portion of donor skin, preservation of as much subcutaneous skin on the pedicle as possible, and avoidance of tension and kinking in the pedicle.

POSTOPERATIVE CARE

When possible, the patient should meet the hand therapist preoperatively. Active and passive range of motion

Sensory reeducation Scar massage

Moberg advancement flap: thumb spica splint for 10 days to 2 weeks, followed by range-of-motion exercises

Lateral V-Y advancement and volar V-Y advancement flaps: finger splintage of only the involved joint for 10 days to 2 weeks, followed by range-of-motion exercises

Cross-finger flap and reverse cross-finger flap: A nonadherent bolster dressing is applied to the skin graft site and a splint is applied. PIP joints and the DIP joint of the donor finger can be gently ranged 2 weeks after flap inset, taking care to avoid tension on the flap. After flap division at 3 weeks, range-of-motion exercises are directed toward extending the PIP joints. Severe contractures may be treated with static progressive splinting.

Thenar flap: A splint is applied postoperatively. Gentle range of motion of unaffected digits is started 2 weeks after flap inset, with care taken to avoid tension on the flap. Full range-of-motion exercises are started after flap division at 3 weeks. Severe contractures may be treated with static progressive splinting.

Neurovascular island flap: The splint is changed 10 days after surgery, when sutures can be removed; gentle active range of motion is started, with full range of motion delayed until 3 weeks after surgery. Sensory reeducation is necessary to help differentiate thumb from middle finger sensation.

Distal fingertip replantation: The Kirschner wire is removed in 4 weeks and a finger splint is kept on for an additional 2 weeks for lifting and during sleep. Otherwise, therapy for range-of-motion exercises is begun.

OUTCOMES

Moberg flaps consistently provide return of normal two-point discrimination or within 2 mm of the contralateral digit and may result in a decrease in the hyperextensibility of the interphalangeal joint with no functional impairment.

V-Y advancement flaps result in return of sensation to within 2.75 mm of the contralateral digit but may also result in paresthesia, hypersensitivity, and cold intolerance (50%).

Patients who undergo a cross-finger flap have a return of protective sensation (8 mm of two-point discrimination), most predictably in younger patients, but the sensation remains less than the normal pulp.

Hematoma or seroma significantly impairs the return of sensation.

Thenar flaps provide superior return of sensation compared to cross-finger flaps but still less than normal.

Neurovascular island flaps may result in hyperesthesia (23%) and cold intolerance (32%), which can be

minimized by proper attention to detail and technique.

COMPLICATIONS

Moberg flap: interphalangeal joint flexion contracture and skin necrosis

Lateral V-Y advancement flaps (Kutler): scarring at the fingertip, which may be insensate or painful Volar V-Y advancement flap (Atasoy-Kleinert): hook nail or hypersensitivity

Cross-finger flap: deficiency of fingertip pulp and hair growth on the fingertip Thenar flap: PIP joint flexion contracture of recipient finger

Hematoma Seroma Infection Skin necrosis

Dysesthesia or altered sensation Flexion contractures

Loss of flap

Epidermal inclusion cysts Nail deformities Symptomatic neuromas

Soft Tissue Coverage of Fingertip Amputations

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Soft Tissue Coverage of Fingertip Amputations

DEFINITION

The fingertip is the most sensitive area of the hand.

ANATOMY

FIG 1 • Cross-section of a fingertip depicting key anatomic structures.

Fingertip Amputation Classification (Tamai)

PATHOGENESIS

NATURAL HISTORY

PATIENT HISTORY AND PHYSICAL FINDINGS

IMAGING AND OTHER DIAGNOSTIC STUDIES

NONOPERATIVE MANAGEMENT

SURGICAL MANAGEMENT

Preoperative Planning

Positioning

Approach

TECHNIQUE

Skin Grafting

TECH FIG 1 • A. Ulnar defect of the long finger with the proposed hypothenar graft drawn out. (continued)

TECH FIG 1 • (continued) B. The hypothenar full-thickness skin graft is harvested, taking great care to

Moberg Advancement Flap

Lateral V-Y Advancement Flaps (Kutler)

Volar V-Y Advancement Flap (Atasoy-Kleinert)

TECH FIG 4 • A. Volar-based V is incised. B. The volar flap is advanced distally to cover the distal defect.

C. The flap is secured distally, and the donor area is closed primarily in a volar V-Y fashion.

Cross-Finger Flap

TECH FIG 5 • (continued) F,G. Illustration of the operative method. H,I. Intraoperative photographs after cross-finger flap division at 3 weeks.

Reverse Cross-Finger Flap

TECH FIG 6 • A. Dorsal defect of the right index finger with the flap drawn out on the adjacent long finger.

Thenar Flap

TECH FIG 7 • (continued) C. Dissection of the flap is performed at the level of the thenar musculature. Note the digital nerve present in the field of dissection. D. The flap is sewn in position. (Courtesy of Thomas R. Hunt III, MD.)

Neurovascular Island Pedicle Flap (Littler)

Distal Tip Replantation

TECH FIG 9 • A. Positioning the amputated part between the surgeon's ring fingers of both hands. B.

PEARLS AND PITFALLS

POSTOPERATIVE CARE

OUTCOMES

COMPLICATIONS

SUGGESTED READINGS

**TECH FIG 1 • (continued) B. The hypothenar full-thickness skin graft is harvested, taking great care to**

**TECH FIG 5 • (continued) F,G. Illustration of the operative method. H,I. Intraoperative photographs after cross-finger flap division at 3 weeks.**