Reuben A. Bueno, Jr. and Elvin G. Zook
DEFINITION
Injury to the nail usually occurs in the traumatic setting. Because of its location at the distal end of the digits, the perionychium is the most frequently injured part of the hand.9
Restoration of normal nail appearance is best achieved by acute treatment of the nail matrix.
Reconstructive techniques may be used to provide a more normal-appearing nail.
Excision of benign and malignant tumors involving the nail bed matrix may require techniques of nail bed repair and reconstruction also used in the traumatic setting.
Optimal treatment depends on thorough understanding of the components of the perionychium—skin, sterile matrix, germinal matrix, eponychial fold, and distal phalanx—and their anatomic relationship with each other.
ANATOMY
The nail serves multiple functions: protecting the fingertip, regulating peripheral circulation, and contributing to sensory feedback of the fingertip.9
The perionychium includes the nail plate, nail bed, hyponychium, eponychium and fold, and paronychium (FIG 1).
The proximal portion of the nail matrix is the germinal matrix, and the distal portion is the sterile matrix. The germinal matrix produces about 90% of the nail, while the sterile matrix produces the remaining 10% of the nail and produces the cells on the undersurface of the nail responsible for nail adherence.
The hyponychium is the skin distal to the nail bed, the paronychium is the skin on each side of the nail, and the eponychium is the skin over the nail fold.
The nail bed is adherent to the distal phalanx.
PATHOGENESIS
The main causes of nail deformity are trauma and tumor.
The middle finger is the most commonly injured finger.13
Inadequate treatment in the acute setting often leads to a nail deformity.
There is an associated distal phalanx fracture in 50% of nail bed injuries. This type of injury should be considered an open fracture and treated as such, with irrigation and débridement, reduction of the fracture and fixation if necessary, and repair of the nail bed (FIG 2).1,4
Scarring can lead to a split nail deformity.
Absence of nail matrix can lead to detachment of the nail.
Lack of support from the distal phalanx leads to the hook nail deformity.
Benign tumors (glomus tumor, distal interphalangeal joint ganglion), and malignant tumors (squamous cell carcinoma, melanoma) can affect nail appearance.
NATURAL HISTORY
Repair in the acute period provides the best chance for normal appearance of the nail.
The nail plate grows at about 0.1 mm per day or 2 to 3 mm per month. When the nail plate is removed for nail bed repair, new nail growth is delayed for 3 to 4 weeks.9
If placed back on after repair, the old nail will remain adherent for 1 to 3 months and then fall off as a new nail pushes out the old nail.12
After nail repair, it will take about 12 months for the nail to achieve its final appearance. Thickening of the nail proximal to the level of injury is seen for about 50 days (FIG 3).9,12,13
PATIENT HISTORY AND PHYSICAL FINDINGS
Traumatic injury to the perionychium is usually caused by a crush injury.1,4
In the acute setting, the status of the entire fingertip must be assessed: quality of the skin, presence of a subungual hematoma, quality of the nail matrix, capillary refill, sensory function, flexion and extension at the distal interphalangeal joint, presence of a distal phalanx fracture.
FIG 1 • The perionychium and its associated structures.
FIG 3 • A. Nail appearance at 3 months after repair. Patients should be aware of the heaped-up appearance as the nail grows distally. B. Nail appearance at 1 year after repair.
FIG 2 • A. Radiograph showing distal phalanx fracture associated with a nail bed crush injury. B. Nail bed injury with concomitant distal phalanx fracture. With a break in the periosteum, there is communication of the distal phalanx with the outside environment. There is a risk for osteomyelitis if not treated appropriately.
Features of acute nail bed injury
Subungual hematoma (FIG 4A,B): bleeding beneath the nail from laceration of the nail bed
Pain secondary to pressure in the space between the nail plate and the nail bed
Treated with evacuation of hematoma by trephination
Laceration of nail bed (FIG 4C,D)
Mechanism of injury usually is crush.
Concomitant injury to fingertip skin or distal phalanx fracture may be present.
Nail lacerations can be described in one of four ways: simple laceration, stellate laceration, severe crush, and avulsion.
Repair of nail bed laceration and Kirschner wire fixation of distal phalanx fracture if unstable
Nail bed avulsion (FIG 4E)
Quality of avulsed nail matrix and size of defect will determine treatment.
Treatment options include returning avulsed piece back on defect or harvesting a split nail graft from the adjacent matrix or from the great toe.
Posttraumatic nail deformities
Nail nonadherence or split nail (FIG 4F)
Usually due to injury to the sterile matrix, which produces the cells responsible for adherence
Excision of scar and primary closure or nail matrix reconstruction with a split graft from the great toe
Hook nail deformity (FIG 4G)
Due to excessive tension at junction of nail bed and hyponychial skin and loss of support of distal phalanx
Revision amputation or reconstruction of nail bed and bone graft to the distal tip of the distal phalanx
Nail remnant (FIG 4H)
Due to presence of residual germinal matrix not completely ablated at the time of initial repair or revision amputation
Complete nail matrix ablation or revision amputation
Pincer nail deformity (FIG 4I): characterized by excessive transverse curvature of the nail and progressive pinching off of the distal fingertip, causing pain and abnormal appearance
Partial or complete nail ablation
Reconstruction of nail bed with elevation of the lateral nail bed using dermal graft or AlloDerm
IMAGING AND OTHER DIAGNOSTIC STUDIES
AP and lateral radiographs of the distal phalanx are recommended to rule out a fracture.
Depending on the level of injury, the following fractures are seen: distal tuft fracture, comminuted fracture, and a transverse or oblique fracture of the midshaft.
Intra-articular fractures at the distal interphalangeal joint are rare with an associated nail bed injury.
DIFFERENTIAL DIAGNOSIS
Trauma
Benign tumor
Glomus tumor
Distal interphalangeal joint ganglion cyst
Malignant tumor
Squamous cell carcinoma
Melanoma
NONOPERATIVE MANAGEMENT
Left untreated, traumatic injury to the nail matrix may result in an abnormal appearance of the nail.
FIG 4 • Nail deformities. A,B. Subungual hematoma. C,D. Laceration of nail bed. E. Nail bed avulsion out of eponychial fold. F. Split nail deformity. G. Hook nail deformity. H. Nail remnant. I. Pincer nail deformity.
SURGICAL MANAGEMENT
Repair in the acute period increases the chance of a normalappearing nail.
Both surgeon and patient should be aware of the stages of nail growth and characteristic appearance at different points in the healing process as the nail grows out.
Reconstruction of the nail matrix in a chronic injury should be approached with realistic expectations.
Reconstruction of the nail matrix after tumor excision will depend on the amount of nail bed excised and the amount remaining.2,6–8
Preoperative Planning
Management of malignant tumors involving the nail bed requires an understanding of the safe level of amputation (usually to the level of the more proximal joint) and the need for sentinel node biopsy.
Positioning
To provide a bloodless field, use of a Penrose drain tourniquet at the base of the digit secured with a clamp is recommended (FIG 5).
Use of a portion of a surgical glove as a tourniquet is discouraged because of the risk of leaving the tourniquet at the base of the digit after repair and placement of the dressing. The dressing may then hide the tourniquet, and vascular compromise and subsequent necrosis of the finger is possible in the postoperative period.
Approach
Sterile preparation and draping is done.
A digital block with 1% plain lidocaine (maximum dose 7 mg/kg) is administered.
Use of surgical loupes (2.5× magnification is sufficient) is recommended for the most accurate repair.
A Kleinert elevator is used to separate the nail plate from the nail matrix.
FIG 5 • Use of Penrose drain tourniquet at base of digit.
The nail plate is cleaned and soaked in povidone–iodine (Betadine) as nail bed repair is done. If the nail plate is not available, a silicone sheet or nonadherent gauze can be used to maintain the eponychial fold after repair.
Minimal débridement of the nail matrix is performed to preserve as much of the nail bed as possible.
Incisions perpendicular to the eponychial fold may be necessary for adequate exposure of the germinal matrix (FIG 6).
FIG 6 • Incisions made perpendicular to eponychial fold for exposure of the germinal matrix.
TECHNIQUES
DRAINAGE OF SUBUNGUAL HEMATOMA
A standard surgical preparation is performed to prevent introducing bacteria into the subungual space.
Trephination of the nail can be accomplished using a heated paper clip, needle, or handheld battery-powered cautery (TECH FIG 1).
Nail removal and repair is recommended if more than 50% of the nail is lifted up by the underlying hematoma or if the nail edges are not intact.
TECH FIG 1 • Trephination of the nail to drain a subungual hematoma using a heated paper clip (A) or battery-powered cautery (B).
REPAIR OF NAIL BED LACERATION
Use a digital block, standard surgical preparation, and a Penrose drain at the base of the digit to serve as tourniquet.
Use the Kleinert elevator to separate the nail plate from the nail bed for adequate exposure (TECH FIG 2A).
Repair the laceration under loupe magnification using simple sutures of 7-0 chromic (TECH FIG 2B).
Avoid aggressive débridement of the nail bed.
Clean the nail plate, soak it in Betadine, and rinse it with normal saline; then place it back into the proximal fold to maintain this space and to serve as a splint for a distal phalanx fracture (TECH FIG 2C).
TECH FIG 2 • Repair of nail bed laceration. A. Laceration with nail plate present. The nail plate is cleaned and will be used later as a splint to maintain the eponychial fold. B. Repair of nail bed and surrounding skin after débridement. (continued)
TECH FIG 2 • (continued) C. Nail plate being placed back into fold. D. Completed nail bed laceration repair.
A figure 8 suture of 5-0 nylon or a simple stitch from nail to hyponychium can be used to hold the nail in place if desired (TECH FIG 2D).
A silicone sheet may be used if the nail plate is not available.
Repair of a nail bed avulsion and resultant proximal germinal matrix disruption may require incisions perpendicular to the curved portion of the eponychial fold for exposure.
TREATMENT OF NAIL BED DEFECTS
A defect amenable to reconstruction may be present after excision of scar (causing nonadherence or a split nail deformity) from prior injury to the nail bed (TECH FIG 3A).
Small areas (less than 5 mm) can be left to heal by secondary intention but may result in recurrent scarring and nail deformity.
Defects larger than 5 mm can be treated with splitthickness nail bed grafts from the adjacent noninjured nail bed, the nail bed from another digit, or the nail bed from a toe (TECH FIG 3B).2,6,9,13
Prepare and drape the recipient and donor sites in standard surgical fashion and perform a digital block.
Exsanguinate the digit and place a Penrose drain tourniquet at its base.
Expose both nail beds and measure the defect.
Harvest split-thickness nail bed graft from the sterile matrix of the donor digit using a no. 15 scalpel (TECH FIG 3C,D).
To reduce the risk of donor-site nail deformity, the germinal matrix should not be used as a graft for a defect of the sterile matrix.
Graft is carefully harvested by placing the blade parallel to the nail bed and taking it thin enough so that the blade can be seen through the graft.
Suture the split-thickness nail bed graft in place using 7-0 chromic, as is done in a laceration repair (TECH FIG 3E).
Reconstruction of the germinal matrix with subsequent nail growth on the recipient digit requires harvest of a full-thickness germinal matrix graft from a toe (preferably the second toe) (TECH FIG 3F).10
TECH FIG 3 • Treatment of nail bed loss with split nail graft. A. Initial presentation of this nail bed crush injury. B. Available tissue has been repaired, leaving a significant nail matrix defect. Exposed bone is visualized deep to the defect. C. Harvest of split sterile nail matrix graft from toe. D. Harvested split sterile nail matrix graft. E. Graft inset into defect to cover the exposed bone. F. Harvest of germinal matrix from the toe.
NAIL MATRIX ABLATION
A nail remnant may grow at the site of a previous nail ablation (TECH FIG 4A). It may grow in a dorsal direction, catching on clothes and requiring frequent clipping. This remnant may be a source of persistent pain, irritation, or infection.
A cyst may form from a nail remnant after a revision amputation and become a source for a subcutaneous abscess (TECH FIG 4B).
Complete excision of the residual germinal matrix is the goal of treatment.
It is important to tell the patient that a nail will no longer grow at the fingertip.
Re-enter the old incision, preserving skin to allow adequate primary closure.
Dissect to the proximal portion of the distal phalanx at the expected location of germinal matrix.
The distal interphalangeal joint is used as a landmark to guide dissection to the level of the germinal matrix. It may be difficult to distinguish scar from residual germinal matrix after traumatic injury.
Use a scalpel, curette, or rongeur (or some combination) to ablate the residual nail bed germinal matrix (TECH FIG 4C,D).
To preserve length yet fully ablate the nail, a full-thickness skin graft can be used to cover the distal phalanx.
The distal phalanx is a unique area where a skin graft may survive even after being placed directly on bone without the presence of periosteum.
TECH FIG 4 • A. Right small finger after nail bed avulsion from fingertip trauma treated with nail bed ablation. Fullthickness skin graft was placed directly on the distal phalanx to preserve length and avoid revision amputation. Good take of skin graft was seen, but a nail remnant appeared on the proximal ulnar aspect of the fingertip, causing pain. B. Subcutaneous abscess from a nail remnant after revision amputation. C. Ablation of symptomatic nail remnant shown in A. An elliptical incision was made and all residual germinal matrix was removed with a scalpel. A curette was used to scrape the distal phalanx. D. A nail cyst is seen after incision and drainage of the abscess shown in B. The nail remnant was found within the cyst. Cyst and nail remnant were removed, and symptoms resolved.
TREATMENT OF HOOK NAIL DEFORMITY
Hook nail deformity can be caused by overaggressive débridement of the distal phalanx, resulting in lack of support, or by too much tension on the closure at the tip, creating an unnatural, curved appearance of the nail.
If the germinal matrix is still present, the nail will continue to grow but will hook without adequate bony support.
Three treatment options exist: doing nothing, reconstruction of the nail to produce a flatter nail with or without bone graft, and revision amputation.
Additional soft tissue bulk to the volar pad may be required to support the reconstructed nail.
A thenar flap is available for reconstruction of the index or middle fingertips.
Bone graft can be used for support, but there is a high rate of resorption.
A favorable cosmetic result is often difficult to achieve.
TREATMENT OF PINCER NAIL DEFORMITY
The goal of treatment is to flatten out the excessive curvature of the nail and correct the “pinched-in” appearance of the nail (TECH FIG 5A).
Elevate the lateral margins of the nail bed from the distal phalanx using a Kleinert-Kutz elevator (TECH FIG 5B).
Avoid injuring the paronychium as the nail bed is elevated.
Make stab incisions on the ulnar and radial fingertip.
Through these stab incisions, create subcutaneous tunnels to the radial and ulnar eponychium using the elevator. Make a second set of stab incisions at that proximal location (TECH FIG 5C).
Cut dermal graft or AlloDerm to the appropriate length and place it through each tunnel.
Pull the graft through the tunnel, distal to proximal, with the aid of a suture. This positions the graft in the desired location (TECH FIG 5D).
Close the stab incisions with 6-0 nylon and replace the nail (TECH FIG 5E,F).
TECH FIG 5 • Treatment of pincer nail deformity. A. Pincer nail deformity with characteristic “pinched-in” appearance. B. The lateral borders of the nail are lifted from the distal phalanx in an atraumatic manner with a Kleinert-Kutz elevator. C. Creation of subcutaneous tunnels through stab incisions on the radial and ulnar sides. D. Placement of AlloDerm or dermal graft in subcutaneous tunnel. The graft is pulled into the tunnels with the aid of a suture in a distal-to-proximal direction. E. The wounds are closed and the stitch is placed to hold the nail under the proximal nail fold. F. Postoperative appearance.
POSTOPERATIVE CARE
The postoperative dressing is left on for 5 to 7 days and may need to be soaked in a mixture of hydrogen peroxide and water for removal. The repaired nail is checked for signs of infection, seroma, and hematoma.
Nonadherent gauze placed to maintain the eponychial fold should be removed. Any suture used to hold the nail or silicone sheet within the fold should also be removed at 5 to 7 days postoperatively.
Sutures placed in the skin of the hyponychium or paronychium should be removed at 10 to 14 days after repair.
A fingertip splint that does not include the proximal interphalangeal joint can be used for the first 3 to 5 weeks after injury to protect the nail bed repair and immobilize a distal phalanx fracture if present.
Early motion of the proximal interphalangeal joint should be encouraged. The fingertip splint provides protection of the tip and will allow earlier motion of the injured digit.
Hypersensitivity of the tip may be present for 1 to 3 months after injury, and desensitization exercises may be necessary to promote use of the affected digit.
OUTCOMES
While repair in the acute period provides the best chance for a normal-appearing nail (FIG 7), scarring at the site of injury may produce a nail deformity, and patients should be reminded of this possibility at the time of repair.10,13,14
Results of nail bed repair are adversely affected by avulsion or crush injury of the fingertip, presence of a distal phalanx fracture, three or more sites injured, and the need to use a silicone sheet for replacement of the nail.1,4,13
Late reconstruction of the nail bed is often not as successful as surgeon or patient would desire.9
Management plans must be individualized and realistic expectations must be discussed when treating patients with nail bed injuries.
FIG 7 • Appearance of the nail in Techniques Figure 3, 1 year after nail matrix reconstruction with a split graft from the toe.
COMPLICATIONS
Complications in the acute or subacute setting include soft tissue infection, osteomyelitis of the distal phalanx, nonunion of the distal phalanx fracture, and posttraumatic stiffness and loss of motion at the distal interphalangeal joint.
Complications or unfavorable outcomes in the chronic setting include scarring in the sterile matrix, leading to a split nail or nonadherent nail; scarring at the eponychial fold, which may interfere with nail plate growth; and persistent nail growth after an unsuccessful attempt at nail ablation.
REFERENCES
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2. Brown RE, Zook EG, Russell RC. Reconstruction of fingertips with combination of local flaps and nail bed grafts. J Hand Surg Am 1999;24A:345–351.
3. Brown RE, Zook EG, Williams J. Correction of pincer-nail deformities using dermal grafting. Plast Reconstr Surg 2000;105:1658.
4. Guy RJ. The etiologies and mechanisms of the nail bed injuries. Hand Clin 1990;6:9–21.
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10. Zook EG. Reconstruction of a functional and aesthetic nail. Hand Clin 2002;18:577–594.
11. Zook EG. The perionychium: anatomy, physiology and care of injuries. Clin Plast Surg 1981;8:21–31.
12. Zook EG, Brown RE. The perionychium. In Green DP, ed. Operative Hand Surgery, 3rd ed. New York: Churchill Livingstone, 1993.
13. Zook EG, Guy RJ, Russell RC. A study of nail bed injuries: causes, treatment and prognosis. J Hand Surg Am 1984;9A:247–252.
14. Zook EG, Van Beek AL, Russell RC, et al. Anatomy and physiology of the perionychium: a review of the literature and anatomic study. J Hand Surg Am 1980;5:528–536.