Fingertip Injuries & Amputations

Definition. A fingertip injury is one distal to the insertion of flexor digitorum profundus and the extensor tendon. That territory holds two specialised organs, the nail complex and the highly sensate digital pulp, and it is the commonest injury in the hand.

The goal. Treatment aims to restore a functional, sensate and non-painful tip. Flap reconstruction is elegant, but for small defects simple healing by secondary intention often gives the better functional and cosmetic result.

What a reconstructed tip must be. Sensate, with useful tactile gnosis; painless, meaning no neuroma; durable, meaning thick padding; and stable, so the pulp does not shift under pinch. Every option below is judged against those four.

The perionychium. The nail plate is hard keratin. It is made almost entirely by the germinal matrix, the proximal part of the nail bed lying under the fold and extending proximally as far as the insertion of the extensor tendon; it produces 90% of the plate, so injury here stops the nail growing or splits it. The sterile matrix is the distal part of the bed, under the plate and distal to the lunula, and it produces only a thin layer of keratin whose job is to keep the plate stuck to the bed; scar here gives a non-adherent nail.

The surrounding skin has its own names. The hyponychium is the thickened skin at the distal edge and a barrier to infection; the eponychium is the dorsal fold, the cuticle; the paronychium is the lateral fold on each side.

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Nail growth. A fingernail grows about 0.1mm a day, roughly 3mm a month, so the whole plate is replaced in about 100 days, three to four months. Toenails grow at half that speed.

The pulp. The pulp is highly specialised skin stabilised by Cleland's and Grayson's ligaments. Its fibrous septae stop the skin shearing under load, and they also contain infection, the pulp abscess or felon. Once the septae are disrupted the pulp moves like a bag of fluid. Sensibility is paramount: two-point discrimination is 2-4mm.

Blood supply. The digital arteries trifurcate at the level of the DIPJ. A dorsal branch supplies the nail matrix, a volar branch the pulp, and an arcade connects the two sides distally. That rich anastomosis is what lets a flap like the Atasoy survive on nothing more than subcutaneous perforators.

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Allen. The level of tissue loss, from distal to proximal, decides how much can be left to heal and how much needs bone or a flap. Types I and II are the most amenable to conservative management; the more proximal the level, the more often bone shortening or flap coverage is needed.

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Geometry. The angle of the cut decides which local flap, if any, will reach:

• Transverse - a guillotine cut
• Dorsal oblique - more nail lost than pulp; a V-Y flap can be used
• Volar oblique - more pulp lost than nail; harder to treat because there is not enough pulp left for a V-Y
• Lateral - a side slice

Volar oblique injuries have the worst prognosis for local flap coverage.

Presentation. The patient arrives acutely after a mechanism they remember clearly: a crush in a door or under a hammer, a sharp laceration from a knife or saw, or an avulsion from a ring or a pull. They report throbbing pain, bleeding and an obvious deformity or loss of tissue. The clinical task is rapid triage into a treatable category: is there exposed bone, is the nail bed disrupted, and is there a concealed tendon injury shown by loss of active DIP flexion or extension?

History. The mechanism predicts the injury: a crush bursts the nail bed, a laceration cuts it cleanly, an avulsion pulls. The rest of the history decides what the patient needs from the tip and how well they will heal.

• Time since injury - clean wounds can be closed up to 12-24 hours
• Occupation - a manual labourer needs a durable tip; a pianist needs sensation and shape
• Hand dominance - the index finger and thumb are critical
• Hobbies - musical instruments, sport, fine motor activities
• Smoking - a risk for flap necrosis, and cessation is critical if a Moberg or Atasoy flap is planned; counsel now
• Diabetes - impaired healing and infection risk
• Medications - anticoagulants, immunosuppressants

Red flags. Each of these needs urgent specialist referral:

• Tendon injury - inability to flex the DIP means a lost FDP, a zone 1 injury
• Jersey finger - FDP avulsion with a bone fragment, seen as a volar fragment on the radiograph
• Mallet finger - extensor avulsion with a DIP droop
• Vascular compromise - a cool, pale or cyanotic digit
• Compartment syndrome - rare in the fingertip; consider it after a severe crush
• High-pressure injection - paint or grease under pressure needs emergent debridement

Examination. Test sensation first, two-point discrimination against a normal of 2-4mm, and document it before any lignocaine goes in. Then perfusion: capillary refill, temperature, and an Allen's test to the digits.

• Bone exposure - look carefully and probe the wound; small exposed tufts may granulate
• Nail bed - subungual haematoma, laceration or avulsion
• Nail plate - intact, lacerated, or avulsed from the fold
• Tendons - confirm FDP and extensor function if the injury is proximal to their insertions
• Defect size - measure it in millimetres; it drives the treatment plan

Assessing a subungual haematoma. Estimate the percentage of the nail involved, decide whether the plate is lacerated or avulsed, check that it is still seated in the eponychial fold, and look for haematoma extending beyond the nail bed. Those four observations, not the size alone, decide whether the nail comes off.

Radiographs. PA and lateral views of the finger. The tuft fracture is the common finding after a crush, a comminuted fracture of the distal tip that usually needs no fixation; a shaft fracture may need a K-wire. Look also for the avulsion fractures that mark a tendon injury, an FDP avulsion (jersey finger) or an extensor avulsion (mallet), and for glass or metal foreign bodies.

Ultrasound finds the radiolucent foreign body, a thorn or a splinter of wood, that the radiograph cannot show.

The "differential" in fingertip trauma is less about disease and more about correctly categorising the injury, because the category dictates the treatment. Misclassification is the commonest source of error.

The decision. Two questions sort almost every fingertip: is bone exposed, and is it the thumb?

1. No exposed bone and a defect under 1cm - dressings and secondary intention. This gives the best sensation and the best padding.
2. Exposed bone - shortening is simple and effective and suits a labourer; a local flap if length must be preserved; a graft takes poorly over bare bone, which needs periosteum to support it.
3. The thumb - a distinct entity, in which length is critical and preserving it outweighs cosmetic concerns. The Moberg flap is the answer.

Secondary intention. Clean the wound, apply a non-adherent dressing and change it weekly. Healing takes 3-5 weeks, during which the wound contracts by about 50%; the result is excellent sensation and a durable tip. Exposed bone is the contraindication, because of the risk of osteomyelitis, though tips often granulate over a small exposed tuft. Patience is the treatment, so warn the patient about the "ugly duckling" phase before it arrives.

Algorithm

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Choosing the flap. The geometry of the defect and the digit choose the flap, and each flap is defined by the vessel it lives on and the direction it moves.

AtasoyMobergCrossFingerNailBed

The V-Y advancement flap. For the transverse or dorsal oblique amputation. Draw a V on the volar pulp with its apex at the DIPJ crease, so that the scar does not contract across the joint. Cut skin only, then tease the fibrous septae deep to the flap to free it; the base carries the blood supply and must not be undercut. Advance the flap distally over the bone and close it as a Y. It advances about 5-10mm at most.

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The Moberg flap. For the thumb tip, and only the thumb. The thumb alone has dorsal blood supply dominance, so the whole volar skin can be lifted on both neurovascular bundles without the dorsal skin dying; in a finger the same dissection risks dorsal skin necrosis. Make mid-lateral incisions on both sides, elevate the entire volar skin with both bundles off the flexor sheath, and advance it distally by up to 1-1.5cm; flexing the IPJ gains more length. The thumb IPJ is then splinted in flexion for 2-3 weeks.

The cross-finger flap. For the large volar oblique defect. Raise a skin flap from the dorsum of the adjacent finger's middle phalanx, fold it over to cover the volar defect, and skin-graft the donor site. It costs two stages, a risk of stiffness and an ugly donor scar. The classic use is an index finger defect covered from the dorsum of the middle finger.

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Nail bed repair. Use 6-0 or 7-0 chromic catgut or Vicryl Rapide under loupe magnification, which is essential; undermine the bed slightly to take the tension off the repair, and bring the sterile matrix together accurately, because a step here becomes a ridge in the nail. 2-octylcyanoacrylate glue is a faster alternative to suture. Replace the nail plate, or a foil substitute, as a splint that keeps the fold open and prevents synechiae.

The subungual haematoma. A haematoma over 50% of the nail under an intact plate is trephined, and only trephined, with a large 18G needle or cautery. Trephination is for pain relief, not volume reduction. The nail comes off for repair only when the plate is visibly disrupted or avulsed out of the fold.

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The Seymour fracture - the one to not miss in a child. A child with a bleeding nail fold, a slightly flexed fingertip and a "mallet-looking" DIP is not a closed mallet: it is a displaced Salter-Harris I or II fracture of the distal phalanx physis with the nail bed (germinal matrix) trapped in the fracture, and the torn nail fold makes it an open fracture communicating with the physis. The classic picture is the nail plate lying superficial to the eponychial fold rather than under it, with the tip held in flexion because the extensor inserts on the epiphysis and flexor digitorum profundus on the diaphysis.

Why it matters: treated as a closed mallet in a splint, it becomes osteomyelitis and physeal arrest with permanent nail deformity and a short digit. Treated properly it does well. Management is formal irrigation and debridement, extraction of the interposed nail bed from the fracture, nail bed repair, reduction (K-wire if unstable) and antibiotics - and take the child to theatre rather than treating it in the emergency department, since the only significant difference in complication rate in the paediatric nail-bed series below was more early infections when repair was done in the emergency room.

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Neuroma. A painful nerve ending. It is resected and the nerve end buried in muscle or bone.

Nail deformity. Scar in the germinal matrix gives a split nail; scar in the sterile matrix gives a non-adherent one. The hook nail is the third pattern and has its own cause and its own prevention.

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Hypersensitivity is common and is treated with a desensitisation programme of tapping and texture rubbing. Cold intolerance is a persistent problem after replants and flaps.

The principle. Early motion is what prevents DIPJ stiffness, and a desensitisation programme graded from soft to rough textures is what prevents a hypersensitive tip. A custom tip guard protects the return to work, work hardening simulates the job, and psychological support is worth offering, because fingertip injuries can be distressing.

Sensation. Healing by secondary intention gives better sensation, two-point discrimination of 3-4mm, than a graft or a cross-finger flap, which manage 6-8mm. Cold intolerance follows the same pattern: rare after secondary intention, common after a flap.

Appearance. A flap looks better at first, but secondary intention produces a surprisingly normal fingerprint pattern. In the long term, nail deformity is the most common complaint.

Global Epidemiology

• Burden: The fingertip is the single most commonly injured part of the hand worldwide; distal phalanx/fingertip trauma accounts for a large share of all hand injuries presenting to emergency departments across high- and low-income settings.
• Demographics: Bimodal pattern. A working-age male peak (roughly 20-50 years) driven by machinery, power tools and crush injuries; and a young-child peak (1-4 years) driven by door-crush injuries to the dominant-hand digits.
• Mechanism: Doors are the leading cause in children; industrial machinery, saws and presses dominate occupational injury globally.
• Most-injured digits: Middle and ring fingers (longest, most exposed in grip); the thumb is treated as a distinct priority because of its functional dominance.

Guidelines Compared Side by Side

Registry & Outcome Notes

• Fingertip injuries are not implant procedures, so they do not feature in joint registries (NJR, AJRR, AOANJRR). The evidence base instead rests on RCTs and systematic reviews (antibiotics, glue vs suture, subungual haematoma) and large conservative-management series.
• National hand-trauma networks (e.g. UK BOAST hand-trauma standards, regional trauma datasets) emphasise early senior decision-making and access to hand therapy as the key determinants of outcome.

High- vs Limited-Resource Practice Variation

• High-resource settings: Ready access to operating theatres, microsurgery and dedicated hand therapy enables flap reconstruction, composite grafting in children and formal nail bed repair under loupe magnification.
• Limited-resource settings: Conservative management (secondary intention / semiocclusive dressing) is especially valuable — it is cheap, avoids theatre time, needs no microsurgical skill and reliably restores a sensate, durable pulp for small and moderate defects.
• Universal principles: Tetanus prophylaxis per local immunisation status, meticulous wound toilet, preservation of length (especially the thumb), and early mobilisation to prevent DIPJ stiffness apply everywhere regardless of resource level.

Repair or decompress the nail bed. Traditional teaching mandated nail removal and formal nail bed repair for any subungual haematoma over 50 percent. Systematic review evidence (Dean et al.) shows no cosmetic advantage of repair over simple decompression when the plate is stable. The pragmatic position is to decompress the painful nail and reserve formal repair for a clearly avulsed or disrupted plate.

Conservative or flap for exposed bone. A small area of exposed bone is not an absolute indication for a flap. Many tips granulate and epithelialise over a small exposed tuft under occlusive dressings, with excellent sensation at the end of it. Flaps preserve length faster but add donor morbidity, stiffness and cold intolerance, so the decision is patient-specific: occupation, length needs and comorbidity.

Composite grafting in adults. Replacing the amputated tip as a composite graft is reliable in young children but unpredictable in adults, where take is poor distal to a few millimetres. There is no firm age cut-off; success falls with age and with a more proximal level of injury.

Antibiotics - how far the evidence goes. The RCT evidence against routine antibiotics applies to clean, well-irrigated open distal phalanx fractures in healthy adults. It should not be extrapolated uncritically to grossly contaminated, bite, farmyard or immunocompromised injuries, where prophylaxis remains reasonable.