Seymour Fracture and Paediatric Nail-bed Injuries

A Seymour fracture is a paediatric distal phalanx physeal or juxta-epiphyseal fracture with associated nail-bed injury. In practical terms it is an open fracture until proven otherwise: the X-ray may look small, but the open nail-bed wound makes the injury high risk.

The trap. Seymour fractures resemble mallet finger, but the treatment is different. Each finding that suggests a mallet has a different meaning here, and a cost if it is treated as one.

Four questions. The consultation should answer them in turn:

1. Is this a nail-bed wound communicating with bone?
2. Is the fracture through or near the open distal phalanx physis?
3. Is germinal matrix or nail bed interposed in the fracture?
4. Is the reduction stable after the soft-tissue block is cleared?

The great toe. The great toe has an equivalent injury after axial load or stubbing trauma. It is less commonly discussed than the finger injury, but the logic is the same: nail-bed injury plus distal phalangeal physis involvement requires open-fracture thinking.

Where it is missed. In a series of five boys with open physeal fractures of the hallux distal phalanx, 40% were initially missed and 60% arrived as transfers. It is a small series, but the pattern is consistent with how these present: a stubbed toe with a bit of blood at the nail fold does not read as an open fracture to anyone. Treat the recognition step as the hard part.

Once it is recognised. Suture-only stabilisation produced no infections, no reoperations and no physeal bars on follow-up imaging, so the toe does not necessarily demand K-wire fixation once it is recognised and properly cleaned. The evidence level is low: five patients, short median follow-up, and suture-only fixation has not been compared directly against pinning.

Mechanism. The usual mechanism is a crush or forced-flexion load to the fingertip. Door-crush injuries are common, but ball sports, falls, machinery, direct blows and toe-stubbing injuries can produce the same pattern. The child often presents with pain, swelling, bleeding at the nail fold and a fingertip that appears flexed at the DIP joint.

The physis. The distal phalanx physis lies near the base of the distal phalanx, close to the nail-bed complex. The load forces the distal phalanx into a flexed posture through the weak physeal or juxta-epiphyseal region, so the fracture passes through or near the growing base of the bone.

The tendons. The terminal extensor tendon is attached dorsally near the epiphysis, which creates the mallet-like posture that misleads the clinician. The FDP insertion is volar and distal; it contributes to the flexion posture and to control of the distal fragment.

The germinal matrix. This is the important soft-tissue structure. It produces most of the nail, sits deep to the proximal nail plate and tears at the same level as the fracture. When the nail plate is avulsed or displaced, the germinal matrix can fold into the fracture gap, which creates two problems:

• It blocks reduction
• It leaves devitalised or contaminated soft tissue inside an open physeal fracture, which increases infection risk

Why it is open. The open physis and the nail-bed laceration connect the outside environment with the growth plate and the distal phalanx. That is why the injury behaves differently from a simple tuft fracture or mallet finger, and why early antibiotics, debridement, reduction and nail-bed repair matter.

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Four injuries in one. Like a mallet finger, the distal phalanx appears flexed. Like an open fracture, there is communication through the nail bed. Like a physeal fracture, growth disturbance is possible if it is missed or infected, and like a nail-bed laceration, the final nail appearance depends on precise soft-tissue repair.

Why it is underestimated. The wound may be tiny, the child may move the finger, and the X-ray may show only subtle physeal widening. The red flag is the combination of distal phalanx posture and proximal nail-fold injury.

History. The history should quickly determine mechanism, contamination, delay and infection risk. Beyond the mechanism, establish:

• Time from injury - delayed presentation changes infection risk and debridement planning
• Nail symptoms - bleeding at the proximal nail fold, nail plate avulsion, a nail plate sitting high, subungual haematoma or a visible nail-bed wound
• Contamination - soil, farm injury, water exposure, bite, dirty sports field or foreign material
• Previous treatment - antibiotics, splinting, trephination, nail removal or attempted reduction
• Infection symptoms - increasing pain, redness, discharge, fever, odour or progressive swelling
• Functional context - digit involved, hand dominance, school or sport needs, and associated fingertip injuries

Examination. Inspection is the most important part. A Seymour fracture may look like a minor nail injury unless the proximal nail fold is examined carefully.

The nail plate sign. A normal nail plate tucks beneath the eponychial fold. In a Seymour fracture its proximal edge may sit on top of the fold, making the nail look too long, and a plate perched there means the germinal matrix is likely disrupted. This subtle sign may be more obvious than the X-ray.

Motion misleads. A child may still flex through the FDP and may have pain-limited extension. Preserved motion does not exclude an open physeal injury.

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Radiographs. Obtain dedicated true AP and true lateral radiographs of the affected digit, not just a hand X-ray. The AP view helps with alignment and associated fractures, but the true lateral is the key image: it shows the relationship between the distal phalanx epiphysis, physis, metaphysis and nail plate. Look for:

• Widening of the distal phalanx physis
• A Salter-Harris I or II pattern, or a juxta-epiphyseal fracture just distal to the physis
• Flexion deformity or volar angulation of the distal fragment
• Nail plate displacement or soft-tissue swelling
• Subtle physeal asymmetry compared with the contralateral digit, if uncertain

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Imaging does not replace the nail fold. A tiny radiographic abnormality with proximal nail-fold bleeding is still clinically important. Conversely, an apparent mallet posture in a skeletally immature patient should not be accepted as a simple tendinous mallet injury until the nail bed and the lateral film are reassuring.

Blood tests and MRI. In a delayed or infected case, FBC, CRP, ESR and cultures (if there is discharge or systemic illness) guide infection severity and the antibiotic plan. When osteomyelitis is suspected, MRI defines marrow involvement and abscess if the extent is uncertain or the symptoms are disproportionate.

The differential matters because each injury has a different treatment pathway.

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The principle. A Seymour fracture is small in size but high in consequence. If the nail bed is violated and the distal phalanx physis is injured, it is an open fracture, and the aims follow: prevent infection, remove the soft-tissue block, restore distal phalanx alignment, repair the nail bed, protect the reduction until union, and follow the nail and physis.

Emergency care. Before anything definitive:

• Give analgesia and protect the fingertip with a sterile dressing
• Treat as an open fracture when nail-bed laceration or proximal nail-fold bleeding is present
• Start antibiotics according to local open-fracture and hand-injury protocol
• Check tetanus status
• Obtain dedicated digit X-rays before definitive manipulation, unless vascular compromise demands immediate action

Aftercare. The wound and the reduction both need watching:

• Non-adherent dressing, protective splint and elevation advice
• Early review for the wound, nail fold, pain, discharge and, if wired, the pin site
• Repeat X-ray to confirm maintained reduction and union
• Wire removal according to healing and local practice, commonly around three to four weeks
• Warn parents to return for increasing pain, redness, fever, discharge, foul smell or pin loosening

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Preparation. Confirm the diagnosis clinically and radiographically, and give antibiotics according to local open-fracture and paediatric hand protocols. Use a digital block, sedation or general anaesthesia depending on age, cooperation and local practice, and prepare and drape the hand so the digit can be assessed and imaged properly.

Consent. Explain the operation as open-fracture care plus nail-bed reconstruction, and cover open fracture care, nail-bed repair, possible K-wire fixation, infection, nail deformity, stiffness, malunion, non-union, physeal disturbance and possible further surgery.

Exposure and debridement. Operative care should be meticulous but not aggressive.

Clearing the reduction block. The germinal matrix or nail bed is often folded into the fracture, which is why closed reduction may repeatedly fail. Extract the interposed tissue gently with fine instruments, and do not keep forcefully manipulating the distal phalanx against a soft-tissue block.

Reduction and fixation. Reduce the distal phalanx anatomically and confirm alignment clinically and on AP and lateral imaging. Whether to wire depends on stability:

The wire often crosses the DIP joint to hold the distal phalanx, but fixation should follow fracture stability, child factors and local hand-surgery practice. Avoid repeated physeal trauma during wire placement.

Nail-bed repair. Repair the germinal or sterile matrix precisely with fine (6-0 or 7-0) absorbable sutures, under good lighting and magnification where available. The aim is smooth nail-bed continuity without inversion, overlap or excessive tension.

Stenting the fold. Preserve a clean nail plate if it can be reused. Replace it, or a sterile substitute, beneath the eponychial fold as a stent, to prevent fold adhesion (synechiae) and support nail regrowth.

The infection numbers. Across 35 open Seymour fractures at a level 1 paediatric trauma centre, infection rates fell into three tiers: 0% (0/11) with acute appropriate treatment, 15% (2/13) with acute partial treatment and 45% (5/11) with delayed treatment. There were 7 infections in total, 5 of them osteomyelitis.

The middle tier changes practice. "Appropriate" meant all three of irrigation and debridement, fracture reduction and antibiotics. Children treated acutely but incompletely, reduced without proper debridement or splinted with antibiotics but never formally cleaned, still had a 15% infection rate.

Completeness protects the child. Speed alone does not. Seeing the patient within 24 hours and then doing two of the three things is a substantially worse outcome than doing all three, and that is the single most useful sentence to carry into a viva. It reframes the injury from "a mallet that needs a quick splint" to "an open physeal fracture that needs open-fracture treatment".

The counterweight. Of 65 consecutive children presenting within 24 hours, 58 (89%) were managed successfully in the emergency department with irrigation, debridement, reduction and a first-generation cephalosporin such as cephalexin. Only 7 required primary theatre, usually for unsuccessful closed reduction, and complications were rare, superficial infection the commonest.

Not every Seymour fracture goes to theatre. A stable, adequately reduced, properly debrided acute injury can be definitively treated in the emergency department, and theatre is for unsuccessful or unstable reduction. Four emergency-department children needed unplanned later surgery, usually for redisplacement, so the follow-up appointment is part of the treatment. Both series are retrospective and single-centre, and "stable reduction" is operator-dependent.

Antibiotic choice. Choice and duration should follow local paediatric open-fracture and hand-injury protocols, and a typical clean acute injury is usually covered for skin flora. Gross contamination, a bite, or farm or water exposure changes antibiotic and debridement planning. Broaden the discussion with senior clinicians for these, and for immunocompromise, delayed presentation or established infection.

Early complications include:

• Missed open fracture and delayed antibiotics
• Pin-site infection when fixation is used
• Loss of reduction from unrecognised matrix interposition or inadequate fixation
• Soft-tissue necrosis from crush injury or tight dressings
• Persistent pain, swelling and stiffness

Late complications include:

• Osteomyelitis, especially after delayed diagnosis
• Non-union or malunion of the distal phalanx
• Persistent mallet deformity or extensor lag
• Nail deformity, including ridging, split nail, hook nail or absent nail growth
• Premature physeal arrest and distal phalanx growth disturbance
• DIP stiffness and a hypersensitive fingertip

How common. In a review of 206 paediatric distal phalanx fractures, Seymour fractures accounted for only 6% of the cohort but carried a 62% complication rate. That is second only to Salter-Harris IV injuries (100%) and clearly above mallet fractures (49%), against an overall rate of 31% across all distal phalanx fractures. The commonest complications were infection (22%), stiffness (15%) and nail deformity (13%).

Small injury, big consequence. A fingertip injury that looks trivial to a parent and to a busy department sits among the highest-risk distal phalanx fractures a child can sustain, which is why the open-fracture discipline above is not over-treatment. Note the design before quoting the figures: a single-centre retrospective review with clinician-recorded rather than independently adjudicated complications.

Follow-up. Structured follow-up is not optional, because nail deformity and stiffness declare late. Review covers union, the pin site, infection, nail growth, mallet posture and the physis. The child is seen until the nail has grown out and the DIP is moving, and nail growth and distal phalanx growth are followed until the complication window has passed.

The strongest answer starts by naming the injury correctly: an open distal phalanx physeal or juxta-epiphyseal fracture with nail-bed injury. That opening phrase immediately separates it from a simple mallet finger.

The next step is to explain why the clinical appearance is deceptive. The distal phalanx is flexed, but the nail fold is the dangerous clue. If the proximal nail plate sits superficial to the eponychial fold, the germinal matrix has probably been disrupted. If germinal matrix is trapped in the fracture, reduction fails until the tissue is cleared.

Nail-bed repair is not cosmetic trivia. It is part of fracture management because the nail bed and fracture communicate. Poor matrix alignment causes nail deformity. Missed contamination causes infection. Persistent soft-tissue interposition causes malunion, non-union or redisplacement.

A safe family explanation is:

"This is a small bone injury at the end of the finger, but because the nail bed is torn it behaves like an open fracture. We need to clean it properly, put the nail bed and bone back in the right position, give antibiotics, and then watch for infection, healing and nail growth."

Common pitfalls

• Calling it a mallet finger and treating with extension splint alone.
• Ordering only a hand X-ray and missing the true lateral digit view.
• Not looking under or around the proximal nail fold.
• Trying repeated closed reductions despite a soft-tissue block.
• Forgetting antibiotics and tetanus assessment.
• Repairing skin but leaving the nail bed and physis untreated.

The Seymour fracture is too rare to feature in standalone society guidelines or arthroplasty registries; instead it is governed by general paediatric open-fracture principles, which are broadly concordant across major bodies. The clinically useful comparison is therefore between the open-fracture frameworks that surgeons apply to this injury worldwide.

Global epidemiology

• Seymour fractures account for roughly 6 percent of paediatric distal phalanx fractures in referral series, making them uncommon but clinically high-consequence.
• Peak incidence is in school-age children and early adolescents (mean age around 9 to 10 years across series), reflecting open-physis anatomy and crush mechanisms.
• A boy predominance is consistent across hand and great-toe series. The middle finger and great toe are the most exposed digits.
• Diagnostic delay is common worldwide, with up to a third of cases presenting or being treated late, driving the infection and osteomyelitis burden.

Side-by-side principles from major bodies

High- versus limited-resource practice variation

The unifying message across every framework is identical: recognise the hidden open fracture, give early antibiotics, clear the soft-tissue block, repair the nail bed and protect the physis.

The Seymour fracture is uncommon, so the evidence base is dominated by small retrospective series and a single registered systematic review protocol rather than randomised trials. Several practical questions remain genuinely unsettled, and they are favourite viva discussion points.