The Seymour fracture is a physeal fracture of the distal phalanx with associated nail bed injury. Often there is associated subluxation of the nail (ungual subluxation).
It is a mallet finger type injury.
It is estimated that 20-30% of phalangeal fractures involve the physis in children. Physeal injuries of the middle finger are most common.
Seymour fracture involves distal phalanx physis and can be Salter-Harris I or II physeal injury.
The nailbed injury could be simple laceration or subluxation.
Germinal matrix could interpose between the fracture fragments.
The of the pattern of injury was first described N Seymour in 1966, a Scottish surgeon.
The injury is also called as juxta-epiphyseal fracture of the distal phalanx.
The mean age of this injury is about 10 years
Pathophysiology of Seymour Fracture
The injury can occur by direct trauma or crush injury. Fall of a heavy object, finger getting caught in the door are the common causes.
The injury typically occurs when the distal phalanx of a fully extended digit undergoes forceful flexion, or the distal phalanx gets crushed. The mechanism is similar to a mallet finger injury in adults.
The injury results in flexion deformity similar to mallet finger. The deformity occurs because there is an imbalance between the flexor and the extensor tendons at the level of the fracture.
This imbalance is created because the flexor and extensor tendons insert at different levels on the distal phalanx.
The extensor tendon inserts into the epiphysis of the distal phalanx and flexor tendon insert into metaphysis of the distal phalanx.
Sometimes, the tissue gets interposed between the fracture site and results in widening of the physis.
The patient is a skeletally immature patient who comes to seek help for a mallet finger deformity and associated soft tissue trauma at the proximal nail fold. T
Depending on the injury, the nail plate may show avulsion or subluxation.
The nail may lie superficial to the nail fold. Sometimes, the nail bed injury may be more proximal deep to the nail fold. There could be ecchymosis and swelling.
Recommended views are anteroposterior/posteroanterior and lateral views.
The x-ray typically shows a fracture demonstrating a Salter-Harris type I or type II pattern through the physis of the distal phalanx.
Or there could be a fracture involving the proximal metaphysis 1-2 mm distal to the epiphyseal plate.
In addition, there would be volar angulation of the diaphysis.
AP view x-rays may appear normal or could show widened physis or displacement between epiphysis/metaphysis
Flexion deformity at fracture site seen on the lateral view.
Disruption of the overlying soft tissue with or without subcutaneous emphysema.
In crush injuries, retained foreign bodies may be visible.
Mallet finger is a differential diagnosis. However, pediatric mallet finger is usually bony avulsion Salter-Harris type III or IV injuries.
Whereas mallet finger fracture line enters the distal interphalangeal joint, Seymour fracture line traverses physis and does not enter the joint.
Treatment of Seymour Fracture
Treatment could be nonoperative or operative.
The nonoperative treatment is indicated in closed fractures which are minimally displaced and there is no interposition of soft tissue at the fracture site.
The treatment consists of closed reduction and splinting for 3 weeks, followed by immobilization.
Operative treatment is indicated in displaced fractures, open fractures, and fractures with soft-tissue interposition making them nonreducible.
The closed displaced fractures without any soft tissue interposition can be managed by closed reduction and k-wire fixation across the distal interphalangeal joint.
Closed fractures with soft-tissue interposition require open reduction and pinning with K-wire.
Fractures with nailbed injuries also require nailbed repair.
Prognosis and Complications
A treated injury has a good prognosis.
A high index of suspicion should be maintained because the failure to recognize the injury can result in complications like
- Nail dystrophy
- Growth disturbance of the distal phalanx and nail
- Chronic osteomyelitis (esp in open injuries)
- Flexion deformity
- Malunion, non-union