Seymour Fracture

A Seymour fracture refers to juxtaepiphyseal fractures of the distal phalanx of the finger. These include transverse fractures of the proximal metaphysis of the distal phalanx, as well as Salter 1 and 2 physeal fractures of the distal phalanx.

Clinically, Seymour fractures can mimic a mallet finger (flexion at the distal interphalangeal (DIP) joint and extension at the proximal interphalangeal joint). However, Seymour fractures do not lead to true mallet fingers, because the flexion in a Seymour fracture is at the fracture plane, not at the DIP joint.

The mechanics of the flexor and extensor tendon insertions at the DIP joint help explain the appearance. The terminal extensor tendon inserts on the epiphysis only, while the flexor digitorum profundus tendon inserts at both the epiphysis and metaphysis. Therefore, a fracture of the proximal metaphysis or through the physis will lead to unopposed flexion of the distal fracture fragment.

While traditionally described in children and adolescents, this pattern of fracture can also be seen in adults when the fracture plane is just distal to the insertion of the extensor tendon.

Seymour fractures are often open and associated with tarnsverse lacerations through the nail bed. While Dr. Seymour's initial paper in 1966 reported that Kirschner wire (K-wire) fixation led to unacceptably high rates of complication, recent studies have found that proper debridement and antiobiotic prophylaxis are vital to forestall osteomyelitis with K-wire fixation.

References

• Al-Qattan MM. Extra-articular transverse fractures of the base of the distal phalanx (Seymour's fracture) in children and adults. J Hand Surg Br. 2001 Jun;26(3):201-6.
• Ganayem M, Edelson G. Base of distal phalanx fracture in children: a mallet finger mimic. J Pediatr Orthop. 2005 Jul-Aug;25(4):487-9.