Case Reoprt: Isolated fracture of pisiform: case report of a rare injury of wrist

Isolated fracture of the pisiform is an extremely rare injury. Generally fractures of the pisiform are associated with fractures of other carpal bones or the distal radius. Fractures of the carpals and metacarpals account for roughly 6% of all fractures. The average incidence of pisiform fractures is 0.2% of all carpal fractures and approximately half of them are isolated fractures. Fracture of the pisiform may be missed on standard radiographs due to orientation of the fracture, improper wrist positioning, superimposition of adjacent bones, an inadequate number of projections or more obvious fractures of other carpal bones. Special radiographic projections such as carpal tunnel, scaphoid or supinated oblique view are indicated if routine AP and lateral views fail to demonstrate a fracture. MRI is the second-step imaging method in patients whose radiographs are negative or indistinct. MRI not only shows the fracture line but also shows marrow edema within the pisiform bone indicating fracture. Late sequels include pisotriquetral chondromalacia, subluxation and osteoarthritis consequent to poor alignment of the articular surfaces. KEY WORDS: Isolated fracture; Pisiform; Wrist injury