Age / Sex : 20 / M

Chief complaint: acute finger pain after a hyperextension injury
                          

Avulsion fracture of the volar plate

Discussion

Findings:

 (a) The lateral radiograph of the second finger shows a small bone fragment (arrow) arising from the volar aspect of the base of the middle phalanx. (b) The longitudinal US image shows a small bone fragment (arrow) and adjacent fluid collection (arrowhead) at the volar aspect of the base of the middle phalanx. The volar plate is deformed and it has low echogenicity (open arrow). (c) The sagittal T1-weighted MR image shows an avulsion fracture of the volar plate (arrow). Irregularity of the donor site from the base of the middle phalanx is also seen (arrowhead).

Diagnosis: avulsion fracture of the volar plate

Discussion:

 A volar plate avulsion fracture is a common injury that occurs at the proximal interphalangeal joint. The volar plate is a fibrocartilaginous structure that is attached to the base of the middle phalanx distal to the joint and prevents hyperextension. Volar plate avulsion fractures typically occur when forceful hyperextension is applied to the finger tip, especially during ball-handling sports . Radiographs show a small fragment of bone avulsed from the volar aspect of the base of the middle phalanx. US can show small bony fragments and adjacent fluid collection at the volar aspect of the base of the middle phalanx. MRI can more definitively depict bone and soft tissue edema and adjacent fluid collection. Treatment options are conservative and range from early active motion with or without buddy strapping to immobilization at various degrees of flexion/extension.

References:

Kang R, Stern PJ. Fracture dislocations of the proximal interphalangeal joint. J Am Soc Surg Hand 2002;2(2):47-59.

Freiberg A, Pollard BA, Macdonald MR, Duncan MJ. Management of proximal interphalangeal joint injuries. J Trauma 1999;46(3):523-528.