Avulsion Injuries of the Hand and Wrist

Abstract

Injuries of the hand and wrist are frequently encountered in radiology. Avulsions of the hand and wrist are a heterogeneous group of injuries, but they often have a characteristic imaging appearance that relates to the intricate bone and soft-tissue anatomy and the mechanism of injury. The imaging appearance and this intricate form and function dictate treatment of hand and wrist avulsions. This article reviews frequently and infrequently encountered avulsion injuries and describes abnormalities that may mimic the imaging appearance of avulsions. Specifically discussed entities include the Bennett and reverse Bennett fracture, ulnar collateral ligament avulsion, radial and ulnar styloid process avulsion, triquetral avulsion, mallet and jersey finger, central slip avulsion, and acute and chronic volar plate avulsion injuries. Uncommon avulsion injuries are also described and include avulsions of the scapholunate ligament, extensor carpi radialis longus and brevis tendons, trapeziometacarpal ligament, radial collateral ligament, and flexor digitorum profundus tendon. Emphasis is placed on the relevant anatomy and typical imaging findings for each diagnosis, with pertinent clinical history, pathophysiologic evaluation, and treatment discussed briefly. Understanding the anatomy and expected imaging findings can aid the radiologist in recognizing and characterizing these injuries. ©

Glossary of terms for musculoskeletal radiology

“…Pathogenesis Avulsion fracture is a focal, traumatic detachment of bone due to tensile forces transmitted through a tendon, ligament, or joint capsule. Common sites include the humeral tuberosities, olecranon process, phalangeal base, iliac spines, ischial tuberosity, tibial plateau, lateral tibial rim, fibular head, and fifth metatarsal base [25]. Whereas impaction fracture may be depressed due to compressive mechanism, avulsion fracture is often distracted due to tensile mechanism.…”

Acute Bony Injuries of Hand and Wrist

“…The most common is the avulsion of the dorsal base of the distal phalanx in the "mallet finger." 41,44 It results from a forced hyperflexion of the DIP joint, leading to an injury of the insertion of the extensor tendon (►Fig. S23).…”

“…Another avulsion at the palmar base of the distal phalanx is seen in the "jersey finger." 44 The trauma mechanism is hyperextension of the DIP joint, resulting in an avulsed fragment at the insertion of the flexor digitorum profundus. In contrast to the mallet finger, these lesions are very often treated operatively.…”

Volar Plate Injuries of the Proximal Interphalangeal Joint

“…24 Some delayed presentations of VPIs may have isolated hyperextension at the PIP joint without a swan-neck deformity. 25 Patients with a delayed presentation of VPI with instability may complain of painful "snapping" as the lateral bands slide over the head of the proximal phalanx in attempted flexion. 3 Disruption of the volar plate from the proximal phalanx can cause a flexion deformity of the PIPJ, a "pseudo-boutonniere deformity" with an intact extensor mechanism.…”