Magnetic resonance imaging of the wrist and hand

Abstract

The anatomy of the wrist and hand is complex and contains numerous small structures. Magnetic resonance imaging (MRI) is often an ideal imaging modality in the assessment of various traumatic and pathologic conditions of this region, and it is frequently performed after initial radiographs. In this manuscript we describe the normal anatomy, imaging techniques, and MRI findings of various traumatic and pathologic conditions of the wrist and hand including occult fractures, osteonecrosis, ligamentous and tendon injuries, and entrapment neuropathies.

Pulley, Flexor, and Extensor Tendon Injuries of the Hand

“…The extrinsic extensor tendon continues with central and lateral slips distally to the proximal interphalangeal (PIP) joint. [4][5][6] The central slip inserts on the base of the middle phalanx. The lumbrical tendons form the lateral slips.…”

“…A mallet finger is the most common finger tendon injury in sports and refers to a disruption of the terminal extensor apparatus at the base of the distal phalanx. 5,6 This condition leads to a flexion deformity of the DIP joint with or without possible compensatory hyperextension at the PIP joint (swan neck deformity). 8 The term "mallet finger" includes both bony avulsion injuries at the base of the distal phalanx or injuries to the terminal tendon itself without bony avulsion.…”

“…This muscle is innervated by the median and ulnar nerves and functions to flex the wrist, MCP, PIP, and DIP joints. 5 Within the carpal tunnel, the four lesser fingers FDS tendons lie superficial to the four FDP tendons under the flexor retinaculum and continue along the volar aspect of the hand and metacarpals to the proximal phalangeal bases. At the level of the proximal phalangeal bases, the FDS tendons split into two parts: radial and ulnar slips (termed Camper's chiasm), through which the FDP passes.…”

“…5 Vincula breve and longum provide the nutrients to the flexor tendons and are typically not well seen on MRI. 5 Within the carpal tunnel, the flexor tendons (except the flexor pollicis longus) are located within the ulnar bursa, which is frequently in continuity with the little finger flexor tendon sheath. The index, middle, and ring finger flexor tendons sheaths do not commonly communicate with the ulnar bursa, with known anatomical variations.…”

“…33 The normal FDS and FDP tendons show low signal intensity on all MRI sequences and may show increased signal due to the magic angle on short TE sequences. 5 The flexor tendons of the lesser fingers are secured to the phalanges by the five annular pulleys (A1-A5) (►Fig. 12), usually well seen on high-resolution MRI, and three cruciform pulleys (C1-C3), usually not well seen on MRI.…”