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Type:
Educational Exhibit
Keywords:
Trauma, Education and training, Education, Diagnostic procedure, Ultrasound, Musculoskeletal system, Musculoskeletal joint, Anatomy
Authors:
N. Romano1, M. Marino2, I. Mussetto3, A. Fischetti1, A. Muda1; 1Genova/IT, 2Roma/IT, 3Genoa/IT
DOI:
10.1594/ecr2017/C-0637
Background
The extensor digitorum communis tendons are the primary extensors of the digits; their muscle originates from the lateral epicondyle of the humerus and lies centrally in the dorsal forearm.
Over the wrist,
the tendons pass through the 4th compartment formed by the extensor retinaculum and radius,
after which they fan out towards the digits,
passing over the carpal bones toward the metacarpophalangeal (MCP) joints [1,2].
Distal to the MCP joint,
each extensor tendon splits into a central slip,
that inserts into the base of the middle phalanx,
and two lateral slips that conjoin with the intrisic muscles,
forming the terminal tendon and inserting onto the base of the distal phalanx [3] (Fig.1).
Extensor tendons must be evaluated both with transverse and longitudinal scans.
The last ones may be very useful especially during finger extension and flexion (Fig.2,
Fig.3,
Fig.4).
Dynamic examination consists in obtaining longitudinal US images over the dorsal aspect of the injured finger during passive extension and flexion movements of both proximal and distal phalanges (Fig.2,
Fig.3,
Fig.4).
Dynamic US evaluation enables the identification of subtle lesions,
which may not be visible in static conditions. It is also essential for differentiating between partial and complete tendon's rupture.
There are two typical tendon tears in the finger: the rupture of the central slip of the extensor tendon and the injuries at the distal insertion of tendon onto the base of the distal phalanx[4].