Article

Various studies have found that 6.6 to 31% of supracondylar elbow
fractures in children have nerve-related complications. One-third of these are
cases of anterior interosseous nerve (AIN) palsy that usually result in a deficit
of active thumb and index flexion. The goal of this cadaver study was to describe
the course of the AIN to achieve a better understanding of how it may get
injured. METHODS: On 35 cadaver specimens, the median nerve and its
collateral branches destined to muscles were dissected at the elbow and forearm
levels. The distance at which the various branches arose was measured relative to
the humeral intercondylar line. Interfascicular dissection of the AIN was used to
map its distribution within the median nerve. RESULTS: The AIN arises at an
average of 45 mm from the humeral intercondylar line. Before emerging from the
median nerve, the AIN fascicles were always found in the dorsal part of the
median nerve. After emerging, the AIN was divided into two zones. Zone 1 was the
transitional portion from its exit point until its entrance into the interosseous
space, where it changes direction. Zone 2 was the interosseous portion between
the radius and ulna that comes into contact with the anterior interosseous
membrane to which it is attached over its entire length until it ends in the
pronator quadratus (PQ) muscle. The muscle branches of the AIN destined for the
flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) muscles mostly
originated in Zone 1, which is the transitional portion between the median nerve
and the fixed Zone 2. The branches destined to the pronator teres (PT) and flexor
carpi radialis (FCR) originating from the median nerve are more proximal and
superficial. DISCUSSION: The injury mechanisms leading to selective AIN palsy
secondary to supracondylar elbow fracture in children are probably the result of
two factors: direct contusion of the posterior aspect of the median nerve, and
thereby the AIN fascicles, by the proximal fragment; stretching of AIN in Zone 1,
which has less ability to withstand stretching than the median nerve and its
other branches because the AIN is fixed in Zone 2. CONCLUSION: Details about the
origin and course of the AIN can explain the high percentage of AIN palsy in
supracondylar elbow fractures in children. LEVEL OF EVIDENCE: Level IV. Anatomic
study.
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Langue : FRANCAIS