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Page 4 of 12 Costa et al. Plast Aesthet Res 2020;7:32 I http://dx.doi.org/10.20517/2347-9264.2020.43

Figure 3. Anterior interosseous nerve (AIN) to ulnar deep motor transfer. The AIN is followed into the pronator quadratus. Proximal
neurolysis of the motor fascicle of the ulnar nerve enables tensionless coaptation. Yellow: functional nerves; pink: nonfunctional nerves

associated with a loss of strength and fluidity of movement. In isolated lesions of the ulnar nerve, various
techniques reported in the literature involve the median nerve as a donor of motor and/or sensitive fibers in
the distal forearm and in the hand [21-24] . The preferred motor donor is the distal AIN to restore functionality
of the intrinsic musculature. It is possible to achieve neurolysis of the motor branch of the ulnar nerve
for up to 14 centimeters proximally to the radial styloid, allowing adequate length to achieve tensionless
coaptation with the AIN donor branch [Figure 3]. In cases of injury to both the ulnar and median nerves,
the radial nerve can act as a fiber donor.

Motor nerve transfers in forearm
When there are no median nerve injuries, the anterior interosseous nerve in its distal portion directed to
the pronator quadratus muscle can be used as a fiber donor for the motor component of the ulnar nerve.
[25]
Brown et al. performed the first such case in 1991 and several authors have since successfully reported
this technique.

This technique is frequently executed end-to-end, and proximal neurolysis of the ulnar nerve avoids
the need for a nerve graft. Battiston and Lanzetta showed good results in seven patients who underwent
terminal anterior interosseous nerve-to-ulnar motor nerve transfer in distal forearm, proximal to Guyon’s
[22]
canal .
[4]
Brown and Mackinnon have shown that neurolysis up to 14 cm proximal to the radial styloid can be
performed for the ulnar nerve.

The reverse end-to-side or “supercharge” nerve transfer [26,27] can also improve intrinsic function and allow
the ulnar nerve to regenerate spontaneously .
[28]
Barbour et al. also suggested through their experience in nerve transfers to the ulnar nerve that
[28]
supercharged coaptations can keep the motor end plates good, as well as serve as a “babysitter”, until “native
parent” axons return.

With validation of the idea that axons can regenerate if a nerve is sutured in end-to-side fashion,
[29]
supercharged end-to-side (SETS) nerve transfers began to be used .
[30]
In a retrospective matched-cohort study, Baltzer et al. compared the outcomes of supercharged end-to-
side procedures with the conventional technique in patients with a high ulnar nerve injury. As a result,
the group in which the AIN SETS was implemented had better results and recovery of the intrinsic
functionality of the hand.