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Page 6 of 12 Bryan et al. Plast Aesthet Res 2022;9:53 https://dx.doi.org/10.20517/2347-9264.2022.39

[25]
MRC grade 4 strength and no donor site morbidity .

Summary: This technique shows great results with 10/10 cases of nerve to ECRB to AIN regaining MRC
grade 4 finger flexion strength. This contrasts with brachialis to AIN, in which the majority of patients only
regained MRC grade 3 strength. In addition to good reported outcomes, there were no cases of donor site
morbidity.

Supinator to AIN
Technique: This technique utilizes an expendable branch of the radial nerve, the nerve to the supinator, to
reinnervate the AIN. First, an incision is made below the antecubital fossa. To visualize the median nerve
and branches, the superficial head of the pronator teres is retracted medially. Next, the AIN is identified and
dissected from the median nerve. The radial nerve can be identified by locating the superficial radial nerve
and following it proximally. There are typically 1 to 3 small nerve branches to the supinator, which can be
confirmed with nerve stimulation. The nerve(s) to the supinator is then divided distally, and the AIN is
divided proximally to allow for tension-free end-to-end coaptation.

This technique is advantageous because it does not preclude future tendon transfer to muscles innervated
by the AIN if the resulting motor function is not adequate after the transfer. Furthermore, as forearm
supination is primarily powered by the biceps, there is minimal donor site deficiency after transfer .
[26]

Outcomes: There are fewer reports on this technique in the literature than on transferring the nerve to the
brachialis or nerve to the supinator to the AIN. Notably, Hsiao et al. described a case report of a patient
with median nerve palsy following a proximal humerus fracture who received nerve transfers of supinator
[26]
to AIN and ECRB to the pronator teres branch of the median nerve . At 1-year follow-up, grip strength
and pinch strength were regained at MRC grade 4+ for FPL and 4- for FDP. Although strength was
adequate, the patient underwent tenodesis at 18 months to improve index finger flexion strength .
[26]
Murphy et al. also described a unique case of a 56-year-old woman with median nerve loss who underwent
transfer of a branch of the nerve to the ECRB to the pronator nerve and nerve to the ECRB and supinator to
AIN . The patient regained MRC grade 3 thumb and index finger flexion after one year and almost
[27]
complete function and MRC grade 4 FPL strength by 4 years .
[27]
Summary: Although there are not many cases reported in the literature, this technique is promising, with
2/2 cases of supinator to AIN regaining MRC grade 4 FPL and FDP flexion strength. Although this has
shown equal MRC grade 4 strength compared to ECRB to AIN, the latter technique has been more widely
reported.

Distal radial nerve transfers
FDS to ECRB
Technique: This technique transfers the branch of the median nerve innervating the flexor digitorum
superficialis (FDS) muscle to the branch of the radial nerve innervating the ECRB muscle. An incision is
made below the antecubital crease in the proximal forearm. An intraoperative nerve stimulator is then used
to identify the median nerve and its branches. The FDS branch can be identified by visualizing finger flexion
at the proximal interphalangeal joints after stimulation. Of note, there can be significant anatomical
variation in the location of the FDS branch. Once the median nerve and its branches are protected, the
radial sensory nerve is identified and followed proximally to find the PIN and the branch to the ECRB.
Following the identification of all nerves, the ECRB is divided proximally, and the FDS is divided distally to
allow minimal tension and is repaired end-to-end with microsurgical techniques .
[28]