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

Figure 4. (A) Illustration of relevant anatomy for nerve to supinator to PIN nerve transfer technique. (B) Identification of the nerves
prior to transfer: Radial Nerve (Radial N.), Superficial branch of the radial nerve (Superficial Br.), nerve to supinator (NTS), and posterior
interosseous nerve (PIN). (C) The donor nerve to the supinator (NTS) is transferred to the recipient PIN.

The patient also achieved MRC grade 4 on thumb and finger flexion with brachialis to AIN transfer . In
[36]
another investigation, van Zyl et al. reported a case series of 16 participants with spinal cord injury and 59
total nerve transfers . Of the nerve transfers, supinator to PIN had the highest-rated satisfaction. In these
[39]
cases, 19/21 limbs receiving supinator to PIN nerve transfers achieved MRC grade 3 or higher finger
[39]
extension, and 17/21 achieved at least MRC grade 3 thumb extension at 24 months follow-up . Khalifeh et
al. reported worse outcomes in a case series of 17 participants and 42 nerve transfers after spinal cord
injury . Thirteen out of forty-two nerve transfers were supinator to PIN, and only 7/13 achieved MRC
[40]
grade 3 or higher finger extension , although this could be attributed to the longer delay from the time of
[40]
injury to surgery . Finally, Souza et al. reported a case series of 11 patients with lower brachial plexus
[19]
injuries who received brachialis to AIN and supinator to PIN within 13 months of injury . After 12 to 24
[22]
months postoperatively, 8/11 patients achieved MRC grade 3 or better finger extension with supinator
transfer and finger flexion with brachialis transfer. There was no significant loss in donor site function .
[22]
Summary: Supinator to PIN is one of the most widely documented upper extremity nerve transfer
techniques and has shown good outcomes, with 50/62 cases achieving at least MRC grade 3 finger extension
and 33/38 achieving at least MRC grade 3 thumb extension. Although results are similar to FCR to PIN, this
technique is more widely documented and has been reported to have very high patient satisfaction scores.

CONCLUSION
Distal nerve transfer techniques provide new options to restore function after median and radial nerve
injuries. The ECRB to AIN nerve transfer has shown the most promising results for restoration of finger
flexion, with all cases examined recovering MRC grade 4 finger flexion.

Regarding transfer techniques for radial nerve injuries, supinator to PIN is a well-documented method for
reinnervation of finger and thumb extension. Moreover, it is often used in conjunction with other nerve
transfer techniques for finger flexion restoration in the cases of spinal cord or brachial plexus injuries.
Although FCR to PIN has shown promising outcomes, there have been few descriptions of this technique
published in the past few years, partially due to the popularity of the supinator to PIN. The FCR to PIN
nerve transfer does have a role in proximal radial nerve injuries where the supinator branches are not