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Bryan et al. Plast Aesthet Res 2022;9:53 https://dx.doi.org/10.20517/2347-9264.2022.39 Page 7 of 12

Outcomes: Although outcomes for this seem promising, there are few reports in the literature. Good
outcomes for radial nerve branch transfers are defined by achieving at least grade MRC grade 3 on
[29]
extension . In 2007, Mackinnon et al. described a case report of a 32-year-old woman with radial nerve
palsy after intramedullary humerus rod placement who received a transfer of FDS and FCR to ECRB and
PIN, respectively . At 18 months postoperatively, she regained MRC grade 4 finger and wrist extension
[28]
strength . Similarly, Ukrit et al. described two case reports of patients with C5, C6, and C7 avulsion
[28]
injuries who received FDS to ECRB . Both patients recovered MRC grade 4 wrist extension strength at the
[30]
2-year follow-up visits .
[30]
Summary: There are not many reports of this technique in the literature, but this technique is very
promising, with 3/3 cases of FDS to ECRB regaining MRC grade 4 extension strength.

Distal AIN (PQ) to ECRB
Technique: The nerve to the pronator quadratus is transferred to the nerve to the ECRB in this technique.
An oblique incision is made in the proximal forearm, a few centimeters below the antecubital fossa. The
nerve to the ECRB can be identified by tracing the superficial branch of the radial nerve proximally.
Following identification of the ECRB branch, the incision is extended distally and the distal AIN can be
identified through a trans-FCR approach to expose the proximal aspect of the pronator quadratus. The AIN
can then be seen entering the pronator quadratus. Contraction of the pronator quadratus with nerve
stimulation confirms the correct identification of the AIN. The AIN is traced proximally, and care is taken
to preserve the branch to the FPL. The ECRB is cut proximally at its origin, and the AIN is cut distally and,
if necessary, further dissected within the substance of the pronator quadratus muscle for additional length.
Following division, the AIN is turned proximally and passed radially to allow for coaptation to the ECRB
motor branch.

Outcomes: In 2012, Bertelli et al. described the technique for transferring the distal AIN branch to pronator
quadratus to the ECRB motor branch and reported 4 patients with brachial plexus injuries who underwent
surgery within 10 months of injury . At 12 months postoperatively, all patients gained MRC grade 4 wrist
[31]
[31]
extension without loss or downgrading of pronation or strength in FPL or FDP flexion . In another case
series by Bertelli et al., 28 patients with C5-8 root injuries had this operation within 7 months after injury .
[32]
At approximately 22 months postoperatively, 25/28 patients scored MRC grade 4 extension, 2/28 scored
MRC grade 3, and one scored MRC grade 2. Furthermore, there was no loss of function or downgrading of
the FPL or FDP flexion strength . Similarly, Bhatia et al. reported results of 20 patients with C5-8 root
[32]
injuries who underwent operations within 9 months of injury . In this series, 17/20 patients gained MRC
[33]
grade 4 wrist extension, with the remaining 3 gaining MRC grade 3 extension. However, the authors
reported that the 3 patients with lower scores had MRC grade 3 recordings of the DIP and thumb flexion
before the transfer, indicating weakness of the donor nerve. Additionally, there was no loss in pronation in
14/20 patients, while 4/20 were downgraded to MRC grade 3 and one patient had complete loss of
pronation. There were no cases of thumb and DIP flexion strength loss or downgrading . Bertelli recently
[33]
reported a larger case series of 14 patients with radial nerve lesions who received AIN to ECRB and FCR to
[34]
PIN in 2020. 13/14 recovered M4 and 1/14 recovered M3 wrist extension strength .
Summary: Distal AIN (PQ) to ECRB is a reliable technique with very good reported outcomes, as 59/66
cases of PQ to ECRB regained MRC grade 4 wrist extension strength. This technique is much more widely
reported compared to FDS to ECRB, although outcomes with FDS to ECRB are similar.