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Page 12 of 17 Toyoda et al. Plast Aesthet Res 2022;9:17 https://dx.doi.org/10.20517/2347-9264.2021.118

nonabsorbable monofilament sutures in an epimysial-to-epineural fashion. These constructs are located
[68]
away from the surgical incision and deep to any weight-bearing surface [Figure 3] .
Creating an RPNI construct takes an estimated 7-10 min, according to the inventor group. Surgical creation
of RPNI is technically simple and does not require expertise in microsurgery, unlike that with TMR. When,
in TMR, the appropriate recipient motor nerves are difficult to identify, there is a limit on the number of
independent muscle targets, or the patient is unable to tolerate a longer operation, RPNI is an excellent
alternative option which can be elected for intraoperatively. This efficient, reproducible, and effective
procedure has the potential to be implemented by surgeons from many disciplines with minimal additional
cost RPNI, like TMR, can be coded as pedicle nerve transfer (64905).
[68]

Outcomes of RPNI [Table 1]
RPNI has demonstrated promising clinical results in improving neuroma pain and phantom pain.
Woo et al. conducted a retrospective case series of sixteen upper and lower extremity amputees with
[74]
symptomatic neuromas. Patients have interviewed an average of 7.5 months after RPNI surgery using
patient-reported pain scores, which were adapted from PROMIS instruments . There was an average 71%
[74]
[74]
reduction in neuroma pain and 53% in that for phantom pain . This was also associated with 56% of
patients reporting decreased analgesic use with no patients using more than preoperatively . Aggregate
[74]
pain interference scores for both neuroma and phantom pain decreased from an average of 4.6
preoperatively to 2.15 postoperatively, and 94% of patients claimed they would choose to undergo surgery
again if given the option . Further studies are underway to corroborate these results with a larger sample
[74]
size as well as a longer follow-up .
[29]
As with TMR, primary RPNI at the time of amputation has also been increasingly explored with excellent
[75]
preliminary results. A retrospective case series by Kubiak et al. compared 45 patients who underwent
primary RPNI, with both upper and lower extremity amputations to 45 control patients who underwent
amputations without interfaces. Operative time was significantly longer in the primary RPNI group, with a
mean of 152 min compared to 90 min in the control group who did not require identification of the major
nerves. At a mean follow-up of nearly one year, those who had primary RPNI had a significantly fewer
incidence of symptomatic neuroma and phantom limb pain. In fact, none of the primary RPNI patients
[75]
developed symptomatic neuromas .
A combination technique of TMR with vascularized RPNI has also been trialed. In this technique,
[76]
Valerio et al. performed TMR in the usual fashion, and the neurorrhaphy was wrapped with a pedicled,
vascularized surrounding muscle cuff from freshly denervated muscle. Formal results are still pending from
this study, but so far, only three out of 119 patients have developed symptomatic neuromas with this
technique. The theoretical benefits include buffering of any axonal escape after coaptation with TMR given
the size mismatch, which is often inevitable when solely performing TMR. This combination technique may
also provide additional focal muscle targets for reinnervation and muscle stimulation for functional
prosthetics .
[76]

CONCLUSION
Identification of the significant individual and systems burden of amputation, advances in microsurgery, as
well as collaborative efforts with medicine-adjunct fields such as mechanical and bioengineering for
prosthetics as well as neuromodulation are what birthed TMR and RPNI. These techniques to treat and,
increasingly, prevent post-amputation pain are newer additions to the plastic surgeons’ armamentarium,
which have allowed further evolution of the top rungs of the reconstructive ladder in an often challenging