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Page 8 of 17 Qiu et al. Plast Aesthet Res 2022;9:19 https://dx.doi.org/10.20517/2347-9264.2021.126

combinations of tendon transfers may be required to optimize strength, knee stability, and function. For
example, free functional muscle transfers may be augmented with medial compartment tendon transfers.
Investigations into outcomes for these tendon transfers are ongoing.

Reconstruction of sciatic nerve injuries
Sciatic nerve injuries carry a poor prognosis and are almost always associated with chronic disability,
particularly in the adult and elderly populations. Incomplete lesions or injuries due to compression fare
better than complete lesions, and distal injuries fare better than proximal injuries . If the nerve is in
[41]
continuity, exploration and neurolysis can have good results. However, it is not uncommon for a neuroma-
in-continuity to be present. In those cases, if there are no nerve action potentials crossing the neuroma, then
excision and fascicular repair of the tibial and peroneal components of the nerve are indicated. Generally,
the CPN component of the sciatic nerve is more prone to injury due to its lateral position and decreased
elastic tolerance owing to its double point of fixation at the greater sciatic notch and fibrous tunnel around
the knee. The tibial nerve, on the other hand, is more elastic, has better blood supply, and has more
perineural connective tissue, which is thought to help protect its axons. As observed in a large series of 806
sciatic nerve injuries, outcomes appear to be better for tibial nerve repair than CPN repair for both primary
coaptation and secondary grafting .
[42]
For high sciatic nerve injuries where nerve regeneration to the posterior compartment of the lower leg is
unlikely, early nerve transfers are indicated [Figure 5]. Reconstruction of the tibial nerve is generally
prioritized over CPN reconstruction, because of its important role in balance during gait and the availability
of alternative strategies for managing CPN palsy (e.g., orthoses). The goal of reconstruction is then to
[43]
restore forceful plantarflexion. Yin et al. report a series of 5 patients with sacral plexus injuries in which
they transferred the ipsilateral obturator nerve to the branch of the tibial nerve innervating the medial head
of the gastrocnemius to restore knee flexion and ankle plantarflexion. Three of five patients achieved MRC
[44]
grade 3 or better. Moore et al. report two patients in which femoral to tibial nerve transfers were
performed for high sciatic nerve injuries. In the first patient, the nerve to the vastus medialis was transferred
to the nerve to the medial head of the gastrocnemius with an interpositional peroneal nerve graft. In the
second patient, the same transfer was performed, except with direct coaptation, and a concomitant transfer
of the branch to the vastus lateralis to the lateral gastrocnemius was performed. Both patients achieved
MRC grade 3 plantarflexion by 18 months. The peroneal nerves were not reconstructed in these two
patients.

With respect to the normal gait cycle, the femoral and tibial nerves activate sequentially: the quadriceps are
active just before heel strike throughout early stance, after which the plantar flexors activate to provide some
forward propulsion and, more importantly, to stabilize the ankle as it dorsiflexes through mid- to late-
state . Because of their sequential roles in the gait cycle, femoral to tibial nerve transfer may be a
[45]
reasonable option to rehabilitate. Alternatively, the obturator nerve branches to the gracilis play little role in
the gait cycle, making them attractive, expendable options for transfer. The obturator nerve is our preferred
donor for motor restoration of the tibial nerve in a sciatic nerve injury.

To prevent long-term complications from chronic injury, the sensory deficit of the plantar foot is the most
important tibial nerve function to restore. This will be discussed in the section below on reconstructing
tibial nerve injury.

Reconstruction of isolated common peroneal nerve injuries
Owing to its superficial position at the fibular neck and inability, injuries to the CPN are the most frequent
among the lower extremity nerves. These are associated with knee trauma and iatrogenic injury, usually