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Page 6 of 17 Qiu et al. Plast Aesthet Res 2022;9:19 https://dx.doi.org/10.20517/2347-9264.2021.126

Figure 2. Key phases and active muscle synergies during the gait cycle.

Figure 3. Reconstruction algorithm for complete femoral nerve injuries.

vastus lateralis, primarily [Figure 4]. Variations in number of donor and recipient branches, sub-muscular
vs. supra-muscular tunneling over the adductor longus, and use of contralateral obturator nerve have been
described [32,33] . While other potential donor nerves, such as the nerve to the tensor fascia lata (TFL) and the
sciatic nerve can be considered when the obturator nerve is not available, our experience supports the
obturator nerve as a reliable donor for achieving functional knee stability and extension and negligible
donor morbidity.

In the absence of recipient nerves for transfers to the quadriceps muscles either due to muscular injury,
resection, or delayed presentation, tendon or muscle transfers must be used to recruit a new neuromuscular
unit for knee extension. If proximal femoral nerve fibers are available to neurotize a functional muscle
transfer and intuitive control without the need for cortical re-education, then local or free functional muscle
transfers can be used to restore intuitive knee extension. The latissimus dorsi muscle has been described in
multiple reports as a viable option for functional free muscle transfer, with modest results that depended on
the degree of quadriceps extirpation [34,35] . In patients who lost all four quadriceps muscles, knee extension
improved from 0/5 immediately post-op to 2 or 3/5 after reinnervation of the latissimus; in patients who
[35]
lost three quadriceps muscles, strength improved from 2/5 to 4/5 with reinnervation . In our opinion, the
pedicled gracilis is the most practical and high-yield option for functional muscle transfer. As described by