Page 83 - Read Online

Xu et al. Plast Aesthet Res 2022;9:33 https://dx.doi.org/10.20517/2347-9264.2021.116 Page 3 of 17

[17]
genitourinary organ) have been approved by OPTN . These include 11 centers for upper extremity and
three for lower extremity transplantation: Brigham and Women’s Hospital, Medstar Georgetown
[17]
Transplant Institute, and University of Chicago Medical Center .

RISK-BENEFIT PROFILE OF VCA
The primary ethical conflict surrounding VCAs is whether the quality-of-life benefits to the patient
outweigh the long-term risks associated with an extensive non-lifesaving procedure. In ethical terms, this is
considered a conflict between beneficence and nonmaleficence. Beneficence holds that patient’s best
interests are paramount, while nonmaleficence refers to an obligation to avoid preventable harm. The
OPTN Final Rule provides a distribution framework for organ transplantation focused on the just allocation
of scarce resources, as there is more demand for traditional, lifesaving transplants (e.g., kidney, liver, heart)
than available organs . In contrast, the primary ethical issue in VCA is focused on whether the procedure
[18]
itself is ethical, rather than fair allocation. A standardized protocol for measuring and reporting outcomes
does not currently exist, but the benefits and risks of upper extremity VCA are well-documented in the
literature and can be largely extrapolated to the conversation on lower extremity VCA - although key
differences do exist.

Benefits
The main goal of VCA of the extremity is to improve quality of life via restoration of sensation and motor
function after limb loss. All viable transplanted hands have demonstrated normal skin color and texture as
[19]
well as normal hair and nail growth, arterial blood supply, and venous outflow . Reports released by the
IRHCTT have shown that all documented upper extremity allograft recipients have recovered protective
sensibility (i.e., ability to detect pain, thermal stimuli), with 91% of patients redeveloping tactile sensibility
and 82% regaining partial discriminative sensibility . There is no reason to expect that VCA of the lower
[20]
extremity cannot also demonstrate such successful restoration of sensory function. Importantly, the first
lower extremity allograft recipient has recovered diminished but present sensation to light touch . The
[7]
most recent recipient demonstrated early signs of sensory recovery as well, although long-term data is not
available . Recovery of protective sensibility and proprioception, which contribute to effective ambulation,
[13]
alone would represent a substantial benefit over available prostheses - the most common alternative to VCA
[21]
of the extremity .

Currently, the level of functional recovery required for restoration of lower extremity gait, balance, and
postural control is unknown, although these motor functions are far less intricate than those of the hand
and are arguably easier to achieve. The distal intrinsic muscle reinnervation critical to restoring near
baseline function for the hand is speculated to be less crucial to attaining meaningful lower extremity
[22]
function . This is rooted in the fact that the knee plays a greater role in ambulation than the foot and
[23]
ankle, giving greater importance to proximal versus distal innervation . To date, many hand transplant
recipients have exhibited motor function sufficient to perform gripping and pinching actions and recovery
of a number of manual skills. Patients with bilateral transplantations have also been able to achieve
[19]
symmetric use of their hands . In the short term, the two initial attempts at lower extremity VCA have
shown a return to ambulation with assistance and a nearly normal passive range of motion with good
strength throughout, although the active range of motion was markedly decreased compared to baseline .
[7,8]
The most recent attempt has also shown some active range of motion and partial weight-bearing at six-
months postop . The greater distance that must be traversed with nerve regeneration in the lower versus
[13]
upper extremity must be another consideration, however, as nerves regenerate at a peak rate of 1 mm/day-3
mm/day while motor endplates remain responsive only on the scale of years after denervation, after which
functional recovery is unlikely [24,25] . Accordingly, denervation muscle atrophy can present a greater challenge