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Crowe et al. Plast Aesthet Res 2019;6:4 I http://dx.doi.org/10.20517/2347-9264.2018.70 Page 7 of 15

Care should be taken to identify five nerves intraoperatively: tibial, superficial peroneal, deep peroneal,
saphenous, and sural. These should be cut proximally and buried in soft tissue away from the planned
incision in order to prevent neuroma formation.

Forces traveling between prosthesis, residual limb, and the remaining body are primarily transmitted
through the retained bone in the amputated limb. Managing the edges of severed bone is essential to pain
free healing and reduces the chance that bone will erode the overlying skin. The distal corner of tibia should
be removed with 45° anterior beveling and edges should be softened with a saw or rasp. The fibula should be
1-2 cm shorter than the tibia and beveled to remove the lateral edge.

Prosthesis and orthosis for below-knee amputations
Below-knee amputation prostheses can be subdivided into the following elements: socket, interface,
suspension, shank, and foot/ankle. The prosthetic socket encases the residual limb, and is often classified
as either “patellar tendon bearing” - dispersing weight distribution onto several pressure-tolerant areas
including patellar tendon - or “total surface bearing,” creating a more equal weight distribution throughout
[33]
the entirety of the socket. In modern practice, most designs are a hybrid of the two . The interface describes
the material between the socket and the residual limb, which is often a liner. Common interface options
include hard-socket with an underlayer of cloth sock, pelite (foam), or silicone. Interface prescriptions take
into account maturity and shape of the residual limb, suspension method, patient activity level, patient
cognition, upper extremity function, and patient preference.

The mechanical properties of several liner materials - such as tension, compression, shear, and friction -
[34]
have been well studied . It has been suggested that stiffer liners are superior for patients with excess soft
[35]
tissue, while softer, more conformable liners are better for patients with bony prominences . Furthermore,
liners have an effect on stump moisture and heat retention. Liner materials are generally impermeable to
[37]
[36]
moisture and non-conductive for heat transfer , thus contributing to residual limb maceration, dermatitis,
hyperhidrosis, and cellulitis. Generally speaking, modern liners make use of roll-on elastomer materials, a
[38]
more durable and adhesive alternative to foam liners . Socks of varying ply are often utilized between the
liner and skin and can be added or removed to accommodate for inevitable limb volume changes.
Suspension refers to the method of attachment to the residual limb. Options are numerous and may
use anatomic structures to suspend the socket. This may include supracondylar cuffs and brims, may
use additional componentry such as neoprene sleeves, thigh corsets, and pin-locks, or utilize pressure
differentials as in the case of suction or vacuum assisted suspension. Again, prescriptions take into account
anatomical, cognitive, social, and other personal factors. The shank connects the socket to the foot and
ankle, and can be categorized as either endo- or exo-skeletal. Endoskeletal pylons are most commonly
utilized as they are modular, allowing for modification to height, rotation, and alignment, and also have the
potential to be lighter in weight.

There are many prosthetic foot options, which vary in terms of weight, durability, and functionality.
Generally, these include solid-ankle cushioned heel, single-axis, multi-axis, and energy-storing/dynamic
response, hydraulic, and microprocessor feet. It has been suggested that energy-storing feet provide both
vascular and traumatic amputees with a more comfortable stride length and walking speed as compared
to traditional solid ankle cushion heel devices [39-41] . A single-axis foot may be more useful for less active
patients, as it provides an early foot-flat stability and timely transfer of weight onto the supporting
[42]
prosthetic . The disadvantage of these devices is less restraint of dorsiflexion and therefore less stability in
late stance phase [43,44] . Consequently, there is no single prosthetic foot/ankle that provides superior function
to all patients, and instead the prosthetic prescription must be tailored to each patient’s baseline, projected
functional status, and unique needs.