Allotransplantation is a commonly used type of transplantation of which nerve repair is one specific aspect.
It is human nerve tissue, processed to remove cellular and noncellular factors such as cells, fat, blood, axonal debris and chondroitin sulfate proteoglycans while preserving the three-dimensional scaffold and basal lamina tubular structure of the nerve.
This means the nerve allograft only consists of extracellular matrix (ECM), which is sterile and decullularized.
This defect needs to be repaired in order to regain full or partial sensory and motor function.
Damaged nerve fibers continuously excite electric pulses, inducing pain or abnormal sensation dysesthesia.
It has been shown that in allograft surgeries, post-operative neuropathic pain was present in some patients, but only if they had this condition pre-operatively.
Thirdly, a longer anaesthesia time is needed because of the additional surgical site for the donor nerve.
Despite these downsides, reducing the function of the affected area is beyond the risks committed with harvest of the donor nerve.
To prevent this rejection, new immunosuppressive techniques are performed on the graft, before it is transplanted into the receiver.
The donated nerve tissue is disinfected, by selectively removing cellular components and debris to cleave growth inhibitors and then terminally sterilized.
The proximal and distal segments of the injured nerves should be debrided to healthy tissue by visual and tactile signs.
The processed nerve allografts come in different sizes, so that a gap can be closed without unwanted tension.
This means the sutures which connect the allograft with the damaged nerve are placed in the epineurium.
Because allografts are human nerves, processed in such a way that the immune response against the transplant is not provoked, the procedure differs little from the autograft-procedure except for the fact that there is no need to create a 'donorplace' defect.
After the nerve is repaired, whether it is by using an autograft or an allograft, wallerian degeneration will be seen distal to the coaptation.
This means that the part of the nerve that lies distal to the breaking point starts dissolving.
[5][8][10] In other words, the sensation and movement of the affected body parts, in most studies the forearm, equally improved.
Efforts are being made to determine which procedure, i.e. autograft or allograft surgery, is preferred for each nerve type, but more research needs to be done.
No comparison of these two procedures has been made in one single clinical study, let alone in a randomized controlled trial.