September 28, 2019 at 4:25 pm #94912
AVANCE processed nerve allograft is a compelling solution for the nerve gap, providing a bespoke option without the risks of complication and morbidity associated with autograft harvest. However what is the current evidence base? There is an excellent safety profile for use in sensory and mixed motor-sensory nerve gap reconstruction, however what about efficacy data?
There is sufficient high quality data from the RANGER registry study and from independent randomised controlled trials to demonstrate similar efficacy in short gap digital nerve repair or reconstruction. The evidence for larger sensory nerves and mixed nerves is less compelling at this stage. The data available from the RANGER registry reports useful recovery in both of the latter groups and compared with historic autograft studies the results look similar. Comparative studies are still required.
In the UK the National Institute for Health and Care Excellence has provided interventional procedure guidance (IPG597) for surgeons and reviews the available literature:
As a specialist nerve surgeon, AVANCE allograft offers me another option in my reconstruction toolbox. My primary indication is in the reconstruction of established neuromas, either from missed nerve injuries or in the setting of a neuroma after previous nerve repair. When sensory recovery is less important and the primary objective is the management of neuropathic pain, AVANCE is difficult to ignore. In primary digital nerve gaps greater than 12mm, the results of conduits are limited and AVANCE offers a superior option, again without donor morbidity.
What about large trunk sensory nerves? I use allograft for reconstruction after tumour resection or nerve biopsy, or when there are other more critical associated mixed nerve injuries which require the limited autograft. Interst is developing in using allograft during planned autologous flap reconstruction of the breast to provide sensory reinnervation from the lateral intercostals to the DIEP flap segmental terminal 11th and 12th intercostal branches.
What about mixed nerve injuries? I do use allograft in a select number of cases, however as recommended by NICE the surgeon must ensure that the patient understands the limited evidence base. In cases of significant co-morbidity where there is a contraindication to general anaesthesia for sural nerve harvest or where the lower limb skin condition is poor, mobility is impaired or there is limited autograft, allograft provides a useful alternative. Interestingly there is increasing patient awareness of the option and some are now asking for this as a solution. It is important that nerve surgeons continue to contribute to the evidence base and explore the indication and limitations further.
There is a group where allograft is clearly superior. As mentioned previously, reconstruction of neuromas is a useful indication, however there are other situations such as end neuromas or in the management of post-amputation neuropathic pain where allograft may be used as a bridge to relocate neuroma to better tissues, deeper tissues or to muscle for targeted muscle reinnervation. Perhaps in the acute amputation the use of “spare parts” approaches should allow primary autograft “bridge to nowhere” or targeted motor reinnervation, however the established post-amputation stump neuropathic pain is the ideal candidate for AVANCE allograft which avoids creating new pain drivers elsewhere from autograft harvest and contralateral limb impairment in the lower limb unilateral amputee.September 30, 2019 at 2:06 pm #95470
Other areas where I have found Avance fits into my practice is for nerve gap reconstruction during limb or digit replantation where there doubt over the survival of the extremity makes alternatives to autograft attractive.
A concern over how well the larger diameter allografts vascularise has lead me to think about using cables of allograft of a smaller diameter instead, as one would do for an autograft reconstruction.
I have noticed that regeneration across a segment of Avance takes much longer, possibly twice as long, as one would expect for a similar length of autograft. I’d be interested to hear other surgeons experiences.October 1, 2019 at 5:39 am #95511
Thanks for your thoughts. I agree with the concept of replant advance allograft to avoid potential sacrifice of autograft in a part that eventually may be amputated. The option to delay the nerve reconstruction until 3 months after digit survival I have always found challenging. Re-exploration of a digit with a vascular reconstruction poses a risk of damage to the vascular repair and delays functional sensory recovery. The challenge is justifying the cost for what may become an amputated digit.
In the gap reconstruction I am reviewing my large allograft cases as I agree with your thoughts on cabled allograft as potentially being a superior option to a large diameter allograft. The evidence for this from the RANER database hasn’t been presented or published to date but it makes sense that the greater surface area: volume ration enhances vascular ingrowth.
Regarding the duration of recovery through the graft, do you have any prospective data on rate of Tinel’s progression in your cases to support your claim. I personally agree that recovery, particularly in motor reconstruction cases seems to take twice as long as a comparable autologous graft. Perhaps we should pool our cases and look at this aspect of allograft recovery?
- This reply was modified 2 weeks, 6 days ago by Dominic Power.
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