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  • Sciatic Nerve Regeneration in Rats with Cold Preserved Allografts with and without Wrapping of Human Amniotic Membrane: Functional and Histological Outcome Study

    Final Number:

    Chandan Mohanty; B. Indira Devi; Dhananjaya I. Bhat MBBS, MCh Neurosurgery; T.C. Yasha MD

    Study Design:
    Laboratory Investigation

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2011 Annual Meeting

    Introduction: The overall outcome following nerve repair remains far from satisfactory. One of the major causes being the formation of perineural scar and inflammation following a repair with nerve graft. Amniotic membrane (AM) has been used to protect the anastomosis site and reduce perineural scarring and inflammation. However studies evaluating use of AM wrapping in nerve repair is limited. Our objective is to evaluate the effect of AM wrapping in nerve grafting and if its use is associated with improved functional and histological outcomes.

    Methods: Forty Sprague-Dawley rats were divided into six groups - Group A (Cold preserved allografts with immediate repair, n= 8 ), Group B (Cold preserved allografts with immediate repair and AM wrapping, n=8 ), Group C (Cold preserved allografts with delayed repair, n=8), Group D (Cold preserved allografts with delayed repair and AM wrapping, n = 8), Group E (Fresh allografts with immediate repair, n= 4), Group F (Fresh allografts with immediate repair and wrapping with AM, n=4). AM was harvested from human placenta obtained after caesarean section. Functional assessment was done comparing step-length ratio (SLR) before surgery and 6 weeks following surgery, along with histological evaluation.

    Results: Group D showed superior functional outcome compared to group C (p < 0.05) and decreased fibrosis compared to groups A and B. Also rats with AM wrapping (B, D) showed decreased fibrosis and inflammation compared to rats without AM wrapping (A,C) ( p < 0.05). Rats with fresh untreated grafts (E, F) had a uniformly poor functional and histological outcome (p < 0.05)

    Conclusions: Cold preservation of grafts reduces the host immune response and is associated with improved functional and histological outcomes compared to fresh untreated grafts. Delayed repair with pretreated allograft is better than immediate repair with allograft. Use of AM enhances repair and has a better functional outcome which may be due to decreased fibrosis and inflammation.

    Patient Care: The need for immunosuppression in the host and its associated adverse effects can be avoided by use of allografts.Use of amniotic membrane in conjunction with nerve banking – where cold preserved grafts can be kept for a long duration, may open up new avenues for management of peripheral nerve injuries.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of cold preserved grafts in nerve grafting. 2. Describe the importance of of amniotic membrane in nerve grafting. 3. Describe the role of step-length ratio in functional assessment following nerve grafting in rats.


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