Mateusz Gładysz FESSH prep

FESSH prep Peripheral nerve injury Weber's PGA conduit trial, the RECON allograft versus conduit trial, RANGER registry and gap length, Schwann cell senescence in long acellular grafts, sural donor morbidity

Reconstruction of peripheral nerve gaps: conduit, processed allograft and autograft

Last reviewed v1.0

FESSH-058Peripheral nerve injury●●● advanced

Regarding reconstruction of peripheral nerve gaps:

  1. 1.In Weber's randomised trial of digital nerve repair, polyglycolic acid conduits gave better sensory recovery than end-to-end repair for gaps of 4 mm or less.

  2. 2.In a large randomised trial of digital nerve gaps, processed nerve allograft outperformed collagen conduits for short gaps of 5–14 mm but not for longer gaps of 15–25 mm.

  3. 3.In the RANGER registry, meaningful recovery after processed nerve allograft reconstruction was independent of gap length up to 70 mm.

  4. 4.In experimental models, failure of axonal regeneration across long acellular nerve allografts is associated with senescence of the host Schwann cells that must populate the graft.

  5. 5.Most patients report sensory loss at the donor site after sural nerve harvest, mainly over the lateral side of the foot.

FESSH marking: +1 per correct statement, 0 for blank, −1 for incorrect. Click the same TRUE/FALSE button twice to clear it.

Question ID
FESSH-058
First published
Last reviewed
Version
v1.0
Answer key and explanations — open after answering

  1. 1. In Weber's randomised trial of digital nerve repair, polyglycolic acid conduits gave better sensory recovery than end-to-end repair for gaps of 4 mm or less.

    True

    Weber randomised 136 digital nerve transections to standard repair (end-to-end or nerve graft) or a polyglycolic acid conduit. Overall results did not differ, but for gaps of 4 mm or less the mean moving two-point discrimination was 3.7 mm after conduit repair against 6.1 mm after end-to-end repair (p = 0.03). Rinkel's systematic review graded the evidence for conduits in gaps of 4 mm or less and 8 mm or more as low quality.

    • Weber RA, Breidenbach WC, Brown RE, Jabaley ME, Mass DP. A randomized prospective study of polyglycolic acid conduits for digital nerve reconstruction in humans. Plast Reconstr Surg. 2000;106(5):1036-45; discussion 1046-8. PMID 11039375
    • Rinkel WD, Huisstede BM, van der Avoort DJ, Coert JH, Hovius SE. What is evidence based in the reconstruction of digital nerves? A systematic review. J Plast Reconstr Aesthet Surg. 2012;66(2):151-64. PMID 23000782

  2. 2. In a large randomised trial of digital nerve gaps, processed nerve allograft outperformed collagen conduits for short gaps of 5–14 mm but not for longer gaps of 15–25 mm.

    False

    The finding was the reverse. In Isaacs's 220-patient multicentre trial, static two-point discrimination was similar for allograft and conduit in short gaps (7.3 and 7.5 mm), whereas for 15–25 mm gaps the allograft was better (6.1 against 7.5 mm) and normal sensation was achieved in 40% of allograft repairs against 18% of conduit repairs.

    • Isaacs J, Nydick JA, Means KR, Merrell GA, Ilyas A, Levin LS, et al.. A Multicenter Prospective Randomized Comparison of Conduits Versus Decellularized Nerve Allograft for Digital Nerve Repairs. J Hand Surg Am. 2023;48(9):904-913. PMID 37530686
    • Means KR, Rinker BD, Higgins JP, Payne SH, Merrell GA, Wilgis EF. A Multicenter, Prospective, Randomized, Pilot Study of Outcomes for Digital Nerve Repair in the Hand Using Hollow Conduit Compared With Processed Allograft Nerve. Hand (N Y). 2016;11(2):144-51. PMID 27390554

  3. 3. In the RANGER registry, meaningful recovery after processed nerve allograft reconstruction was independent of gap length up to 70 mm.

    False

    Safa's report of 624 repairs found 82% meaningful recovery overall, but significantly less for 50–70 mm gaps than for gaps under 15 mm (69% against 91% in the upper limb), and less after complex injuries than after lacerations; most repairs in the 50–70 mm group (29 of 43) followed complex injuries. The registry is industry-sponsored; it found no difference by nerve type, age, time to repair or smoking in the upper limb.

    • Safa B, Jain S, Desai MJ, Greenberg JA, Niacaris TR, Nydick JA, et al.. Peripheral nerve repair throughout the body with processed nerve allografts: Results from a large multicenter study. Microsurgery. 2020;40(5):527-537. PMID 32101338

  4. 4. In experimental models, failure of axonal regeneration across long acellular nerve allografts is associated with senescence of the host Schwann cells that must populate the graft.

    True

    Acellular allografts depend on host Schwann cells proliferating into the graft. In Saheb-Al-Zamani's rat sciatic model, regeneration fell with graft length (20, 40 and 60 mm), the isograft outperformed the acellular graft at every length, and failure of the regenerating axonal front was associated with raised senescence markers (senescence-associated β-galactosidase, p16INK4A and IL6). Poppler showed axonal growth halted within long grafts by 4 weeks while short grafts were crossed.

    • Saheb-Al-Zamani M, Yan Y, Farber SJ, Hunter DA, Newton P, Wood MD, et al.. Limited regeneration in long acellular nerve allografts is associated with increased Schwann cell senescence. Exp Neurol. 2013;247:165-77. PMID 23644284
    • Poppler LH, Ee X, Schellhardt L, Hoben GM, Pan D, Hunter DA, et al.. Axonal Growth Arrests After an Increased Accumulation of Schwann Cells Expressing Senescence Markers and Stromal Cells in Acellular Nerve Allografts. Tissue Eng Part A. 2016;22(13-14):949-61. PMID 27297909

  5. 5. Most patients report sensory loss at the donor site after sural nerve harvest, mainly over the lateral side of the foot.

    True

    Bamba's systematic review of 240 patients found sensory loss in 87.2%, pain in 25.6%, cold sensitivity in 22.2% and functional impairment in 10%; sparing the proximal sural nerve reduced sensory loss and pain. Shah found decreased sensation most often over the calcaneus and cuboid on the lateral foot, with nociception preserved and no long-term pain complaints after full-length harvest.

    • Bamba R, Loewenstein SN, Adkinson JM. Donor site morbidity after sural nerve grafting: A systematic review. J Plast Reconstr Aesthet Surg. 2021;74(11):3055-3060. PMID 33985927
    • Shah HR, Bertelli JA. Long-Term Donor-Site Morbidity Following Entire Sural Nerve Harvest for Grafting. J Hand Surg Am. 2023;48(11):1173.e1-1173.e7. PMID 37923488