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Nerve Surface Texture Analysis Following Excision of Nerve Ends Using Various Instruments
Ryan Adam Rose, MD1, Ryan Bliss, MD2, Timothy Bromage, PhD3, Bin Hu, MD3 and Eitan Melamed, MD3, (1)UTHSCSA, San Antonio, TX, (2)Baton Rouge Orthopaedic Clinic, Baton Rouge, LA, (3)New York University, New York, NY

Nerve Surface Texture Analysis Following Excision of Nerve Ends Using Various Instruments Hypothesis: We believe that the various instruments used for excision of nerve ends will have a different surface roughness, and nerve cutting scissors will have the least rough surface texture. Methods Fresh frozen cadavers were received following standard protocols. Median and Ulnar nerves were dissected and 1-2cm lengths of nerves were cut. An 11 blade, razor blade and nerve scissors were used, which made up our three different arms. Each cut used a new 11 blade and razor. After nerves were cut, they were immediately placed into a 10% formalin solution for one week then washed in ethanols. Three-dimensional surface analysis of roughness (Sa) for each specimen was performed using ZeeScan optical hardware and GetPhase software (PhaseView, Buisson, France). Stata v13.1 (StataCorp LP, College Station, TX) was used for all statistical analyses. We then used ANOVA or Kruskal Wallis test, as appropriate according to data distribution, to compare roughness measures among cutting techniques. We defined p<0.05 as statistically significant. Results Forty cut nerves were included. Of these, 13 (32.5%) were cut using scissors, 15 (37.5%) using a razor blade, and 12 (30%) using an 11 blade. An ANOVA test showed statistical evidence for a difference in Sa among cutting techniques (p=0.002), where the lowest mean Sa was seen in surfaces cut with scissors (7.2 micrometers, 95% CI: 5.34 to 9.06), followed by 11 blade (7.29 micrometers, 95% CI: 5.22 to 9.35), and razor blade (11.03 micrometers, 95% CI: 9.43 to 12.62). A post-hoc t-test comparing Sa between surfaces cut with scissors and those with 11 blades were not statistically different (p=0.944). Median Ra (surface profile roughness) was 4.58 (IQR: 2.62-5.46). Kruskal-Wallis test also showed evidence for a statistical difference in Ra among cutting techniques (p=0.003), with the lowest being an 11 blade with (3 micrometers, IQR:1.87-4.38), followed by scissors (3.29 micrometers, IQR: 1.56 to 4.96), and razor (5.41 micrometers, IQR: 4.95-6.21). Summary Points To our knowledge, there is no evidence about which instrument is best for excising damaged nerve ends and neuromas. With our novel technique of using three-dimensional surface analysis for evaluating surface roughness, we found that use of a fresh straight razor had a poor roughness. Furthermore, a fresh 11 blade did as well as nerve specific scissors. These findings will help guide the treatment of nerve injuries and the instrumentation used to do so.


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