Improving Nerve End Preparation for Neurorrhaphy through Use of a Circumferentially Constraining Surgical Device
Brandon Smetana, MD1; Konrad Wolfmeyer, BS2; Archana Lovett, PhD3; Brian Romot, MS4; Michael Orrico, MS4; Jeffrey A Greenberg, MD5; (1)Indiana Hand to Center, Indianapolis, IN, (2)Purdue University, West Lafayette, IN, (3)University of Florida, Gainesville, FL, (4)AxoGen, Alachua, FL, (5)Indiana Hand to Shoulder Center, Indianapolis, IN
Introduction: The use of surgical scissors or a scalpel on a hard surface such as a tongue depressor are conventional techniques for preparing human peripheral nerve for coaptation. However, previous studies have demonstrated that use of these instruments can lead to crushing at the nerve end and/or uneven cuts, and may result in poorly aligned fascicles at the coaptation site. This study investigated the use of a circumferential constraint around the nerve in conjunction with an optimized (sharp, thin) blade in order to minimize crush damage and fascicular distortion during cutting.
Methods: Sectioning of thawed, 1-2 mm diameter human cadaveric nerve was performed using surgical scissors as well as #10 and #21 surgical scalpel blades each with a tongue depressor or a circumferential constraint. A separate nerve was used for each cut. Diameter of the nerve was measured before and after resection to determine the percentage of deformation. Immediately following resection, nerve sections were prepared for SEM imaging by fixation and drying using the critical point technique. Mounted nerve sections were then imaged under high vacuum at an accelerating voltage of 10 kV.
Results: Resection using the circumferentially constraining device resulted in diametric deformation of 5-10% as well as visibly preserved localization of nerve fascicles and interfascicular perineurium compared to cutting without circumferential constraint. Use of surgical scissors resulted in 15% deformation with destruction of observable interfascicular perineurium and obscured nerve fascicles. Use of a blade with a tongue depressor resulted in 20% deformation, destruction of interfascicular perineurium, and visible relocation of nerve fascicles (Figure 1).
Conclusion: Established surgical techniques for nerve end preparation result in ultrastructural destruction of internal nerve architecture due to un-constrained shear forces seen when utilizing conventional surgical instrumentation. A surgical device employing circumferential constraint of the nerve during resection can minimize destruction of intraneural structure at the resection interface and preserve nerve fascicle integrity. Preservation of ultrastructural nerve architecture through the use of a circumferentially constraining device has the potential to optimize axonal alignment, which may affect functional outcomes post-surgery.
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