Background Successful microvascular anastomosis depends on sutures that adequately oppose both cut vessel edges. Trainees tend to take oversized or uneven bite. To improve early microsurgical skill acquisition using the rat, this study tests the belief that such bites compromise early patency by applying exaggerated bites to end-to-end arterial anastomoses. Methods Twelve Sprague–Dawley rats were randomly assigned to one of the four bite techniques to be applied to both femoral arteries (mean diameter, 0.8 mm). Large (L) and standard (S) bites measured 1.0 and 0.2 mm from the edge, respectively. Eight simple interrupted anastomoses were performed per bite technique, each labeled according to every proximal end bite size, followed by every distal end bite size: LL, LS, SL, and SS. Anastomosis time and blood flow rates were recorded and analyzed statistically. After sacrifice 5 days postoperation, anastomosis sections of each technique were examined histologically. Results All 24 anastomoses (100%) maintained patency for 5 days. There was no statistical difference between all postoperative blood flow measurements at any given time. Anastomosis times using LL, LS, SL, and SS bite techniques were 41.6, 33.2, 34.8, and 25.5 minutes, respectively. Anastomosis time for the traditional bite technique (SS) was significantly shorter than all other bite techniques (p< 0.05). Histological examination of the harvested segments from each group revealed similar pathophysiological features. Conclusion Oversized bites (1 mm), placed symmetrically and asymmetrically across the anastomosis, do not affect early patency in the rat femoral artery. A reduced reliance on conventional guidelines for suture bites appears acceptable during microarterial anastomoses if the goal is vessel patency. However, we believe clinical competence involves the ability to place small, even bites consistently and uniformly. During microsurgical training, the occasional large bite need not be replaced; however, the trainee should be encouraged to take standard bites.

Background Nerve wrapping has been advocated to minimize scarring and adhesion following neurorrhaphy or neurolysis. A wrap should provide an enclosure that is snug enough to protect and support the affected nerve without strangulating the nerve. The degree to which resorbable wraps should be “tightened” around the nerve is largely subjective with scant literature on the subject. The purpose of this study was to evaluate the effects of tightly fitting resorbable nerve wraps around intact rat sciatic nerves. Methods Twenty-four Sprague-Dawley rats underwent exposure and circumferential measurement of the right sciatic nerve. Porcine-derived extracellular matrix (ECM) wraps were trimmed and sutured to enclose the nerve with a tight (same as that of the nerve, n = 8) or loose (2.5x that of the nerve, n = 8) circumference. Sham-surgery control animals (n = 8) had no wrap treatment. Functional outcome was recorded biweekly by sciatic functional index (SFI) with walking track analysis and electrical stimulation. Animals were sacrificed at 12 weeks for histologic analyses. Results No withdrawal response could be evoked in the tight-wrap group until week 9, while significant improvement in SFI first occurred between weeks 5 and 7. By week 12, the tight-wrap group required 60% more current compared with baseline stimulation to produce a withdrawal response. They recovered 81% of SFI baseline values but also demonstrated significantly greater intraneural collagen content (p < 0.001) and lower axon density (p < 0.05) than in the loose-wrap and sham groups. The loose-wrap group had comparable functional and histologic outcomes to the sham control group. Conclusion Resorbable ECM nerve wraps applied tightly around intact rat sciatic nerves caused significant functional impairment and histological changes characteristic of acute nerve compression. Significant but incomplete functional recovery was achieved by the tight-wrap group after 12 weeks, but such recovery may not apply in humans.