The use of autograft resulted in better motor recovery than did the use of allograft or a collagen conduit for a short nerve gap in rats. A longer evaluation time of sixteen weeks after segmental nerve injuries in rats would be beneficial as more substantial muscle recovery was seen at that time.

Use of a nerve conduit filled with collagen-GAG matrix to bridge a motor or mixed nerve defect may result in superior functional motor recovery compared with commercially available empty collagen conduit. However, nerve autograft remains the gold standard for reconstruction of a segmental motor nerve defect.

No abstract

Isometric tetanic muscle force has been described in a rat model to evaluate motor recovery in a segmental sciatic nerve defect reconstructions. However, to test longer nerve defects, an alternative and larger animal model is necessary. The purpose of this study is to describe and validate a technique for isometric force measurement of the tibialis anterior (TA) muscle in New Zealand rabbits. Muscle preload and electrical stimulation parameters were optimized to obtain the highest tetanic contraction bilaterally in 10 animals. Electrophysiology, muscle weight, peroneal nerve length, and histomorphometry were also analyzed. Only the peroneal nerve length and the ratio of highest muscle force/muscle weight demonstrated the equivalence between the sides. A small variability of TA muscle force and TA muscle weight was observed between the sides suggesting dominance. Optimization of electrical stimulation and preload as well as the use of correct anesthesia were fundamental to acquire the highest muscle force.

Frozen bone allografts are susceptible to nonunion and fracture due to limited revascularization and incomplete bone remodeling. We aim to revascularize bone allografts by combining angiogenesis from implanted arteriovenous (AV) bundles with delivery of fibroblast growth factor (FGF-2) and/or vascular endothelial growth factor (VEGF) via biodegradable microspheres. Rat femoral diaphyseal allografts were frozen at À808C, and heterotopically transplanted over a major histocompatibility mismatch. A saphenous AV bundle was inserted into the intramedullary canal. Growth factor was encapsulated into microspheres and inserted into the graft, providing localized and sustained drug release. Forty rats were included in four groups: (I) phosphate-buffered saline, (II) FGF-2, (III) VEGF, and (IV) FGF-2 þ VEGF. At 4 weeks, angiogenesis was measured by the hydrogen washout method and microangiography. Bone remodeling was evaluated by quantitative histomorphometry and histology. Bone blood flow was significantly higher in groups III and IV compared to control (p < 0.05). Similarly, bone remodeling was higher in VEGF groups. FGF-2 had little effect on allograft revascularization. No synergistic effect was observed with use of both cytokines. Delivered in microspheres, VEGF proved to be a potent angiogenic cytokine, increasing cortical bone blood flow and new bone formation in frozen allografts revascularized with an implanted AV bundle.