Delayed Presentation of Displaced Salter-Harris III Distal Tibia Fracture: Does Transfracture Reduction Yield Satisfactory Outcomes?

LEVELS OF EVIDENCE: Level V.

Side-to-side supercharging nerve allograft enhances neurotrophic potential.

INTRODUCTION: Critical limitations of processed acellular nerve allograft (PNA) are linked to Schwann cell function. Side-to-side bridge grafting may enhance PNA neurotrophic potential. METHODS: Sprague-Dawley rats underwent tibial nerve transection and immediate repair with 20-mm PNA (n = 33) or isograft (ISO; n = 9) or 40-mm PNA (n = 33) or ISO (n = 9). Processed acellular nerve allograft groups received zero, one, or three side-to-side bridge grafts between the peroneal nerve and graft. Muscle weight, force generation, and nerve histomorphology were tested 20 weeks after repair. Selected animals underwent neuron back labeling with fluorescent dyes. RESULTS: Inner axon diameters, g-ratios, and axon counts were smaller in the distal vs proximal aspect of each graft (P < .05). Schwann cell counts were greater, with a lower proportion of senescent cells for groups with bridges (P < .05). Retrograde labeling demonstrated that 6.6% to 17.7% of reinnervating neurons were from the peroneal pool. DISCUSSION: Bridge grafting positively influenced muscle recovery and Schwann cell counts and senescence after long PNA nerve reconstruction.

Cerebrovascular regulation in men and women: stimulus-specific role of cyclooxygenase.

Greater cerebral artery vasodilation mediated by cyclooxygenase (COX) in female animals is unexplored in humans. We hypothesized that young, healthy women would exhibit greater basal cerebral blood flow (CBF) and greater vasodilation during hypoxia or hypercapnia compared to men, mediated by a larger contribution of COX. We measured middle cerebral artery velocity (MCAv, transcranial Doppler ultrasound) in 42 adults (24 women, 18 men; 24 ± 1 years) during two visits, in a double-blind, placebo-controlled design (COX inhibition, 100 mg oral indomethacin, Indo). Women were studied early in the follicular phase of the menstrual cycle (days 1-5). Two levels of isocapnic hypoxia (SPO2 = 90% and 80%) were induced for 5-min each. Separately, hypercapnia was induced by increasing end-tidal carbon dioxide (PETCO 2) 10 mmHg above baseline. A positive change in MCAv (ΔMCAv) reflected vasodilation. Basal MCAv was greater in women compared to men (P < 0.01) across all conditions. Indo decreased baseline MCAv (P < 0.01) similarly between sexes. Hypoxia increased MCAv (P < 0.01), but ΔMCAv was not different between sexes. Indo did not alter hypoxic vasodilation in either sex. Hypercapnia increased MCAv (P < 0.01), but ΔMCAv was not different between sexes. Indo elicited a large decrease in hypercapnic vasodilation (P < 0.01) that was similar between sexes. During the early follicular phase, women exhibit greater basal CBF than men, but similar vasodilatory responses to hypoxia and hypercapnia. Moreover, COX is not obligatory for hypoxic vasodilation, but plays a vital and similar role in the regulation of basal CBF (~30%) and hypercapnic response (~55%) between sexes.