Second Look—Clinical News and Views

If you missed these Headline News Now items the first time around, AAOS Now gives you a second chance to review them. Headline News Now—the AAOS thrice-weekly, online update of news of interest to orthopaedic surgeons—brings you the latest on clinical, socioeconomic, and political issues, as well as important announcements from AAOS.

Treating tarsal navicular stress fractures
Non–weight-bearing conservative management should be considered the standard of care for tarsal navicular stress fractures, according to a systematic literature review published in the American Journal of Sports Medicine (May). The authors used a mixed generalized linear model with study as a random effect and treatment as a fixed effect, and compared cases based on type of treatment: conservative, weight bearing permitted; conservative, non–weight bearing (NWB); and surgical. No statistically significant difference in outcomes was found between NWB conservative treatment and surgical treatment, but a statistical trend favored NWB management over surgery. Weight bearing as a conservative treatment was shown to be significantly less effective than either NWB or surgical treatment.

Causes of local anesthetic chondrotoxicity
A study in the American Journal of Sports Medicine (June) finds that the chondrotoxicity of local anesthetics containing epinephrine may be due to a combined effect of low pH and the preservative sodium metabisulfite. The authors harvested human chondrocytes and cultured 10 batches, using a custom bioreactor designed to simulate metabolism of medication. After 24 hours of perfusion, viability assays were performed. Cultures with media titrated to pH 4.5, pH 5.0, and local anesthetics containing epinephrine (pH 4.0–5.5) had high cell death rates compared with controls at all time points; cultures containing 1:100000 and 1:200000 epinephrine alone had no increased death rate. Also, 0.5 mg/mL sodium metabisulfite preservative had a significant effect on cell death, yet the preservative methylparaben had no effect. The percentage of cell death was not significant for 1 percent lidocaine and 0.25 percent bupivacaine.

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