Oral Treatments With the TrkB Ligand Prodrug, R13, Promote Enhanced Axon Regeneration Following Peripheral Nerve Injury.

Axon regeneration after peripheral nerve injury is slow and inefficient, leading to generally poor functional recovery. Activity-dependent experimental therapies that increase expression of brain-derived neurotrophic factor (BDNF) and its TrkB receptors enhance regeneration, suggesting that treatments with BDNF might also be effective. However, recombinant human BDNF (rhBDNF), as well as 7,8-dihydroxyflavone (7,8-DHF), a small molecular BDNF mimetic, may have limited treatment applications because of their modest oral bioavailability and pharmacokinetic profile. R13 is a 7,8-DHF prodrug. Upon oral administration, it is converted in the liver to 7,8-DHF. In immunoblots from tissues at the site of nerve injury, a single oral treatment with R13 to mice following sciatic nerve transection and repair produced a rapid and prolonged increase in immunoreactivity to phosphorylated TrkB, prolonged phosphorylation of mitogen activated protein kinase (MAPK/Erk1/2), and a rapid but transient increase in phosphorylated AKT (protein kinase B). Intramuscular injections of fluorescent retrograde tracers into the gastrocnemius and tibialis anterior muscles 4 weeks after nerve injury resulted in significantly greater numbers of labeled motoneurons and dorsal root ganglion neurons in R13-treated mice than in vehicle-treated controls. Direct electromyographic (EMG) responses (M waves) were significantly larger in R13-treated mice 4 weeks after injury than vehicle-treated controls or mice treated with oral 7,8-DHF. Oral treatments with the prodrug, R13, are a potent therapy for stimulating axon regeneration and functional recovery after peripheral nerve injury.

Direct Anterior Approach for Hip Hemiarthroplasty.

PURPOSE: The purpose of this video is to demonstrate a surgical technique for a hemiarthroplasty of the hip joint through a direct anterior approach. We have found this technique to be a viable option for the treatment of displaced femoral neck fractures. METHODS: Multiple approaches to the hip are described for arthroplasty. Direct anterior approach for hemiarthroplasty is a safe, reproducible approach. RESULTS: The video displays our technique for performing a direct anterior approach to the hip joint for a hemiarthroplasty in the setting of a displaced femoral neck fracture. CONCLUSIONS: Hemiarthroplasty after femoral neck fractures in the elderly population is becoming increasingly more common. The direct anterior approach to the hip joint provides a safe approach for this procedure. The following video demonstrates our key principles when performing this technique.