Defining the Salvage Time Window for the Use of Ischemic Postconditioning in Skeletal Muscle Ischemia Reperfusion Injury.

BACKGROUND: The aim of this study was to determine the optimal salvage time window within which ischemic postconditioning can be used to ameliorate ischemia/reperfusion (I/R) injury in skeletal muscle. METHODS: A total of 48 Sprague-Dawley rats were divided into two groups: I/R only (control) and I/R with postconditioning. Subgroups were divided by duration of ischemia (2, 4, 6, and 8 hours). A pedicled gracilis muscle model was used. The postconditioning protocol consisted of six cycles of 15 seconds of reperfusion followed by 15 seconds of ischemia (total time = 3 minutes). Muscles were harvested 24 hours after I/R injury to examine tissue viability, histology, myeloperoxidase activity, and protective gene expression. RESULTS: Postconditioning groups showed improved muscle viability after 4 and 6 hours of ischemia time as compared with controls (p < 0.05). Higher expression of mitochondrial complexes I, II, III, endothelial nitric oxide synthase, inducible nitric oxide synthase, and Bcl-2 were observed in the postconditioning group after 4 and 6 hours of ischemia (p < 0.05). Lower expression of tumor necrosis factor-α and caspase 3 was observed in the postconditioning group at 4 hours (p < 0.05). Myeloperoxidase activity was similar in both groups at all-time points except 8 hours ischemia, where the control group had higher activity (p < 0.05). CONCLUSION: Results of this study demonstrate that the effective time window within which postconditioning is most effective for the salvage of skeletal muscle is between 4 and 6 hours of ischemia. Postconditioning offered improved mitochondrial and vascular function with decreased inflammation and cell death. This may be clinically useful as a postinjury salvage technique to attenuate I/R injury after 4 to 6 hours of ischemia.

Metacarpal and Phalangeal Nonunions.

The majority of phalangeal and metacarpal fractures will proceed to union when appropriately treated. However, when a nonunion does occur, it can lead to significant functional impairment for patients and societal costs. Operative intervention is typically required in these cases, but the technique can vary depending on each individual patient scenario. This article provides an overview of nonunions of the metacarpals and phalanges in the hand, including incidence, risk factors, current treatment options, and postoperative care.

Polyethylene Glycol Fusion and Nerve Repair Success: Practical Applications.

Peripheral nerve injuries are potentially devastating injuries leading to pain and impairment in motor and sensory functions. Since the first published use of microsurgical epineural repair of peripheral nerves in 1964, a wide variety of adjuncts have been studied. Polyethylene glycol is a fusogen that has been shown to restore axolemmal membranes. The use of polyethylene glycol in nerve injuries was first described in 1986, and animal studies have shown fusion of transected sensory and motor nerves following early application at the time of surgical repair with improved motor and sensory outcomes. Early human clinical trials have shown promising results, although more data are needed to provide specific indications and protocols. This article summarizes the background, current evidence, and future directions as well as potential applications of polyethylene glycol-mediated nerve fusion.

Compression Neuropathies: Revisions and Managing Expectations.

Most compression neuropathies can be reliably treated with surgical decompression; however, in approximately 25% of the cases, this release fails, requiring revision surgery. Defining the correct diagnosis after a failed nerve decompression (ie, persistent, recurrent, or new symptoms) is of the utmost importance and guides toward the optimal treatment. This article describes the clinical categorization of secondary carpal tunnel syndrome and cubital tunnel syndrome, intraoperative principles of revision surgery and treatment options that are currently available.

A Microbiological and Ultrastructural Comparison of Aseptic versus Sterile Acellular Dermal Matrix as a Reconstructive Material and a Scaffold for Stem Cell Ingrowth.

BACKGROUND: Recent data suggest an increased risk for infection when acellular dermal matrix is used in breast reconstruction. This may be because some acellular dermal matrices are actually not terminally sterilized but are instead "aseptically processed." This study evaluates aseptic and sterile matrices for evidence of bacterial contamination and whether or not terminal sterilization affects matrix collagen architecture and stem cell ingrowth. METHODS: Five separate samples of 14 different matrices were analyzed by fluorescent in situ hybridization using a bacterial DNA probe to detect bacterial DNA on the matrices. Separate samples were incubated for bacteria, acid-fast bacilli, and fungi for 2 to 6 weeks to detect living organisms. The impact of terminal sterilization on the collagen network and stem cell ingrowth on the matrices was then assessed. RESULTS: Traces of bacterial DNA were encountered on all matrices, with more bacteria in the aseptic group compared with the sterile group (3.4 versus 1.6; p = 0.003). The number of positive cultures was the same between groups (3.8 percent). Electron microscopy demonstrated decreased collagen organization in the sterile group. Stem cell seeding on the matrices displayed a wide variation of cellular ingrowth between matrices, with no difference between aseptic and sterile groups (p = 0.2). CONCLUSIONS: Although there was more evidence of prior bacterial contamination on aseptically processed matrices compared with sterile matrices; clinical cultures did not differ between groups. Terminal sterilization does not appear to affect stem cell ingrowth but may come at the cost of damaging the collagen network. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.