An analysis of differential gene expression in peripheral nerve and muscle utilizing RNA sequencing after polyethylene glycol nerve fusion in a rat sciatic nerve injury model.

Application of polyethylene glycol (PEG) to a peripheral nerve injury at the time of primary neurorrhaphy is thought to prevent Wallerian degeneration via direct axolemma fusion. The molecular mechanisms of nerve fusion and recovery are unclear. Our study tested the hypothesis that PEG alters gene expression in neural and muscular environments as part of its restorative properties. Lewis rats underwent unilateral sciatic nerve transection with immediate primary repair. Subjects were randomly assigned to receive either PEG treatment or standard repair at the time of neurorrhaphy. Samples of sciatic nerve distal to the injury and tibialis muscle at the site of innervation were harvested at 24 hours and 4 weeks postoperatively. Total RNA sequencing and subsequent bioinformatics analyses were used to identify significant differences in differentially expressed genes (DEGs) and their related biological pathways (p<0.05) in PEG-treated subjects compared to non-PEG controls. No significant DEGs were identified in PEG-treated sciatic nerve compared to controls after 24 hours, but 1,480 DEGs were identified in PEG-treated tibialis compared to controls. At 4 weeks, 918 DEGs were identified in PEG-treated sciatic nerve, whereas only 3 DEGs remained in PEG-treated tibialis compared to controls. DEGs in sciatic were mostly upregulated (79%) and enriched in pathways present during nervous system development and growth, whereas DEGs in muscle were mostly downregulated (77%) and related to inflammation and tissue repair. Our findings indicate that PEG application during primary neurorrhaphy leads to significant differential gene regulation in the neural and muscular environment that is associated with improved functional recovery in animals treated with PEG compared to sham non-PEG controls. A detailed understanding of key molecules underlying PEG function in recovery after peripheral nerve repair may facilitate amplification of PEG effects through systemic or focal treatments at the time of neurotmesis.

Medicare Reimbursement in Hand and Upper Extremity Procedures: A 20-Year Analysis.

PURPOSE: Concern exists that Medicare physician fees for procedures have decreased over the past 20 years. The Centers for Medicare & Medicaid Services (CMS) is set to re-evaluate these physician fees in the near future for concern that these procedures are overvalued. Our study sought to analyze trends in Medicare reimbursement rates from 2000 to 2019 for the top 20 most billed hand and upper extremity surgical procedures at our institution. METHODS: The financial database of a single academic tertiary care center was queried to identify the Current Procedural Terminology codes most frequently utilized in orthopedic hand and upper extremity procedures in 2019. The Physician Fee Schedule Look-Up Tool from the CMS was queried for annual physician fee data. Monetary data were adjusted for inflation using the consumer price index of Urban Research Series (CPI-U-RS) and expressed in 2019 constant US dollars (USD). The average annual and total percent change in reimbursement were calculated via linear regression for all procedures (P < .05). RESULTS: Accounting for inflation, the total average physician reimbursement decreased by 20.9% from 2000 to 2019, with 12 of 20 codes decreasing by more than 20%. The greatest decrease pertained to arthrodesis of the wrist at 33.9%. Upon linear regression, all procedures were found to decrease annually, with arthrodesis of the wrist decreasing by an average of 2.3% annually over this period. CONCLUSIONS: Over the past 2 decades, physician reimbursement for hand and upper extremity procedures has significantly decreased.