Washers do not affect the rate of implant removal or elbow motion in medial epicondyle fractures.

The use of a washer to supplement screw fixation can prevent fragmentation and penetration during the surgical treatment of pediatric medial epicondyle fractures. However, concerns may arise regarding screw prominence and the need for subsequent implant removal. The purpose of this study is to evaluate the impact of washer utilization on the need for hardware removal and elbow range of motion (ROM). All pediatric medial epicondyle fractures treated with a single screw over a 7-year period were queried for this retrospective case-control study. Hardware removal was performed only if the patient experienced a complication or implant-related symptoms that were refractory to non-operative management. Of the 137 patients included in the study, a washer was utilized in 90 (66%). Thirty-one patients (23%) ultimately underwent hardware removal. There was not an increased need for implant removal in those with a washer (P = 0.11). When analyzing a subgroup of 102 athletes only, there was similarly no difference in the rate of implant removal if a washer was used (P = 0.64). Overall, 107 (78%) patients regained full ROM at a mean of 13.9 ± 9.7 weeks after surgery with no significant difference along the lines of washer use. Use of a washer did not affect the need for subsequent implant removal or elbow ROM after fixation of medial epicondyle fractures, even in athletes. If there is concern for fracture fragmentation or penetration, a washer can be included without concern that future unplanned surgeries may be required.

Roles of H3K27me2 and H3K27me3 Examined during Fate Specification of Embryonic Stem Cells.

The polycomb repressive complex 2 (PRC2) methylates lysine 27 of histone H3 (H3K27) through its catalytic subunit Ezh2. PRC2-mediated di- and tri-methylation (H3K27me2/H3K27me3) have been interchangeably associated with gene repression. However, it remains unclear whether these two degrees of H3K27 methylation have different functions. In this study, we have generated isogenic mouse embryonic stem cells (ESCs) with a modified H3K27me2/H3K27me3 ratio. Our findings document dynamic developmental control in the genomic distribution of H3K27me2 and H3K27me3 at regulatory regions in ESCs. They also reveal that modifying the ratio of H3K27me2 and H3K27me3 is sufficient for the acquisition and repression of defined cell lineage transcriptional programs and phenotypes and influences induction of the ESC ground state.