Mechanical strain induces ex vivo expansion of periosteum.

Segmental bone defects present complex clinical challenges. Nonunion, malunion, and infection are common sequalae of autogenous bone grafts, allografts, and synthetic bone implants due to poor incorporation with the patient's bone. The current project explores the osteogenic properties of periosteum to facilitate graft incorporation. As tissue area is a natural limitation of autografting, mechanical strain was implemented to expand the periosteum. Freshly harvested, porcine periosteum was strained at 5 and 10% per day for 10 days with non-strained and free-floating samples serving as controls. Total tissue size, viability and histologic examination revealed that strain increased area to a maximum of 1.6-fold in the 10% daily strain. No change in tissue anatomy or viability via MTT or Ki67 staining and quantification was observed among groups. The osteogenic potential of the mechanical expanded periosteum was then examined in vivo. Human cancellous allografts were wrapped with 10% per day strained, fresh, free-floating, or no porcine periosteum and implanted subcutaneously into female, athymic mice. Tissue was collected at 8- and 16-weeks. Gene expression analysis revealed a significant increase in alkaline phosphatase and osteocalcin in the fresh periosteum group at 8-weeks post implantation compared to all other groups. Values among all groups were similar at week 16. Additionally, histological assessment with H&E and Masson-Goldner Trichrome staining showed that all periosteal groups outperformed the non-periosteal allograft, with fresh periosteum demonstrating the highest levels of new tissue mineralization at the periosteum-bone interface. Overall, mechanical expansion of the periosteum can provide increased area for segmental healing via autograft strategies, though further studies are needed to explore culture methodology to optimize osteogenic potential.

Cost Analysis of Medical Students Applying to Orthopaedic Surgery Residency: Implications for the 2020 to 2021 Application Cycle During COVID-19.

Although studies have evaluated the economic burden to medical students desiring an orthopaedic residency broadly, no study has evaluated in detail the application costs, away rotation costs, interview costs, and total costs. Given that the Association of American Medical Colleges and the American Orthopaedic Association's Council of Orthopaedic Residency Directors have recommended orthopaedic surgery residency programs for the 2021 residency application cycle cancel away rotations and in-person interviews, our objective was to evaluate the cost savings to medical students applying during this time and the potential implications. METHODS: Using the 2019 to 2020 Texas STAR Dashboard database, we queried responses from applicants applying to orthopaedic surgery residency. The dashboard was queried to record the application costs, away rotation costs, interview costs, and total costs for medical school seniors applying to orthopaedic surgery residency. Demographic information for applicants was also recorded. Mean and median costs were reported with percentile distributions and geographic comparisons. A Kruskal-Wallis H test was used to determine whether there were statistically significant differences in mean costs by medical school region. RESULTS: The 2019 to 2020 Texas STAR Dashboard database had 473 responses from applicants to orthopaedic surgery residency. The mean application costs were $1,990, away rotation costs were $3,182, interview costs were $3,129, and total costs were $8,205. The mean total costs for applicants from Midwest schools were significantly less than Western schools ($7,410/applicant vs. $9,909/applicant) (p = 0.008). There was no significant difference between the mean application fees between regions. Away rotation costs for applicants from schools in the Midwest ($2,413/applicant) were significantly less compared with Northeast ($3,279/applicant), South ($3,343/applicant), and West ($3,913/applicant) (all p < 0.002). Interview costs for applicants from schools in the Northeast ($2,891/applicant) were less than applicants from Western US schools ($3,831/applicant) (p = 0.038). CONCLUSION: In the COVID-19 era, orthopaedic residency applicants could save on average $6,311 through the use of virtual interviews and lack of away rotations. There are geographic implications, with applicants from Western US medical schools potentially saving most.