Large Femoral Heads in Total Hip Arthroplasty With Vitamin E Highly Cross-Linked Polyethylene: Head Penetration Rates Compared to Highly Cross-Linked Polyethylene.

BACKGROUND: Highly cross-linked polyethylene with vitamin E (VE-HXLPE) has shown superior tribological properties and has been rapidly adopted in total hip arthroplasty. However, the majority of studies compare VE-HXLPE to conventional or moderately cross-linked polyethylene using standard femoral head sizes. This study's purpose was 2-fold: (1) compare radiographic femoral head penetration (FHP) between VE-HXLPE and HXLPE and (2) evaluate FHP in large femoral heads ≥40 mm. METHODS: One hundred forty-two consecutive primary total hip arthroplasties using ceramic femoral heads (n = 84 VE-HXLPE; n = 58 HXLPE) in a single implant system were retrospectively reviewed. FHP was measured radiographically utilizing Martell method at 4-week, 1-year, and latest radiographs. FHP, cup position, and demographic variables were compared between VE-HXLPE and HXLPE liners. RESULTS: Median linear FHP was lower for VE-HXLPE compared to HXLPE during the initial "bedding-in" period between 4-week and 1-year (0.383 vs 0.551 mm, P = .650) and between 1-year and latest follow-up (0.131 vs 0.270 mm/y, P = .636) although without statistical significance. Acetabular cup inclination and anteversion did not influence linear or volumetric FHP (P ≥ .204). Large femoral heads (≥40 mm) were predictive of higher FHP during the early bedding-in period (P ≤ .025) but did not have an effect beyond 1 year in multivariate regression with numbers available. No radiographic osteolysis was observed in any case. CONCLUSION: These findings support others that VE-HXLPE is the optimal polyethylene bearing surface to minimize FHP during the bedding-in period and beyond. Surprisingly, large ceramic femoral heads appear to influence FHP during the initial bedding-in period but do not increase FHP beyond 1 year. Further longer term follow-up remains warranted. LEVEL OF EVIDENCE: III.

Bibliometric and authorship trends over a 30 year publication history in two representative US sports medicine journals.

Bibliometric studies are important to understand changes and improvement opportunities in academia. This study compared bibliometric trends for two major sports medicine/arthroscopy journals, the American Journal of Sports Medicine® (AJSM®) and Arthroscopy® over the past 30 years. Trends over time and comparisons between both journals were noted for common bibliometric variables (number of authors, references, pages, citations, and corresponding author position) as well as author gender and continental origin. Appropriate statistical analyses were performed. A p < 0.001 was considered statistically significant. One representative year per decade was used. There were 814 manuscripts from AJSM® and 650 from Arthroscopy®. For AJSM® the number of manuscripts steadily increased from 86 in 1986 to 350 in 2016; for Arthroscopy® the number of manuscripts increased from 73 in 1985/1986, to 267 in 2006, but then dropped to 229 in 2016. There were significant increases in all bibliometric variables, except for the number of citations which decreased in Arthroscopy®. There were significant differences in manuscript region of origin by journal (p = 0.000002). Arthroscopy® had a greater percentage of manuscripts from Asia than AJSM® (19.3% vs 11.5%) while AJSM® had a greater percentage from North America (70.3% vs 59.2%); both journals had similar percentages from Europe (18.2% for AJSM® and 21.6% for Arthroscopy®). For AJSM® the average percentage of female first authors was 13.3%, increasing from 4.7% in 1986 to 19.3% in 2016; the average percentage of female corresponding authors was 7.3%. For Arthroscopy®, the average percentage of female first authors was 8.1%, increasing from 2.8% in 1985/1986 to 15.7% in 2016 (p = 0.00007). In conclusion, AJSM® and Arthroscopy® showed an increase in most variables analyzed. Although Arthroscopy® is climbing at a higher rate than AJSM® for female authors, AJSM® has an overall greater percentage of female authors.