Ten-year survivorship of primary total hip arthroplasty in patients 30 years of age or younger.

Aims: For this retrospective cohort study, patients aged ≤ 30 years (very young) who underwent total hip arthroplasty (THA) were compared with patients aged ≥ 60 years (elderly) to evaluate the rate of revision arthroplasty, implant survival, the indications for revision, the complications, and the patient-reported outcomes. Patients and Methods: We retrospectively reviewed all patients who underwent primary THA between January 2000 and May 2015 from our institutional database. A total of 145 very young and 1359 elderly patients were reviewed. The mean follow-up was 5.3 years (1 to 18). Logistic generalized estimating equations were used to compare characteristics and the revision rate. Survival was evaluated using Kaplan-Meier curves and hazard rates were created using Cox regression. Results: The overall revision rate was 11% (16/145) in the very young and 3.83% (52/1359) in the elderly groups (odds ratio (OR) 2.58, 95% confidence interval (CI) 1.43 to 4.63). After adjusting for the American Society of Anesthesiologists (ASA) score, gender, and a history of previous surgery in a time-to-event model, the risk of revision remained greater in the very young (adjusted hazard ratio (HR) 2.48, 95% CI 1.34 to 4.58). Survival at ten years was 82% (95% CI, 71 to 89) in the very young and 96% (95% CI, 94 to 97) in the elderly group (p < 0.001). The very young had a higher rate of revision for complications related to metal-on-metal (MoM) bearing surfaces (p < 0.001). At last follow-up, the very young group had higher levels of physical function (p = 0.002), lower levels of mental health (p = 0.001), and similar levels of pain (p = 0.670) compared with their elderly counterparts. Conclusion: The overall revision rate was greater in very young THA patients. This was largely explained by the use of MoM bearings. Young patients with non-MoM bearings had high survivorship with similar complication profiles to patients aged ≥ 60 years. Cite this article: Bone Joint J 2018;100-B:867-74.

Isolation and characterization of microsatellite markers from three species of swallows in the genus Tachycineta: T. albilinea, T. bicolor and T. leucorrhoa.

We describe 30 microsatellite loci developed from three species of swallows in the genus Tachycineta: T. bicolor (tree swallow), T. albilinea (mangrove swallow), and T. leucorrhoa (white-rumped swallow). These commonly studied birds nest in secondary cavities and are distributed from Alaska to Argentina. Primer pairs were designed for each species individually and tested for cross-amplification in 40-48 individuals of all three species. Polymorphism ranged from 5 to 65 alleles per locus (mean = 19.1). These markers will allow comparative studies of extra-pair paternity rates among members of the genus as well as the assessment of population structure.

Isolation and characterization of microsatellite markers from the acacia-ant Crematogaster mimosae.

We describe 10 microsatellite loci developed from Crematogaster mimosae, an ant species that nests mutualistically in Acacia drepanolobium trees in east Africa. Polymorphism ranged from 4 to 16 alleles per locus (mean = 7.3). Observed and expected heterozygosities ranged from 0.485 to 0.813 (mean 0.626), and from 0.502 to 0.894 (mean 0.674), respectively. These markers will foster studies of the population structure, colony structure, and reproductive strategies of these ants.

Isolation and characterization of SNP variation at 90 anonymous loci in the banded wren (Thryothorus pleurostictus).

Single nucleotide polymorphisms (SNPs) are becoming more commonly used as molecular markers in conservation studies. However, relatively few studies have employed SNPs for species with little or no existing sequence data, partly due to the practical challenge of locating appropriate SNP loci in these species. Here we describe an application of SNP discovery via shotgun cloning that requires no pre-existing sequence data and is readily applied to all taxa. Using this method, we isolated, cloned and screened for SNP variation at 90 anonymous sequence loci (51kb total) from the banded wren (Thryothorus pleurostictus), a Central American species with minimal pre-existing sequence data. We identified 168 SNPs (a mean of one SNP/305 bp, with SNPs unevenly distributed across loci). Further characterization of variation at 41 of these SNP loci among 256 individuals including 37 parent-offspring families suggests that they provide substantial information for defining the genetic mating system of this species, and that SNPs may be generally useful for this purpose when other markers are problematic.

Congruent population structure inferred from dispersal behaviour and intensive genetic surveys of the threatened Florida scrub-jay (Aphelocoma coerulescens).

The delimitation of populations, defined as groups of individuals linked by gene flow, is possible by the analysis of genetic markers and also by spatial models based on dispersal probabilities across a landscape. We combined these two complimentary methods to define the spatial pattern of genetic structure among remaining populations of the threatened Florida scrub-jay, a species for which dispersal ability is unusually well-characterized. The range-wide population was intensively censused in the 1990s, and a metapopulation model defined population boundaries based on predicted dispersal-mediated demographic connectivity. We subjected genotypes from more than 1000 individual jays screened at 20 microsatellite loci to two Bayesian clustering methods. We describe a consensus method for identifying common features across many replicated clustering runs. Ten genetically differentiated groups exist across the present-day range of the Florida scrub-jay. These groups are largely consistent with the dispersal-defined metapopulations, which assume very limited dispersal ability. Some genetic groups comprise more than one metapopulation, likely because these genetically similar metapopulations were sundered only recently by habitat alteration. The combined reconstructions of population structure based on genetics and dispersal-mediated demographic connectivity provide a robust depiction of the current genetic and demographic organization of this species, reflecting past and present levels of dispersal among occupied habitat patches. The differentiation of populations into 10 genetic groups adds urgency to management efforts aimed at preserving what remains of genetic variation in this dwindling species, by maintaining viable populations of all genetically differentiated and geographically isolated populations.