Midterm Results of an Anatomical Radial Head Arthroplasty for Treating Fractures and Degenerative Joint Diseases of the Radial Head

Background: Radial head arthroplasty (RHA) is typically performed to restore elbow stability or function in patients with fractures or degenerative joint diseases. The procedure requires a specific operating technique to avoid complications such as overstuffing, capitellar erosion, stiffness, instability, micro motion, and loosening. It is difficult to restore native radial head function reliably. Methods: We reviewed the medical records of 45 patients who underwent radial head arthroplasty using the ALIGN radial head implant (ALIGN Radial Head System, Skeletal Dynamics, Miami, FL) at our institution. A total of 15 patients met inclusion criteria and were contacted to complete a QuickDASH questionnaire, with additional questions on range of motion, strength, stability, pain, and satisfaction. The monoblock ALIGN implant has a long, press-fit stem coated in titanium plasma spray (TPS), is comprised of cobalt chrome, and is anatomically aligned by the provided alignment jig. Results: Of the 15 patients, one reported severe loss of motion. No patient reported severe loss of strength, loss of stability, or pain. The average QuickDASH score was 12.62 (SD, 18.06) of 100, and the average patient satisfaction score was 8.80 (SD, 2.18) of 10. Conclusions: Radial head arthroplasty may result in suboptimal performance. Functional outcomes after using this implant with monoblock design have been favorable. The design may accurately replicate the anatomical function of the native radial head, and the long, TPS-coated press-fit stem may provide more stability and osseous integration than other implants. The results of this study indicated satisfactory midterm results after use of the ALIGN implant in radial head arthroplasty

Multiple late-Pleistocene colonisation events of the Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae) reveal the recent arrival of native Antarctic vascular flora

Aim: Antarctica's remote and extreme terrestrial environments are inhabited by only two species of native vascular plants. We assessed genetic connectivity amongst Antarctic and South American populations of one of these species, Colobanthus quitensis, to determine its origin and age in Antarctica. Location: Maritime Antarctic, sub‐Antarctic islands, South America. Taxon: Antarctic pearlwort Colobanthus quitensis (Caryophyllaceae). Methods: Four chloroplast markers and one nuclear marker were sequenced from 270 samples from a latitudinal transect spanning 21–68° S. Phylogeographic, population genetic and molecular dating analyses were used to assess the demographic history of C. quitensis and the age of the species in Antarctica. Results: Maritime Antarctic populations consisted of two different haplotype clusters, occupying the northern and southern Maritime Antarctic. Molecular dating analyses suggested C. quitensis to be a young (<1 Ma) species, with contemporary population structure derived since the late‐Pleistocene. Main conclusions: The Maritime Antarctic populations likely derived from two independent, late‐Pleistocene dispersal events. Both clusters shared haplotypes with sub‐Antarctic South Georgia, suggesting higher connectivity across the Southern Ocean than previously thought. The overall findings of multiple colonization events by a vascular plant species to Antarctica, and the recent timing of these events, are of significance with respect to future colonizations of the Antarctic Peninsula by vascular plants, particularly with predicted increases in ice‐free land in this area. This study fills a significant gap in our knowledge of the age of the contemporary Antarctic terrestrial biota. Adding to previous inferences on the other Antarctic vascular plant species (the grass Deschampsia antarctica), we suggest that both angiosperm species are likely to have arrived on a recent (late‐Pleistocene) time‐scale. While most major groups of Antarctic terrestrial biota include examples of much longer‐term Antarctic persistence, the vascular flora stands out as the first identified terrestrial group that appears to be of recent origin

The “Trojan horse” strategy: Seed fungal endophyte symbiosis helps to explain the invasion success of the grass, Poa annua, in Maritime Antarctica

Aim Poa annua L. (annual bluegrass) is presently the sole invasive vascular plant species to have successfully established in Maritime Antarctica, where it poses a significant conservation threat to native plant species. However, the reasons for its success in the region have yet to be established. Here, we determined whether the invasiveness of P. annua, and its competitiveness with the native Antarctic hairgrass Deschampsia antarctica, is influenced by symbioses formed with seed fungal endophytes, and whether plants derived from seeds from four global regions differ in their performance. Locations Four regions (Maritime Antarctica, sub-Antarctica, South America and Europe). Methods Endophyte frequency was measured in P. annua seeds collected from the four regions. The germination, survival, biomass accumulation, flowering and competitiveness with D. antarctica of P. annua plants grown from endophyte-uncolonised and uncolonised seeds was determined in the laboratory. The effects of endophytes on P. annua seed germination and survival and seedling osmoprotection were also assessed in the Maritime Antarctic natural environment using locally-sourced seeds. Results Endophytes were at least twice as frequent in seeds from Maritime Antarctica than in those from other regions. A higher proportion of endophyte-colonized seeds germinated and survived than did uncolonised seeds, but only when they originated from Maritime Antarctica. Seed endophytes increased the competitiveness of P. annua with D. antarctica, but only for plants grown from Maritime Antarctic seeds. In the field, endophyte-colonized seeds from Maritime Antarctica germinated and survived more frequently than uncolonised seeds, and osmoprotection was higher in seedlings grown from colonized seed. Main Conclusions The findings indicate beneficial effects of seed endophytes on invasion-related traits of P. annua, such as survival, germination success and flowering. Together with vegetative and reproductive traits facilitating the colonization process, the seed-fungal endophyte symbiosis can be invoked as an important factor explaining the invasiveness of P. annua in Maritime Antarctica