Bone Bed Research Articles

Effect of macrogeometry and bone type on insertion torque, primary stability, surface topography damage and titanium release of dental implants during surgical insertion into artificial bone

This study investigated the influence of implant macrogeometry and bone type on insertion torque (IT), primary stability (ISQ), surface topography damage, and the amount of titanium (Ti) released during insertion. Forty implants with different macrogeometries (Facility - Cylindrical with spiral-shaped threads; Alvim - Tapered with buttress-shaped threads) were inserted into artificial bone types I-II and III-IV. Surface morphology was evaluated by Scanning Electron Microscope (SEM) and roughness parameters with Laser Scanning Confocal Microscopy (LSCM) before and after insertion (AI). Implant macrogeometry was characterized by LSCM. The chemical composition of bone beds was determined by SEM associated with Energy Dispersive X-Ray Spectroscopy. The amount of Ti released was analyzed with Energy Dispersive X-Ray Fluorescence. Alvim had greater IT and ISQ than Facility. Bone types I-II require higher IT of implants. Alvim also had greater internal threads angle, higher initial roughness, and significant reduction of roughness AI, compared to Facility. The functional surface height reduced AI, especially in flank and valley of threads. Height of surface roughness of Alvim and Facility implants was similar AI. Implants surface morphology changes and metallic particles on bone beds were observed after implant insertion, mainly into bone types III-IV. Implants inserted into bone types I-II showed less surface damage. Alvim implants released more Ti (37.52 ± 25.03 ppm) than Facility (11.66 ± 28.55 ppm) on bone types III-IV. The implant macrogeometry and bone types affect IT, ISQ, surface damage, and Ti amount released during insertion. Alvim implants were more wear susceptible, releasing higher Ti concentration during insertion into bone types III-IV.

Eucynodont teeth from the Late Triassic of Krasiejów, Southern Poland

ABSTRACT Recent discoveries of Mammaliamorph teeth in the Keuper of southern Poland have extended the global record of eucynodonts in the Late Triassic and revealed a significant diversity of the group at that time. Here, we expand on this record with the description of new cynodont postcanine teeth from the Krasiejów bone bed. They show the dental morphology typical for Dromatheriidae, with a single root and crown without cingulum. We assigned them to Polonodon woznikensis, described from Woźniki. None of the 38 teeth from Krasiejów and Woźniki exhibit signs of serious wear, potentially indicating a very fast rate of tooth replacement in Polonodon.

Metatarsals of a large caenagnathid cf. Anzu wyliei (Theropoda: Oviraptorosauria) from the Hell Creek Formation in South Dakota, USA1

Isolated metatarsals III and IV of a caenagnathid theropod likely referable to Anzu wyliei are described from a locality of the Hell Creek Formation in northwestern South Dakota, USA. These bones are missing from the holotype and only partial shafts have been described for a specimen referable to this species. Accordingly, the present description adds further anatomical information on this already well-known species of Caenagnathidae. The present finding also demonstrates the significance of isolated or fragmentary specimens found in multitaxic bone beds.

Выбор методов фиксации костных фрагментов при аутопластике дефектов длинных трубчатых костей

The aim of the study was to analyze the effect of different methods of fixing bone fragments after transplantation of the fibula into a large defect of long tubular bones on the results of treatment. The study included 10 patients (group 1) with major tibia defects in whom the method of postoperative fixation of the segment of the operated limb allowed to give an early mechanical load on the graft itself and 10 patients (group 2) where the impact of mechanical load on the graft was excluded due to its transplantation into the hummers defect (6 cases) or minimized when replacing the tibia defect (4 cases). The degree of graft hypertrophy, the rate of its fusion with the recipient bed, and the number of postoperative complications under different conditions of mechanical stimulation of the fibula graft were studied. The rate of fusion of the graft with the recipient bed in both groups of patients was the same, but the incidence of complete stress fractures of the fibula graft in the second group was three times higher than in the first and was 30%, against the background of a slight degree of graft hypertrophy (from 19% to 45%). The use of the Ilizarov device for fixing fragments of the post-resection bone bed and graft in a stable and dynamic mode allows to give an early postoperative load on the lower limb, stimulates the rate of graft hypertrophy and reduces the likelihood of developing complete stress fractures.

Microvertebrates from the Rhaetian basal bone bed of Saltford, near Bath, SW England

The famous Rhaetian bone bed (Late Triassic, 205 Ma) is well known because it marks a major switch in depositional environment from terrestrial red beds to fully marine conditions throughout the UK and much of Europe. The bone bed is generally cemented and less than 10 cm thick. However, we report here an unusual case from Saltford, near Bath, S.W. England where the bone bed is unconsolidated and up to nearly 1 m thick. The exposure of the basal beds of the Westbury Formation, Penarth Group includes a bone bed containing a diverse Rhaetian marine microvertebrate fauna dominated by sharks, actinopterygian fishes and reptiles. Despite the unusual sedimentary character of the bone bed, we find similar proportions of taxa as in other basal Rhaetian bone beds (55–59 % Lissodus teeth, 13–16 % Rhomphaiodon teeth, 12–14 % Severnichthys teeth, 6–9% Gyrolepis teeth, 3–4% undetermined sharks’ teeth, 1–3% undetermined bony fish teeth, and < 1% of each of Hybodus, Parascylloides, and Sargodon), the only differences being in the proportions of Rhomphaiodon teeth, which can represent 30–40 % of specimens elsewhere. This suggests that taphonomic bias of varying Rhaetian bone beds may be comparable despite different sedimentary settings, and that the proportions of taxa say something about their original proportions in the ecosystem.

The assessment of temperature amplitude arising during the implant bed formation in relation to variable preparation parameters – in vitro study

The main purpose of this study was to analyse the temperatures generated during the bone bed preparation, given the internal structure of the bone bed, the geometry of the hole, and the treatment parameters such as the type of cooling and the rotational speed of the drill. The investigated material was domestic pig ribs, in which holes were drilled three times using two drill bit systems used for Hiossen® and Paltop® dental implantation. The ThermaCAM® P640 thermal imaging camera was used for measurement of drilling temperatures. After the holes were drilled, each rib was examined using the 1172 SkyScan microtomograph, Bruker®, to compare the geometry of the machined holes. The presented study proved that larger diameter drill bits (Hiossen® drill bits) generate more heat during the machining process, as evidenced by higher temperatures obtained for the Hiossen system in each case. It was proved that rotational speed, drill bit diameter and cooling system have a significant effect on the amount of heat generated during bone tissue preparation. The density and type of bone tissue in which the hole is prepared are significant factors affecting the amount of heat generated.

КОНСЕРВИРОВАННЫЙ АЛЛОПЛАСТИЧЕСКИЙ МАТЕРИАЛ В ЛЕЧЕНИИ ОПУХОЛЕЙ И ОДОНТОГЕННЫХ КИСТ У ДЕТЕЙ

Long-term clinical observations on the treatment and rehabilitation of 117 children with tumors and tumor-like formations of the maxillofacial region are presented. To replace jaw defects, we used transplants preserved in various ways: frozen — in 48 patients, preserved in 0,5% formalin — in 7 patients, Kostma — in 7 pati¬ents, Deprotex — in 28 patients, Orgamax — in 27 patients. In the postoperative period, orthopedic and orthodontic rehabilitation of patients was carried out using removable and non-removable orthodontic appliances and dental implant systems. In the near term, no complications were revealed in 108 patients; consolidation of the graft with the bone bed occurred. 9 patients developed a purulent inflammatory process with allograft sequestration. The follow-ups of the patients showed that after transplantation, the allograft was gradually resorbed and replaced with a full-fledged organotypic regenerate within a period of 1,0 to 3 years. During the long-term up to 10 years follow-up, 92 patients (89,3 %) obtained good anatomical, functional and aesthetic results of rehabilitation, characterized by full restoration of the function of the dentition and facial aesthetics. In 11 patients (10,7 %), the results were satisfactory.

THE AMVROSIIVKA BISON BONE BED AND FEATURES OF ITS USE

The Amvrosiivka Upper Palaeolithic complex, composed of a camp site and nearby bison bone bed is located in the Donetsk oblast’, at the top of the Kazenna ravine, a right tributary of the Krynka river, which drains into the Mius river. The site is dated by an average of 19000—18000 uncal BP and belong to Epigravettian tradition.&#x0D; The results of the long-term research the Amvrosiivka bison bone bed was analyzed in the article. The features of topography (a gully-terrace on board of a ravine), planigraphy, stratigraphy of a bone bed (the ledges-thresholds and some sterile layers in cultural remains distribution), and also the seasons of the kill of animals (alternative, with prevalence of cold) was summarized.&#x0D; Data about the bison bones (Bison priscus, MNI = 650 and bones with cultural modifications) is presented. The prevalence of the hunter projectile weapon details (27 bone points and about 90 flint micropoints-inserts), and also flint tools for butchering animals among the archaeological finds is determined.&#x0D; The interpretation of the bone bed at the same times was controversial: as a refuse dump near dwelling (Evseev), as a resulted from a one-time (Pidoplichko) or repeated (Efimenko) mass drive of bison, or as a ritual locale (Boriskovskij). At present the site is interpreted as a place of numerous mass drive of bison and, mainly, primary butchering of hunting bag, and also, probably, storages of meat products in the form of the frozen carcasses of bison in a cold season (Krotova, Snizhko, Julien).&#x0D; The ethnoarchaeological data about methods of collective kills by Paleoindian and Indian pedestrian hunters on bison of the North America (Frison 2004) for the reconstruction of possible variants of the mass drive of bison in Amvrosiivka is used. The conclusion is made that for the purpose organization of the series of mass drive of bison at different seasons the hunters in Amvrosiivka used a natural trap — the gully-terrace on a board of ravine — the right tributary of a Kazenna ravine. This terrace with one abrupt and rather high (4—5 m) board, obviously, used for a drive of bison from above, a plateau (method of «jump») that the hunters, obviously, at a certain stage having added with the restraining structure (pens) which should keep the escaped and wounded animals. The variant of a possible shelter from below, a thalweg of the Kazenna ravine (an «arroyo trap» method) also is not excluded.

Experimental and numerical investigations of fracture and fatigue behaviour of implant-supported bars with distal extension made of three different materials.

The aim of this study was to investigate experimentally the fatigue and stability of three bar materials with distal extension at the molar region and to numerically analyse the biomechanical properties of the bar materials connected to overdentures in a patient individual model. A milled bar was designed for the mandible on fourimplants in the canine and second premolar region. Three bar materials were investigated: titanium (Ti), cobaltchromium (CoCr), and polyetherketonketon (PEKK). Firstly, static and fatigue tests were performed based on EN ISO 14801 in a commercial permanent loading set-up. Unilateral axial force was applied on the distal extension ofthe bars. Secondly, numerical models were created. Different bar materials and loading scenarios were analysed. The static fracture limit of the three materials was 1,750N, 780N, 310N for Ti, CoCr, and PEKK, respectively. The Wöhler curves showed comparable fatigue limits of 200N, 160N, and 150N for titanium, CoCr, and PEKK, respectively. The stress at the distal extension was 2,600MPa (Ti), 1,000MPa (CoCr), and 270MPa (PEKK). All loading simulations with the PEKK bar showed higher stresses in the implants and in the bone bed as well as higher displacements of the over denture in comparison to metal bars. PEKK showed different mechanical behaviour compared to Ti and CoCr. The distribution of stresses within the PEKK bar was wider than the area of loading which probably leads to fatigue of the whole bar and not only the part under load.

RESULTS OF MATHEMATICAL MODELING OF TENSION-DEFORMED CONDITION OF COMPONENTS OF KNEE JOINT ENDOPROSTHESIS IN CONDITIONS OF PRESENCE OF DEFECT EFFECTS

Summary. Gonarthrosis is reported in 50.6–54.5% of cases among patients with the lower extremities large joints’ dystrophic diseases. In 86% of cases, it affects people of working age, and in 6.5–14.6% - leads to disability. That is why, gonarthrosis is an acute medical and social problem. However, despite the large number of surgeries, the matter of choosing a method (bone plastic, metal insertion) to cover a bone bed’s defects for total knee arthroplasty (KJ) is still ambiguous. Objective: to conduct a computer simulation of strains occurring upon a regular and extended tibial stem of a knee prosthesis, depending on different tibial condylar defects. Materials and methods: the laboratory of biomechanics of the SI “ITO NAMS of Ukraine” created a computer model to study stress-deformed conditions of a KJ endoprosthesis upon a varus deformity of an extremity and knee arthroplasty with a regular and an extended tibial stem, if a bone defect has been replaced with a bone autograft of 5 and 10 mm. Results. It was determined that if a knee arthroplasty occurs upon conditions of a varus deformity, with an internal tibial condyle’s defect, the defect can be filled with an autograft insert up to 5 mm high, and a regular (short) prosthetic stem is suitable. If such a lesion is from 5 mm to 13.5 mm, an extended prosthetic stem is biomechanically justified. If a height of the defect exceeds 13.5 mm, it must be replaced with a massive metal insert. Practical essence: the study will be helpful to elaborate a differentiated approach to various tibial condyles’ defects treatment in the course of the total knee arthroplasty. Conclusions. The implementation of recommendations resulting from this study will increase the efficiency of treatment to this severe category of patients.

The amphibians and reptiles from the Early Pleistocene of Coste San Giacomo (Anagni Basin, Italy)

ABSTRACT The site of Coste San Giacomo, in the Anagni Basin, is renowned for its mammal fauna of Early Pleistocene (Gelasian) age, including 32 taxa of small and large mammals. Adding to these, a small amount of remains of amphibians and reptiles was also recovered during recent excavations focused on collecting small vertebrates as well. The analysis of these remains resulted in the identification of a total of at least six different taxa: three anurans (Bufonidae indet., Pelophylax sp., and Rana sp.) and three reptiles (Lacertidae indet., Pseudopus sp., and Natrix sp.). This assemblage is comprised of taxa that are common in the Italian Quaternary, but also presents the first occurrence of the large anguid Pseudopus from the Apennine Peninsula in this period. On the whole, the herpetofauna indicates the presence of humid conditions in CSG at the moment of deposition of the bone bed that yielded the vertebrate remains.

The postcranial skeleton of the erythrosuchid archosauriform Garjainia prima from the Early Triassic of European Russia.

Erythrosuchidae were large-bodied, quadrupedal, predatory archosauriforms that dominated the hypercarnivorous niche in the aftermath of the Permo-Triassic mass extinction. Garjainia, one of the oldest members of the clade, is known from the late Olenekian of European Russia. The holotype of Garjainia prima comprises a well-preserved skull, but highly incomplete postcranium. Recent taxonomic reappraisal demonstrates that material from a bone bed found close to the type locality, previously referred to as ‘Vjushkovia triplicostata', is referable to G. prima. At least, seven individuals comprising cranial remains and virtually the entire postcranium are represented, and we describe this material in detail for the first time. An updated phylogenetic analysis confirms previous results that a monophyletic Garjainia is the sister taxon to a clade containing Erythrosuchus, Shansisuchus and Chalishevia. Muscle scars on many limb elements are clear, allowing reconstruction of the proximal locomotor musculature. We calculate the body mass of G. prima to have been 147–248 kg, similar to that of an adult male lion. Large body size in erythrosuchids may have been attained as part of a trend of increasing body size after the Permo-Triassic mass extinction and allowed erythrosuchids to become the dominant carnivores of the Early and Middle Triassic.

Does implant surface hydrophilicity influence the maintenance of surface integrity after insertion into low-density artificial bone?

ObjectiveTo evaluate the influence of hydrophilicity on the surface integrity of implants after insertion in low-density artificial bone and to determine the distribution of titanium (Ti) particles along the bone bed. MethodsForty-eight dental implants with different designs (Titamax Ex, Facility, Alvim, and Drive) and surface treatments (Neoporos® and Aqua™) were inserted into artificial bone blocks with density compatible with bone type III-IV. Hydrophobic Neoporos® surfaces were obtained by sandblasting and acid etching while hydrophilic Aqua™ surfaces were obtained by sandblasting, acid etching, and storage in an isotonic 0.9% NaCl solution. The surface integrity was evaluated by Scanning Electron Microscope (SEM) and the surface roughness parameters (Sa, Sp, Ssk, Sdr, Spk, Sk, and Svk) and surface area were measured with Laser Scanning Confocal Microscopy before and after installation. Bone beds were inspected with Digital Microscopy and micro X-Ray Fluorescence (μ-XRF) to analyze the metallic element distribution along the bone bed. ResultsAcqua™ implants had higher initial Sa and a pronounced reduction of Sa and Sp during insertion, compared to NeoPoros® implants. After insertion, Sa and Sp of Acqua™ and NeoPoros® implants equalized, differing only between designs of Acqua™ implants. Surface damage was observed after insertion, mainly in the apical region. Facility implants that are made of TiG5 released fewer debris particles, while the highest Ti intensity was detected in the cervical region of the Titamax Ex Acqua™ and Drive Acqua™ implants. SignificancePhysicochemical modifications to achieve surface hydrophilicity created a rougher surface that was more susceptible to surface alterations, resulting in more Ti particle release into the bone bed during surgical insertion. The higher Ti intensities detected in the cervical region of bone beds may be related to peri-implantitis and marginal bone resorption.

New U-series dates from Stump Cross Caverns, Yorkshire, UK, and constraints on the age of the Banwell Bone Cave Mammal Assemblage Zone

Stump Cross Caverns house one of the important Pleistocene fossil bone beds of the UK. Yet, the dates of the Banwell Bone Cave Mammal Assemblage Zone (MAZ), to which these belong, have not yet been well constrained. Here we present new U-Th dates showing that Late-MIS 5 bison-reindeer-wolverine fauna was present in northern England at least as early as 91.9 ± 0.5 ka (the oldest date yet published); and that the Banwell Bone Cave fauna probably occupied the Yorkshire Dales from soon after ∼100 ka to 80 ka (late MIS 5c-early MIS 5a). This adds to the very small number of dates for this fauna, is somewhat older than the timing proposed in the literature, and suggests that the fauna arrived in NW Britain more than 5 kyr in advance of SW Britain. We also found an older bone bed dating from 175 to 172 ka, MIS 6d. This is only the second reported occurrence in the Yorkshire Dales of a fauna that pre-dates the Last Interglacial. Our results confirm that calcite deposition in this cave is precluded during interglacial peaks by local flooding, but at other times is similar to other caves of NW Europe. The oldest dates, on calcites from the uppermost levels, show dewatering by at least ∼430 ka (early MIS 11), adding to our understanding of the antiquity of the caves and the geomorphology of the region.

Fish and crab coprolites from the latest Triassic of the UK: From Buckland to the Mesozoic Marine Revolution

Coprolites from the Rhaetian bone beds in south-west England can be assigned to crustaceans and fishes. Here, we report crustacean microcoprolites, including Canalispalliatum and Favreina, the first records from the British Rhaetian, from Hampstead Farm Quarry near Bristol, evidence for diverse lobsters and their relatives not otherwise represented by body fossils. Further, we identify five fish coprolite morphotypes that differ in shape (cylindrical, flattened) and in presence or absence of a spiral internal structure. Many coprolites show bony inclusions on the surface, often relatively large in proportion to the coprolite; these show little or no evidence for acid damage, suggesting that the predators did not have the physiological adaptations of many modern predatory fishes and reptiles to dissolve bones. CT scanning has revealed the nature, packing and identity of inclusions within the coprolites, mainly fish scales, and some coprolites can contain more than twenty. An extraordinary discovery in one coprolite comprises a single sculptured skull element of the large bony fish Severnichthys together with two caudal vertebrae of the marine reptile Pachystropheus: did the coprolite producer, likely a fish, scavenge some flesh from the head of Severnichthys and then bite off the tail of the reptile? Assigning coprolites to producers is difficult, but it seems that Gyrolepis was preyed on by nearly every predator. The faunas and trophic relations revealed by the coprolites show that this was a modern-style marine ecosystem, with abundant crustaceans and several species of durophagous fishes, evidence for an early stage in the Mesozoic Marine Revolution.

Bone demineralization improves onlay graft consolidation: A histological study in rat calvaria.

Previous data suggest that bone demineralization may promote bone graft consolidation as well as proliferation and differentiation of pre-osteoblasts, but the biological mechanisms involved in this process need to be clarified. This study investigated the effects of bone demineralization with citric acid (CA) and tetracycline (TCN) on the repair of onlay bone grafts. Onlay bone grafts were performed on the calvaria of 126 Wistar rats. The contacting surfaces between bone graft and receptor bone bed were demineralized for 15, 30, and 60 seconds with TCN (50mg/mL), or 10% CA, (pH 1), constituting the following test groups (n=18): TCN15, TCN30, TCN60, CA15, CA30, and CA60. Control grafts (C) were performed without demineralization (n=18). After 7, 30, and 60 days, biopsies were obtained for quantitative and qualitative histological analysis (a=6). Demineralization accelerated the bone repair early from 7 days of healing. Higher percentage area of newly formed bone was observed in CA15 and TCN60 groups when compared to C in all evaluation periods (P=0.02). At 30 days, C specimens had lower percentage of consolidated surfaces than TCN60, TCN30 and CA15 (P=0.0015). At 60 days, CA15, CA60, and TCN60 presented bone surfaces almost completely filled by newly formed bone, against about 75% in C specimens (P=0.0015). Both CA and TCN were effective in accelerating osteogenesis at the interface between bone grafts and receptor bone beds, especially when applied for 15 seconds and 60 seconds, respectively.

New investigations at Bonfire shelter, Texas examine controversial bison jumps and bone beds

Bonfire Shelter (41VV218) is a nationally significant site in the Lower Pecos region of the West Texas borderlands that contains a record of episodic use by hunter-gatherers spanning at least twelve millennia. At least two major bison hunting episodes are evident at Bonfire Shelter, one associated with Paleoindian Plainview and Folsom projectile points (Bone Bed 2), and another associated with Late Archaic Castroville and Montell points (Bone Bed 3). The approximately 12,000-year-old layers comprising Bone Bed 2 may represent the oldest and southernmost bison jump in North America, but this interpretation is the subject of recent debate. In addition, older deposits containing Rancholabrean fauna but lacking stone tools (Bone Bed 1) date to approximately 14,000 years ago and are proposed by previous researchers to be at least partially the result of human activity. This article reviews the issues surrounding Bone Bed 2 and Bone Bed 1 and presents new radiocarbon dates, artifacts, features, along with some initial observations and ongoing plans for renewed field investigations at Bonfire Shelter carried out by the Ancient Southwest Texas Project at Texas State University.

Late Silurian zircon U–Pb ages from the Ludlow and Downton bone beds, Welsh Basin, UK

The Ludlow Bone Bed (Welsh Basin) is a critical stratigraphic horizon and contains a rich assemblage of fish scales. Units above provide insights into the early evolution of animal and plant life. The bed has not yet been radioisotopically dated. Here, we report 207 secondary ion mass spectrometry (SIMS) ages from 102 zircon (ZrSiO 4 ) grains from the Ludlow ( n = 2) and stratigraphically higher Downton ( n = 1) bone beds. SIMS ages are middle Ordovician (471.6 ± 20.7 Ma) to late Devonian (375.7 ± 14.6 Ma, 238 U– 206 Pb, ±1σ analytical uncertainty). Cathodoluminescence images show that the youngest ages appear affected by alteration. Chemical abrasion isotope dilution thermal ionization mass spectrometry (CA-ID-TIMS) U–Pb geochronology was utilized to improve precision. Detrital zircon grains from Downton yield 424.91 ± 0.34/0.42/0.63 Ma and from Ludlow 424.85 ± 0.32/0.41/0.62 Ma ( n = 5 each, 238 U– 206 Pb, ±2σ analytical, tracer or systematic uncertainty). These ages provide a maximum deposition age. Results overlap the basal Přídolí age (423.0 ± 2.3 Ma) in its stratotype (Požáry Section, Reporyje, Prague, Czech Republic). The Ludlow Bone Bed marks the base of the local Downton Group, which has previously been correlated with the base of the Přídolí Series. The CA-ID-TIMS ages are older than those for other land arthropod-bearing sediments, such as the Cowie Harbour Fish Bed and Rhynie Chert. Supplementary material: An Excel file containing detailed information on the SIMS analyses, a figure showing calibration curves for AS3 standards sputtered over sessions 1 and 2, and a figure showing CA-ID-TIMS U–Pb age data (concordia and weighted mean plots) are available at https://doi.org/10.6084/m9.figshare.c.5087031

What Are the Long-term Results of Cemented Revision THA with Use of Both Acetabular and Femoral Impaction Bone Grafting in Patients Younger Than 55 Years?

The increasing number of THAs in younger patients will inevitably result in an increase of revision procedures. However, there is little evidence about the outcome of revision procedures in this patient group. Therefore, we updated a previous study conducted 5 years ago about the outcome of revision procedures in patients younger than 55 years. We sought to provide a concise update on the previously reported (1) long-term failure rate as defined by repeat revision, (2) clinical outcome as defined by the Oxford Hip score and the Harris Hip score, and (3) radiographic outcome of cemented revision THA performed with impaction bone grafting on both the acetabular and femoral sides in one surgery in patients younger than 55 years old. Between 1991 and 2007, we performed 86 complete THA revisions in patients younger than 55 years. In 38% (33 of 86) of revisions, bone impaction grafting was used on both the acetabular and femoral side because of acetabular and femoral bone stock loss. Mean age at time of revision was 46 ± 8 years. No patient was lost to follow-up, but six patients died during follow-up, including three since 2015. Still, the hips of all 33 patients were included in analysis at a mean of 17 ± 5 years. Failure was calculated using competing risk analysis. For clinical outcome, we assessed the Harris Hip score and the Oxford Hip score from our longitudinally maintained institutional database. Radiographic analysis was performed to evaluate radiographic loosening, defined as radiolucencies ≥ 2 mm in all zones or ≥ 5 mm migration for both components. The acetabular component was also considered loose with tilting ≥ 5°. The 15-year failure rate of revision THA was 27% (95% CI 13 to 44) for re-revision of any component for any reason and 10% (95% CI 3 to 25) for re-revision of any component for aseptic loosening. The mean Harris Hip score increased from 55 ± 18 preoperatively to 74 ± 22 at latest follow-up. Eight cups were considered radiographically loose, seven of which were re-revised. No stems were considered radiographically loose. Failure rate with endpoint radiographic loosening at 15 years was 23% (95% CI 10 to 39). We found that impaction bone grafting with a cemented cup and a cemented stem is a valuable biological revision technique that results in a stable and durable solution, after one or even multiple previous revision THAs. Although current implants may prove sufficient in most cases, they do not promote bone stock preservation. We believe that in young patients with bone stock loss, impaction bone grafting can be used as long as the defect can be contained adequately with a metal mesh and viable bone bed is available for revascularization. Level IV, therapeutic study.

Mortality curves and population structures of late early Miocene Rhinocerotidae (Mammalia, Perissodactyla) remains from the Béon 1 locality of Montréal-du-Gers, France

Mortality curves are a valuable tool to study taphonomy and to infer population structure in ancient communities; however, they rely on the precise determination of ontogenetic ages of individual animals, which is often uncertain for fragmentary and isolated fossil remains. In this paper, we develop a new protocol to construct mortality curves for fossil rhinocerotids using both tooth rows and isolated teeth, based on dental wear. We tested and calibrated this protocol using 29 skulls and 18 jaws of extant rhinoceroses (Diceros bicornis, Rhinoceros sondaicus, and R. unicornis). We then applied it to four extinct rhinocerotid species from the late early Miocene locality of Béon 1 of Montréal-du-Gers, SW France: the teleoceratines Brachypotherium brachypus and Prosantorhinus douvillei, the basal rhinocerotine Plesiaceratherium mirallesi, and the early elasmotheriine Hispanotherium beonense. Findings allow us to estimate population structures of these rhinocerotids, based on the percentage of juveniles, subadults and adults. The mortality curves of Béon 1 rhinocerotids reveal several major periods of vulnerability: birth, weaning, sexual maturity, and middle-late adulthood. When compared to extant populations (D. bicornis, Ceratotherium simum, and R. unicornis) and other ancient case studies (Miocene of USA, Pleistocene of Southeast Asia and France), mortality rate curves from Béon 1 are similar in early and late life; however, they lack the increased socially-driven mortality that is observed between 25 and 50% of the potential lifespan in some populations of D. bicornis and in the Miocene teleoceratine Teleoceras proterum. The population structures of Pr. douvillei, Pl. mirallesi, and H. beonense are close to those of extant populations of D. bicornis. In contrast, adult specimens of B. brachypus are overrepresented at Béon 1, similarly to Aphelops malacorhinus at Love Bone Bed (USA), probably due to taphonomical bias. It is important to note that considering isolated or associated teeth alone results in significant differences in mortality curves and population structures at Béon 1, hence both samples should be studied.