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1.
J Environ Manage ; 341: 118024, 2023 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-37141726

RESUMEN

Any functional utility gained through corporate social responsibility (CSR) depends on "responsibility" as the governing principle between "corporate" and "social" interests. We argue that Porter and Kramer's highly popularised notion of "shared value" has been pivotal to the erosion of responsibility as a moderating concept in CSR. Under this approach, "strategic" CSR becomes an instrument to leverage corporate advantage, rather than fulfil social responsibilities and address business-related harms. In mining, this approach has supported shallow, derivative ideas including the wellknown CSR artefact: "social license to operate" (SLTO). We argue that CSR, and the related concept corporate social irresponsibility (CSI), suffer from the single actor problem, where the corporation too easily becomes the exclusive focus of analysis. We advocate for a reinvigorated debate about mining and social responsibility in which the corporation is but one actor in the (ir)responsibility landscape.


Asunto(s)
Comercio , Responsabilidad Social , Organizaciones
2.
Environ Sci Technol ; 55(8): 4324-4331, 2021 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-33760596

RESUMEN

Criticality and supply risk models seek to address concerns of potential disruption to global metal supply. These models need to incorporate disruption events that arise from within the mining industry's market structure. In this paper, we review what we refer to as events of "mine life cycle disruption". These include project abandonments, premature closures, care and maintenance, and ownership changes. Life cycle disruptions not only cause production disruptions but also embed social and environmental risks in global metal markets. They arise from the highly variable business environment in which the resources sector operates. Changing commodity prices directly influence mining revenues and drive decisions on whether to halt or push forward a project. While some disruptions are involuntary and induced by external economic conditions, others are purposefully triggered by certain mining companies that use them to their advantage. We examine the frequency of these disruptions based on a contemporary global inventory of 35,000 mining projects and present the findings against recent developments in the research literature. We conclude that life cycle disruption events are an important consideration in balancing the demand for metals and the social and environmental impacts of mining and propose pathways for managing these events and their effects.


Asunto(s)
Minería , Propiedad , Animales , Ambiente , Estadios del Ciclo de Vida , Metales
3.
J Chem Phys ; 155(2): 024114, 2021 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-34266248

RESUMEN

Progress in electrochemical technologies, such as automotive batteries, supercapacitors, and fuel cells, depends greatly on developing improved charged interfaces between electrodes and electrolytes. The rational development of such interfaces can benefit from the atomistic understanding of the materials involved by first-principles quantum mechanical simulations with Density Functional Theory (DFT). However, such simulations are typically performed on the electrode surface in the absence of its electrolyte environment and at constant charge. We have developed a new hybrid computational method combining DFT and the Poisson-Boltzmann equation (P-BE) capable of simulating experimental electrochemistry under potential control in the presence of a solvent and an electrolyte. The charged electrode is represented quantum-mechanically via linear-scaling DFT, which can model nanoscale systems with thousands of atoms and is neutralized by a counter electrolyte charge via the solution of a modified P-BE. Our approach works with the total free energy of the combined multiscale system in a grand canonical ensemble of electrons subject to a constant electrochemical potential. It is calibrated with respect to the reduction potential of common reference electrodes, such as the standard hydrogen electrode and the Li metal electrode, which is used as a reference electrode in Li-ion batteries. Our new method can be used to predict electrochemical properties under constant potential, and we demonstrate this in exemplar simulations of the differential capacitance of few-layer graphene electrodes and the charging of a graphene electrode coupled to a Li metal electrode at different voltages.

4.
J Arthroplasty ; 36(1): 356-361, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-32829970

RESUMEN

BACKGROUND: Early clinical results of a new total knee arthroplasty (TKA) implant design show promise for improved outcomes and patellofemoral function scores. However, reports of early tibial component-cement interface debonding requiring revision have been published. This study investigated the biomechanical properties of three different tibial baseplates to understand potential causes of failure. METHODS: PFC Sigma (control), Attune (1st generation) and Attune S+ (2nd generation) tibial baseplates were implanted into 4th generation sawbone tibia models using a standardized technique. Three of each baseplate were cemented with and without additional bovine bone marrow fat. All models were tested to failure with measured axial distraction force. Implant type, presence or absence of bovine marrow and load to failure were all recorded and compared. Two-way ANOVA followed by post-hoc pairwise comparisons were used to determine statistical significance, which was set to P < .05. RESULTS: The 2nd generation tibial baseplates required significantly more force to failure. The presence of bovine marrow significantly reduced the pullout force of the implant designs overall. No significant difference was detected between the 1st generation and control baseplates. Failure mode for each model was also noted to be different irrespective of the presence or absence of bone marrow fat. CONCLUSION: The 2nd generation baseplates required significantly more force to failure compared with older designs. The presence of bone marrow during cementation of a tibial base plate significantly decreased axial pullout strength of a tibial baseplate in this laboratory model. All 1st generation baseplates exhibited debonding at the cement-implant interface.


Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Animales , Cementos para Huesos , Médula Ósea , Bovinos , Humanos , Diseño de Prótesis , Tibia/cirugía
5.
J Environ Manage ; 279: 111593, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33221043

RESUMEN

Progress towards deep sea mining (DSM) is driven by projected demands for metals and the desire for economic development. DSM remains controversial, with some political leaders calling for a moratorium on DSM pending further research into its impacts. This paper highlights the need for governance architectures that are tailored to DSM. We conceptualise DSM as a type of complex orebody, which encompasses the breadth of environmental, social and governance (ESG) risks that make a mineral source complex. Applying a spatial overlay approach, we show that there are significant data gaps in understanding the ESG risks of DSM. Such uncertainties are compounded by fact that there are no extant commercial DSM projects to function as a precedent - either in terms of project design, or the impacts of design on environment and people. Examining the legislation of the Cook Islands and International Seabed Authority, we demonstrate how regulators are defaulting to terrestrial mining governance architectures, which cannot be meaningfully implemented until a fuller understanding of the ESG risk landscape is developed. We argue that DSM be approached as a distinct extractive industry type, and governed with its unique features in frame.


Asunto(s)
Industrias , Minería , Humanos , Metales , Minerales , Incertidumbre
6.
Environ Sci Technol ; 53(18): 10571-10579, 2019 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-31432668

RESUMEN

Rising consumer demand is driving concerns around the "availability" and "criticality" of metals. Methodologies have emerged to assess the risks related to global metal supply. None have specifically examined the initial supply source: the mine site where primary ore is extracted. Environmental, social, and governance ("ESG") risks are critical to the development of new mining projects and the conversion of resources to mine production. In this paper, we offer a methodology that assesses the inherent complexities surrounding extractives projects. It includes eight ESG risk categories that overlay the locations of undeveloped iron, copper, and aluminum orebodies that will be critical to future supply. The percentage of global reserves and resources that are located in complex ESG contexts (i.e., with four or more concurrent medium-to-high risks) is 47% for iron, 63% for copper, and 88% for aluminum. This work contributes to research by providing a more complete understanding of source level constraints and risks to supply.


Asunto(s)
Metales , Minería , Cobre , Monitoreo del Ambiente , Predicción , Hierro
8.
J Arthroplasty ; 32(8): 2556-2562, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28433426

RESUMEN

BACKGROUND: Cement fixation of total knee components remains the gold standard despite resurgence in cementless fixation with the goal of long-term durable fixation. Initial stability is paramount to achieve bony ingrowth of cementless components. METHODS: Twelve cemented and cementless tibial baseplates were implanted into sawbones and tested using a physiological medial-lateral load distribution for 10,000 cycles to represent 8 weeks of in vivo function. Micromotion was measured at 5 locations around the baseplate during loading. RESULTS: Cycling had a significant effect on the change in micromotion between maximum and minimum loads at the anterior, medial, lateral, posteromedial, and posterolateral tray edge locations. A significant effect of fixation technique was detected for the anterior (P < .001), medial (P = .002), and lateral (P = .0056) locations but not for the posteromedial (P = .36) or posterolateral (P = .82) locations. Differences in micromotion between cemented and cementless components did not exceed 150 µm at any tested location. CONCLUSION: The micromotion experienced by cementless tibial components in the present study may indicate a lower initial mechanical stability than the cemented group. However, this difference in initial stability may be subclinical because the differences between average cemented and cementless micromotion were <150 µm at all measured locations under the loading regime implemented.


Asunto(s)
Artroplastia de Reemplazo de Rodilla/instrumentación , Prótesis de la Rodilla , Diseño de Prótesis , Cementos para Huesos , Humanos , Articulación de la Rodilla/fisiología , Articulación de la Rodilla/cirugía , Tibia/cirugía , Soporte de Peso
9.
J Arthroplasty ; 32(6): 2023-2027, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28209401

RESUMEN

BACKGROUND: Despite literature to support the use of various cerclage techniques to address intraoperative femoral fractures in total hip arthroplasty, there are limited data to support prophylactic cerclage wiring of the femur during cementless implant placement. This study aims to evaluate the effect of prophylactic calcar cerclage wires on the biomechanical parameters required to produce periprosthetic femoral fractures and on the morphology of these fracture patterns in stable cementless femoral implants. METHODS: Ten pairs of matched fresh frozen cadaveric femurs were implanted with anatomic tapered cementless implants with or without the addition of 2 monofilament calcar wires. Specimens were axially loaded and externally rotated to failure. Initial torsional stiffness, rotation and energy to failure, and torque at failure were measured. Statistical significance was set at P < .05. Fracture patterns were classified according to a well-known classification system. RESULTS: Wired specimens required significantly more rotation (P = .039) and energy to failure (P = .048). No significant difference was detected in initial torsional stiffness (P = .63) or torque at failure (P = .10). All unwired samples developed a Vancouver B2 fracture pattern. Seven of the 8 wired specimens also developed a Vancouver B2 fracture pattern, while the eighth wired specimen developed a Vancouver B1 fracture pattern. CONCLUSION: Prophylactic cerclage wire placement increases the rotation and energy to failure in well-fixed press-fit femoral implants. The increase in torsional energy needed for failure may reduce the risk of early periprosthetic fracture. Further studies are needed to evaluate cost vs benefit and long-term outcomes of prophylactic wiring. Based on the results of our study, consideration of prophylactic wiring should be addressed on a case-to-case basis.


Asunto(s)
Artroplastia de Reemplazo de Cadera/instrumentación , Artroplastia de Reemplazo de Cadera/métodos , Hilos Ortopédicos , Fracturas del Fémur/cirugía , Fijación Interna de Fracturas/métodos , Fracturas Periprotésicas/cirugía , Anciano , Anciano de 80 o más Años , Femenino , Fémur/cirugía , Humanos , Masculino , Persona de Mediana Edad , Osteotomía , Factores de Riesgo , Torque
10.
Eur J Orthop Surg Traumatol ; 27(8): 1103-1108, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-28597401

RESUMEN

INTRODUCTION: For proximal femur fractures, long cephalomedullary nails (CMNs) are often selected to avoid a diaphyseal stress riser at the tip of a shorter nail. Secondary peri-implant fracture rates for long and short CMN have not been shown to differ clinically. This study biomechanically compares both CMN in a cadaveric model. METHODS: Ten matched pairs of cadaveric femora with short or long CMN were axially loaded and internally rotated to failure. RESULTS: Resulting fractures involved distal interlocking screws of the short and long CMN. Energy and rotation to failure were significantly greater for short CMN. Torque at failure trended higher for short CMN but not significantly. No statistical difference was detected in stiffness of the short and long CMN. DISCUSSION: A greater risk of secondary fracture is not indicated for short versus long CMN under torsional stress. Short CMN may be suitable in the younger patient.


Asunto(s)
Clavos Ortopédicos/efectos adversos , Tornillos Óseos/efectos adversos , Fracturas del Fémur/etiología , Fijación Intramedular de Fracturas/efectos adversos , Fracturas Periprotésicas/etiología , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Femenino , Fijación Intramedular de Fracturas/instrumentación , Humanos , Masculino , Persona de Mediana Edad , Medición de Riesgo , Rotación , Torque
11.
Clin Orthop Relat Res ; 474(11): 2513-2517, 2016 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-27339122

RESUMEN

BACKGROUND: Surgical gloves can be damaged during the course of a procedure, which can place the surgeon and patient at risk. Glove perforation may not always be readily apparent, and determining the risk factors for glove perforation can aid the surgeon in deciding when a glove change is advisable. Time of wear and needle sticks have been well studied; however, other mechanisms including mechanical stress from surgical equipment have had limited evaluation to date. QUESTIONS/PURPOSES: We evaluated the risk of glove perforation in gloves that were caught in a surgical rotatory device (such as drills and reamers). The aims of our study were (1) to determine the percentage of undetected microperforations after entanglement on a rotatory tool during orthopaedic procedures, (2) to determine which kinds of rotatory devices most commonly cause such microperforations, and (3) to assess whether time of wear had an effect on the risk of perforation. METHODS: From July 2014 to September 2015, 33 gloves were obtained from all orthopaedic subspecialties at our Level I trauma center if they were caught in a rotatory device greater than one revolution. Time of glove wear and location of the glove that was caught in a rotatory device were recorded. After an evaluation for macroperforations (≥ 5 mm), the gloves were evaluated for microperforations (< 5 mm) via the American Society for Testing and Materials (ASTM) one-liter load test. Time of wear was compared among gloves with macroperforations, microperforations, and no perforations. RESULTS: The 33 gloves obtained came from 33 procedures. Seventeen of 33 (52 %) gloves had perforations. Seven of the 17 perforated gloves had macroperforations while 10 had microperforations. Eleven of 33 entanglements were caught by drills, nine by reamers, eight by K-wires, and the remaining five gloves were caught by various other instruments. Eight of 17 perforations were caused by drills, three by reamers, three by K-wires, and three by various other instruments. The average time of wear was 58 minutes which did not differ with pattern of glove damage. CONCLUSION: Surgical gloves caught in a rotatory power instrument are likely to have been perforated, regardless of the amount of time that they had been worn. Visual inspection appears to be an inadequate test of glove integrity. When a glove becomes entangled in a rotary instrument such as a drill, pin, or reamer, a surgeon should change the gloves regardless of whether he or she believes a perforation is present. LEVEL OF EVIDENCE: Level IV, therapeutic study.


Asunto(s)
Guantes Quirúrgicos , Salud Laboral , Procedimientos Ortopédicos/efectos adversos , Procedimientos Ortopédicos/instrumentación , Cirujanos Ortopédicos , Instrumentos Quirúrgicos/efectos adversos , Falla de Equipo , Análisis de Falla de Equipo , Humanos , Ensayo de Materiales , Tempo Operativo , Medición de Riesgo , Factores de Riesgo , Estrés Mecánico , Factores de Tiempo
12.
J Hand Surg Am ; 41(4): 526-31, 2016 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-26880494

RESUMEN

PURPOSE: To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 distal fixation techniques for an active tendon implant used in the reconstruction of flexor tendons. METHODS: We evaluated percent stretch after cyclical loading and at failure, stiffness during load-to-failure, and peak load of 28 bone-prosthesis junctions using cadaveric canine middle phalanges to study 2 fixation techniques: metal cleat and screw versus polyester cords secured with a knot. RESULTS: The knot constructs displayed greater percent stretch during and following cyclical loading between 2 N and 50 N and at peak load. The screw construct showed greater stiffness from 50 N to 150 N during load-to-failure. Both fixation techniques failed at a mean peak load greater than 340 N. CONCLUSIONS: Both fixation techniques for active tendon implants withstood loads seen with passive and active motion in the immediate postoperative period. Knot constructs displayed significant stretch during cyclical and load-to-failure testing, which would need to be compensated for during surgery. The screw constructs showed greater stiffness than the constructs secured with the surgeon's knot, but failure created an intra-articular fracture. CLINICAL RELEVANCE: The results may aid the surgeon in choosing which fixation technique to use, during tensioning of cords, and in permitting active motion following surgery.


Asunto(s)
Tornillos Óseos , Anclas para Sutura , Traumatismos de los Tendones/cirugía , Tenodesis/métodos , Animales , Perros , Ensayo de Materiales , Soporte de Peso
13.
J Arthroplasty ; 31(3): 721-6, 2016 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-26639983

RESUMEN

BACKGROUND: Highly porous metal acetabular components illustrate a decreased rate of aseptic loosening in short-term follow-up compared with previous registry data. This study compared the effect of component surface roughness at the bone-implant interface and the quality of the bone on initial pressfit stability. The null hypothesis is that a standard porous coated acetabular cup would show no difference in initial stability as compared with a highly porous acetabular cup when subjected to a bending moment. Second, would bone mineral density (BMD) be a significant variable under these test conditions. METHODS: In a cadaveric model, acetabular cup micromotion was measured during a 1-time cantilever bending moment applied to 2 generations of pressfit acetabular components. BMD data were also obtained from the femoral necks available for associated specimen. RESULTS: The mean bending moment at 150 µm was not found to be significantly different for Gription (24.6 ± 14.0 N m) cups vs Porocoat (25 ± 10.2 N m; P > .84). The peak bending moment tolerated by Gription cups (33.9 ± 20.3 N m) was not found to be significantly different from Porocoat (33.5 ± 12.2 N m; P > .92). No correlation between BMD and bending moment at 150 µm of displacement could be identified. CONCLUSION: The coefficient of friction provided by highly porous metal acetabular shells used in this study did not provide better resistance to migration under bending load when compared with a standard porous coated component.


Asunto(s)
Artroplastia de Reemplazo de Cadera/instrumentación , Prótesis de Cadera , Diseño de Prótesis , Acetábulo , Femenino , Fricción , Humanos , Masculino , Metales , Porosidad , Falla de Prótesis
14.
J Hand Surg Am ; 40(1): 109-14, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25534839

RESUMEN

PURPOSE: To study the biomechanical characteristics (percent stretch, stiffness, and ultimate load) of 2 tendon-prosthesis techniques used to connect the proximal tendon stump to silicone active tendon implants used in reconstruction of flexor tendons. METHODS: We evaluated percent stretch following cyclic loading and at failure, stiffness during load to failure, and ultimate load of 16 tendon-prosthesis junctions using cadaveric canine flexor digitorum profundus tendons to re-create 2 junction techniques: the tendon loop (TL) and the polyester weave (PW). RESULTS: The TL junction showed greater percent stretch at a static load of 2 N, following 500 cycles of loading between 2 N and 50 N, and at peak load. The PW junction displayed greater stiffness from 50 to 150 N during load to failure. Both junctions failed at a mean ultimate load greater than 220 N. CONCLUSIONS: The described proximal junction techniques for active tendon implants were strong enough to resist early active motion in the immediate postoperative period without significant elongation. The PW technique displayed greater stiffness and ultimate load compared with the TL. CLINICAL RELEVANCE: Data on tendon-prosthesis characteristics of these 2 methods may aid the surgeon in choosing which junction technique to use, during surgical tensioning decisions, and in considering activity protocols after surgery. These data may also serve as a baseline for further investigations regarding active tendon implants.


Asunto(s)
Traumatismos de la Mano/cirugía , Procedimientos de Cirugía Plástica/métodos , Traumatismos de los Tendones/cirugía , Tendones/cirugía , Animales , Fenómenos Biomecánicos , Cadáver , Perros , Modelos Animales , Prótesis e Implantes , Implantación de Prótesis/métodos , Técnicas de Sutura , Tendones/fisiopatología
15.
J Foot Ankle Surg ; 54(5): 830-5, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-25960057

RESUMEN

Given the high rates of wound complications with a standard lateral extensile incision, small dual incision techniques might result in less soft tissue destruction. The goal of the present study was to compare the biomechanical performance between a single locking plate and a dual locking plating system for an intra-articular calcaneal fracture model. A Sanders IIB type joint depression calcaneal fracture was created in 10 paired, fresh-frozen, cadaveric calcanei (age 47 ± 12, range 35 to 78 years). The calcanei of each pair were randomly assigned for fixation using either a lateral locking reconstruction plate or lateral and medial locking reconstruction plates. The specimens were axially loaded in cyclic fashion for 1000 cycles, followed by load to failure. The relative fragment movement was monitored optically in both the sagittal and the coronal planes. The amount of overall construct displacement increased with cycling, although no difference was found between the plating techniques. For fragment movement during cycling, the lateral joint fragment migrated anteroinferiorly along the fracture line relative to the tuberosity fragment for dual plated specimens by a small, but statistically significant, amount. This same translation was smaller for lateral plated specimens but was not found to be significant. During load to failure testing, no statistically significant differences were found for construct stiffness. A tendency was seen toward more interfragmentary motion in the sagittal plane (lateral joint fragment movement relative to the fracture line), with less movement overall in the coronal plane (anterior fragment translation and twist) for dual plating, although the difference from the lateral plate was not statistically significant. The present study demonstrated that for this calcaneal fracture model, the dual plating technique experienced a small amount of fragment translation during cycling that was significantly different statistically from that with lateral plating but was not clinically relevant. During the load to failure, the dual plating technique was comparable to the lateral plate. Thus, dual plating could be a viable biomechanical option for fracture reduction if avoidance of a large extensile lateral approach associated with lateral plating is warranted.


Asunto(s)
Placas Óseas , Calcáneo/cirugía , Fijación Interna de Fracturas/instrumentación , Fracturas Intraarticulares/cirugía , Adulto , Anciano , Articulación del Tobillo/cirugía , Fenómenos Biomecánicos , Cadáver , Calcáneo/lesiones , Diseño de Equipo , Seguridad de Equipos , Fijación Interna de Fracturas/métodos , Fracturas Óseas/cirugía , Humanos , Persona de Mediana Edad , Sensibilidad y Especificidad , Estrés Mecánico
16.
Clin Orthop Relat Res ; 472(7): 2231-6, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24664196

RESUMEN

BACKGROUND: Experimental studies have suggested that initial micromotion of cementless components may lead to failure of osteointegration. Roentgen stereophotogrammetric analyses have shown durable implant fixation can be achieved long-term even when initial instability exists, as evidenced by subsidence. However improved implant stability as a result of subsidence, before osteointegration, has not been shown biomechanically. QUESTIONS/PURPOSES: We asked whether insertionally loose cementless tapered femoral stems show (1) less rotational stability (more toggle); (2) more subsidence; and (3) reduced ability to resist torsion (lower initial construct stiffness), lower torque at failure, and greater rotation to failure in comparison to well-fixed cementless tapered femoral stems. METHODS: Ten matched pairs of cadaveric femurs were implanted with well-fixed and loose cementless tapered stems. The loose stem construct was obtained by appropriately broaching the femur but afterwards inserting a stem one size smaller than that broached. Femoral stem rotational stability of implanted femurs was tested by measuring the angular rotation (ie, toggle) required to produce a torque of 2 N-m at 0 N, 250 N, and 500 N vertical load in 25° adduction simulating single-legged stance. Subsidence was measured as vertical movement during the toggle tests. Then at 500 N initial vertical load, femoral stems were externally rotated to failure. The construct stiffness between 5 and 40 N-m was determined to assess ability to resist torsion. The torque and rotation to failure were recorded to compare failure characteristics. Groups were compared using mixed model ANOVA followed by Tukey-Kramer post hoc pairwise comparison for toggle and subsidence tests and by Student's paired t-tests for stiffness, torque at failure, and rotation to failure tests. RESULTS: Loose tapered cementless stems were less stable (ie, more toggle) than well-fixed at 0 N of load (p < 0.0001), but no difference was detectable in toggle between loose and well-fixed stems at 250 N (p = 0.7019) and 500 N (p = 0.9970). Loose tapered cementless stems showed significant subsidence at 250 N (p < 0.0001) and 500 N (p < 0.0001), which was not found in the well-fixed stems at 250 N (p = 0.8813) and 500 N (p = 0.1621). Torsional stiffness was lower for loose stems as compared with well-fixed stems (p = 0.0033). No difference in torque at failure (p = 0.7568) or rotation to failure (p = 0.2629) was detected between loose and well-fixed stems. CONCLUSIONS: In this study, we observed that insertionally loose cementless stems have the ability to subside and become rotationally stable with loading. They did not exhibit a lower torque or rotation to failure in comparison to well-fixed stems when under simulated single-legged stance. CLINICAL RELEVANCE: Secondary rotational stabilization may prevent insertionally loose tapered stems from producing a stress pattern that predisposes to early postoperative periprosthetic fracture around loose cemented stems.


Asunto(s)
Artroplastia de Reemplazo de Cadera/instrumentación , Fémur/cirugía , Prótesis de Cadera , Oseointegración , Anciano , Anciano de 80 o más Años , Artroplastia de Reemplazo de Cadera/efectos adversos , Fenómenos Biomecánicos , Cadáver , Análisis de Falla de Equipo , Femenino , Fémur/fisiopatología , Humanos , Masculino , Persona de Mediana Edad , Fracturas Periprotésicas/etiología , Fracturas Periprotésicas/fisiopatología , Diseño de Prótesis , Falla de Prótesis , Rango del Movimiento Articular , Factores de Riesgo , Estrés Mecánico , Torque
17.
J Hand Surg Am ; 39(11): 2214-9, 2014 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-25227598

RESUMEN

PURPOSE: To investigate whether inclusion of the volar plate in repair of flexor digitorum profundus avulsions increases the strength of the repair and resists gapping. METHODS: Cadaveric fingers (n = 18) were divided into 3 equal groups. The first technique involved 2 micro-suture anchors only (A). The second used only volar plate repair (VP). The third group was a hybrid, combining a micro-suture anchor with volar plate augmentation (AVP). Specimens were loaded cyclically to simulate passive motion rehabilitation before being loaded to failure. Clinical failure was defined as 3 mm of gapping, and physical failure as the highest load associated with hardware failure, suture breakage, anchor pullout, or volar plate avulsion. RESULTS: Gapping throughout cycling was significantly greater for the A group than VP and AVP with no difference detected between VP and AVP groups. Gapping exceeded 3 mm during cycling of 3 A specimens, but in none of the VP or AVP specimens. Load at clinical and physical failure for A was significantly lower than for VP and AVP, whereas no difference was detected between VP and AVP. CONCLUSIONS: In this cadaveric model, incorporating the volar plate conferred a significant advantage in strength, increasing the mean load to physical failure by approximately 100 N. CLINICAL RELEVANCE: According to previous biomechanical studies, current reconstructive strategies for flexor digitorum profundus zone I avulsions are not strong enough to withstand active motion rehabilitation. We demonstrated the potential use of volar plate augmentation and the prospective advantageous increase in strength in this cadaveric model. In vivo performance and effects on digital motion are not known.


Asunto(s)
Traumatismos de los Dedos/cirugía , Placa Palmar/cirugía , Técnicas de Sutura , Traumatismos de los Tendones/cirugía , Cadáver , Dedos , Humanos , Rango del Movimiento Articular/fisiología , Anclas para Sutura , Resistencia a la Tracción/fisiología , Soporte de Peso/fisiología
18.
J Arthroplasty ; 29(5): 1038-42, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24238907

RESUMEN

The primary goal of this study was to determine the initial press-fit stability in acetabular components without screw fixation. Mechanical testing was performed with the implantation of press-fit acetabular components in cadaveric specimens. No significant difference was found in load to failure testing between 1 and 2 mm of under-reaming. However, there was significant variability in bending forces required to create 150 µm of micromotion ranging from 49.3 N to 214.4 N. This study shows that cups implanted in a press-fit fashion, which are felt to be clinically stable, have high degrees of variability in resisting load and may be at risk for loosening. There is a need for more objective intra-operative techniques to test cup stability.


Asunto(s)
Acetábulo/cirugía , Artroplastia de Reemplazo de Cadera , Articulación de la Cadera/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Cadáver , Articulación de la Cadera/cirugía , Prótesis de Cadera , Humanos , Persona de Mediana Edad , Diseño de Prótesis
19.
Eur J Orthop Surg Traumatol ; 24(8): 1415-20, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-24121825

RESUMEN

PURPOSE: There are numerous constructs employed in the treatment of metacarpal fractures with varying degrees of success. While plate fixation commonly involves dorsal application of a bicortical non-locking plate, there has been recent exploration of other fixation options including unicortical locked plating. The purpose of this study was to evaluate the biomechanical integrity of a polyetheretherketone (PEEK) inset locking plate and, in doing so, compare it to standard plate fixation (utilizing a clinically proven bicortical non-locking titanium plate) in a simulated porcine metacarpal fracture model. METHODS: Reproducible mid-shaft fractures were created in porcine second metacarpals. The fractured specimens were reduced and plated with either a bicortical non-locking plate or a unicortical locking plate with a PEEK locking design. Constructs were then loaded to failure in the same fashion as performed to create the fracture. Peak load was measured as the apex on the load-to-failure deflection curve. Stiffness was calculated as the linear slope on the load-to-failure deflection curve. Data were analyzed via Student's t test. RESULTS: Unicortical locking constructs failed at 344 ± 119 N, while bicortical non-locking constructs were found to fail at 277 ± 101 N (p = 0.19). The unicortical locking constructs demonstrated a stiffness of 80 ± 36 N/mm compared with the bicortical non-locking constructs (69 ± 36 N/mm) although again the difference was not found to be statistically different (p = 0.49). CONCLUSION: Based on this study, a locked plating construct using a polymer mechanism provides an interesting new locking fixation method for small bone fractures and with our limited number of specimens tested, provided at least a similar strength and rigidity profile in comparison with bicortical fixation in the treatment of metacarpal fractures.


Asunto(s)
Placas Óseas , Fijación Interna de Fracturas/métodos , Fracturas Óseas/cirugía , Huesos del Metacarpo/lesiones , Animales , Fenómenos Biomecánicos , Fijación Interna de Fracturas/instrumentación , Fracturas Óseas/fisiopatología , Humanos , Huesos del Metacarpo/fisiopatología , Huesos del Metacarpo/cirugía , Porcinos
20.
J Orthop Res ; 42(3): 518-530, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38102985

RESUMEN

Musculoskeletal infections (MSKI), which are a major problem in orthopedics, occur when the pathogen eludes or overwhelms the host immune system. While effective vaccines and immunotherapies to prevent and treat MSKI should be possible, fundamental knowledge gaps in our understanding of protective, nonprotective, and pathogenic host immunity are prohibitive. We also lack critical knowledge of how host immunity is affected by the microbiome, implants, prior infection, nutrition, antibiotics, and concomitant therapies, autoimmunity, and other comorbidities. To define our current knowledge of these critical topics, a Host Immunity Section of the 2023 Orthopaedic Research Society MSKI International Consensus Meeting (ICM) proposed 78 questions. Systematic reviews were performed on 15 of these questions, upon which recommendations with level of evidence were voted on by the 72 ICM delegates, and another 12 questions were voted on with a recommendation of "Unknown" without systematic reviews. Two questions were transferred to another ICM Section, and the other 45 were tabled for future consideration due to limitations of available human resources. Here we report the results of the voting with internet access to the questions, recommendations, and rationale from the systematic reviews. Eighteen questions received a consensus vote of ≥90%, while nine recommendations failed to achieve this threshold. Commentary on why consensus was not achieved on these questions and potential ways forward are provided to stimulate specific funding mechanisms and research on these critical MSKI host defense questions.


Asunto(s)
Procedimientos Ortopédicos , Ortopedia , Humanos , Consenso , Antibacterianos/uso terapéutico , Inmunoterapia
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