Total Hip Replacement Prostheses Research Articles

COMPARISON OF RATES OF ASEPTIC LOOSENING IN HIGH OFFSET VERSUS STANDARD OFFSET CEMENTLESS FEMORAL STEMS

Increasing femoral offset in total hip replacement (THR) has several benefits including improved hip abductor strength and enhanced range of motion. Biomechanical studies have suggested that this may negatively impact on stem stability. However, it is unclear whether this has a clinical impact. Using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), the aim of this study was to determine the impact of stem offset and stem size for the three most common cementless THR prostheses revised for aseptic loosening.The study period was September 1999 to December 2020. The study population included all primary procedures for osteoarthritis with a cementless THR using the Corail, Quadra-H and Polarstem. Procedures were divided into small and large stem sizes and by standard and high stem offset for each stem system. Hazard ratios (HR) from Cox proportional hazards models, adjusting for age and gender, were performed to compare revision for aseptic loosening for offset and stem size for each of the three femoral stems.There were 55,194 Corail stems, 13,642 Quadra-H stem, and 13,736 Polarstem prostheses included in this study. For the Corail stem, offset had an impact only when small stems were used (sizes 8-11). Revision for aseptic loosening was increased for the high offset stem (HR=1.90;95% CI 1.53–2.37;p<0.001).There was also a higher revision risk for aseptic loosening for high offset small size Quadra-H stems (sizes 0-3). Similar to the Corail stem, offset did not impact on the revision risk for larger stems (Corail sizes 12-20, Quadra-H sizes 4-7). The Polarstem did not show any difference in aseptic loosening revision risk when high and standard offset stems were compared, and this was irrespective of stem size.High offset may be associated with increased revision for aseptic loosening, but this is both stem size and prosthesis specific.

A Real Time Electrochemical Analysis of Co-Sputtered (Co-Cr) and (Co-Cr-Mo) Alloy Thin Film Libraries in Ringer’s Solution at 37 oc

Cobalt-based alloys are used as total hip replacement prostheses due to their exceptional tribocorrosion properties in the human physiological environment[1]. Due to continuous mechanical and corrosive conditions, the dissolution of Cr and Co in the body fluid is unavoidable. These metallic particles and ions can cause cancer and gene mutation in the body, therefore their leaching should be diminished by proper passivation[2].In this work, two combinatorial thin film libraries namely a binary Co-Cr and a ternary Co-Cr-Mo were prepared by means of co-sputtering. Both libraries were characterized by state of the art high resolution scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chromium content for binary Co-Cr library varied from 14-40 at.% (balanced Co) while for ternary Co-Cr-Mo library a compositional spread of Co (46-79 at.%), Cr (17-48 at.%) and Mo (3-11 at.%) was obtained. In both libraries roundish spike shaped grains were revealed at high cobalt content which gradually changed to refined and compact grains with the increment of Cr. Similarly, molybdenum (>-7 at.%) brought additional grain refinement. Furthermore, weak, and broad XRD peaks of rt HCP and ht FCC pure Co were disclosed at nearly all compositions. No intermetallic phase was determined in either library.The real time electrochemical screening and corrosion stability were accomplished by a in house-built flow type scanning droplet cell microscope (FT-SDCM) in conjunction with an inductively couple plasma optical emission spectroscope (ICP-OES). Various electrochemical techniques i.e. open circuit potential, linear sweep voltammetry and Tafel extrapolation were utilized. No significant passive behavior was obtained for the alloys containing the Co content higher than (68-70 at.%) irrespective of Cr and Mo concentration. However, further increment in the Cr content significantly improved the alloy nobility and restricted the active to passive dissolution. The addition of Mo improved the transpassive dissolution. A graphical model was developed on the basis of this study and a composition range of (7-10) at.% Mo and (36-48) at.% Cr (complementary Co) is recommended as likely candidate for biomedical use.

Detecting total hip replacement prosthesis design on plain radiographs using deep convolutional neural network.

Identifying the design of a failed implant is a key step in the preoperative planning of revision total joint arthroplasty. Manual identification of the implant design from radiographic images is time-consuming and prone to error. Failure to identify the implant design preoperatively can lead to increased operating room time, more complex surgery, increased blood loss, increased bone loss, increased recovery time, and overall increased healthcare costs. In this study, we present a novel, fully automatic and interpretable approach to identify the design of total hip replacement (THR) implants from plain radiographs using deep convolutional neural network (CNN). CNN achieved 100% accuracy in the identification of three commonly used THR implant designs. Such CNN can be used to automatically identify the design of a failed THR implant preoperatively in just a few seconds, saving time and improving the identification accuracy. This can potentially improve patient outcomes, free practitioners' time, and reduce healthcare costs.

Evidence for Gender-Specific Bone Loss Mechanisms in Periprosthetic Osteolysis.

Osteolysis adjacent to total hip replacement (THR) prostheses is a major cause of their eventual failure. Periprosthetic osteolysis is associated with the production of bioactive particles, produced by the wear of articulating prosthesis surfaces. Wear particles invade the periprosthetic tissue, inducing inflammation and bone resorption. Previous studies have shown that osteocytes, the most numerous cell type in mineralised bone, can respond to wear particles of multiple orthopaedic material types. Osteocytes play important roles in bone resorption, regulating bone resorption by osteoclasts and directly through osteocytic osteolysis, also known as perilacunar remodelling. In this study, we perform a histological analysis of bone biopsies obtained from cohorts of male and female patients undergoing either primary THR surgery or revision THR surgery for aseptic loosening. The osteocyte lacunae area (Ot.Lac.Ar) and percentage lacunar area/bone area (%Ot.Lac.Ar/B.Ar) were significantly larger overall in revision THR bone than bone from similar sites in primary THR. Analysis by patient gender showed that increased Ot.Lac.Ar, indicative of increased perilacunar remodelling, was restricted to female revision samples. No significant differences in osteoclast parameters were detectable between the cohorts. These findings suggest previously unrecognised gender-specific mechanisms of bone loss in orthopaedic wear particle-induced osteolysis in humans.

Experimental and numerical static failure analyses of total hip replacement interfaces.

In joint replacement surgery, the critical point in the success of cemented implants is the stabilisation between the implant and bone. The stronger the interlocking achieved on both the implant-cement interface and the cement-bone interface, the more durable is the surgical intervention. However, to date, it has not been possible to prevent aseptic loosening of hip implants, thus making a revision surgery necessary after a period of about 10 years. In this study, the tensile and shear strengths of the implant-cement and cement-bone interfaces and factors which can affect these strengths such as sandblasting parameters and implant material choice were investigated experimentally. The stresses on the total hip replacement interfaces were then determined via finite element analysis and the findings compared with the strength values obtained from the mechanical tests. The total hip replacement prosthesis was designed using SolidWorks software, and material properties and boundary conditions were modelled with the ANSYS Workbench software. Stresses due to the loads applied to the femur head had exceeded the highest tensile and shear strength values obtained by the classical test methods and damaged the contact surfaces in some regions. In light of these findings, the damage sites of the interfaces were determined.

Structural, Mechanical, Imaging and in Vitro Evaluation of the Combined Effect of Gd3+ and Dy3+ in the ZrO2-SiO2 Binary System.

Mechanical strength and biocompatibility are considered the main prerequisites for materials in total hip replacement or joint prosthesis. Noninvasive surgical procedures are necessary to monitor the performance of a medical device in vivo after implantation. To this aim, simultaneous Gd3+ and Dy3+ additions to the ZrO2-SiO2 binary system were investigated. The results demonstrate the effective role of Gd3+ and Dy3+ to maintain the structural and mechanical stability of cubic zirconia ( c-ZrO2) up to 1400 °C, through their occupancy of ZrO2 lattice sites. A gradual tetragonal to cubic zirconia ( t-ZrO2 → c-ZrO2) phase transition is also observed that is dependent on the Gd3+ and Dy3+ content in the ZrO2-SiO2. The crystallization of either ZrSiO4 or SiO2 at elevated temperatures is delayed by the enhanced thermal energy consumed by the excess inclusion of Gd3+ and Dy3+ at c-ZrO2 lattice. The addition of Gd3+ and Dy3+ leads to an increase in the density, elastic modulus, hardness, and toughness above that of unmodified ZrO2-SiO2. The multimodal imaging contrast enhancement of the Gd3+ and Dy3+ combinations were revealed through magnetic resonance imaging and computed tomography contrast imaging tests. Biocompatibility of the Gd3+ and Dy3+ dual-doped ZrO2-SiO2 systems was verified through in vitro biological studies.

Proximal femur segmental resection for the management of prosthetic tip fracture: An innovative procedure

Fractures at the tip or just below the tip of a total hip replacement (THR) prosthesis are treated with a longer prosthetic stem, a longer stem with distal interlocking, a THR combined with a locking compression plate (LCP), and unicortical locking screws in proximal fragment with or without circumferential wiring or cables. As LCP remains weaker construct chances of failure are more and in cases with a failed LCP with THR, one may have to opt for a limb preservation system as an alternate to LCP. None of these techniques were possible in this 40 year patient and we had to opt for some innovation to help him. We are reporting an innovative technique where a proximal femur segmental resection was done for the management of prosthetic tip fracture continuing with the same THR stem.

The Appropriate Variable to Compare Wear in Total Hip Prostheses: Commentary on an article by Donald W. Howie, MBBS, FRACS, PhD, et al.: "The Wear Rate of Highly Cross-Linked Polyethylene in Total Hip Replacement Is Not Increased by Large Articulations. A Randomized Controlled Trial".

An important limiting factor in the longevity of any total joint replacement is its propensity to wear. Unlike bearings such as ball bearings and hydrodynamically lubricated bearings that produce virtually no wear, sliding bearings that have contact surfaces with relative motion will always wear. For total hip replacement prostheses, wear occurs with all of the currently used technologies. We study wear in these prostheses because of the 2 failure modes associated with it: loss of mechanical integrity and, more commonly, wear-induced biological failure. The latter failure mode is the most important clinical problem facing the bearing designer, the treating surgeon, and the patient. It is, therefore, important that the models used to predict the longevity of a particular bearing design are based on the most logical scientific evidence available. The most valuable evidence for predicting longevity is based on clinical observation. Toward this end, …

Bone Mineral Density and Fracture Risk Assessment to Optimize Prosthesis Selection in Total Hip Replacement.

The variability in patient outcome and propensity for surgical complications in total hip replacement (THR) necessitates the development of a comprehensive, quantitative methodology for prescribing the optimal type of prosthetic stem: cemented or cementless. The objective of the research presented herein was to describe a novel approach to this problem as a first step towards creating a patient-specific, presurgical application for determining the optimal prosthesis procedure. Finite element analysis (FEA) and bone mineral density (BMD) calculations were performed with ten voluntary primary THR patients to estimate the status of their operative femurs before surgery. A compilation model of the press-fitting procedure was generated to define a fracture risk index (FRI) from incurred forces on the periprosthetic femoral head. Comparing these values to patient age, sex, and gender elicited a high degree of variability between patients grouped by implant procedure, reinforcing the notion that age and gender alone are poor indicators for prescribing prosthesis type. Additionally, correlating FRI and BMD measurements indicated that at least two of the ten patients may have received nonideal implants. This investigation highlights the utility of our model as a foundation for presurgical software applications to assist orthopedic surgeons with selecting THR prostheses.

Periprosthetic osteolysis after total hip replacement: molecular pathology and clinical management

Periprosthetic osteolysis is a serious complication of total hip replacement (THR) in the medium to long term. Although often asymptomatic, osteolysis can lead to prosthesis loosening and periprosthetic fracture. These complications cause significant morbidity and require complex revision surgery. Here, we review advances in our understanding of the cell and tissue response to particles produced by wear of the articular and non-articular surfaces of prostheses. We discuss the molecular and cellular regulators of osteoclast formation and bone resorptive activity, a better understanding of which may lead to pharmacological treatments for periprosthetic osteolysis. We describe the development of imaging techniques for the detection and measurement of osteolysis around THR prostheses, which enable improved clinical management of patients, provide a means of evaluating outcomes of non-surgical treatments for periprosthetic osteolysis, and assist in pre-operative planning for revision surgery. Finally, there have been advances in the materials used for bearing surfaces to minimise wear, and we review the literature regarding the performance of these new materials to date.

Pre-clinical evaluation of ceramic femoral head resurfacing prostheses using computational models and mechanical testing

Ceramic-on-ceramic hip resurfacing can potentially offer the bone-conserving advantages of resurfacing while eliminating metal ion release. Thin-walled ceramic resurfacing heads are conceivable following developments in the strength and reliability of ceramic materials, but verification of new designs is required. The present study aimed to develop a mechanical pre-clinical analysis verification process for ceramic resurfacing heads, using the DeltaSurf prosthesis design as a case study. Finite element analysis of a range of in vivo scenarios was used to design a series of physiologically representative mechanical tests, which were conducted to verify the strength of the prosthesis. Tests were designed to simulate ideal and worst-case in vivo loading and support, or to allow comparison with a clinically successful metallic device. In tests simulating ideal loading and support, the prosthesis sustained a minimum load of 39 kN before fracture, and survived 10 000 000 fatigue cycles of 0.534 kN to 5.34 kN. In worst-case tests representing a complete lack of superior femoral head bone support or pure cantilever loading of the prosthesis stem, the design demonstrated strength comparable to that of the equivalent metal device. The developed mechanical verification test programme represents an improvement in the state of the art where international test standards refer largely to total hip replacement prostheses. The case study's novel prosthesis design performed with considerable safety margins compared with extreme in vivo loads, providing evidence that the proposed ceramic resurfacing heads should have sufficient strength to perform safely in vivo. Similar verification tests should be designed and conducted for novel ceramic prosthesis designs in the future, leading the way to clinical evaluation.

Arthroscopic Treatment of Unstable Total Hip Replacement

Hip arthroscopy may be useful in the diagnosis and treatment of apparently well-implanted but unstable total hip replacement prostheses. We present 2 cases of arthroscopically assisted capsular tightening in unstable total hip replacements. Both cases had significant capsular laxity. Case 2 had impingement of the lower part of the acetabulum with the lesser trochanter that caused hip dislocation. Early revision surgery can be avoided with the use of this technique in selected cases of unstable total hip replacements.

Using digital templating to predict the size of prosthesis in total hip arthroplasty.

Objective To evaluate application of the measurement methods of digital templates to select an hip prosthesis. Methods From January 2005 to February 2007, 122 patients (132 hips), including 68 males and 54 females, were studied. The hospital network system of digital imaging and digital templates on the computer were applied in preoperative template measurement of total hip replacement. For the sur-geon group and radiologist group, digital template measurements were used to predict the required size of models, and to compared with the actual prosthesis used in the operation. Results Surgeon group acetabu-lar prosthesis model and femoral prosthesis model hefore and after surgery were no significant difference be-tween measurements (Z=0.4531, P=0.6505; Z=0.5452, P=0.5856). Surgeon predicted preoperative acetabular prosthesis model with intraoperative acetabular prosthesis significant correlation between the models (r= 0.9361, P=0.0068), preoperative surgenn predict femoral prosthesis model with intraoperative application of femoral prosthesis significant correlation between the models (r=0.9435, P=0.0087). Acetabular prosthesis model and femoral prosthesis model of radiologist group, before and after surgery, were no difference between measurements (Z=0.6834, P=0.4934; Z=0.1027, P=0.8990). Radiologist preoperative prediction model of ac-etabular prosthesis with intraoperative acetabular prosthesis significant correlation between the models (r= 0.9214, P=0.0051), preoperative radiologist prediction model with the femoral prosthesis surgery Application of femoral prosthesis significant correlation between type (r=0.9357, P=0.0072). Total hip arthroplasty using the digital measurement of choice prosthesis template model and the practical application of prosthesis surgery models, compared acetabular prosthesis accuracy rate of 71.59%, femoral prosthesis 78.04% accura-cy rate. Conclusion The measurement of preoperative digital template design, selection of artificial total hip replacement prosthesis with high aeeuraey and credibility. Key words: Arthroplasty,replacement,hip; Image processing,computer-assisted; Hip prosthesis

Modeling the Cost-Effectiveness for Cement-Less and Hybrid Prosthesis in Total Hip Replacement in Emilia Romagna, Italy

The aim of the present study was to assess the cost-effectiveness of cement-less versus hybrid prostheses in total hip replacement (THR) in patients diagnosed with primary osteoarthritis. Effectiveness data were obtained from the Emilia-Romagna Regional Registry on Orthopaedic Prosthesis (RIPO), which collects information on all orthopaedic intervention performed in Emilia-Romagna (41,199 total hip replacements performed from 2000 to 2007), and from which we obtained survival curves and transition probabilities for the cement-less and hybrid prostheses, respectively. Conversely, costs were derived from regional databases through a specific procedure, which allowed us to register individual component's costs for both primary and subsequent revision interventions. A specific Markov transition model was constructed in order to consider the 3 types of revisions that an implant could possibly undergo through its life-span: total, cup or stem, head insert or neck. The cost-effectiveness was expressed in terms of cost per "revision-free" life year. Considering a 70-y old patient undergoing THR, the cementless strategy resulted more effective but more costly than the hybrid solution, with an incremental cost effectiveness ratio of 2401.63 € per revision-free life year. Following a deterministic sensitivity analysis, hybrid and cementless fixation showed, respectively, a dominance profile for patients older than 83 y and younger than 43 y, whereas for all ages in between, we report a progressive increase in the ICER of cementless prostheses. Our results proved to be robust, as underlined by the probabilistic sensitivity analysis performed using cost distributions.

Modelling of Processing of FGM Bioimplants

Bioimplants composed of metal and ceramic parts are recently widely used in medicine. It was shown that properties of these implants might be substantially improved with functionally graded materials (FGM). In this work ceramics FGM are considered with emphasis on the optimal processing technique. For ceramic balls and liners of total hip replacement prosthesis optimal sintering procedure is very important irrespectively on the initially selected graded composition profile to get beneficial stresses distribution after sintering and assembling. Different examples are shown and influence of the sintering and gradient profile selection on final properties is discussed.

Design Optimization of a Total Hip Prosthesis for Wear Reduction

Aseptic loosening from polyethylene debris is the leading cause of failure for metal-on-polyethylene hip implants. The accumulation of wear debris can lead to osteolysis, the degradation of bone surrounding the implant components. In the present study, a parametric three-dimensional finite element model of an uncemented total hip replacement prosthesis was constructed and implanted into a femur model constructed from computed tomography (CT) scan data. Design optimization was performed considering volumetric wear as an objective function using a computational model validated in a previous study through in vitro wear assessment. Constraints were used to maintain the physiological range of motion of wear-optimum designs. Loading conditions for both walking and stair climbing were considered in the analysis. In addition, modification of the acetabular liner surface nodes was performed in discrete intervals to reflect the actual wear and creep damage occurring on the liner surface. Stair climbing was found to produce 49% higher volumetric wear than walking. Using a sensitivity analysis, it was found that the objective function sensitivity to the chosen design variables was identical for both walking and stair climbing. The greatest reduction in volumetric wear achieved while maintaining a physiological range of motion was 16%. It was found that including nodal modification in the sensitivity analysis produced little or no difference in the sensitivity analysis results due to the linear nature of volumetric wear progression. Thus, nodal modification was not used in optimization. An increase in the maximum contact pressure was observed for all wear-optimized designs, and an increase in head-liner penetration was found to be related to a reduction in volumetric wear.

Tensile and tribological properties of high‐crystallinity radiation crosslinked UHMWPE

Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

Flexion reminder device to discourage recurrent posterior dislocation of a total hip replacement: a case report

IntroductionRecurrent dislocation of a total hip replacement prosthesis is a frustrating complication for both the surgeon and the patient. For positional dislocations with no indications for revision surgery, the current best treatment is physiotherapy, the use of abduction braces and avoidance of unsafe hip positions. Abduction braces can be cumbersome and have poor compliance. We report the successful use of a new lightweight flexion reminder device that can be used to treat people with this condition.Case presentationA 64-year-old British woman experienced recurrent positional posterior dislocation after primary hip replacement, particularly when involved in activities involving unsafe flexion of the operated hip. She disliked using an abduction brace and hence was given a simple 'flexion reminder device' that could be strapped to the thigh. Beyond the safe flexion limit, the padded top end of the device hitched against the groin crease and reminded her not to flex further, to avoid dislocation. She experienced no discomfort in wearing the device continuously throughout the day and was very satisfied. She has had no further dislocations in the 2 years since she began using it.ConclusionIn cases of arthroplasty dislocation caused mainly by an unsafe hip position, and with no indication for revision surgery, this new lightweight and easily worn flexion reminder device may be a good option for avoiding such positional dislocations, particularly those caused by unsafe flexion.

Durability of Zirconia-Based Ceramics and Composites for Total Hip Replacement

Ceramics have been increasingly used in orthopaedics during the last 30 years. Their biological inertness, high hardness and good mechanical strength make them excellent candidates for components such as femoral heads and acetabular cup in Total Hip Replacement prostheses. Currently used bio-inert ceramics – alumina and zirconia – give good clinical results, especially compared to metal – polymer couplings. However, they are subjected to severe biological, tribological and mechanical solicitations during more than fifteen years for the most successful prostheses. They answer these solicitations by presenting specific degradation mechanisms. We will thus examine the phenomena that can account for the long-term behaviour of zirconia components (heads and cups) in THR prostheses.

Biocompatibility of novel polymer‐apatite nanocomposite fibers

On the basis of the bioactivity of hydroxyapatite (HA) and the excellent mechanical and biocompatible performance of polyethylene terephthalate (PET), composite microfibers made of nanograde HA with PET was designed and fabricated to mimic the structure of biological bone, which exhibits a composite of nanograde apatite crystals and natural polymer. The PET/HA nanocomposite was molded into fibers so that the bulk structures' mechanical properties can be custom tailored by changing the final 3D orientation of the fibbers. This study focused on the in vitro biocompatibility evaluation of the PET/HA composite fibers as potential bone fixation biomaterial for total hip replacement prosthesis surfaces. The MTT assay was performed with the extracts of the composite fibers in order to evaluate the short-term effects of the degradation products. The cell morphology of L929 mouse fibroblast cell line was analyzed after direct contact with the fiber scaffolds for different time periods, and the cell viability was also analyzed by the Alamar Blue assay. The release of the inflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), from RAW 264.7 macrophages in the presence of fiber extracts and fibers was used as a measure of the inflammatory response. The ability of the fiber matrices to support L929 attachment, spreading, and growth in vitro, combined with the compatible degradation extracts and low inflammation potential of the fibers and extracts, suggests potential use of these fibers as load-baring bone fixation biomaterial structures.