Metal Femoral Head Research Articles

Use of 1.5-Stage Functional Articulating Hip Spacers for Two-Stage Treatment of Hip Infection

BackgroundA two-stage treatment is commonly used for chronic hip infections. This study compared the clinical efficacy and complications associated with 1.5-stage functional articulating hip spacers (FAHS) and handmade spacers utilized during two-stage treatment. MethodsThis retrospective study included 50 patients who had hip infections, of which 41 were periprosthetic joint infections, 3 were internal fixation infections, and 6 had septic arthritis. They were divided into two groups according to the spacer type: 23 patients treated with handmade spacers comprising 1 to 2 Kirschner wires as an endoskeleton (group A) and 27 patients treated with 1.5-stage FAHS comprising a cemented femoral stem, metal femoral head, and polyethylene acetabular liner or cemented acetabular cup (group B). Clinical characteristics, surgical data, infection control rate, spacer complications, modified Harris hip, visual analog scale, and 36-item short-form physical functioning scale scores were compared between the groups. All patients were followed up for at least 24 months after the last surgical procedure. ResultsNo significant differences were noted in the infection eradication rate between the two groups (100 versus 96.30%, P = 1.0). The incidence of mechanical complications, especially spacer fracture, was significantly lower in group B than in group A (P = .044). Hip function and quality of life were significantly better in group B during the interim period. Group B patients had a longer interval time (median 7.40 versus 4.30 months, P = .004) and a lower reimplantation rate than group A patients (42.31 versus 82.61%, P = .004). ConclusionsThe 1.5-stage FAHS surgical technique is feasible for the treatment of hip infection, with a lower mechanical complication rate, better hip function, and better quality of life during the interim period compared to that of handmade spacers. The 1.5-stage FAHS with maintained function could delay or negate the need for second-stage revision.

The size of the femoral head does not influence metal ion levels after metal-on-polyethylene total hip arthroplasty: a five-year report from a randomized controlled trial.

In metal-on-polyethylene (MoP) total hip arthroplasty (THA), large metal femoral heads have been used to increase stability and reduce the risk of dislocation. The increased size of the femoral head can, however, lead to increased taper corrosion, with the release of metal ions and adverse reactions. The aim of this study was to investigate the relationship between the size of the femoral head and the levels of metal ions in the blood in these patients. A total of 96 patients were enrolled at two centres and randomized to undergo MoP THA using either a 32 mm metal head or a femoral head of between 36 mm and 44 mm in size, being the largest possible to fit the thinnest available polyethylene insert. The levels of metal ions and patient-reported outcome measures (Oxford Hip Score, University of California, Los Angeles Activity Scale) were recorded at two and five years postoperatively. At five years, the median levels of chromium, cobalt, and titanium were 0.5 μg/l (interquartile range (IQR) 0.50 to 0.62), 0.24 μg/l (IQR 0.18 to 0.30), and 1.16 μg/l (IQR 1.0 to 1.68) for the 32 mm group, and 0.5 μg/l (IQR 0.5 to 0.54), 0.23 μg/l (IQR 0.17 to 0.39), and 1.30 μg/l (IQR 1 to 2.05) for the 36 mm to 44 mm group, with no significant difference between the groups (p = 0.825, p = 1.000, p = 0.558). There were increased levels of metal ions at two years postoperatively in seven patients in the 32 mm group, compared with four in the 36 mm to 44 mm group, and at five years postoperatively in six patients in the 32 mm group, compared with seven in the 36 mm to 44 mm group. There was no significant difference in either the OHS (p = 0.665) or UCLA (p = 0.831) scores between patients with or without an increased level of metal ions. In patients who underwent MoP THA, we found no differences in the levels of metal ions five years postoperatively between those with a femoral head of 32 mm and those with a femoral head of between 36 mm and 44 mm, and no corrosion-related revisions. As taper corrosion can start after five years, there remains a need for longer-term studies investigating the relationship between the size of the femoral head size and corrosion in patients undergoing MoP THA.

Geometric distortion caused by metallic femoral head prosthesis in prostate cancer imaging on an MR Linac: in-vivo measurements of spatial deformation.

Metallic implants cause artefacts and distortion on MRI. To ensure accurate dose delivery and plan adaptation on an MR Linac, there is a need to evaluate distortion caused. Participants were imaged on an MR Linac (Elekta Unity, Elekta AB Stockholm). Three sequences were evaluated. Two vendor supplied (T2W TSE 3D), and one T2W TSE 3D optimized to reduce metal artefact distortions. Images were rigidly registered to CT images by a single observer, using bony anatomy. Three coronal and three axial images were selected, and six paired, adjacent, bony landmarks were identified on each slice. Images bisecting treatment isocentre were included. Difference between landmark coordinates was taken to be measure of distortion. Five observers participated. Thirty six pairs of bony landmarks were identified. Median difference in position of landmarks was ≤3 mm (range 0.3-4.4 mm). One-way analysis of variance (ANOVA) between observer means showed no significant variation between sequences or patients (P = 1.26 in plane, P = 0.11 through plane). Interobserver intra class correlation (ICC) was 0.70 in-plane and 0.78 through-plane. Intra-observer ICC for three observers was 0.76, 0.81, 0.83, showing moderate to good reliability on this small cohort. This in-vivo feasibility study suggests distortion due to metallic hip prosthesis is not an obstacle for pelvic radiotherapy on an MR Linac. Research on the impact on plan quality is warranted. This work supports feasibility of treating patients with metallic hip prosthesis on an MR Linac.

In vivo corrosion on retrieved hip endoprostheses and in vitro effects of corrosion products on bone mineralization.

In vivo corrosion of modular endoprostheses remains a great concern, as the release of heavy metal ions can impair the implant's service life and the wellbeing of the patient. The detailed corrosion mechanisms that occur in vivo are so far not completely understood. In this context, the effects of implant released cobalt (Co) and chromium (Cr) ions on osteoblast mineralization and gene expression have not been investigated extensively. This comprehensive study aimed at furthering the understanding of in vivo implant corrosion from the clinical signs via prosthesis retrievals and histology of the synovial membranes down to the molecular processes instigated by corrosion products and its effects on bone mineralization. A detailed in vivo failure analysis was performed investigating 22 retrieved hip endoprostheses from different manufacturers and taper material combinations. The aim was to find a correlation of taper damage and especially corrosion to susceptible biomedical alloys and its effect on periprosthetic tissue as well as the clinical implant performance with regard to revision diagnosis and presence of radiolucent lines (RLL). A second part investigated the effects of Co and Cr ions on the in vitro mineralization process of osteoblasts. Cell cultures were exposed to relevant concentrations of CoCl2 and CrCl3 (0μM, 100μM, 200μM) with and without addition of phosphate. Mineralization behavior was analyzed with Alizarin Red assay and Von Kossa staining of calcium depots, alkaline phosphatase activity of osteoblasts and gene expression was analyzed with real time quantitative PCR. The retrieval study provides evidence of in vivo fretting and crevice corrosion on all metallic tapers combined with either ceramic or metal femoral heads. Within the modular taper junctions, selective dissolution of the α phase occurred in wrought TiAl6V4 alloys, and etching of the fine-grained wrought CoCr28Mo6 alloy implants was observed in formed crevices. In addition, significant amounts of wear particles and corrosion products were detected in retrieved synovial membranes. An increased risk for the occurrence of a RLL in the proximal zones was determined for patients with a corroded mixed metal taper. Whereas Co ions have hardly any effects on mineralization, Cr ions cause a significant concentration dependent decrease in mineralization rate of osteoblasts. However, this effect is alleviated by addition of a phosphate source. Our data reveal that Cr ions depleted dissolved phosphates by forming an insoluble complex (CrPO4), which inhibits the phosphate dependent mineralization process. No significant effect of the heavy metal ions on osteoblast activity by means of alkaline phosphate activity as well as on gene expression is determined. This study broadens the understanding of in vivo corrosion of metallic modular implants and its clinically relevant effects on mineralization. Based on these findings, in vivo corrosion of CoCr28Mo6 endoprostheses should be limited to avoid inhibitory effects of Cr3+ on bone mineralization which can contribute to premature implant failure.

Metal-Driven Autoantifriction Function of Artificial Hip Joint.

The service life of an artificial hip joint is limited to 10-15years, which is not ideal for young patients. To extend the lifespan of these prostheses, the coefficient of friction and wear resistance of metallic femoral heads must be improved. In this study, a Cu-doped titanium nitride (TiNX -Cu) film with "autoantifriction" properties is deposited on a CoCrMo alloy via magnetron sputtering. When delivered in a protein-containing lubricating medium, the Cu in TiNX -Cu quickly and consistently binds to the protein molecules in the microenvironment, resulting in the formation of a stable protein layer. The proteins adsorbed on the TiNX -Cu surface decompose into hydrocarbon fragments owing to the shear stress between the Al2 O3 /TiNX -Cu tribopair. The synergistic effect of the catalysis of Cu and shear stress between the Al2 O3 /TiNX -Cu tribopair transforms these fragments into graphite-like carbon tribofilms with an antifriction property. These tribofilms can simultaneously reduce the friction coefficient of the Al2 O3 /TiNX -Cu tribopair and enhance the wear resistance of the TiNX -Cu film. Based on these findings, it is believed that the autoantifriction film can drive the generation of antifriction tribofilms for lubricating and increasing the wear resistance of prosthetic devices, thereby prolonging their lifespan.

New polyethylenes in total hip arthroplasty : a 20- to 22-year follow-up study.

A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade. Between January 1999 and December 2001, 90 patients underwent surgery using the same acetabular and femoral components with a 28 mm metallic femoral head and either a Durasul or Sulene liner. A total of 66 hips of this prospective randomized study were available for a minimum follow-up of 20 years. The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Dorr method on digitized radiographs with a software package. In the Durasul group, no patients underwent revision due to loosening or showed radiological evidence of osteolysis. In the Sulene group, four patients (four hips) were revised due to femoral component loosening. The 20-year cumulative failure incidence in the presence of the competing event of death for revision surgery was 4.5% (95% confidence interval (CI) 0.8 to 13.6) in the Durasul group, and 8.9% (95% CI 2.8 to 19.5) in the Sulene group. The mean wear one year after surgery was 0.09 mm (SD 0.007) in the Durasul group and 0.24 (SD 0.015) in the Sulene group (p < 0.001). From one to 20 years after surgery, the mean total penetration was 0.32 mm (SD 0.045) in the Durasul group and 1.07 mm (SD 0.13) in the Sulene group (p < 0.001). Mean femoral head penetration at 20 years was approximately 70.0% less in the Durasul group than the Sulene group. The significant reduction in femoral head penetration obtained with the Durasul compared with Sulene in uncemented THA resulted in lower osteolysis and revision rates after 20 years.Cite this article: Bone Joint J2022;104-B(9):1032-1038.

Experimental Investigation of Material Transfer on Bearings for Total Hip Arthroplasty-A Retrieval Study on Ceramic and Metallic Femoral Heads.

Metallic deposition is a commonly observed phenomenon on the surface of revised femoral heads in total hip arthroplasty and can lead to increased wear due to third bodies. In order to find out the origin and composition of the transfer material, 98 retrieved femoral heads of different materials were examined with regard to the cause of revision, localization, pattern and composition of the transfer material by energy dispersive X-ray spectroscopy. We found that in 53.1%, the deposition was mostly in the region of the equator and the adjacent pole of the femoral heads. The most common cause for revision of heads with metallic deposition was polyethylene wear (43.9%). Random stripes (44.9%), random patches (41.8%) and solid patches (35.7%) were most prevalent on retrieved femoral heads. Random patches were a typical pattern in ceramic-on-ceramic bearing couples. The solid patch frequently occurred in association with dislocation of the femoral head (55%). The elemental analysis of the depositions showed a variety of different materials. In most cases, titanium was an element of the transferred material (76.5%). In addition to metallic components, several non-metallic components were also detected, such as carbon (49%) or sulfur (4.1%). Many of the determined elements could be assigned with regard to their origin with the help of the associated revision cause. Since the depositions lead to an introduction of third-body particles and thus to increased wear, the depositions on the bearing surfaces should be avoided in any case.

Computational Contact Pressure Prediction of CoCrMo, SS 316L and Ti6Al4V Femoral Head against UHMWPE Acetabular Cup under Gait Cycle

Due to various concerns about the use of metal-on-metal that is detrimental to users, the use of metal as acetabular cup material was later changed to ultra high molecular weight polyethylene (UHMWPE). However, the wear on UHMWPE releases polyethylene wear particles, which can trigger a negative body response and contribute to osteolysis. For reducing the wear of polyethylene, one of the efforts is to investigate the selection of metal materials. Cobalt chromium molybdenum (CoCrMo), stainless steel 316L (SS 316L), and titanium alloy (Ti6Al4V) are the frequently employed materials. The computational evaluation of contact pressure was carried out using a two-dimensional axisymmetric model for UHMWPE acetabular cup paired with metal femoral head under gait cycle in this study. The results show Ti6Al4V-on-UHMWPE is able to reduce cumulative contact pressure compared to SS 316L-on-UHMWPE and CoCrMo-on-UHMWPE. Compared to Ti6Al4V-on-UHMWPE at peak loading, the difference in cumulative contact pressure to respective maximum contact pressure is 9.740% for SS 316L-on-UHMWPE and 11.038% for CoCrMo-on-UHMWPE.

Total hip arthroplasty

Primary total hip arthroplasty has become one of the most successful surgical procedures over the past 50 years and is currently performed worldwide with similar techniques and excellent results. Despite variations in technique and implant selection, medium and long term outcome studies have demonstrated over 90% implant survival at 15 to 25 years. Previous problems with implant fixation have now been reduced, and the focus has shifted to the selection of improved bearing surfaces to limit wear, hip replacement options for younger patients, and improved surgical and anesthetic techniques. Current surgical approaches to the hip rely most often on direct lateral or posterolateral exposure. The most commonly utilized bearing surface for both hip replacement and hip resurfacing in Canada is a metal (cobalt-chrome) femoral head combined with a second-generation cross-linked polyethylene, combined with cementless implant fixation. Alternative bearings such as ceramic-on-ceramic and metal-on-metal may be considered for hip replacement in younger patients. Although it has not been determined which surface will prove best for younger patients in the long term, there is no question about the benefits of total hip arthroplasty. With current techniques, the results are favorable, and patient satisfaction, pain relief, and long-term implant survival are excellent.

Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) as Desired Polymer Material for Biomedical

It is very important that any materials used as implant material work in harmony with the body. There will be drawback with every material. No matter how good, as nothing can be 100% identical as the natural human tissue. The body operates in an environment at a constant temperature of 37°C and pH of 7.25, so choice of materials will have to withstand these conditions. Incorrect use of material can cause rejection by the body, infection and even cancer, leading to more pain and discomfort by the patient. In turn the possibility of even further damage to the joint. The implant must work in the same way as the body part it is replacing- clear understanding of how the joint works is needed. Ultrahigh molecular weight polyethylene is considered as the standard material for Artificial joints to decrease the total weight and the wear rate to make it more flexible. This is what makes Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) such an appropriate polymer. It is very widely used in total hip and knee joint replacements having the highest known impact strength of any thermoplastic presently made, can highly withstand abrasion, and has a very low coefficient of friction. Therefore, these properties, connected with extremely low moisture absorption, make UHMWPE especial material for the medical industry due to good industrial impact and wear resistance sliding applications. For moving joints, the friction would be damaging without the natural lubrication. In implant components this does not exist, however UHMWPE is self-lubricating, making it ideal for component such as an acetabular cup, which would wrap around a metallic femoral head in a hip joint. Also, UHMWPE has high impact strength, high toughness, and low elastic modulus, but it has disadvantages such as low tensile, transverse and compressive strengths with high creep rate. This review article deals with the history of UHMWPE, its material properties that make it an ideal candidate for total joints, implant-component fabrication procedures and provides insights as to why some of the implants eventually fail.

Hip Instability Leading to Metallosis, Polyethylene Wear, and Failure of an Oxinium Femoral Head: A Case Report and Review of Literature

AbstractOxinium is a zirconium metal alloy with an oxidized (ceramicized) surface that aims to mimic the superior wear properties of a ceramic femoral head while maintaining the high strength of metal-bearing surfaces. There are several reports that illustrate the wear and/or failure of Oxinium femoral heads following abnormal head contact with metal cup, with only a few studies reporting on the occurrence of metallosis. We present a case of metallosis and failure of Oxinium femoral head following two incidents of hip instability and one closed reduction. Successful revision was performed with cemented cup and metal femoral head, with 68 months of follow-up. We aimed to highlight the importance of achieving stable and well-oriented hip components when using Oxinium-bearing surfaces and to present a short literature review regarding the wear of oxidized zirconium-bearing surfaces in hip arthroplasty.

Does increased diameter of metal femoral head associated with highly cross-linked polyethylene augment stress on the femoral stem and cortical hypertrophy?

Cortical hypertrophy (CH) after total hip arthroplasty (THA) is thought as a process of femoral cortical functional adaptation against the stem. However, no study has been performed to investigate the association between CH and femoral head size. The purpose of this study is to investigate the factors related to femoral CH around the cementless stem after THA. THAs in 31 patients using 36-mm metal head and as a control, age-matched 62 THAs with 32-mm metal head have been analyzed. Radiographs were reviewed at four years to determine cortical thickness change from immediate post-operative one. Pre-operative and immediate post-operative radiographs were used to calculate the femoral morphology, canal fill ratio, stem alignment, and femoral and acetabular offset. Univariate and multivariate logistic regression analyses were performed to identify the risk factors for CH. Patients with a 36-mm metal head had a significantly higher rate of severe CH (P = 0.001) than those with a 32-mm metal head. The multivariate logistic regression analysis with dependent variables of CH showed that the use of a 36-mm metal head had a significantly positive effect on CH. The odds ratio of a 36-mm metal head in mild CH was 2.517 (95% confidence interval, 1.032-6.143; P = 0.043), and that in severe CH was 8.273 (95% confidence interval, 2.679-25.551; P = 0.000). Age and the canal flare index were weakly and negatively influenced by mild CH. The use of a 36-mm metal head was the dominant risk factor for CH.

Satisfactory Outcomes in Patients Operated With Primary Total Hip Arthroplasty for Perthes-like Deformities: Results From a Surgical Technique Utilizing a Conical Stem, an Elevated Hip Center, and No Shortening Femoral Osteotomy.

BackgroundTotal hip arthroplasty (THA) performed on patients with Perthes-like deformities are technically challenging because of the patient’s abnormal hip anatomy. Patients with Perthes-like deformities are at a higher risk of revision, aseptic loosening, nerve injury, and intraoperative fracture after THA, especially if shortening osteotomies are performed. This analysis sought to examine the clinical and radiographic outcomes of a patient cohort with Perthes-like deformities receiving THA with a conical stem, an elevated hip center, and no shortening femoral osteotomy.MethodsTwenty-six patients (27 hips) received THA with MODULUS femoral stems, ceramic or metal femoral heads, and highly cross-linked polyethylene liners between April 2011 and March 2016. All patients were treated at a single center by 4 participating surgeons. Patients completed 2 questionnaires preoperatively and at the final follow-up visit (between 1 and 5 years postoperatively): Harris Hip Score and Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire. Differences in patient-reported outcome measures (PROM) scores were measured by paired t-tests. Preoperative and postoperative anteroposterior radiographs were analyzed to monitor patient outcomes.ResultsSignificant clinical improvements were observed in all individual subcategories of the Harris Hip Score and of the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire; the largest magnitude improvements were observed in the subcategory of pain relief for both questionnaires. No complications, including intraoperative and postoperative femoral fractures, nerve palsy, dislocations, or deep venous thrombosis, were observed.ConclusionThis study found that patients treated with an elevated hip center and low stem-positioning technique using a conical, modular implant system had good clinical outcomes and did not suffer complications at the mean follow-up from surgery of 2.8 years (range: 1-5 years).

Hip Spacers with a Metal-on-Cement Articulation Did Not Show Significant Surface Alterations of the Metal Femoral Head in Two-Stage Revision for Periprosthetic Joint Infection.

Two-stage revision is considered the gold standard treatment for chronic periprosthetic joint infection (PJI). During the interim period, between explantation of the infected hip endoprosthesis and revision arthroplasty, individually formed articulating hip spacers made of polymethylmethacrylate (PMMA) bone cement can be used to provide better soft tissue preservation, local antibiotic release, and improved postoperative mobilization. If effective prevention from luxation is achieved, hip function and hence overall patient satisfaction is improved. Zirconium oxide particles inside conventional PMMA bone cement, however, are known to enhance third-body wear, which may cause alterations of the metal head in the articulating spacer and hence become a serious risk for the patient. Therefore, the aim of our study was to analyze whether the articular surface of cobalt-chrome (CoCr) femoral heads is significantly altered in the setting of a metal-on-cement articulation during the interim period of two-stage revision for PJI. We analyzed a consecutive series of 23 spacer cases and compared them with femoral heads from two series of conventional hip arthroplasty revisions with metal-on-polyethylene articulations and different time intervals in situ. To investigate metallic wear, the femoral heads were thoroughly examined, and their surface roughness was measured and analyzed. We found no significant differences between the two conventional hip arthroplasty groups, despite their very different times in situ. Furthermore, the individually different times in situ within the spacer group had no significant impact on surface roughness, either. Compared with the spacer group, the surface roughness of the metal femoral heads from both conventional hip arthroplasty groups were even higher. Within the spacer group, roughness parameters did not show significant differences regarding the five predefined locations on the metal head. We conclude that metal-on-cement articulations do not cause enhanced surface alterations of the metal femoral head and hence do not limit the application in articulating hip spacers in the setting of two-stage revision for PJI.

Are Oxinium Femoral Heads Superior to Alternative Bearing Surface Materials? A Systematic Review

AbstractOxidized zirconium (OxZr) femoral heads were developed to emulate the superior wear and scratch properties of ceramics while eliminating their unwanted tendency for brittle fracturing. Studies using OxZr have demonstrated reduced linear and volumetric wear of polyethylene (PE) liners when compared with cobalt chrome, ceramic, and steel femoral heads. The purpose of this systematic review was to determine the difference in revision rates, radiologically determined linear wear rates, and patient-reported outcomes among OxZr and alternative bearing materials. Following the Preferred Reporting Items for Systematic Review and Meta-Analysis protocols, a systematic review of published literature through April 24, 2018 was conducted. Among the 862 cases included at a mean weighted follow-up of 4.78 years, the revision THA rate and patient-reported outcomes were similar among OxZr and alternative bearing materials. One of the five studies demonstrated significantly lower linear wear rates in the OxZr group when paired with ultrahigh molecular-weight PE (OxZr 0.03 mm/y vs. stainless-steel 0.11 mm/y; p &lt; 0.001) and when paired with highly-crosslinked PE (OxZr 0.02 mm/y vs. stainless-steel 0.04 mm/y; p &lt; 0.001). The remaining four studies found no difference in linear wear rates. OxZr demonstrated similar outcome to that of modern-day ceramic and metal femoral heads for short- and mid-term revision surgery rates and patient-reported outcomes. Longer term studies are needed to evaluate if any long-term wear advantages are seen with the use of OxZr femoral heads and if the use of OxZr is cost effective compared with ceramic or metal alternatives. The level of evidence of the study is level II, systematic review.

Polyethylene Wear With Ceramic and Metal Femoral Heads at 5 Years: A Randomized Controlled Trial With Radiostereometric Analysis

BackgroundA common bearing combination in total hip arthroplasty today is a metal femoral head articulating with polyethylene in the cup. Ceramic heads are thought to be more resistant to third-body damage, and have better wettability and decreased surface roughness, which taken together have been suggested to result in less polyethylene wear. The purpose of this study is to compare the initial creep deformation and follow wear pattern, using radiostereometric analysis, of ceramic and metal femoral heads that articulate with a modern highly cross-linked polyethylene cup liner. MethodsFifty patients with primary osteoarthritis and scheduled for an uncemented total hip arthroplasty were randomized 1:1 to either a ceramic (BIOLOX delta) or a metal (CoCr) femoral head. The patients were followed up for 5 years with repeated radiostereometric analysis examinations (postoperatively, then at 14 days, 3, 12, 24, and 60 months), as well as a hip-specific outcome questionnaire. ResultsDuring the first 3 months both groups showed expected creep within the liner of 0.12 mm (standard deviation 0.03) for the ceramic and 0.08 mm (standard deviation 0.02) for the metal heads. Between 3 months and 5 years there was very little wear of the liner in either group, corresponding to 0.003 mm/y for ceramic and 0.007 mm/y for metal heads. There was no difference in cup migration or clinical outcome between the groups and no cups were revised. ConclusionWith the introduction of modern highly cross-linked polyethylene, the ceramic head demonstrates no superiority when it comes to either early deformation or polyethylene wear compared with the metal head.

Comparative Biomechanical Study of Crosslinked Polyethylene Wear with 36-mm Ceramic Femoral Heads and with 32-mm Metal Femoral Heads.

Objective This study aims to compare the in vitro wear rate of crosslinked, high molecular weight polyethylene coupled to 36-mm diameter ceramic heads and 32-mm diameter metal heads. Methods Ceramic-on-polyethylene (36 mm) and metal-on-polyethylene (32 mm) tribological pairs were submitted to biomechanical tests in a simulator to determine the wear rate after 15 × 10 6 cycles. Results A statistically significant difference ( p = 0.0005) was detected when comparing the wear rate of assemblies with metallic heads (average wear: 14.12 mg/MC) and ceramic heads (average wear: 7.46 mg/MC). Conclusion The present study demonstrated the lower wear rate in prosthetic assemblies using 36-mm crosslinked ceramic-on-polyethylene tribological pairs compared to 32-mm crosslinked metal-on-polyethylene assemblies. This finding demonstrates the effectiveness of ceramic-on-polyethylene tribological pairs, even with large diameter heads.

Results of primary THA using 36 mm femoral heads on first-generation highly cross-linked polyethylene in patients less than 60 years of age: Minimum 10-year follow-ups.

Long-term results of total hip arthroplasty (THA) using highly cross-linked polyethylene (HXLPE) and metal femoral head with more than 10 years of follow-up have already been reported. However, most studies included results with a head size of 28 mm that could affect wear rates. The aim of this study was to evaluate the results of 36-mm metallic femoral heads on first-generation HXLPE in patients less than 60 years of age with a minimum follow-up of 10 years. Retrospective analysis included 54 cases from 47 patients. The mean age at the time of surgery was 47.22 years and the mean follow-up period was 131.04 months. Porous-coated cementless acetabular cups (Trilolgy®; Zimmer Inc., Warsaw, Indiana, USA) and HXLPE acetabular liners (Longevity®; Zimmer Inc.) were used for all cases. Acetabular cup abduction angles, anteversion angles, and wear rates of liner were measured using polyWare pro 3D distal version 5.10. The average modified Harris hip score at the final follow-up was 88.48 (range 80-96). Average Merle d'Aubigne and Postel score was 15.57 (range 14-18). There was no acetabular cup or femoral stem failing due to aseptic loosening. The average steady-state wear rate determined using radiographs taken at 1 year postoperatively and at the latest follow-up was 0.053 ± 0.025 mm/year. There were no statistically significant differences in liner wear rate with respect to age, variety of the femoral stem, or liner thickness. Results of THA with 36-mm metallic femoral heads on first-generation HXLPE in patients less than 60 years of age were satisfactory.

Survival of Ceramic vs. Metal Femoral Heads in Total Primary Hip Arthroplasty; An Observational Registry Study

Survival of Ceramic vs. Metal Femoral Heads in Total Primary Hip Arthroplasty; An Observational Registry Study

The impact of polyethylene abrasion on the occurrence of periprosthetic proximal femoral fractures in patients with total hip arthroplasty.

In addition to abrasion-induced osteolysis and ensuing instabilities, the polyethylene (PE) abrasion of total hip arthroplasty (THA) inlays can also cause gait instability due to the decentralization of the hip joint. The current literature yields, as yet, insufficient findings whether these two factors are linked directly or indirectly to a higher risk for periprosthetic proximal femoral fractures (PPFF). The aim of our retrospective evaluation is to analyse the impact of PE abrasion on the pathology of PPFF in patients with THA. The retrospective evaluation comprises all PPFF in patients with THA in the period from 01/2010 up to 12/2016. The study group (SG) included 66 cases (n = 66). The control group (CG) was comprised of patients with asymptomatic THA (n = 66), who were treated by our outpatient department including routine check-ups and X-ray examinations. We used the matched-pair methodology to scale the period of postsurgical care of the CG to the lifetime of the implant up to PPFF in the SG. We included epidemiologic data, radiological femoral head decentralization, osteolysis (Gruen classification), instabilities, acetabular cup position, and implant properties in our analysis. For the SG, we also included intra-operative signs of abrasion. The SG showed significantly higher numbers of decentralized THA as signs of inlay erosion with 73% compared to only 41% in the CG (p > 0.001). The SG showed 1 ± 0.68mm hip joint decentralization as to 0.5 ± 0.59mm in the CG (p = 0.004). We found significantly more cases of osteolysis in the SG (n = 25) than in the CG (n = 13) (p = 0.003). We found no notable differences in acetabular cup inclination or anteversion as well as cup size. However, differences were significant in femoral head size (SG 32 ± 2.3mm, CG 36 ± 2.4mm; p = 0.042) and head material. We found more widespread use of metal femoral heads in the SG than in the CG (SG 1:1, CG 1:21; p = 0.001). PPFF patients showed significantly higher rates of inlay erosion, resulting in femoral head decentralization and osteolysis. The higher rate of fracture is likely caused by the increasing instability of the implant fixation due to abrasion-induced osteolysis and the associated degradation of bone quality. It is conceivable that the abrasion and decentralization of the THA can also lead to gait instability, and thus, a higher proneness to falls. Gait instability can also be aggravated by increased granulation tissue and effusion due to the inlay abrasion. Although this cannot be substantiated by the investigation. In patients with decentralization of the THA and osteolysis, a radiological follow-up should be performed, and in case of gait instability (femoral head and) inlay replacements should be considered.