Tantalum Cups Research Articles

One-stage revision for reconstructing acetabular defects by trabecular metal acetabular revision system in periprosthetic joint infection

Objective: To investigates the clinical efficacy of the trabecular metal acetabular revision system (TMARS) in one-stage reconstruction of acetabular deficiencies associated with periprosthetic joint infection (PJI). Methods: This is a retrospective case series study,including the data of 59 patients with PJI underwent acetabular defect reconstruction by TMARS during one-stage revisions in the Department of Orthopaedics, the First Affiliated Hospital of Xinjiang Medical University from January 2013 to December 2021. There were 32 males and 27 females, aged (59.5±14.6) years (range: 26 to 84 years). Among them, 29 cases used tantalum cups, 13 cases used tantalum cups and tantalum reinforcing blocks, 9 cases used cup-cage, and 8 cases used multi-cup reconstruction techniques. The surgery procedure, Harris Hip score (HHS), recovery of the hip rotation center, implant survival rate, postoperative reinfection rate, and complications were recorded. Data were compared using the Wilcoxon rank-sum test. Results: All of the 59 patients underwent the operations successfully. Operation time was (188.9±48.4) minutes (range: 110 to 340 minutes), and intraoperative bleeding volume was (M(IQR)) 1 000(400)ml (range: 600 to 1 800 ml). After a postoperative follow-up of 5.1 (2.6) years (range: 2.0 to 10.5 years), the prosthesis survival rate was 94.9% (56/59). Recurrence of infection occurred in 3 cases (5.1%), aseptic loosening in 1case(1.7%), and hip dislocation in 4 cases (6.8%). At the last follow-up, HHS improved significantly(84 (12) vs. 44 (9), Z=-6.671, P<0.01), and the center of rotation of the hips were recovered in all cases. Conclusions: In one-stage revision surgeries aimed at reconstructing acetabular defects, utilizing the TMARS can provide stable initial fixation, restore a more natural center of rotation, significantly enhance early postoperative hip joint function, and reduce the likelihood of infection recurrence. This approach stands as a reliable choice for addressing acetabular defects during revision surgeries for infected hip joints.

Elevated Blood Tantalum Concentrations in Patients Following Reconstruction of Severe Acetabular Defects in Total Hip Arthroplasty Using Modular Tantalum Augments in Combination With Uncemented Tantalum Cups

IntroductionThe reconstruction of acetabular defects in total hip arthroplasty (THA) can be challenging. An option to treat uncontained acetabular defects is to use modular tantalum augments in combination with cementless press-fit cups. However, modularity is associated with an increased risk of debonding and mechanical failure. In addition, metal wear particles can be released due to micromotions at the implant interface. Clinical data on the long-term results of this treatment strategy is limited. The purposes of this study were: (1) to evaluate the clinical and radiological outcome of complex THA using modular trabecular metal augments and uncemented revision cups; (2) to investigate the blood tantalum concentrations in these patients at mid-term (mean 4.5 year) follow-up; and (3) to report complications and mechanisms of failure related to this procedure. Materials and MethodsIn this single-center study, we retrospectively reviewed data from a consecutive cohort of 27 patients who underwent complex acetabular defect reconstruction using a modular tantalum acetabular augment in combination with an uncemented tantalum cup. We evaluated the implant survival, and the radiological and clinical outcomes after a mean follow-up of 4.5 years (SD 2.1; range 2.5 to 10.6 years) using patient-reported outcome scores (PROMs). Blood samples were analyzed regarding tantalum concentration and compared with a control group. ResultsThe cumulative survival rate at 4.5 years with the endpoint “revision of the acetabular component for aseptic loosening” was 94.4% (95% confidence interval (CI) 71.6 to 99.2) and 82.9% (95 % CI 60.5 to 93.3) for the endpoint “revision for any reason.” The PROMs improved significantly up to the latest follow-up, and radiographic data showed no signs of loosening or implant migration. Median blood tantalum concentrations were significantly higher in the study group (0.15 μg/L) compared to the control group (0.002 μg/L) (P < 0.001). ConclusionsThis study demonstrated acceptable clinical and radiological results of cementless revision THA using modular trabecular metal implants for the reconstruction of large acetabular defects. Tantalum concentrations were significantly higher in patients who had tantalum implants compared to the control group, however, the systemic and local effects of an increased tantalum exposure are not yet fully understood and have to be further investigated.

Porous Tantalum Acetabular Cups in Primary and Revision Total Hip Arthroplasty: What Has Been the Experience So Far?-A Systematic Literature Review.

The global population, especially in the Western world, is constantly aging and the need for total hip arthroplasties has rocketed, hence there has been a notable increase in revision total hip arthroplasty cases. As time has passed, a considerable developments in science and medicine have been attained which have also resulted in the evolution of both surgical techniques and implants. Continuous improvements have allowed large bore bearings to be utilized which provide an increased range of motion, with ameliorated stability and a very low rate of wear. The trend for almost the last two decades has been the employment of porous tantalum acetabular cups. Several studies exist comparing them with other conventional methods for total hip arthroplasties, exhibiting promising short and midterm results. The Preferred Reporting Items for Systematic Reviews and a Meta-Analysis (PRISMA) were used to identify published studies in a comprehensive search up to February 2023, and these studies were reviewed by the authors of the article. Specific rigorous pre-determined inclusion and exclusion criteria were implemented. Fifty-one studies met our inclusion criteria and were involved in the systematic review. Sixteen studies examined postoperative clinical and radiological outcomes of using a tantalum cup in primary and revision total hip arthroplasty, whilst four biomechanical studies proved the superiority of tantalum acetabular components. Five articles provided a thorough comparison between tantalum and titanium acetabular cups, while the other studies analyzed long-terms results and complication rates. Porous tantalum acetabular cups appear to be a valuable option in revision total hip arthroplasty, providing clinical improvement, radiological stability, and promising long-term outcomes. However, ongoing research, longer follow-up periods, and careful consideration of patient factors are essential to further validate and refine the use of tantalum in various clinical scenarios.

Inhibition of adhesive wear in tantalum cup deep drawing by ultrasonic vibration–assisted forming technology

Inhibition of adhesive wear in tantalum cup deep drawing by ultrasonic vibration–assisted forming technology

Use of Customized 3D-Printed Titanium Augment With Tantalum Trabecular Cup for Large Acetabular Bone Defects in Revision Total Hip Arthroplasty: A Midterm Follow-Up Study.

Aims: In revision total hip arthroplasty (THA), large acetabular bone defects pose challenges for surgeons. Recently, wide application of trabecular tantalum, which has outstanding biocompatibility and mechanical properties, and the development of three-dimensional (3D) printing have led to the introduction of new schemes for acetabular reconstruction. However, few studies have focused on the treatment of bone defects with customized 3D-printed titanium augments combined with tantalum trabecular cup. Thus, we aimed to evaluate the effect of this therapy in patients who underwent revision THAs. Patients and Methods: We included 23 patients with Paprosky type III acetabular bone defects who underwent revision THA between January 2013 and June 2019. The preoperative hip rotation center and functional score were compared with those at 2–7 years (average 4.7 years) postoperatively to evaluate the midterm prognosis of our treatment choice. Results: Postoperatively, the rotation centres of all hips were comparable with those of the contralateral hips. Hip function improved with average Harris Hip Score improved from 33.5 (22.7–40.2) to 86.1 (73.5–95.6) and average Oxford Hip Score improved from 8.3 (0–14) to 38.8 (35–48) during follow-up. One dislocation, which occurred due to extreme hip flexion within 6 weeks, was treated with closed reduction, and no recurrent dislocation occurred. No nerve injury, infection, aseptic loosening, or osteolysis were observed and no re-revision was performed in any patient. Conclusion: Satisfactory midterm outcomes were obtained with 3D-printed titanium augment combined with tantalum cup for the treatment of acetabular defects in revision THA. Changes in the Harris Hip Score and Oxford Hip Score suggested a significant improvement in hip function.

Investigation of the effect of porous titanium cups on stress distribution in bone tissue (mathematical modeling)

Introduction. During arthroplasty in patients with altered anatomy and osteoporosis of the acetabulum, stable fixation of the acetabular component of the endoprosthesis is a very difficult task. There are studies on the bone tissue bonding to titanium, tantalum and ceramic coatings of endoprostheses. However, there are insufficient data on the influence of the strength characteristics of modern surfaces of the cups for hip endoprostheses on the distribution of mechanical stresses in the bone tissue around the implanted components. The purpose was to study on a mathematical model the changes in the stress-strain state of the endoprosthesis-bone system as a result of using porous tantalum cup. Materials and methods. A mathematical modeling has been carried out of the stress-strain state of the human hip joint in arthroplasty with porous cup. Du-ring the study, a defect in the acetabular roof filled with a bone implant fixed with two screws was simulated, as well as a defect in the acetabular floor filled with bone “chips”. Endoprosthesis cups were modeled in two versions: from solid titanium with a spray coating of porous titanium, and those entirely made of porous titanium. A distributed load of 540 N was applied to the sacrum. A load was applied between the iliac wing and the greater trochanter of the femur simulating the action of the gluteus medius — 1150 N and the gluteus minimus — 50 N. Results. The use of a cup with a coating of porous titanium in the normal state of the acetabulum leads to the occurrence of maximum stresses (15.9 MPa) in its posterior-upper part. Minimum stresses of 4.6 MPa are observed in the center of the acetabulum. The use of an endoprosthesis with porous titanium cup allows reducing the level of stresses in the bone tissue around the cup. If there is a defect in the acetabular roof, a hip endoprosthesis with porous titanium cup causes less stress than a solid titanium cup with coating of porous titanium. But on the graft, the stress level remains practically unchanged, regardless of the type of cup. The use of porous tantalum cup in the presence of a defect in the acetabular floor causes significantly less stress in the bone tissue around it, compared to an all-metal cup with coating. Conclusions. The cup of the hip endoprosthesis made of porous titanium causes significantly less stress in all control points of the model, compared to a cup made of solid titanium with coating of porous titanium, both with defects in the acetabular roof and floor, and without bone defects.

Mid-term outcomes of tantalum cup\u2013 a single centre study

IntroductionThe cementless acetabular implants are commonly used in primary and revision hip arthroplasty. Reconstruction of acetabulum in case of bone defects can be challenging. The aims of this single center study are to review the mid-term outcomes of porous tantalum cups (TM) and evaluate complications.MethodsThe midterm outcome of a trabecular metal tantalum modular uncemented cup was evaluated in 59 hips in 58 patients. In our group, we had 23 males and 35 females. The mean age was 70.11 years (range, 30 to 87 years). Four patients were lost to follow-up and 13 died during the period without having further surgeries attributed to the hip arthroplasty. The remaining 41 patients (42 revision hip arthroplasties) had complete data available.ResultsThe mean follow-up was 87 months, ranging from 24 to 144 months. Standard pelvic anteroposterior (AP) radiographs were used to assess and preoperatively classify acetabular defects as per Paprosky classification. The serial radiographs showed excellent stability, bone opposition and graft incorporation. Four patients had further surgeries. Two of these were due to infection (one superficial and one deep infection). One of the patients had washout and then removal of metal work, the other patient only had a washout and symptoms settled. One patient had vascular compromise and went for surgery to stem the bleeding. One patient had re-revision due to stem loosening and hence required surgery but the revision cup remained stable. We noted a 96% survival at an average of 7.2 years follow-up.ConclusionThe mid-term results with the trabecular metal cementless cup appeared to be promising in both primary and revision hip arthroplasty, even in the presence of considerable bone loss which requires bone grafting and augments.Level of evidenceIV.

Can porous tantalum acetabular cups and augments restore the hip centre of rotation in revision hip arthroplasty? Long-term results.

Background and aim: Loss of bone stock is the main problem in revision hip arthroplasty. Porous tantalum cups and augment constructs are possible solutions. The aim of this study was to describe results at an average follow-up of 10 years using these cups.Methods: 25 patients underwent to revision hip arthroplasty with porous tantalum cups. Acetabular bone defects were classified according to Paprosky’s in type II and III. All patients were reviewed clinically and radiographically at an average follow-up of 10 years (range 8.5 to 13 years). Changes in inclination angle of the cup and position of the hip centre of rotation (COR — measured and calculated using Pierchon’s method), and possible periacetabular radiolucency lines were assessed. Results: A statistically significant improvement in Harris Hip Score and hip range of motion was observed. The hip COR had been lowered by 19.33 mm after revision and no changes in COR position had been measured at follow-up. Kaplan-Meier survivorship was 100% at an average follow-up of 10 years, considering acetabular revision for any reasons as primary endpoint. 88% of patients was satisfied. Complications were 3 dislocations, 4 asymptomatic heterotopic ossifications and 1 partial reabsorption of greater trochanter. Conclusions: Porous tantalum cups and augments can be considered a valid solution in acetabular revisions for addressing massive bone defects and restoring the hip COR. (www.actabiomedica.it)

Cup-on-cup technique: a reliable management solution for severe acetabular bone loss in revision total hip replacement.

The management of acetabular bone loss is a challenging problem in revision total hip arthroplasty (rTHA). The goals of treatment are a stable acetabular fixation, implant stability, and restoration of hip centre of rotation.This study aims to report clinical, radiological outcomes and complications at short-term to mid-term follow-up of the cup-on-cup technique in the management of severe acetabular bone loss in rTHA. We retrospectively reviewed the records of patient receiving rTHA performed with double porous tantalum cup technique in a single Joint Replacement Unit from 2014 to 2017. Objective and subjective clinical scores (Harris Hip Score, Oxford Hip Score, and visual analogue scale), radiological parameters (centre of rotation, leg-length discrepancy, heterotopic ossification, osseointegration, loosening and radiolucencies) and complications were recorded. We analysed the implant survival rate and periprosthetic joint infection rate. We included 9 patients (9 hips) with a mean follow-up of 35.3 ± 10.8 months. Functional scores showed a statistically significant improvement at the final follow-up (p < 0.01). All patients rated their surgery as satisfactory. The cup-on-cup construct demonstrated radiological osseointegration with the centre of rotation restoration and leg length discrepancy improvement. In 1 patient, periprosthetic joint infection was diagnosed and treated with suppressive antibiotic therapy. No patients underwent acetabular components revision surgery for any reason. Cup-on-cup technique is a valid and safe solution for reconstruction of selected Paprosky type IIIA and IIIB bone defects with satisfactory clinical and radiographic results at short-term and mid-term follow-up.

Safety of Use of Tantalum in Total Hip Arthroplasty.

Tantalum implants have been used in >500,000 orthopaedic patients. Although the risks of metallosis and aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) after total hip arthroplasty (THA) are being debated, we are not aware of any studies investigating the liberation of tantalum ions and their potential effects on the immune system. We evaluated whether tantalum concentrations are elevated after THA with acetabular tantalum implants and assessed potential alterations in T-cell subpopulations. After a mean follow-up of 4 years (range, 0.5 to 8.9 years) of 144 patients who had undergone THA, blood samples were analyzed regarding blood tantalum concentrations, total white blood-cell counts, and lymphocyte subsets in 3 groups of patients: those treated with non-tantalum primary THA ("primary non-tantalum," n = 30), those treated with primary THA with a tantalum cup ("primary tantalum," n = 30), and those who underwent revision surgery with a tantalum shell ("revision tantalum," n = 84). Blood donors served as controls for immunological parameters (n = 59). Correlations between tantalum concentrations and human leukocyte antigen (HLA)-DR T cells were calculated, radiographic signs of implant loosening were assessed, and the Harris hip score (HHS) was used to evaluate hip function. The median tantalum concentration was similar to the detection limit both in the primary non-tantalum group (0.05 µg/L, 95% confidence interval [CI] = 0.05 to 0.05 µg/L) and in the primary tantalum group (0.051 µg/L, 95% CI = 0.050 to 0.055 µg/L), and it was 0.091 µg/L (95% CI = 0.083 to 0.112 µg/L) in the revision tantalum group (p < 0.0001 in the group-wise comparison with both primary non-tantalum and primary tantalum). We found a weak negative correlation of higher tantalum concentration with the concentration of HLA-DR/CD8 T cells (r = -0.22, 95% CI = -0.35 to -0.05, p = 0.01) but no correlation of tantalum concentration with the concentration of HLA-DR/CD4 T cells (r = -0.11, 95% CI = -0.27 to 0.06, p = 0.24). The values for all lymphocyte subgroups were within normal ranges. No implants were deemed loose. The median HHS was good to excellent. Exposure to stable tantalum cups is associated with low blood concentrations of tantalum. Signs of T-cell activation typical of ALVAL seem to be lacking. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Recovery of the Hip Rotation Center with Tantalum in Revision Arthroplasty.

Objective The objective of the present study is to evaluate the restoration capacity of the hip anatomic rotation center with the use of acetabular tantalum cups, associated or not with addition wedges. Methods Retrospective analysis of patients undergoing hip arthroplasty revision using tantalum between June 2013 and April 2017. The abduction angle of the acetabular component and the horizontal and vertical distances of the component to the center of anatomical rotation of the hip were evaluated. The measurements were made through baseline radiographs performed in the preoperative period and at the last follow-up visit. Results A sample of 21 patients was obtained, 11 (52%) men and 10 (48%) women, with a mean age of 62 ± 13 years old. The mean abduction angle of the acetabular cup decreased from 48.76° ± 13.88 ° in the preoperative period to 38.52° ± 10.08 ° in the postoperative period, and this difference was statistically significant ( p = 0.001). The distances from the center of rotation of the prosthesis relative to the center of anatomical rotation of the hip were also lower after revision surgery with tantalum. The mean horizontal distance of 12.74 ± 10.59 mm was reduced to 7.11 ± 4.84 mm, and the mean vertical distance was reduced from 14.79 ± 10.05 mm to 4.89 ± 6.21 mm, and these reductions were statistically significant ( p < 0.001). Conclusion Hip arthroplasty revision with tantalum cups, associated or not with addition wedges, significantly recovered the anatomical rotation center of the hip.

Middle term results of tantalum acetabular cups in total hip arthroplasty following pelvic irradiation

ObjectivesThe aim of this study was to evaluate the middle term cup survival, assess the functional implementation and the radiographic evolution of tantalum acetabular cups implanted on patients with a history of pelvic radiotherapy. MethodsFrom 2005 to 2013, we performed 12 THA replacements (4 males 8 females; mean age: 46.6 years (range 25–75)) on irradiated bone with Trabecular metal acetabular cups, 8 primary implants and 4 revision implants. The mean radiation dose delivered was 5500 cGy (range 3000 cGy–13,600 cGy). The mean follow-up was 68 months, ranging from 38 to 136. Postoperative follow-up time was assessed at 1, 3, 6 and 12 months, then annually. Double projection radiographs were requested at each control. Radiographic signs of loosening were investigated by X-rays looking for radiolucent lines. We used the Harris hip score for the clinical and functional evaluation. ResultsTo now none of the 12 patients in the series needed any revision surgery for aseptic loosening. In the revision group one patient have been revised for septic loosening, two patients have been treated by conservative procedure for hip dislocation. Post-operative Harris hip score improved from an average of 46 points to 85.3 points. At last follow-up we found only in one case radiographic signs of progressive lucent line, without clinical sign of failure. ConclusionIn a clinical setting, tantalum cup seems to provide a good stability due to the integration of the trabecular metal to the underline cancellous bone. The reported results, in agreement with literature data, propose the use of tantalum cups in irradiated bone. Level of evidenceLevel IV, therapeutic study.

Reconstruction of Severe Acetabular Bone Defects in Revision Hip Arthroplasty Management options and clinical outcomes

The objective of this study was to evaluate the effectiveness of different surgical implants for the reconstruction of severe acetabular bone defects in revision arthroplasty of the hip. The current study is a retrospective study on 32 patients with Paprosky type IIIA or IIIB acetabular defects operated between January 2012-December 2015 in a single hospital. The mean follow-up was 21 months (12-43 months). Five different types of reconstruction methods were used: primary uncemented cups with or without screws, cemented acetabular cups, tantalum cups, metal augments and antiprotrusio cages. Bone allograft was available in all cases. Functional outcome after surgery was evaluated using Harris Hip Score. Based on Paprosky classification, the study included 16 type IIIA and 16 type IIIB acetabular defects. Bone graft was used in 71.8% of the cases (23 out of 32 patients). Tantalum cups were used in 15 cases (46.9%), being the preferred implant. Primary uncemented cups were used in 2 cases, cemented acetabular cups were used in 4 cases, trabecular metal augments were used in 5 cases and antiprotrusion cages were used in 6 cases. The mean Harris Hip Score improved from 37.3�7.4 pre-operatively to 82.1�7.2 at final follow-up. In conclusion, the current study demonstrates that various methods of reconstruction are efficient in the short and medium-term.

Meta-analysis of individual registry results enhances international registry collaboration

Background and purpose — Although common in medical research, meta-analysis has not been widely adopted in registry collaborations. A meta-analytic approach in which each registry conducts a standardized analysis on its own data followed by a meta-analysis to calculate a weighted average of the estimates allows collaboration without sharing patient-level data. The value of meta-analysis as an alternative to individual patient data analysis is illustrated in this study by comparing the risk of revision of porous tantalum cups versus other uncemented cups in primary total hip arthroplasties from Sweden, Australia, and a US registry (2003–2015).Patients and methods — For both individual patient data analysis and meta-analysis approaches a Cox proportional hazard model was fit for time to revision, comparing porous tantalum (n = 23,201) with other uncemented cups (n = 128,321). Covariates included age, sex, diagnosis, head size, and stem fixation. In the meta-analysis approach, treatment effect size (i.e., Cox model hazard ratio) was calculated within each registry and a weighted average for the individual registries’ estimates was calculated.Results — Patient-level data analysis and meta-analytic approaches yielded the same results with the porous tantalum cups having a higher risk of revision than other uncemented cups (HR (95% CI) 1.6 (1.4–1.7) and HR (95% CI) 1.5 (1.4–1.7), respectively). Adding the US cohort to the meta-analysis led to greater generalizability, increased precision of the treatment effect, and similar findings (HR (95% CI) 1.6 (1.4–1.7)) with increased risk of porous tantalum cups.Interpretation — The meta-analytic technique is a viable option to address privacy, security, and data ownership concerns allowing more expansive registry collaboration, greater generalizability, and increased precision of treatment effects.

CORR Insights®: Does the Risk of Rerevision Vary Between Porous Tantalum Cups and Other Cementless DesignsAfterRevision Hip Arthroplasty?

CORR Insights®: Does the Risk of Rerevision Vary Between Porous Tantalum Cups and Other Cementless DesignsAfterRevision Hip Arthroplasty?

Early Survival of Two High-Porosity Acetabular Components after Total Hip Arthroplasty Revision

AbstractTotal hip arthroplasty (THA) revision rates remain high and are expected to increase. Different ingrowth surfaces including tantalum and titanium have been introduced to improve fixation and survival. Promising results have been shown with tantalum. This study was conducted to compare the survivorship of titanium and tantalum components after revision THA. A retrospective review of all THA revision cases from January 2002 to December 2010 was performed. Cases, where the questioned components were used, were enlisted in a single continuous cohort. A minimum of 2-year follow-up was required for inclusion. Patients were compared in two groups: titanium versus tantalum components, with the endpoint defined as any failure requiring acetabular component removal. A total of 118 patients were analyzed and included 64 patients in the tantalum group and 56 patients in the titanium group. The average length of follow-up was 50.4 months for both groups. Cases, where tantalum implants were used, were more likely to have a worse acetabular bone loss (p = 0.005). The main cause of index revision was aseptic loosening followed by infection. At the latest follow-up, survivorship was very similar in appearance and failed to achieve statistical difference (log-rank p = 0.1146). Among the variables assessed as potential predictors of failure, only the number of prior revisions was statistically significant (p = 0.004). The high-porosity titanium acetabular components demonstrate same survivorship at 2-year follow-up as the tantalum cups in the setting of revision THA. Only the number of prior revisions was significantly associated with increased failure rate.

Are porous tantalum cups superior to conventional reinforcement rings?

Background and purpose — Porous tantalum cups have been introduced as an alternative to various reinforcement rings in revision hip surgery. We hypothesized that porous tantalum cups would be superior to Müller acetabular roof reinforcement rings (MARRs) in revision hip surgery with re-revision for aseptic loosening as the primary outcome measure.Patients and methods — 207 hips operated with either a porous tantalum cup (TM cup, n = 111) or a MARR (n = 96) at index procedure were identified in our local arthroplasty register. Acetabular defects were classified according to Paprosky. There were 96 men and 111 women with a median age of 71 (35–95) years, presenting acetabular defect size type I in 39 cases, IIA in 22, IIB in 27, IIC in 43, IIIA in 32, and IIIB in 37 cases. Analysis of medical records identified all patients with subsequent re-revision and reasons for re-revisions. Kaplan-Meier survival functions were used to estimate implant survival.Results — With re-revision for aseptic loosening as the endpoint, the 6-year unadjusted cumulative survival was 97% (95% CI: 94–100) for TM cups and 96% (CI: 92–100) for MARR (p = 0.6). Using re-revision for any reason as the endpoint, 6-year survival was 87% (CI: 81–94) for TM cups and 95% (CI: 90–99) for MARR (p = 0.06). The main reason for re-revision in the TM group was dislocation (n = 10), followed by loosening (n = 3), whereas the main reason for re-revision in the MARR group was aseptic loosening (n = 8). Duration of the index procedure and perioperative blood loss were lower in the TM group.Interpretation — Both TM and MARR lead to good 6-year results in acetabular revision surgery. The methods differ in their respective failure mechanisms. We conclude that TM cups are a valuable treatment option in acetabular revision surgery, but the reasons underlying dislocations after the use of TM cups must be analyzed further.

A Novel Method for Assessment of Polyethylene Liner Wear in Radiopaque Tantalum Acetabular Cups: Clinical Validation in Patients Enrolled in a Randomized Controlled Trial

Conventional radiostereometric analysis (RSA) for wear is not possible in patients with tantalum cups. We propose a novel method for wear analysis in tantalum cups. Wear was assessed by gold standard RSA and the novel method in total hip arthroplasty patients enrolled in a randomized controlled trial receiving either titanium or tantalum cups (n=46). The novel method estimated the center of the head using a model based on identification of two proximal markers on the stem and knowledge of the stem/head configuration. The novel method was able to demonstrate a pattern of wear that was similar to the gold standard in titanium cups. The novel method offered accurate assessment and is a viable solution for assessment of wear in studies with tantalum cups.

Do new materials improve acetabular fixation and reduce wear? Commentary on an article by David C. Ayers, MD, et al.: "radiostereometric analysis study of tantalum compared with titanium acetabular cups and highly cross-linked compared with conventional liners in young patients undergoing total hip replacement".

Commentary The bearing articulation remains the nemesis of total hip arthroplasty. Obtaining and maintaining component stability and minimizing wear of the articulation represent the two most important factors for the longevity of any hip replacement. This article by Ayers et al. evaluates the stability of two different types of cementless fixation, a titanium fiber mesh compared with ultra-porous tantalum. The authors further investigate wear of an ultra-high molecular weight conventional polyethylene liner compared with a highly cross-linked polyethylene liner. This article represents a sequel to a previously published two-year follow-up evaluation of noncemented total hip arthroplasty acetabular migration and polyethylene wear as determined by radiostereometric analysis (RSA)1. A total of forty-six young, active individuals undergoing primary total hip arthroplasty were randomized into four cohorts: ultra-high molecular weight conventional polyethylene liner and titanium cup, highly cross-linked polyethylene liner and titanium cup, ultra-high molecular weight conventional polyethylene liner and tantalum cup, and highly cross-linked polyethylene liner and tantalum cup. There were no clinical or non-RSA radiographic differences among the groups. RSA demonstrated significantly less femoral head penetration, a surrogate for polyethylene wear, in the highly cross-linked polyethylene liners compared with ultra-high molecular weight conventional polyethylene liners by an order of magnitude. There was no significant difference in proximal migration between the titanium and tantalum acetabular components through five years of follow-up. The type of polyethylene liner or acetabular component had no effect on patient activity, pain, and well-being, which were maximized by six months following surgical intervention. The strength of this article is that it is a prospective, randomized, blinded study utilizing a very sophisticated technology, namely RSA, to obtain precise measurements of component micromotion relative to the bone that is otherwise undetectable by routine radiographs and to measure femoral head penetration2. The radiodense tantalum cups obscure the identification of the center of the femoral head with use of edge detection. Therefore, Ayers et al. developed a novel method known as the “fictive femoral head” to assess wear. This method is based on the identification of two radiopaque tantalum markers attached to the stem proximally and a priori knowledge of the femoral head and stem configuration of the inserted total hip replacement. From a series of radiographs, a stem configuration library was created, which provided geometrical information used to place a fictive femoral head center in three-dimensional space. This fictive femoral head center will be used by the RSA software. Although others have reported a substantial decrease in the wear of highly cross-linked polyethylene3, this article clearly shows the superiority of highly cross-linked polyethylene over conventional polyethylene, with a tenfold reduction in wear. Wear rates from one to five years were 0.04 mm/yr for ultra-high molecular weight conventional polyethylene liners and 0.004 mm/yr for highly cross-linked polyethylene liners. With respect to fixation, Ayers et al. demonstrated excellent fixation of both titanium mesh and tantalum acetabular components, as has been previously documented4. At the five-year follow-up, the median migration (and standard error) was 0.05 ± 0.20 mm proximally for titanium mesh cups and 0.21 ± 0.05 mm for tantalum cups. No implants were shown to be loose on radiographs. There was no evidence of osteolysis and no revisions were performed through five years of follow-up. The take-home points from this article are as follows. With use of femoral head penetration according to precise RSA measurements as a surrogate for wear, highly cross-linked polyethylene demonstrates ten times lower wear than ultra-high molecular weight conventional polyethylene at up to five years of follow-up3. Titanium mesh and tantalum (Trabecular Metal; Zimmer) materials provide excellent cementless fixation for acetabular components with little evidence of clinically relevant migration as measured by sophisticated RSA technology at up to five years of follow-up4. These results cannot and should not be extrapolated to other types of porous and ultra-porous cementless fixation.

Proximal femoral reconstruction after aseptic loosening following proximal femoral replacement for Ewing sarcoma: a case report with one-year follow-up

We report the case of a 30-year-old patient initially treated for a proximal femoral Ewing's sarcoma when 12 years old. Index treatment comprised tumour resection and total hip arthroplasty. Two years later revision for aseptic loosening was performed. Subsequently, six further surgical revisons were performed for varying causes. At the age of 23 years the proximal femur was resected and a proximal femoral endoprosthesis implanted.Eighteen years after initial diagnosis the patient presented with recurrent aseptc loosening. Both the proximal femur and acetabulum were reconstructed. For acetabular reconstruction a structural allograft and a tantalum cup were utilised. Reconstruction of the femur utilsed extensive wire mesh and circlage wiring with impaction bone allograft into which a femoral stem was implanted.At one-year follow-up the patient was pain free, had no evidence of infection with satisfactory radiographs and no evidence of implant loosening. This is the first case reporting an extended proximal femoral reconstruction with a wire mesh in combination with impaction bone grafting in an aseptic loosened proximal femoral replacement following Ewing's Sarcoma.