Comparative survival analysis of porous tantalum and porous titanium acetabular components in total hip arthroplasty

The Use of Highly Porous 3-D-Printed Titanium Acetabular Cups in Revision Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background/Objectives: As the rate of revision total hip arthroplasty (THA) has risen, there has been a drive to improve the technology in the manufacturing of the implants used. One recent advance has been 3-D printing of trabecular titanium implants to improve implant stability and osteointegration. The aim of this study was to review the clinical and radiological outcomes of these acetabular implants in revision THA. Methods: A manual search of the databases of the US National Library of medicine (PubMed/MEDLINE), Embase, and the Cochrane library was performed. The following keywords of "revision total hip arthroplasty" AND "acetabulum" AND "titanium" AND "porous" were utilised. Results: In total, 106 abstracts were identified during manual search of databases. In total, 11 studies reporting 4 different implants, with a total of 597 operated joints in 585 patients were included in this review. There were 349 (59.7%) female patients, and the mean age per study ranged from 56.0 to 78.4 years. The all-cause survival rate was 95.52% (95% CI: 92.37-97.96) at a mean follow up of 3.8 years (95% CI: 2.6-5.1). The 40 cases that required re-operation included 17 (2.8%) for infection, 14 (2.3%) instability, 2 (0.3%) for shell migration and 5 (0.8%) for aseptic loosening. The most commonly used patient reported outcome measure was the Harris Hip Score with the mean post-operative score of 86.7 (95% CI: 84.3-89.1). Conclusions: Trabecular titanium acetabular implants, when used in revision THA, resulted in excellent short- to mid-term outcomes with improved hip specific outcomes and a survivorship of 95.52% over the reported follow-up period. Future prospective studies evaluating long term outcomes are needed to make comparisons between more established solutions used in revision THA.

Highly Porous Titanium Cups Frequently Presenting with Radiolucent Lines in Cementless Primary Total Hip Arthroplasty: A Retrospective Cohort Study

Background/Objectives: A highly porous titanium cup with a three-dimensional metal interface was recently introduced to improve biological fixation and survival. However, radiography has revealed concerns regarding these cups, despite their excellent short- and mid-term clinical outcomes. This study compared the clinical and radiographic results of a highly porous titanium cup with those of a hydroxyapatite-coated porous titanium cup after primary total hip arthroplasty (THA). Methods: Fifty-one primary THAs were investigated. A highly porous titanium cup was used in 17 hips, and a hydroxyapatite-coated porous titanium cup was used in 34 hips. No significant differences in preoperative patient demographic characteristics were observed between the two groups. The 2-year postoperative clinical and radiographic results were compared. Results: Radiolucent lines were observed in 13 (76%) of 17 hips with highly porous titanium cups and in none (0%) of 34 hips with hydroxyapatite-coated porous titanium cups (p < 0.001). In the highly porous titanium cup group, radiolucent lines were observed in five hips (29%) in one zone, two hips (11%) in two zones, and six hips (35%) in three zones. No cup loosening was observed in either group. Conclusions: Radiolucent lines were significantly more frequent in highly porous titanium cups. This study suggests that, compared to the three-dimensional structure of porous titanium, the hydroxyapatite coating of porous titanium had a greater influence on bone ingrowth in the short term. The meaning of these findings in the long-term is unclear yet.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Does Using Highly Porous Tantalum in Revision Total Hip Arthroplasty Reduce the Rate of Periprosthetic Joint Infection? A Systematic Review and Meta-Analysis

BACKGROUND

Studies suggest tantalum (Ta) implants may have inherent antibacterial properties. However, there is no consensus regarding the effectiveness of Ta in preventing periprosthetic joint infection (PJI) after revision total hip arthroplasty (rTHA).

METHODS

We searched 5 main databases for articles reporting the rate of PJI following rTHA using Ta implants from inception to February 2022. The PJI rates of the Ta group were meta-analyzed, compared with the control group, and represented as relative risks (RRs) in forest plots.

RESULTS

We identified 67 eligible studies (28,414 joints) for assessing the prevalence of PJI following rTHA using Ta implants. Among these studies, only 9 compared the Ta implant group with a control group. The overall PJI rate following rTHA using Ta implants was 2.9% (95% confidence interval [CI]: 2.2%-3.8%), while it was 5.7% (95% CI = 4.1%-7.8%) if only septic revisions were considered. Comparing the Ta and control groups showed a significantly lower PJI rate following all-cause rTHA with an RR = 0.80 (95% CI = 0.65-0.98, P < .05). There was a trend toward lower reinfection rates in the Ta group after rTHA in septic cases, although the difference was not statistically significant (RR = 0.75, 95% CI = 0.44-1.29, P = .30).

CONCLUSIONS

Ta implants are associated with a lower PJI rate following all-cause rTHA but not after septic causes. Despite positive results, the clinical significance of Ta still remains unclear since the PJI rate was only reduced by 20%.

LEVEL OF EVIDENCE

IV.

Bioactivity and antibacterial properties of zinc-doped Ta2O5nanorods on porous tantalum surface

This paper focuses on the preparation of Zn2+-doped Ta2O5nanorods on porous tantalum using the hydrothermal method. Porous tantalum is widely used in biomedical materials due to its excellent elastic modulus and biological activity. Porous tantalum has an elastic modulus close to that of human bone, and its large specific surface area is conducive to promoting cell adhesion. Zinc is an important component of human bone, which not only has spectral bactericidal properties, but also has no cytotoxicity. The purpose of this study is to provide a theoretical basis for the surface modification of porous tantalum and to determine the best surface modification method. The surface structure of the sample was characterized by x-ray diffractometer, x-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope, and the Zn-doped Ta2O5nanorods are characterized by antibacterial test, MTT test, ICP and other methods. The sample has good antibacterial properties and no cytotoxicity. The results of this study have potential implications for the development of new and improved biomedical materials.

Preparation, modification, and clinical application of porous tantalum scaffolds

Porous tantalum (Ta) implants have been developed and clinically applied as high-quality implant biomaterials in the orthopedics field because of their excellent corrosion resistance, biocompatibility, osteointegration, and bone conductivity. Porous Ta allows fine bone ingrowth and new bone formation through the inner space because of its high porosity and interconnected pore structure. It contributes to rapid bone integration and long-term stability of osseointegrated implants. Porous Ta has excellent wetting properties and high surface energy, which facilitate the adhesion, proliferation, and mineralization of osteoblasts. Moreover, porous Ta is superior to classical metallic materials in avoiding the stress shielding effect, minimizing the loss of marginal bone, and improving primary stability because of its low elastic modulus and high friction coefficient. Accordingly, the excellent biological and mechanical properties of porous Ta are primarily responsible for its rising clinical translation trend. Over the past 2 decades, advanced fabrication strategies such as emerging manufacturing technologies, surface modification techniques, and patient-oriented designs have remarkably influenced the microstructural characteristic, bioactive performance, and clinical indications of porous Ta scaffolds. The present review offers an overview of the fabrication methods, modification techniques, and orthopedic applications of porous Ta implants.

Outcomes of novel 3D-printed fully porous titanium cup and a cemented highly cross-linked polyethylene liner in complex and revision total hip arthroplasty

INTRODUCTION

A novel fully porous acetabular titanium shell has been designed to reduce stiffness mismatch between bone and implant and promote osseointegration in complex (cTHA) and revision total hip arthroplasty (rTHA). A highly cross-linked polyethylene (XLPE) liner is cemented within the cup to reduce wear rates and increase survivorship. This study reported the outcomes of an XLPE liner cemented into a novel 3D-printed fully porous cup in cTHA and rTHA.

METHODS

Presented was a multicenter retrospective review of 40 patients (6 cTHA and 34 rTHA) who underwent THA with a fully porous titanium acetabular cup and cemented XLPE liner. Data were collected on demographics, surgical information, outcomes, including osseointegration and migration and implant survivorship.

RESULTS

On average, patients were 71.42 ± 9.97 years old and obese (BMI: 30.36 ± 6.88 kg/m²) and were followed up for a mean time of 2.21 ± 0.77 years. Six patients underwent cTHA and 34 patients underwent rTHA. The mean hospital length of stay was 5.34 ± 3.34 days. Three (7.5%) 90-day readmissions were noted. Harris Hip Scores improved, on average, from 53.87 ± 12.58 preoperatively to 83.53 ± 12.15 postoperatively (P<0.001). One case of acetabular shell aspetic loosening with migration was noted. Thirty-nine of the 40 acetabular components were fully osseointegrated without migration. Two patients underwent re-revision surgery for PJI and one patient received acetabular shell+liner re-revision due to aseptic loosening. Kaplan-Meier analysis showed an all-cause revision-free survival rate of 95.0% at 6 months and 1 year, and 92.0% at 4-years. Aseptic acetabular cup, liner dislocation/loosening, and fracture-free survival was 100% at 6 months and 1-year, and 97.1% at 2 years.

CONCLUSION

The combined use of a novel 3D-printed fully porous titanium acetabular shell and cemented XLPE acetabular liner yielded excellent rates of osseointegration, and all-cause and acetabular aseptic loosening survivorship at a minimum 1-year follow-up. Further long-term studies are needed to assess the longevity of this construct.

Revision for Aseptic Loosening of Highly Porous Acetabular Components in Primary Total Hip Arthroplasty: An Analysis of 20,993 Total Hip Replacements

BACKGROUND

Highly porous-coated titanium acetabular components have a high coefficient of friction and ultraporous surfaces to enhance bone ingrowth and osseointegration in total hip arthroplasty (THA). There have been concerns with the development of early radiolucent lines and aseptic loosening of highly porous acetabular components. It is unclear whether these concerns relate to a specific implant or the entire class. The aim of this study is to compare the revision rates for aseptic loosening of highly porous acetabular combinations in primary THA using data from a large joint replacement registry.

METHODS

Data were retrieved from the Australian Orthopedic Association National Joint Replacement Registry for the study period September 1999 to December 2019. All primary THA procedures recorded and performed for osteoarthritis using the most common combinations for each highly porous acetabular component with highly cross-linked polyethylene and a 32-mm or 36-mm femoral head were included. The primary outcome measure was revision for aseptic loosening of the acetabular component. Results were adjusted for patient age and gender.

RESULTS

There were 20,993 primary THA procedures performed for osteoarthritis using a highly porous acetabular component across 6 combinations. Relative to the POLARSTEM/R3 (StikTite), the Exeter V40/Tritanium had a significantly higher risk of revision for aseptic loosening of the acetabular component (hazard ratio 0.21, 95% confidence interval 0.06-0.74, P = .014). There was no difference between any other highly porous acetabular component combination and no late revisions for aseptic loosening.

CONCLUSION

Highly porous-coated titanium acetabular components have low rates of aseptic loosening with long-term follow-up. A difference between components may exist.

LEVEL OF EVIDENCE

Level III.

Do trabecular metal cups achieve better results when compared to hemispherical porous titanium cups in acetabular revision surgery?

BACKGROUND

Trabecular metal (TM) cups were introduced in order to achieve better ingrowth and stability of the cup in acetabular revision surgery. As their use has evolved over time, we have queried whether TM cups would improve results in terms of the rate of aseptic loosening when compared to historical uncemented porous titanium cups used in revision surgery for acetabular bone loss in Hospital La Paz (Madrid, Spain).

METHODS

We retrospectively reviewed 197 acetabular revisions performed between 1991 and 2015. Titanium cups were used in 81 cases and TM cups in 116. The mean follow-up was 8.1 years (range 1-15); 12.0 ± 7.8 for titanium group and 5.4 ± 3.1 for TM group. The most common reason for revision was aseptic loosening. A Kaplan-Meier analysis was used to determine the survival of the cup, with radiological failure and re-revision due to aseptic loosening as the endpoints. Cox multivariate regression analyses were performed to assess different risk factors for failure.

RESULTS

1 TM cup and 1 titanium cup were re-revised due to aseptic loosening (p = 0.61). Radiological cup loosening was observed in 4 TM cups and 2 titanium cups (p = 1.0). At 6 years, the probability of not having radiological cup loosening was 97.4% (95% CI, 93.9-100) for the titanium cups and 95.1% for the TM cups (95% CI, 90.1-99.9) (p = 0.59). Another 5 cups were re-revised due to dislocation. Hips with a greater Paprosky defect showed a higher risk of loosening (p < 0.05, hazard risk (HR) 3.04; 95% CI, 0.97-9.54).

CONCLUSIONS

This study shows there was no significant difference in re-revision due to aseptic loosening or radiological loosening between titanium and TM cups in revision surgery for acetabular bone loss. Both types of cups demonstrate excellent results with a low failure rate and minimal complications.

Evaluation of the bone morphology around four types of porous metal implants placed in distal femur of ovariectomized rats

Background

To compare structural features of the femoral bone of ovariectomized and non-ovariectomized rats after implantation of porous materials (TANTALUM, CONCELOC, TTM, ATLANT).

Methods

Experiments were carried out on 56 white laboratory female rats aged 6 months. Rats were randomly assigned into groups: sham-operated control group (SH) or ovariectomy group (OVX). Four different commercial implant materials (TTM, CONCELOC, TANTALUM, ATLANT) were placed into the defects (diameter 2.5 mm, depth 3.0 mm) in the distal metaphysis of femurs. Rats were sacrificed 45 days after surgery. Histological study was performed and the percentage of the bone area (BA%) around the implant at a distance of 500 μm in the cancellous area was measured.

Results

Formation of mature bone tissue of varying degrees around all of the implants was detected. In OVX rats cancellous bone defect zone was characterized by a high density of osteocytes on the surface. In the SH group, no differences in BA% among implant materials were found. In OVX rats, the BA% around ATLANT implants was 1.5-time less (p = 0.002) than around TANTALUM. The BA% around the rest of the materials was not statistically different.

Conclusions

Bone formation around the studied porous titanium and tantalum materials in the osteoporosis model was lower than in normal bone. There were differences in bone formation around the different materials in the osteoporosis model, while in the normal bone model, these differences were absent.

Implant Survival of 6,080 Tritanium Cups in Primary Total Hip Arthroplasty: Data from the Finnish Arthroplasty Register from 2009 to 2017

BACKGROUND

To enhance osseointegration in total hip arthroplasty (THA), ultraporous or highly porous-coated cups were introduced. Implant survival data on these new devices have been scarce. The aim of our study was to assess the survivorship of ultraporous Tritanium cups (Stryker) in a population-based register study.

METHODS

In this study, we collected data on 6,080 primary THAs using a Tritanium cup and 25,670 THAs using a conventional cup (control group) from the Finnish Arthroplasty Register; these procedures were performed from January 1, 2009, to December 31, 2017. We calculated the Kaplan-Meier survival estimates with 95% confidence intervals (CIs). The end point was revision for any reason or for aseptic loosening of the cup. The revision risks were assessed with use of the Cox multiple regression model. The variables assessed in the Cox model were femoral head size, age group, involved side, operation year, sex, diagnosis, and fixation of the stem. The proportional hazards assumption of the Cox model was not fulfilled, so the follow-up time was divided into 3 time periods: 0 to 2 years, >2 to 4 years, and >4 years.

RESULTS

When comparing the 2 groups with regard to revision for any reason, the 5-year Kaplan-Meier survivorship of the Tritanium group (94.7% [95% CI, 94.0% to 95.4%]) was inferior to that of the control group (96.0% [95% CI, 95.7% to 96.3%]). In the Cox regression analysis of the 2 groups for the time period of >4 years, the Tritanium group had an increased risk of revision for any reason compared with the control group (hazard ratio [HR], 3.12 [95% CI, 1.82 to 5.35]; p < 0.001). With regard to revision for aseptic loosening of the cup, the Tritanium group had an increased risk of revision compared with the control group for both 0 to 2 years (HR, 3.80 [95% CI, 1.76 to 8.24]; p < 0.001) and >2 to 4 years (HR, 11.2 [95% CI, 3.28 to 38.0]; p < 0.001).

CONCLUSIONS

There was no advantage to using the ultraporous-coated Tritanium cup for primary THA compared with conventional uncemented cups. However, wide CIs for some HR estimates may point to a lack of precision. Therefore, further research on subject is needed.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

In vitro and in vivo evaluations of the fully porous Ti6Al4V acetabular cups fabricated by a sintering technique

A type of canine fully porous Ti6Al4V acetabular cup was fabricated by a well-controlled powder sintering technique. The traditional hydroxyapatite-coated (HA-coated) cups were also prepared as the control. The characteristics, mechanical and biological properties of the two types of cups were evaluated by scanning electron microscopy, mechanical tests, finite element analysis and canine total hip arthroplasty (THA). Results showed that the porous cup had high porosity and large pore size with good mechanical properties without obvious stress shielding, and it had sufficient safety for implantation according to the finite element analysis. Both groups showed good biocompatibility and osteogenic ability after the THA surgeries, but the porous group had more bone ingrowth and higher bone-implant contact rate according to the micro-CT and histopathologic results. Therefore, the canine fully porous Ti6Al4V acetabular cup fabricated by the sintering technique could provide sufficient space and adequate mechanical support without obvious stress shielding effect for bone ingrowth. Compared with the traditional HA-coated cup, the porous cup may be more effective in achieving in vivo stability, which could contribute to reducing the risk of aseptic loosening.

Acetabular reconstruction using porous metallic material in complex revision total hip arthroplasty: A systematic review

Bone defects during acetabular revision of total hip arthroplasty raise a problem of primary fixation and of durable reconstruction. Bone graft with direct cemented fixation or in a reinforcement cage was long considered to be the gold standard; however, failures were reported after 10 years' follow-up, especially in segmental defect of the roof or pelvic discontinuity. In such cases, metallic materials were proposed, to ensure primary fixation by a roughness effect with added screws, and especially to avoid failure due to bone resorption in the medium term. We report a systematic literature analysis, addressing the following questions: (1) What materials are available and can be used with dual mobility (DM) designs? Apart from Trabecular Metal™ (TM), in which a DM cup can be cemented for sizes≥56mm, 4 other porous metals are available (Tritanium™, Trabecular Titanium™, Conceloc™, Regenerex™ and Gription™) although only the first 3 can be associated to DM. (2) Can the cost of these materials be estimated and compared to allograft with reinforcement cage? Considering simply the cost of the implant itself, compared to reconstruction by graft+cage+cemented cup (€2100), TM incurs an extra cost of €534, but with €1434 not covered by the French healthcare insurance. The cost of custom implants (apart from hemi-pelvis) ranges between €4200 and €8500, with only €4749 cover. (3) Do metallic materials ensure better survival than allograft+cage, according to severity of bone loss? Metallic reconstruction is claimed (with a low level of evidence) to reduce the risk of iterative loosening, but with a higher rate of dislocation, probably due to the lack of DM in many series. (4) What are the advantages and drawbacks of modular and custom metallic reconstructions? Modular reconstructions do not require 3D preoperative planning, but incur the risks of complications inherent to modularity. Custom implants can deal with more extensive defects, but require 5 to 8 weeks' production and are difficult to implant for the larger ones and/or when revision is limited to the acetabulum. (5) In what indications are these materials irreplaceable? Prior failure of allograft+cage in Paprosky type III defect with or without pelvic discontinuity shows the greatest benefit from metallic reconstruction, conditional on certain technical tricks. Only reconstructions using TM have more than 10 years' follow-up; other materials will need close monitoring. Failures in allograft with reinforcement cages occurred after about 10 years, and TM will need longer follow-up to prove its effectiveness. The high risk of dislocation should enable DM to be used, especially for small-diameter metallic reconstructions.

Internet Promotion of Direct Anterior Approach Total Hip Arthroplasty by Members of the American Association of Hip and Knee Surgeons

BACKGROUND

The direct anterior approach (DAA) in total hip arthroplasty is of significant interest to both patients and surgeons, largely due to intense marketing. This study addressed the question, "What is the level of promotion of DAA total hip arthroplasty on the internet by American Association of Hip and Knee Surgeons (AAHKS) members?"

METHODS

An internet search was performed to identify surgeon-specific websites for each member of the AAHKS using the members' full name and a previously published set of criteria. Each website was evaluated utilizing a questionnaire to systematically identify claims made regarding proposed DAA-specific risks, benefits, as well as the presence/absence of supporting data.

RESULTS

We identified 1855 qualified websites. The DAA was referenced on 22.8% (423/1855) of these websites. Claims regarding DAA-specific benefits included less invasive/muscle sparing (46.3%), quicker recovery (45.2%), decreased pain (28.1%), decreased hospital stay (22.0%), and decreased dislocation risk (16.3%). Potential DAA risks including lateral femoral cutaneous nerve injury, periprosthetic/greater trochanteric fracture, and wound complication/hematoma were addressed on only 4.7%, 3.1%, and 1.7% of websites, respectively. Supporting peer-reviewed literature was identified on only 3.6% of DAA websites.

CONCLUSION

Over one-fifth of AAHKS members promoted the DAA on the internet. Member websites claimed DAA benefits such as faster recovery and decreased pain approximately 9 times more frequently than any potential risk of the procedure (P < .001). While AAHKS policy does not regulate member marketing, it is the responsibility of all orthopedic surgeons to disseminate accurate, validated information concerning the procedures we perform.