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

Continuous periprosthetic bone loss around the TOP® cup and inferior survival rate at an 8-year follow-up: a prospective cohort study

BACKGROUND

The trabeculae-oriented pattern (TOP®) cup was designed to minimize acetabular periprosthetic bone loss. In our previous prospective study comprising 30 patients with a two-year follow-up we found a substantial decrease in periprosthetic bone mineral density (pBMD) in the proximal and medial regions of the TOP cup. The present study aims to investigate pBMD changes in the mid-term and how this affects implant survival.

METHODS

We followed the previous cohort and estimated implant survival by Kaplan-Meier analysis, evaluated pBMD with dual-energy X-ray absorptiometry (DXA) and clinical outcome using the Harris Hip Score (HHS).

RESULTS

Mean follow-up was 8.6 (range 7.8-9.1) years. The eight-year implant survival rate for cup revision for all reasons was 83% (95% confidence interval {CI}: 70-97) and 86% (CI: 74-99) when cup revision due to aseptic loosening was the endpoint. Mean HHS at eight years was 95 (range 77-100). A further 12% (CI: 5-17) loss in pBMD was detected in the proximal Digas zone 1 and 12% (CI: 7-17) loss in Digas zone 2 also between two and eight years after surgery. pBMD continued to decrease up to 30% (CI: 24-36) in Digas zones 1, 2 and 3 compared to pBMD immediately postoperatively.

CONCLUSIONS

The TOP cup shows inferior mid-term survival rates compared to other uncemented cups, as well as a continuous decrease in pBMD. Periprosthetic bone loss cannot be prevented by this uncemented cup.

CLINICAL TRIAL NUMBER

Not applicable.

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.

Risk factors for liner wear and head migration in total hip arthroplasty: a systematic review

Total hip arthroplasty (THA) is a successful orthopaedic surgical procedure, and its longevity depends on bearing components and implant fixation. Optimizing polyethylene and ceramics has led to improved wear parameters and contributed to improved long-term outcomes. The present systematic review investigated whether time span from implantation, patient characteristics and performance status exert an influence on liner wear and head migration in THA. This study was conducted in conformity to the 2020 PRISMA guidelines. All the clinical investigations which reported quantitative data on the amount of liner wear and head migration in THA were considered. Only studies which reported quantitative data at least on one of the following patient characteristics were suitable: mean age, mean BMI (kg/m2), sex, side, time span between the index THA and the last follow-up (months) were eligible. A multiple linear model regression analysis was employed to verify the association between patient characteristics and the amount of liner wear and/or head migration. The Pearson Product-Moment Correlation Coefficient was used to assess the association between variables. Data from 12,629 patients were considered. The mean length of the follow-up was 90.5 ± 50.9 months. The mean age of patients at surgery was 58.4 ± 9.4 years, and the mean BMI was 27.2 ± 2.5 kg/m2. 57% (7199 of 12,629 patients) were women, and in 44% (5557 of 12,629 patients) THAs were performed on the left. The mean pre-operative Harris hip score was 46.5 ± 6.0 points. There was evidence of a moderate positive association between the amount of liner wear and the time elapsed between the index surgery to the follow-up (P = 0.02). There was evidence of a moderate positive association between the amount of head migration and the time elapsed between the index surgery to the follow-up (P = 0.01). No further statistically significant association was found. The time elapsed between the index surgery to the follow-up was the most important factor which influence the head migration and liner wear in THA. Patients' characteristics and preoperative physical activity did not influence the amount of head migration and liner wear.

Standardized 3D-printed trabecular titanium augment and cup for acetabular bone defects in revision hip arthroplasty: a mid-term follow-up study

BACKGROUND

The aim of this study was to assess the feasibility and outcomes of standardized three-dimensional (3D)-printed trabecular titanium (TT) cups and augments to reconstruct most acetabular defects.

METHODS

We included 58 patients with Paprosky type II and III acetabular bone defects who underwent revision hip arthroplasty between 2015 and 2018. Patients who were revised without 3D-printed augments, and cases who were lost to follow-up and died during follow-up were excluded. Radiographic and clinical outcomes were evaluated. A Kaplan-Meier survivorship curve was generated. The mean follow-up was 64.5 (range 49-84) months.

RESULTS

In total, 48 (82.8%) acetabular revisions were performed using standardized 3D-printed TT cups and augments, and a retrospective review was conducted on 43 revisions. The average position of the vertical center of rotation and leg length discrepancy were significantly decreased from 42.4 ± 9.1 mm and 38.4 ± 10.7 mm to 22.8 ± 3.4 mm and 4.1 ± 3.0 mm, respectively. Non-progressive radiolucent lines were observed in 3 (7.5%) acetabular components with no indications for revision. The mean Harris hip score, Oxford hip score and EuroQol five-dimensional questionnaire score increased from 33.0 ± 10.7, 11.4 ± 3.4 and 0.29 ± 0.09 to 80.3 ± 8.8, 35.8 ± 2.4 and 0.71 ± 0.10, respectively. The revision-free survival rate of the acetabular component was 93.0% (40/43), with a rate of revision for aseptic loosening of 2.3% (1/43).

CONCLUSION

Standardized 3D‑printed TT augments and cups could be used to reconstruct the majority of Paprosky type II and III acetabular defects in revision hip arthroplasty and demonstrated encouraging results at mid-term follow-up.

Efficacy and Safety of Acetabular Cup without Screw Fixation in Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Background and Objectives: Adequate initial fixation of the uncemented acetabular component in total hip arthroplasty is necessary to achieve long-term survival. Although screw fixation contributes to improved cup stability, there is currently no consensus on the use of this method. This study aimed to assess the existing randomized controlled trials (RCTs) on the efficacy and safety of cup fixation in total hip arthroplasty without screws. Materials and Methods: We searched the EMBASE, MEDLINE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov databases to identify RCTs published before February 2022. Primary outcomes were reoperation, cup migration, and Harris Hip Score. Secondary outcomes were the presence of a radiolucent line in the acetabular region, translation and rotation movement, and polyethylene wear. We conducted meta-analyses using the random-effects models. The revised Cochrane risk-of-bias tool was used to assess the risk of bias for outcomes of interest; the Grading of Recommendations, Assessment, Development, and Evaluation approach was used to summarize the body of evidence. Results: We included six reports from four studies. Total hip arthroplasty without screw fixation to the acetabular cup had little to no effect on reoperation (pooled relative risk, 0.98; 95% confidence interval, 0.14-6.68; I2 = 0%), cup migration (pooled relative risk, 1.72; 95% confidence interval, 0.29-10.33; I2 = 1%), Harris Hip Score (mean difference, 1.19; 95% confidence interval, -1.31-3.70; I2 = 0%), radiolucent line (pooled relative risk, 5.91; 95% confidence interval, 0.32-109.35), translation and rotation of all axes, and polyethylene wear (mean difference, 0.01; 95% confidence interval, -0.01-0.04; I2 = 0%), with very low certainty of evidence on all measures. Conclusions: The efficacy of acetabular cups without screw fixation in total hip arthroplasty remains uncertain, suggesting the need for prudent clinical application. Further large-scale, well-designed studies with low risk of bias are required.

Role of Hip Arthroscopy in the Treatment of Avascular Necrosis of the Hip: A Systematic Review

BACKGROUND

Avascular necrosis (AVN) or osteonecrosis of the femoral head occurs as a result of a vascular supply disruption that could lead to hip osteoarthritis. Recently, several joint-preserving procedures have been suggested to improve the outcome of AVN, including hip arthroscopy. This systematic review aimed to investigate the role of hip arthroscopy to preserve hip joints suffering from AVN.

METHODS

This review was conducted to collect data on hip arthroscopy from the available literature for the management of AVN. The collected articles included those that were focused mainly on the management of AVN assisted by arthroscopy and published up to 2020 that were searched in four databases using such keywords as "Avascular Necrosis", "AVN", and "Osteonecrosis" in combination with "Hip Arthroscopy" or "Arthroscopic Hip Surgery".

RESULTS

In total, 13 articles met the eligibility criteria, and no severe complications were reported after arthroscopy in patients with AVN. Moreover, the Harris scores were higher than 79 after the operation. The majority of the assessments showed that the use of arthroscopy was effective in the diagnosis and treatment of patients with AVN, except for one study, which had been performed on patients with stage IV AVN.

CONCLUSION

The findings supported the idea that hip arthroscopy is effective in the treatment of AVN. This approach is becoming more popular for the diagnosis and treatment of hip disorders.

Tantalum Versus Titanium Acetabular Cups in Primary Total Hip Arthroplasty: Current Concept and a Review of the Current Literature

BACKGROUND

Primary total hip arthroplasty (THA) is becoming an increasingly popular and efficacious medical procedure. There have been a number of studies evaluating tantalum acetabular cups compared with the conventional titanium acetabular cups for use in total hip arthroplasties. We conducted a systematic review and summarize clinical studies comparing tantalum acetabular cups with the conventional titanium acetabular cups for use in primary total hip arthroplasties.

METHODS

A literature search was performed to find all relevant clinical studies until March 2020, which then underwent a further selection criteria. The inclusion criteria was set as follows: Reporting on human patients undergoing primary total hip arthroplasty; Direct comparison between tantalum acetabular cups with conventional titanium acetabular cups for use in primary total hip arthroplasty; Radiological evaluation (cup migration, osteointegration); Clinical (functional scores, need for subsequent revision, patient-reported outcomes; Post-operative complications; Reporting findings in the English Language. After a thorough search a total of six studies were included in the review. The primary outcome measures were clinical outcomes, implant migration, change in bone mineral density and rate of revision and infection.

RESULTS

Tantalum is superior to titanium with regards to fewer radiolucencies, 100% survivorship at 12 years post-operatively, improved long-term implant osteointegration and survivorship as well as decreasing osteolysis and mechanical loosening. There has been no significant difference in radioisometric analysis, bone mineral density or Harris Hip Score. Revision and infection rates were found to be significantly lower in tantalum group at 10 years from pooled data of national joint registry (England and Wales), while it was found to be higher in the same at 9 years from pooled data of Swedish and Australian registry although this is not statistically significant.

CONCLUSION

The use of tantalum should be reserved for cases of high risk of failure or mechanical loosening, where failure of a contralateral joint occurred. The use of Tantalum carries lower risk of failure and infection. Further studies with longer follow-up would be useful in drawing further conclusions.

Excellent mid-term outcomes with a hemispheric titanium porous-coated acetabular component for total hip arthroplasty: 7-10 year follow-up

INTRODUCTION

Third-generation hemispheric, titanium porous-coated (HTPC) acetabular cups have been shown to achieve good biologic fixation through enhanced porous ingrowth surfaces. They also allow for a wide range of bearing options, including polyethylene, dual-mobility, and ceramic liners. The purpose of the study is to review the mid-term clinical outcomes an HTPC acetabular cup with a minimum of 7-year follow-up.

METHODS

A retrospective, observational study was conducted on all consecutive patients who underwent total hip arthroplasty (THA) with an HTCP acetabular cup at an urban, tertiary referral centre. Descriptive statistics were used describe baseline patient characteristics. Outcomes collected included postoperative complications, survival free of reoperations, and presence of osteolysis at latest imaging follow-up. Implant survival was analysed using the Kaplan-Meier method.

RESULTS

118 cases (114 primary, 4 revision) underwent THA with the HTCP acetabular cup at an average follow-up of 8.16 ± 0.85 years (range 7.02-10.28 years). Mean patient age at the time of surgery was 61.29 ± 12.04 years. All cases utilised a high-molecular-weight polyethylene (HMWPE) liner. None of the acetabular cups showed loosening or migration at the latest follow-up. There were 2 revisions in our study, 1 for abductor mechanism disruption and 1 due to surgical site infection where the acetabular cup was revised. Kaplan-Meier survivorship analysis for all-cause revision at 7 and 10-year follow-up showed a survival rate of 99.1% (95% confidence interval, 94.1-99.9%). Survivorship analysis for aseptic acetabular revision at 10-year follow-up showed a survival rate of 100%.

CONCLUSIONS

At long-term follow-up, no radiologic and minimal clinical complications were identified in this series. The HTPC acetabular cup system, used in conjunction with a HMWPE liner, demonstrates excellent outcomes and survivorship when compared to earlier mid-term studies published in the literature.

National Trends in Total Hip Arthroplasty Bearing Surface Usage in Extremely Young Patients Between 2006 and 2016

Background

Long-term implant durability is a key concern when considering total hip arthroplasty (THA) in young patients. The ideal bearing surface used in these patients remains unknown. The purpose of this study was to analyze trends in THA bearing surface use from 2006 to 2016 using a large, pediatric national database.

Methods

This was a retrospective review from January 1, 2006, to December 31, 2016, using the Kids’ Inpatient Database. International Classification of Diseases, 9^th revision and 10^th revision codes were used to identify patients who underwent THA and create cohorts based on bearing surfaces: metal-on-metal, metal-on-polyethylene, ceramic-on-polyethylene (CoP), and ceramic-on-ceramic (CoC). Annual utilization of each bearing surface and associated patient and hospital demographics were analyzed.

Results

A total of 1004 THAs were identified during the 11-year study period. The annual number of THAs performed increased by 169% from 2006 to 2016. The mean patient age was 17.1 years. The most prevalent bearing surface used in 2006 was CoC (37.3%), metal-on-metal (31.8%) in 2009, and CoP in 2012 and 2016 (50.6% and 64.8%, respectively). From 2006 to 2016, utilization of CoP increased from 5.0% to 64.8%, representing a 1196% increase over the study period.

Conclusions

The number of THAs performed in pediatric patients is increasing significantly. Although CoC was previously the most commonly used bearing surface in this patient population, CoP is currently the most common. Further investigation is needed to determine whether bearing longevity and clinical outcomes with CoP are superior to other bearing surfaces.

Vitamin E-blended highly cross-linked polyethylene liners in total hip arthroplasty: a randomized, multicenter trial using virtual CAD-based wear analysis at 5-year follow-up

BACKGROUND

Progressive oxidation of highly cross-linked ultra-high molecular weight (UHMPWE-X) liners is considered to be a risk factor for material failure in THA. Antioxidants such as vitamin E (alpha-tocopherol) (UHMWPE-XE) were supplemented into the latest generation of polyethylene liners. To prevent inhomogenous vitamin E distribution within the polymer, blending was established as an alternative manufacturing process to diffusion. The purpose of the present study was to investigate the in vivo wear behavior of UHMWPE-XE in comparison with conventional UHMWPE-X liners using virtual CAD-based radiographs.

METHODS

Until now, 94 patients from a prospective, randomized, controlled, multicenter study were reviewed at 5-year follow-up. Of these, 51 (54%) received UHMWPE-XE and 43 (46%) UHMWPE-X liners. Anteroposterior pelvic radiographs were made immediately after surgery and at 1 and 5 years postoperatively. The radiographs were analyzed using the observer-independent analysis software RayMatch^® (Raylytic GmbH, Leipzig, Germany).

RESULTS

The mean wear rate was measured to be 23.6 μm/year (SD 13.7; range 0.7-71.8 μm). There were no significant differences between the two cohorts (UHMWPE-X: 23.2 μm/year vs. UHMWPE-XE: 24.0 μm/year, p = 0.73). Cup anteversion significantly changed within the 1st year after implantation independent from the type of polyethylene liner [UHMWPE-X: 18.2-23.9° (p = 0.0001); UHMWPE-XE: 21.0-25.5° (p = 0.002)]. No further significant changes of cup anteversion in both groups were found between year 1 and 5 after implantation [UHMWPE-X (p = 0.46); UHMWPE-XE (p = 0.56)].

CONCLUSION

The present study demonstrates that the addition of vitamin E does not adversely affect the midterm wear behavior of UHMWPE-X. The antioxidative benefit of vitamin E is expected to become evident in long-term follow-up. Cup anteversion increment by 5° within the 1st year is likely a result of the released hip flexion contracture resulting in an enhanced posterior pelvic tilt. Therefore, a reassessment of target values in acetabular cup placement might be considered.

Highly Porous Tantalum Acetabular Components Without Ancillary Screws Have Similar Migration to Porous Titanium Acetabular Components With Screws at 2 Years: A Randomized Controlled Trial

BACKGROUND

It is proposed that highly porous coatings on acetabular components, such as a porous tantalum coating, provide adequate fixation without ancillary screw fixation in primary total hip arthroplasty (THA). However, tantalum acetabular components have been associated with higher rates of revision than other uncemented components in national registries. The aim of this randomized controlled trial is to determine whether the early migration of a solid-backed tantalum acetabular component was no greater than that of a titanium acetabular component with ancillary screw fixation that has proven good clinical results.

METHODS

Sixty-six patients aged 40 to 64 years, with osteoarthritis and Charnley grade A or B activity grade and who underwent primary THA, were recruited into the trial. Patients were randomized intraoperatively to receive either the tantalum or titanium acetabular component. All patients received the same cemented polished tapered femoral stem, 28-mm cobalt-chromium femoral head, and highly cross-linked polyethylene liner. Acetabular component migration was measured using radiostereometric analysis at 4-6 days postoperatively and at 6 weeks, 3 months, 1 and 2 years following THA.

RESULTS

The mean proximal migration at 2 years for the tantalum cohort was 0.17 mm (95% confidence interval, 0.09-0.24) which was no greater than that of the titanium cohort which was 0.19 mm (0.07-0.32). Harris hip scores and functional activity scores were similar between groups.

CONCLUSION

These results demonstrate that early stability can be achieved without ancillary screw fixation through the use of a highly porous high friction coating on a solid-backed modular acetabular component.

LEVEL OF EVIDENCE

Level I.

Porous Coatings in Retrieved Acetabular Components

BACKGROUND

We evaluated bone volume fraction in retrieved acetabular shells with 2 types of porous coatings: (1) titanium fiber mesh (HG) components and (2) tantalum metal coating (TM) components.

METHODS

Eight HG shells were matched to 8 TM shells for patient age, body mass index, and gender. The mean age at index surgery was 69 (51-82) years, mean body mass index was 28 (21-40), and patients were evenly divided between male and female (4:4). The length of implantation was 40 (16-96) months for the TM group and 156 (108-216) months for the HG group. Shells were embedded and two 5-mm thick cross-sections were cut through the apex of each component for backscatter scanning electron microscopy assessment. Backscatter scanning electron microscopy images were segmented to threshold for metal, bone, and available space for ingrowth. Slices were assessed regionally for ingrowth at the rim, equator, and pole of the acetabular shell. Differences were assessed using general estimating equations, and P values were adjusted for multiple comparisons using the Holm-Bonferroni step-down procedure.

RESULTS

The mean bone volume fraction was 21 ± 17% for the HG shell and 7 ± 4% for the TM shell (P < .0001). The rim and pole regions both had less bone ingrowth than the equator. No association was found between bone ingrowth and length of implantation for either design.

CONCLUSION

Adequate bone ingrowth is a requirement for successful biological fixation, but the amount of ingrowth may not be a driving factor. Both implants studied had successful outcomes and long-term fixation despite the observation of low amounts of ingrowth.

Femoral Head Penetration Rates of Second-Generation Sequentially Annealed Highly Cross-Linked Polyethylene at Minimum Five Years

BACKGROUND

Highly cross-linked polyethylene (HXLPE) liners in total hip arthroplasty (THA) have demonstrated decreased wear rates, resilience to cup orientation, and reduced osteolysis compared to conventional polyethylene. Sequential irradiation and annealing below the melting temperature is unique compared to most HXLPE which is irradiated and remelted. This study purpose is to provide minimum 5-year femoral head penetration rates of sequentially annealed HXLPE in primary THA.

METHODS

A retrospective review of a prospectively collected database identified 198 consecutive, cementless primary THAs utilizing sequentially annealed HXLPE (X3; Stryker, Mahwah, NJ). Operative technique was standardized. Radiographs were analyzed utilizing the Martell method with minimum 5-year and 1-year radiographs as baseline to minimize the initial bedding-in period.

RESULTS

Seventy-seven hips with minimum 5-year follow-up were analyzed. Mean steady state linear and volumetric head penetration rates were 0.095 mm/y and 76 mm³/y, respectively. Volumetric head penetration was significantly less for 32-mm compared to 36-mm (P = .028). In addition, less head penetration was observed for ceramic 32-mm heads at nearly half the rate compared to cobalt-chromium 36-mm heads (P ≥ .092). No correlations existed between penetration rates and age, body mass index, University of California Los Angeles Activity Level, polyethylene thickness, cup inclination, or anteversion (P ≥ .10). No radiographic osteolysis was observed.

CONCLUSION

Surprisingly, linear head penetration rates of sequentially annealed HXLPE were nearly identical to the osteolysis threshold for conventional polyethylene and greater than reports of irradiated and remelted HXLPE. Furthermore, these data corroborate reports that HXLPE is resilient to cup orientation and demographic variables. Longer term follow-up is recommended.

Radiographic and Clinical Outcomes of Porous Titanium-Coated and Plasma-Sprayed Acetabular Shells: A Five-Year Prospective Multicenter Study

BACKGROUND

New materials in cementless total hip arthroplasty are continuously introduced into clinical practice. The objective of this study was to compare the radiographic and clinical performances of acetabular shells made with porous titanium coating (PTC) and plasma-sprayed titanium (PS).

METHODS

Data from a prospective multicenter study monitoring PTC and PS shells were analyzed. Three hundred and eighty patients (191 with PTC and 189 with PS) with postoperative (within 10 months after the operation) and 5-year radiographs were available for assessment of radiographic outcomes and patient-reported outcome measures (PROMs). A radiolucent distance between the cup and acetabulum of ≥0.5 mm was defined as a gap if it was found on a postoperative radiograph and as a radiolucency if it was found on a later follow-up radiograph for the first time.

RESULTS

Postoperative gaps were more common with the PS shell (40% versus 24%, p < 0.001). However, a higher percentage of the gaps in the PTC group persisted at 5 years (56% versus 4%, p < 0.001). At 5 years, 23% of the PTC shells had a radiolucency versus 5% of the PS shells (p < 0.001). Logistic regression revealed a 5.2-fold increase in the odds for radiolucency with the PTC shell (p < 0.001). No patient underwent revision surgery due to acetabular component loosening within the study period. A PTC shell was the only factor associated with the risk of pain in a logistic regression model (odds ratio = 2.0, p = 0.035).

CONCLUSIONS

PTC shells were associated with more patient-reported pain and a higher risk of radiolucency and a persistent gap at 5 years compared with the PS shells, although these outcomes were not related to each other. The clinical relevance of the radiographic findings is unclear as no prostheses were revised because of loosening, but the findings warrant additional follow-up studies.

LEVEL OF EVIDENCE

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

Trabecular Metal Acetabular Components Reduce the Risk of Revision Following Primary Total Hip Arthroplasty: A Propensity Score Matched Study From the National Joint Registry for England and Wales

BACKGROUND

Trabecular metal (TM)-coated acetabular components are increasingly used in both primary and revision total hip arthroplasty (THA). However, previous studies assessing TM acetabular components have been small single-center cohorts with most lacking a control group. We compared revision rates following primary THA between TM and non-TM-coated acetabular components.

METHODS

A retrospective observational study was performed using National Joint Registry data, which included primary THAs with the same cementless acetabular component (either TM or non-TM coated). TM and non-TM implants were matched for multiple potential confounding factors using propensity scores. Outcomes following primary THA (revision for all-cause acetabular indications, aseptic acetabular loosening, and infection) were compared between matched groups using competing risk regression analysis.

RESULTS

In 18,200 primary THAs (9100 TM and 9100 non-TM), the overall prevalence of acetabular revision, revision for aseptic acetabular loosening, and septic revision was 1.2%, 0.13%, and 0.59% respectively. Five-year revision rates for all-causes (1.0% vs 1.8%, sub-hazard ratio [SHR] 0.57, 95% confidence interval [CI] 0.43-0.76, P < .001), aseptic acetabular loosening (0.1% vs 0.2%, SHR 0.35, 95% CI 0.14-0.90, P = .029), and infection (0.5% vs 0.9%, SHR 0.51, 95% CI 0.34-0.76, P = .001) were all lower in TM compared with non-TM implants.

CONCLUSION

Following primary THA, TM-coated acetabular implants had a reduced risk of both aseptic and septic revision compared with non-TM implants. Although absolute differences in revision risk were small, they may be clinically significant if TM designs were implanted in more complex cases.

Late Dislocations After Total Hip Arthroplasty: Is the Bearing a Factor?

BACKGROUND

Dislocation is a leading cause of revision after primary total hip arthroplasty (THA). Although more common in the first few years after the procedure, dislocation can occur at any time. This study investigated the difference in late dislocation in ceramic-on-ceramic (CoC) bearings compared with metal-on-polyethylene and ceramic-on-polyethylene bearings in THA.

METHODS

Data were used from the Australian Orthopaedic Association National Joint Replacement Registry, and the cumulative percent revision for dislocation was estimated using the Kaplan-Meier method for the different bearing surfaces. There were 192,275 THAs included in the study with 101,915 metal-on-cross-linked polyethylene (MoXLPE), 30,256 ceramic-on-cross-linked polyethylene (CoXLPE), and 60,104 CoC.

RESULTS

The cumulative percent revision for dislocation at 13 years for MoXLPE, CoXLPE, and CoC groups was 1.2 (95% confidence interval [CI], 1.1-1.3), 1.0 (95% CI, 0.7-1.4), and 0.9 (95% CI, 0.8-1.1), respectively. There was an increased risk of revision for dislocation for MoXLPE compared with CoXLPE and CoC. When stratified for head size, there was no difference in the risk of revision for dislocation between MoXLPE, CoXLPE, and CoC in the 28- and 32-mm head sizes. With a head size of 36 mm, MoXLPE had a higher rate of dislocation compared with other materials.

CONCLUSION

Bearing surface has little impact on revision for dislocation.

The Wear Rate of Highly Cross-Linked Polyethylene in Total Hip Replacement Is Not Increased by Large Articulations: A Randomized Controlled Trial

BACKGROUND

Larger articulations reduce the risk of dislocation following primary total hip arthroplasty, leading to increased use of these articulations. The wear rate of highly cross-linked polyethylene (XLPE) is low in standard-diameter articulations but remains unclear in larger articulations. The aim of this randomized controlled trial was to compare the mean wear rates of 36-mm and 28-mm metal-on-XLPE articulations between 1 and 3 years postoperatively.

METHODS

Fifty-six elderly patients undergoing primary total hip arthroplasty were randomized intraoperatively to receive either a 36-mm or 28-mm metal-on-XLPE articulation. Factors that may affect wear were controlled by study design. Wear was measured using radiostereometric analysis.

RESULTS

Mean annual proximal wear rates between 1 and 3 years were 0.00 and 0.01 mm/yr for the 36 and 28-mm articulation cohorts, respectively. No patient had a proximal wear rate of >0.1 mm/yr. Mean wear was very low in all directions, and the wear rate of 36-mm articulations was not significantly greater than that of 28-mm articulations on the basis of proximal, medial 2-dimensional, and 3-dimensional wear.

CONCLUSIONS

The wear rate of a larger 36-mm metal-on-XLPE articulation between 1 and 3 years following primary total hip arthroplasty was low and no greater than that of a 28-mm articulation. However, before a 36-mm metal-on-XLPE articulation is widely recommended, particularly in young active patients, long-term wear rates and association between wear and periprosthetic osteolysis should be determined.

LEVEL OF EVIDENCE

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

Trabecular TitaniumTM cups and augments in revision total hip arthroplasty: clinical results, radiology and survival outcomes

BACKGROUND

Large acetabular defects remain a challenge in hip revision arthroplasty. Experience with Trabecular Titanium™ (TT) cups (Limacorporate S.p.a.) has not been widely reported. Therefore, we assessed the survivorship and clinical and radiological outcomes of patients receiving TT cups, with or without supplementary trabecular titanium hemispherical modules for acetabular reconstruction, in primary and revision total hip arthroplasty (THA).

METHODS

Between January 2009 and July 2014, we performed 67 revisions and 5 primary THAs using TT cups in 69 patients. To achieve stability and/or restore the hip's centre of rotation, hemispherical modules were used in 17 cases based on preoperative templating and/or intraoperative findings. Mean follow-up was 30.5 months. Acetabular bone defects were classified according to the Paprosky classification. Survivorship, functional outcomes (Merle d'Aubigné) and radiological outcomes were analysed.

RESULTS

8 patients underwent cup revision: 2 for loosening, 3 for infection, and 3 for hip dislocation. The remaining cases did not present radiological signs of loosening. None of the cases with Paprosky type I classifications needed revision, while 4 with type II and 4 with type III needed revision (p = 0.028). The respective mean values for pain, walking, and range of motion (Merle d'Aubigné scores ± standard deviation) were 3.6 ± 1.4, 3.7 ± 0.7, and 3.8 ± 0.6 preoperatively, and 5.7 ± 0.7, 5.3 ± 0.7, and 5.6 ± 0.7 at the latest follow-up (p&lt;0.001).

CONCLUSIONS

In the short term, results with TT cups appear to be encouraging, with satisfactory survival rates for both simple and complex cases.