More than 50% reduction of wear in polyethylene liners with alumina heads compared to cobalt-chrome heads in hip replacements: a 10-year follow-up with radiostereometry in 43 hips

Forged to heal: The role of metallic cellular solids in bone tissue engineering

Metallic cellular solids, made of biocompatible alloys like titanium, stainless steel, or cobalt-chromium, have gained attention for their mechanical strength, reliability, and biocompatibility. These three-dimensional structures provide support and aid tissue regeneration in orthopedic implants, cardiovascular stents, and other tissue engineering cellular solids. The design and material chemistry of metallic cellular solids play crucial roles in their performance: factors such as porosity, pore size, and surface roughness influence nutrient transport, cell attachment, and mechanical stability, while their microstructure imparts strength, durability and flexibility. Various techniques, including additive manufacturing and conventional fabrication methods, are utilized for producing metallic biomedical cellular solids, each offering distinct advantages and drawbacks that must be considered for optimal design and manufacturing. The combination of mechanical properties and biocompatibility makes metallic cellular solids superior to their ceramic and polymeric counterparts in most load bearing applications, in particular under cyclic fatigue conditions, and more in general in application that require long term reliability. Although challenges remain, such as reducing the production times and the associated costs or increasing the array of available materials, metallic cellular solids showed excellent long-term reliability, with high survival rates even in long term follow-ups.

Head, acetabular liner composition, and rate of revision and wear in total hip arthroplasty: a Bayesian network meta-analysis

Total hip arthroplasty (THA) is a common procedure for patients suffering from hip pain e.g. from osteoarthritis, osteonecrosis, or hip fractures. The satisfaction of patients undergoing THA is influenced by the choice of implant type and material, with one key factor being the selection of the appropriate material combination for the bearing surface. In this Bayesian network meta-analysis, we investigated the impact of material combinations for the bearing surface on the longevity of hip implants. The wear penetration rate per year and the total wear penetration in the liner resulting from different material combinations, as well as the survival rate at last follow-up, were examined. We analyzed a total of 663,038 THAs, with 55% of patients being women. Mean patient age was 59.0 ± 8.1 years and mean BMI 27.6 ± 2.6 kg/m2. The combination of an aluminium oxide (Al2O3) head and an Al2O3 liner demonstrated the lowest wear penetration at last follow-up and the lowest rate of wear penetration per year. Additionally, the combination of a crosslinked polyethylene (XLPE) liner and a zircon oxide (ZrO2) head demonstrated the lowest rate of revision at last follow-up. These findings underscore the importance of careful material selection for hip implant bearing surfaces to optimize their longevity and patient satisfaction after THA.

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.

Comparison between ceramic-on-polyethylene versus metal-on-polyethylene prostheses in Total Hip Arthroplasties: a systematic review and meta-analysis

The Guidelines Project, an initiative of the Brazilian Medical Association, aims to combine information from the medical field to standardize how to conduct, and to assist in the reasoning and decision-making of doctors. The information provided by this project must be critically evaluated by the physician responsible for the conduct that will be adopted, depending on the conditions and the clinical condition of each patient.

Lower Rates of Ceramic Femoral Head Use in Non-White Patients in the United States, a National Registry Study

BACKGROUND

The purpose of our study was to investigate the association of race and ethnicity with the use of the newest technology and postoperative outcomes in total hip arthroplasty (THA) using the American Academy of Orthopaedic Surgeons (AAOS) American Joint Replacement Registry (AJRR).

METHODS

Adult THA procedures were queried from the AJRR from 2012 to 2020. A mixed-effects multivariate regression model was used to evaluate the association of race and ethnicity with the use of the newest technology (ceramic femoral head, dual-mobility implant, and robotic assist) at 30-day, and 90-day readmission. A proportional subdistribution hazard model was used to model a risk of revision THA.

RESULTS

There were 85,188 THAs with complete data for an analysis of outcomes and 103,218 for an analysis of ceramic head usage. The median length of follow-up was 37.9 months (interquartile range [IQR] 21.6 to 56.3 months). In multivariate models, compared to White non-Hispanic patients, Black (odds ratio [OR] 0.79, 95% confidence interval [CI] 0.69-0.92, P < .001), Hispanic (OR 0.76, CI 0.59-0.99, P = .037), Asian (OR 0.74, CI 0.55-1.00, P = .045), and Native American (OR 0.52, CI 0.30-0.87, P = .004) patients all had significantly lower rates of ceramic head use in THA. Compared to White non-Hispanic patients, Asian (hazard ratio [HR] 0.39, CI 0.18-0.86, P = .008) and Hispanic (HR 0.43, CI 0.19-0.98, P = .043) patients had significantly lower rates of revision. No differences in 30-day or 90-day readmission rates were seen.

CONCLUSION

Black, Hispanic, Native American, and Asian patients had lower rates of ceramic head use in THA when compared to White patients. These differences did not translate into worse clinical outcomes on a short-term follow-up. In fact, Asian patients had lower revision rates compared to non-Hispanic White patients. Additional study is necessary to evaluate the long-term consequence of lower ceramic head use in non-White patients in the United States.

Future Prospects for Clinical Applications of Nanocarbons Focusing on Carbon Nanotubes

Over the past 15 years, numerous studies have been conducted on the use of nanocarbons as biomaterials towards such applications as drug delivery systems, cancer therapy, and regenerative medicine. However, the clinical use of nanocarbons remains elusive, primarily due to short- and long-term safety concerns. It is essential that the biosafety of each therapeutic modality be demonstrated in logical and well-conducted experiments. Accordingly, the fundamental techniques for assessing nanocarbon biomaterial safety have become more advanced. Optimal controls are being established, nanocarbon dispersal techniques are being refined, the array of biokinetic evaluation methods has increased, and carcinogenicity examinations under strict conditions have been developed. The medical implementation of nanocarbons as a biomaterial is in sight. With a particular focus on carbon nanotubes, these perspectives aim to summarize the contributions to date on nanocarbon applications and biosafety, introduce the recent achievements in evaluation techniques, and clarify the future prospects and systematic introduction of carbon nanomaterials for clinical use through practical yet sophisticated assessment methods.

Which is the best bearing surface for primary total hip replacement? A New Zealand Joint Registry study

INTRODUCTION

We have investigated the revision rates of all bearing surface combinations for primary total hip replacement (THR) registered on the New Zealand Joint Registry (NZJR) to determine which coupling has been the most durable and successful over the last 16 years.

METHODS

There were 106,139 primary THRs registered, resulting in 4,960 revisions for any cause. We examined all-cause revision rates, reasons for revision and performed survival analyses.

RESULTS

Ceramic-on-highly cross-linked polyethylene (CoPx) had the lowest all-cause revision rate of 0.54/100-component-years (cys) (95% confidence interval 0.48 to 0.61). This was superior to all other hard-on-soft bearing combinations in unadjusted analysis. Furthermore, the age of patients receiving CoPx was significantly lower than for metal-on-polyethylene (mean 62.9; standard deviation [SD] 10.1 vs. 69.1; SD 9.6; p<0.001). Acetabular loosening was the reason for revision in 14.5% of CoPx, compared to 33% of MoP THRs (p<0.001). Metal-on-metal bearings had the highest revision rate of 1.43/100 cys and were significantly inferior to CoPx (p<0.001). Kaplan-Meier analysis and Cox regression analyses were performed and we adjusted the analyses to control for age, femoral head size, surgical approach and fixation.

CONCLUSIONS

CoPx remained the most durable and successful coupling used in primary THR in New Zealand irrespective of age, gender or size of femoral head.

Is there any difference in survivorship of total hip arthroplasty with different bearing surfaces? A systematic review and network meta-analysis

PURPOSE

Although many total hip bearing implants are widely used all over the world, simultaneous comparisons across the numerous available bearing surfaces are rare. The purpose of this study was to compare the survivorship of total hip arthroplasty (THA) with six available bearing implants.

METHODS

We conducted a systematic review of randomized controlled trials (RCTs) reporting survivorship or revision of ceramic-on-ceramic (CoC), ceramic-on-conventional polyethylene (CoPc), ceramic-on-highly-crosslinked polyethylene (CoPxl), metal-on-conventional polyethylene (MoPc), metal-on-highly-crosslinked polyethylene (MoPxl), or metal-on-metal (MoM) bearing implants. The synthesis of present evidence was performed by both the traditional direct-comparison meta-analysis and network meta-analysis.

RESULTS

In total, 40 RCTs involving a total of 5321 THAs were identified. The pooled data of network meta-analysis showed no difference in relative risk (RR) of revision across CoC, CoPc, CoPxl and MoPxl bearings. However, the MoM bearing was demonstrated with a significant higher risk of revision compared with CoC (RR 5.10; 95% CI=1.62 to 16.81), CoPc (RR 4.80; 95% CI=1.29 to 17.09), or MoPxl (RR 3.85; 95% CI=1.16 to 14.29), and the MoPc bearing was indicated with a higher risk of revision compared with CoC (RR 2.83; 95% CI=1.20 to 6.63). The ranking probabilities of the effective interventions also revealed the inferiority of the MoM and MoPc implants in survivorship (both 0%, 95% CI=0% to 0%) compared with CoC (39%, 95% CI=0% to 100%), CoPc (33%, 95% CI=0% to 100%), CoPxl (7%, 95% CI=0% to 100%) or MoPxl (21%, 95% CI=0% to 100%).

CONCLUSIONS

The present evidence indicated the similar performance in survivorship among CoC, CoPc, CoPxl and MoPxl bearing implants, and that all likely have superiority compared with the MoM and MoPc bearing implants in THA procedures. Long-term RCT data are required to confirm these conclusions and better inform clinical decisions.

Long-term durability of alumina ceramic heads in THA

BACKGROUND

The optimal type of bearing for hip arthroplasty remains a matter of debate. Ceramic-on-polyethylene (CoP) bearings are frequently used in younger and more active patients to reduce wear and increase biocompatibility compared to Metal-on-Polyethylene (MoP) bearings. However, in comparison to metal heads, the fracture risk of ceramic heads is higher. In addition, ceramic head fractures pose a serious complication which often necessitates major revision surgery. To date, there are no long-term data (>20 years of follow-up) reporting fracture rates of the ceramic femoral heads in CoP bearings. The purpose of this research was to investigate long-term CoP fracture rate.

METHODS

We evaluated the clinical and radiographic results of 348 cementless THAs treated with 2nd generation Biolox Al₂O₃ Ceramic-on-Polyethylene (CoP) bearings consecutively implanted between January 1985 and December 1989. The mean age at implantation was 57 years. The patients were followed for a minimum of 20 years. At the final 111 had died, and 5 were lost to follow-up. The cumulative incidence of ceramic head fractures in the long-term was estimated using a competing risk analysis.

RESULTS

The cumulative incidence of ceramic head fracture after 22-years was estimated with a competing risk analysis at 0.29% after 22-years (SE = 2.09%; 95% - CI: 0.03-1.5%). The radiographic analysis revealed no impending failures at final follow-up.

DISCUSSION/CONCLUSION

The fracture rate of second-generation ceramic heads using a CoP articulation remains very low into the third decade after cementless THA.

Processing and Properties of Zirconia-Toughened Alumina Prepared by Gelcasting

Zirconia-toughened alumina (ZTA) using yttria-stabilised zirconia is a good option for ceramic-ceramic bearing couples for hip joint replacement. Gelcasting is a colloidal processing technique capable of producing complex products with a range of dimensions and materials by a relatively low-cost production process. Using gelcasting, ZTA samples were prepared, optimising the stages of fabrication, including slurry preparation with varying solid loadings, moulding and de-moulding, drying and sintering. Density, hardness, fracture toughness, flexural strength and grain size were observed relative to slurry solid loadings between 58 and 62 vol. %, as well as sintering temperatures of 1550 °C and 1650 °C. Optimal conditions found were plastic mould, 4000 g/mol PEG with 30 vol. % concentration, 61% solid loading and T_s = 1550 °C. ZTA samples of high density (maximum 99.1%), high hardness (maximum 1902 HV), high fracture toughness (maximum 5.43 MPa m^1/2) and high flexural strength (maximum 618 MPa) were successfully prepared by gelcasting and pressureless sintering.

The John Charnley Award: Highly crosslinked polyethylene in total hip arthroplasty decreases long-term wear: a double-blind randomized trial

BACKGROUND

The use of highly crosslinked polyethylene (HXLPE) is now commonplace for total hip arthroplasty. Hip simulator studies and short-term in vivo measurements suggest that the wear rate of some types of HXLPE is significantly less than conventional ultrahigh-molecular-weight polyethylene (UHMWPE). However, there are few long-term data to support its use.

QUESTIONS/PURPOSES

The aim of this study was to measure the long-term steady-state wear of HXLPE compared with UHMWPE liners in a prospective, double-blind, randomized controlled trial using radiostereometric analysis.

METHODS

Fifty-four patients were randomized to receive hip arthroplasties with either UHMWPE liners or HXLPE liners. Complete followup was available on 39 of these patients (72%). All patients received the same cemented stem and an uncemented acetabular component. Three-dimensional penetration of the head into the socket was determined at 10 years using a radiostereometric analysis system, which has an in vivo accuracy of <0.1 mm. Oxford Hip Scores were compared between the groups.

RESULTS

At 10 years there was significantly less wear of HXLPE (0.003 mm/year; 95% confidence interval [CI], ±0.010; SD 0.023; range, -0.057 to 0.074) compared with UHMWPE (0.030 mm/year; 95% CI, ±0.012; p<0.001; SD 0.0.27; range, -0.001 to 0.164). The volumetric penetration from 1 to 10 years for the UHMWPE group was 98 mm3 (95% CI, ±46 mm3; SD 102 mm3; range, -4 to 430 mm3) compared with 14 mm3 (95% CI, ±40 mm3; SD 91 mm3; range, -189 to 242 mm3) for the HXLPE group (p=0.01).

CONCLUSIONS

This study demonstrates that HXLPE has little detectable steady-state in vivo wear. This may result in fewer reoperations from loosening; however, careful clinical followup into the second decade still needs to be performed.

LEVEL OF EVIDENCE

Level I, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

10-year results of the uncemented Allofit press-fit cup in young patients

BACKGROUND AND PURPOSE

Uncemented acetabular components in primary total hip arthroplasty (THA) are commonly used today, but few studies have evaluated their survival into the second decade in young and active patients. We report on a minimum 10-year follow-up of an uncemented press-fit acetabular component that is still in clinical use.

METHODS

We examined the clinical and radiographic results of our first 121 consecutive cementless THAs using a cementless, grit-blasted, non-porous, titanium alloy press-fit cup (Allofit; Zimmer Inc., Warsaw, IN) without additional screw fixation in 116 patients. Mean age at surgery was 51 (21-60) years. Mean time of follow-up evaluation was 11 (10-12) years.

RESULTS

At final follow-up, 8 patients had died (8 hips), and 1 patient (1 hip) was lost to follow-up. 3 hips in 3 patients had undergone acetabular revision, 2 for deep infection and 1 for aseptic acetabular loosening. There were no impending revisions at the most recent follow-up. We did not detect periacetabular osteolysis or loosening on plain radiographs in those hips that were evaluated radiographically (n = 90; 83% of the hips available at a minimum of 10 years). Kaplan-Meier survival analysis using revision of the acetabular component for any reason (including isolated inlay revisions) as endpoint estimated the 11-year survival rate at 98% (95% CI: 92-99).

INTERPRETATION

Uncemented acetabular fixation using the Allofit press-fit cup without additional screws was excellent into early in the second decade in this young and active patient cohort. The rate of complications related to the liner and to osteolysis was low.

Orthopaedic implant failure: aseptic implant loosening–the contribution and future challenges of mouse models in translational research

Aseptic loosening as a result of wear debris is considered to be the main cause of long-term implant failure in orthopaedic surgery and improved biomaterials for bearing surfaces decreases significantly the release of micrometric wear particles. Increasingly, in-depth knowledge of osteoimmunology highlights the role of nanoparticles and ions released from some of these new bearing couples, opening up a new era in the comprehension of aseptic loosening. Mouse models have been essential in the progress made in the early comprehension of pathophysiology and in testing new therapeutic agents for particle-induced osteolysis. However, despite this encouraging progress, there is still no valid clinical alternative to revision surgery. The present review provides an update of the most commonly used bearing couples, the current concepts regarding particle–cell interactions and the approaches used to study the biology of periprosthetic osteolysis. It also discusses the contribution and future challenges of mouse models for successful translation of the preclinical progress into clinical applications.