In vivo wear performance of highly cross-linked polyethylene vs. yttria stabilized zirconia and alumina stabilized zirconia at a mean seven-year follow-up

Minimum 7-year results of cementless total hip arthroplasty with vitamin E-diffused and 2-methacryloyloxyethyl phosphorylcholine-grafted highly cross-linked polyethylene

The purpose of this study was to evaluate the mid-term clinical results and polyethylene wear of vitamin E-diffused highly cross-linked polyethylene (HXLPE) and 2-methacryloyloxyethyl phosphorylcholine (MPC)-grafted HXLPE in cementless total hip arthroplasty (THA). Thirty-four THAs with vitamin E-diffused HXLPE (VEPE) and 32-mm cobalt-chromium head, and 116 THAs with MPC-grafted HXLPE and 32-mm alumina head were evaluated. The Merle d'Aubigné and Postel scores were administered. Kaplan-Meier survivorship was analyzed. Annual radiographs were analyzed using computerized method and linear steady-state wear rate was measured. The mean duration of follow-up was 9 years (range, 7-11 years) in VEPE group and 8 years (range, 7-10 years) in MPC group. The mean Merle d'Aubigné and Postel scores improved postoperatively in both groups. Kaplan-Meier survivorship with endpoint of revision was 100% (95% confidence interval, 100%-100%) in VEPE group and 98.3% (95% confidence interval, 93.4%-99.6%) in MPC group at 10 years (P = .44). The mean steady-state wear rate was 0.007 mm/year in VEPE group and 0.006 mm/year in MPC group (P = .60). The clinical results of both groups were good and wear rates of both liners were very low.

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.

Ultra-High-Molecular-Weight Polyethylene in Hip and Knee Arthroplasties

Ultra-high-molecular-weight polyethylene (UHMWPE) wear and particle-induced osteolysis contribute to the failure of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Highly crosslinked polyethylene (HXLPE) was developed in the late 1990s to reduce wear and has shown lower wear rates and loosening than conventional UHMWPE in THA. The irradiation dose for crosslinking is up to 100 kGy. However, during crosslinking, free radical formation induces oxidation. Using HXLPE in THA, the cumulative revision rate was determined to be significantly lower (6.2%) than that with conventional UHMWPE (11.7%) at a mean follow-up of 16 years, according to the Australian Orthopaedic Association National Joint Replacement Registry. However, HXLPE does not confer to TKA the same advantages it confers to THA. Several alternatives have been developed to prevent the release of free radicals and improve polymer mechanical properties, such as thermal treatment, phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine grafting, remelting, and vitamin E addition. Among these options, vitamin E addition has reported good clinical results and wear resistance similar to that of HXLPE without vitamin E, as shown by short-term clinical studies of THA and TKA. This review aims to provide a comprehensive overview of the development and performance of UHMWPE in THA and TKA.

Thirteen-year results of cementless total hip arthroplasty with zirconia heads on highly cross-linked polyethylene

OBJECTIVES

Zirconia ceramic was introduced for femoral heads because of its mechanical strength and fracture toughness. Highly cross-linked polyethylene has been shown to achieve wear reduction compared to conventional polyethylene. The purpose of this study was to investigate the long-term results of cementless total hip arthroplasty with zirconia femoral heads on highly cross-linked polyethylene.

METHODS

Radiographic measurements of two-dimensional femoral head penetration into the polyethylene were performed with a computerized method (PolyWare) in 93 hips at a mean follow-up of 13 years. The steady-state wear rates were measured based on the radiographs from the first year after surgery to the final follow-up.

RESULTS

The mean Merle d'Aubigné and Postel score had improved significantly from 10.9 points preoperatively to 15.3 postoperatively (p < 0.001). Osteolysis was not found around the implant, and no zirconia heads had fractures. The total head penetration rate was 0.04 mm/year, and the steady-state wear rate was 0.02 mm/year. Kaplan-Meier survivorship with the endpoint of revision was 97% (95% confidence interval [CI], 92% to 99%) at 10 years.

CONCLUSION

Zirconia on highly cross-linked polyethylene demonstrated extremely low wear properties at long-term follow-up.

Fabrication, Properties and Applications of Dense Hydroxyapatite: A Review

In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial reconstruction, etc. Amongst the various calcium phosphate compositions, hydroxyapatite, which has a composition similar to human bone, has attracted wide interest. Much emphasis is given to tissue engineering, both in porous and dense ceramic forms. The current review focusses on the various applications of dense hydroxyapatite and other dense biomaterials on the aspects of transparency and the mechanical and electrical behavior. Prospective future applications, established along the aforesaid applications of hydroxyapatite, appear to be promising regarding bone bonding, advanced medical treatment methods, improvement of the mechanical strength of artificial bone grafts and better in vitro/in vivo methodologies to afford more particular outcomes.

Minimum 10-Year Wear Analysis of Highly Cross-Linked Polyethylene in Cementless Total Hip Arthroplasty

Fifty-four patients (64 hips) underwent cementless total hip arthroplasty between 2000 and 2003 with a 22-mm zirconia ceramic bearing on highly cross-linked polyethylene, and were evaluated with a mean 11.9-year postoperative follow-up (range, 10-14 years). Linear wear was measured on the anteroposterior radiograph of the hip. No evidence of osteolysis and loosening was found on the final radiograph in any of the cases, and the steady-state linear wear rate was 0.017±0.018 mm/year. No significant correlation was found between the linear wear rate and age, body weight, cup inclination angle, or polyethylene thickness. Highly cross-linked polyethylene showed excellent wear resistance for >10 years when used in combination with 22-mm zirconia heads.

When and how do prosthetic hips fail after total hip arthroplasties?-A retrospective study

BACKGROUND/PURPOSE

Understanding failure modes, time to revision, and vulnerable components in revision hips could help reduce the risk of revision surgeries. Our aim was to investigate the association between the index diagnosis and the failure mode in patients undergoing revision surgeries.

METHODS

A total of 402 patients who underwent a first revision surgery in a single hospital between 2000 and 2012 were recruited in a retrospective study. Multiple logistic regression analysis was used to evaluate the association of the index diagnosis of the primary total hip arthroplasty and short-term failure, as well as specific failure mode that occurred early, while controlling for sex, age, and the type of prosthesis.

RESULTS

The mean time to revision due to all failure modes was 9.48 (standard deviation = 6.08) years. Defining short-term failure as a time to revision <5 years after total hip arthroplasty, the primary failure mode was infection (32.4%), followed by loosening (25.7%) and instability (17.1%). In multivariate analysis, as compared to osteonecrosis, patients with index diagnosis as infection was significantly associated with revision due to infection (odds ratio = 9.69, p = 0.013). In addition, osteoarthritis increased the odds of loosening (odds ratio = 4.18, p = 0.012). In contrast to studies in the United States and Europe, acetabular component revisions were the most common type found in our study.

CONCLUSION

This study demonstrates that, compared with patients with osteonecrosis, patients with infection and osteoarthritis had higher odds of revision due to infection and loosening, respectively. Further studies are needed to examine the cause-effect relationship between index diagnosis and mode of failure.