Vitamin E diffused highly cross-linked polyethylene in total hip arthroplasty at five years: a randomised controlled trial using radiostereometric analysis

The Use of Large Metal Heads in Thin Vitamin E-Doped Cross-Linked Polyethylene Inserts Does Not Increase Polyethylene Wear in Total Hip Arthroplasty: 5-Year Results From a Randomized Controlled Trial

BACKGROUND

Vitamin E-doped cross-linked polyethylene (VEPE) has encouraged the use of larger heads in thinner liners in total hip arthroplasty (THA). However, there are concerns about wear and mechanical failure of the thin liner, especially when metal heads are used. The aim of this randomized controlled trial was to investigate if the use of a large metal head in thin VEPE liner would increase polyethylene wear compared with a standard 32-mm metal head and to compare periacetabular radiolucencies and patient-reported outcomes in THA.

METHODS

There were 96 candidates for uncemented THA who were randomly allocated to either the largest possible metal head (36 to 44 mm) that could be fitted in the thinnest available VEPE liner (intervention group) or a standard 32-mm metal head (control group). The primary outcome was proximal head penetration, measured with a model-based radiostereometric analysis. Secondary outcomes were periacetabular radiolucencies and patient-reported outcomes. The midterm results of the trial at 5 years are presented.

RESULTS

The median total proximal head penetration (interquartile range) was -0.04 mm (-0.12 to 0.02) in the intervention group and -0.03 mm (-0.14 to 0.05) in the control group (P = .691). The rates of periacetabular radiolucencies were 1 of 44 and 4 of 42 (P = .197), respectively. Patient-reported hip function and health-related quality of life did not differ between the groups, but participants in the intervention group reported a higher level of activity (median University of California Level of Activity score 7 versus 6, P = .020). There were 5 revisions caused by dislocations (2), periprosthetic fracture (1), stem subsidence (1), or iliopsoas impingement (1).

CONCLUSIONS

Large metal heads in thin VEPE liners did not increase liner wear and were not associated with liner failure 5 years after THA.

The Measurement of the Oxidative Index of Polyethylene Obtained during Revision Hip Arthroplasty and Assessment of Its Variability Depending on the Degree of Osteolysis, Implantation Time, as Well as the Size and Material of the Utilized Head

Background/Objectives: Aseptic loosening is the leading cause of late revision in total hip arthroplasty, primarily due to degenerative oxidation of polyethylene components, leading to wear particle formation and periacetabular osteolysis. This study aimed to analyze the oxidation levels in polyethylene liners and cemented cups retrieved from revision surgeries using Fourier-transform infrared spectroscopy (FTIR) and to explore the correlation between oxidation levels and factors such as head size, head material, fixation method, and implant survival time. Methods: Polyethylene liners and cups were analyzed post-revision surgery to assess oxidation levels, which were then compared to periacetabular bone loss measured by the Paprosky classification. This study evaluated the impact of head size (28 mm vs. 32 mm), head material (ceramic vs. metal), and fixation methods on oxidation. The relationship between the mean oxidation index (OI) and implant survival time was also investigated. Results: There was a significant positive correlation between the mean oxidation index of the polyethylene components and the severity of periacetabular osteolysis according to the Paprosky scale. While the mean OI for samples articulating with ceramic heads was lower than for those with metal heads, and the mean OI for samples with a 32 mm head size was lower than for those with a 28 mm size, these differences were not statistically significant. Furthermore, the fixation method did not affect the oxidation index, and no correlation was found between OI and the survival time of the implants. Conclusions: This study confirms a direct correlation between polyethylene oxidation and periacetabular osteolysis in hip replacements, highlighting the importance of material choice and design in potentially reducing the risk of aseptic loosening. Despite the lack of significant differences in oxidation levels based on head material and size, these factors may still play a role in the long-term outcome of hip arthroplasty, warranting further investigation.

Vitamin E-enriched medium cross-linked polyethylene in total knee arthroplasty (VIKEP): clinical outcome, oxidation profile, and wear analysis in comparison to standard polyethylene-study protocol for a randomized controlled trial

BACKGROUND

The gliding surface of total knee endoprostheses is exposed to high loads due to patient weight and activity. These implant components are typically manufactured from ultra-high molecular weight polyethylene (UHMWPE). Crosslinking of UHMWPE by ionizing radiation results in higher wear resistance but induces the formation of free radicals which impair mechanical properties after contact with oxygen. Medium-crosslinked UHMWPE enriched with vitamin E (MXE) provides a balance between the parameters for a sustainable gliding surface, i.e., mechanical strength, wear resistance, particle size, and oxidation stability. Therefore, a gliding surface for knee endoprostheses made up from this material was developed, certified, and launched. The aim of this study is to compare this new gliding surface to the established predecessor in a non-inferiority design.

METHODS

This multicenter, binational randomized controlled trial will enroll patients with knee osteoarthritis eligible for knee arthroplasty with the index device. Patients will be treated with a knee endoprosthesis with either MXE or a standard gliding surface. Patients will be blinded regarding their treatment. After implantation of the devices, patients will be followed up for 10 years. Besides clinical and patient-related outcomes, radiological data will be collected. In case of revision, the gliding surface will be analyzed biomechanically and regarding the oxidative profile.

DISCUSSION

The comparison between MXE and the standard gliding surface in this study will provide clinical data to confirm preceding biomechanical results in vivo. It is assumed that material-related differences will be identified, i.e., that the new material will be less sensitive to wear and creep. This may become obvious in biomechanical analyses of retrieved implants from revised patients and in radiologic analyses.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04618016. Registered 27 October 2020, https://clinicaltrials.gov/study/NCT04618016?term=vikep&checkSpell=false&rank=1 . All items from the World Health Organization Trial Registration Data Set can be found in Additional file 1.

In vivo creep and wear performance of vitamin-E-diffused highly crosslinked polyethylene in total hip arthroplasty

INTRODUCTION

An acetabular liner thickness of around 6 mm remains the "gold standard" in total hip arthroplasty. Some surgeons have been recommending the use of the thickest possible liner because contact stress and strain in articulating surfaces decrease with increasing the wall thickness. The purpose of this study was to determine whether in vivo creep and wear performance could be enhanced using a thicker liner over the standard thickness in vitamin-E-diffused highly crosslinked polyethylene (HXLPE).

MATERIALS AND METHODS

One hundred and twenty-two hips were allocated to age-matched, sex-matched, and body mass index-matched two subgroups implanted either with a 6.8- or 8.9-mm-thick vitamin-E-diffused HXLPE liner against 28-mm cobalt-chrome femoral head, and followed-up for 7 years. Linear and volumetric penetration of femoral head into the liners attributed to creep and wear were analyzed for each group.

RESULTS

Compressive creep strain generated at the initial 6 months was significantly larger in the 6.8-mm group (2.6%) than in the 8.9-mm group (2.2%). The linear steady-state wear observed after 2 years was 0.0019 and 0.0015 mm/year, whereas the volumetric steady-state wear was 0.54 and 0.45 mm3/years in the 6.8- and 8.9-mm-thick groups, respectively. Although less strain in the thicker group resulted in a slightly less wear, it did not reach significant differences in the steady-state wear rates between the groups.

CONCLUSION

No clinical significance for using a thicker liner over the standard thickness (6.8 mm → 8.9 mm) was confirmed in the vitamin-E-diffused HXLPE according to the 7-year follow-up. The wear rates for both thicknesses were very low enough to prevent osteolysis, and no mechanical failure was observed at any follow-up interval. Nevertheless, since the significantly higher strain was seen in the thinner liner, further follow-up is needed to compare the longer term wear and the incidence of osteolysis and component fracture.

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.

Minimum 7-Year Follow-Up of Vitamin E-Diffused and Highly Cross-Linked Polyethylene Liners in Total Hip Arthroplasty: Findings From a Prospective, International, Multicenter Study of 977 Patients

BACKGROUND

Vitamin E-diffused highly cross-linked polyethylene (VEPE) acetabular liners for total hip arthroplasty (THA) have shown favorable results in small cohort studies. However, larger studies are warranted to compare its performance to highly cross-linked polyethylene (XLPE) and demonstrate clinical significance in 10-year arthroplasty outcomes. This study compared acetabular liner wear and patient-reported outcome measures (PROMs) between patients treated with VEPE and XLPE liners in a prospective, international, multicenter study with minimum 7-year follow-up.

METHODS

A total of 977 patients (17 centers; 8 countries) were enrolled from 2007 to 2012. The centers were randomly assigned to implants. At 1-year, 3-year, 5-year, and 7-year postoperative visits, radiographs, PROMs, and incidence of revision were collected. Acetabular liner wear was calculated using computer-assisted vector analysis of serial radiographs. General health, disease progression, and treatment satisfaction reported by patients were scored using 5 validated surveys and compared using Mann-Whitney U tests. At 7 years, 75.4% of eligible patients submitted data.

RESULTS

The mean acetabular liner wear rate was -0.009 mm/y and 0.024 mm/y for the VEPE and XLPE group, respectively (P = .01). There were no statistically significant differences in PROMs. The overall revision incidence was 1.8% (n = 18). The revision incidence in VEPE and XLPE cohorts were 1.92% (n = 10) versus 1.75% (n = 8), respectively.

CONCLUSION

We found that VEPE acetabular liners in total hip arthroplasty led to no significant clinical difference in 7-year outcomes as measured by acetabular liner wear rate, PROMs, and revision rate. While VEPE liners showed less wear, the wear rate for both the VEPE and XLPE liners was below the threshold for osteolysis. Therefore, the difference in liner wear may indicate comparative clinical performance at 7 years, as further indicated by the lack of difference in PROMs and the low revision incidence.

Vitamin E-diffused liners show less head penetration than cross-linked polyethylene liners in total hip arthroplasty: a ten-year multi-arm randomized trial

Aims

The primary outcome was investigating differences in wear, as measured by femoral head penetration, between cross-linked vitamin E-diffused polyethylene (vE-PE) and cross-linked polyethylene (XLPE) acetabular component liners and between 32 and 36 mm head sizes at the ten-year follow-up. Secondary outcomes included acetabular component migration and patient-reported outcome measures (PROMs) such as the EuroQol five-dimension questionnaire, 36-Item Short-Form Health Survey, Harris Hip Score, and University of California, Los Angeles Activity Scale (UCLA).

Methods

A single-blinded, multi-arm, 2 × 2 factorial randomized controlled trial was undertaken. Patients were recruited between May 2009 and April 2011. Radiostereometric analyses (RSAs) were performed from baseline to ten years. Of the 220 eligible patients, 116 underwent randomization, and 82 remained at the ten-year follow-up. Eligible patients were randomized into one of four interventions: vE-PE acetabular liner with either 32 or 36 mm femoral head, and XLPE acetabular liner with either 32 or 36 mm femoral head. Parameters were otherwise identical except for acetabular liner material and femoral head size.

Results

A total of 116 patients participated, of whom 77 were male. The median ages of the vE-PE 32 mm and 36 mm groups were 65 (interquartile range (IQR) 57 to 67) and 63 years (IQR 56 to 66), respectively, and of the XLPE 32 mm and 36 mm groups were 64 (IQR 58 to 66) and 61 years (IQR 54 to 66), respectively. Mean total head penetration was significantly lower into vE-PE acetabular liner groups than into XLPE acetabular liner groups (-0.219 mm (95% confidence interval -0.348 to -0.090); p = 0.001). There were no differences in wear according to head size, acetabular component migration, or PROMs, except for UCLA. There were no cases of aseptic loosening or failures requiring revision at long-term follow-up.

Conclusion

Significantly lower wear was observed in vE-PE acetabular liners than in XLPE acetabular liners. No difference in wear was observed between different head size or PROMs except for the UCLA at ten years.

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.

Comparisons of Different Bearing Surfaces in Cementless Total Hip Arthroplasty: A Systematic Review and Bayesian Network Analysis

BACKGROUND

We aimed to make comparisons of different bearing surfaces in patients after cementless total hip arthroplasty.

METHODS

The network meta-analysis was guided by the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline. The primary outcomes were implant survival and Harris hip score (HHS). Secondary outcomes included linear wear rates and serum level of metal ions. Subgroup analyses were performed by: (1) classifying head sizes as small and large; (2) femoral heads as ceramic and metal; and (3) liners as metal, ceramic, polyethylene, highly cross-linked polyethylene (HXP), or vitamin E-infused highly cross-linked polyethylene (HXPE). A total of 64 eligible RCTs with different bearings were assessed. Overall inconsistency and heterogeneity were acceptable.

RESULTS

In the 10 years follow-up, metal-on-polythene and ceramic-on-polythene bearings with small heads showed higher risk for revisions compared with metal-on-HXP and ceramic-on-HXP bearings with small heads. Similarly, only metal or ceramic-on-polythene bearings with small heads showed inferiority in HHS compared with other bearings. Conventional polyethylene liners showed higher linear wear rates compared with HXP, HXPE, and ceramic liners at 5 and 10 years after surgery, while metal-on-metal and ceramic-on-metal bearings showed higher serum level of cobalt and chromium.

CONCLUSION

Bearings containing HXP, HXPE, and ceramic liners showed comparable survivorship and hip function at follow-up of 5 and 10 years. Hard-on-hard bearings containing metal had higher serum level of metal ions than others. Bearings containing conventional polyethylene had worse performance in terms of implant survival, hip function, and wear rates.

LEVEL OF EVIDENCE

Level I.

Wear rate and osteolysis in two types of second-generation annealed highly cross-linked polyethylene in total hip arthroplasty: A retrospective comparative study with a minimum of five years

BACKGROUND

As no previous study has directly compared the linear wear rate in two types of second-generation annealed highly cross-linked polyethylene, we performed a retrospective study with a minimum of 5-year follow-up to assess primary arthroplasties in the (1) wear rates and (2) incidence of osteolysis of the two types of HXLPE.

HYPOTHESIS

There was no significant difference in the linear wear rate and the incidence of osteolysis between the two types of second-generation annealed highly cross-linked polyethylene.

PATIENTS AND METHODS

In this single-center study, we reviewed 257 cases of primary cementless total hip arthroplasties between 2011 and 2015, which were performed with 32mm delta ceramic on second-generation annealed highly cross-linked polyethylene (X3 and E1 were used in 105 and 103 cases, respectively.). The mean wear rate was evaluated using a computer-assisted method, and the incidence of osteolysis was evaluated based on the appearance of a localized area with loss of trabecular bone or cortical erosion adjacent to the implants during the latest follow-up.

RESULTS

In total, we evaluated 208 cases, followed postoperatively for over 5 years (mean, 6.1 years, range: 5.0-8.0). There were no significant differences between the two groups with respect to age (list in order of Group X, Group E, p value) (61.2±12.3, 62.7±12.1, p=0.36), sex (ratio of male: 17.1%, 14.6%, p=0.61), body mass index (22.9±3.7, 22.8±4.0, p=0.91), pre- (49.9±14.8, 48.5±13.8, p=0.49) and post-operative (91.3±9.1, 92.7±7.0, p=0.23) Japanese Orthopaedic Association Hip Score, cup size (50.8±3.0, 50.9±2.2, p=0.70), cup inclination (38.7±4.8, 37.6±4.8, p=0.10), and cup anteversion (18.7±6.9, 18.5±7.6, p=0.80). The mean linear wear rates of the X3 and E1 groups were 0.057±0.039 (range: 0-0.16) and 0.054±0.037mm/year (range: 0-0.15), respectively (p=0.61). No osteolysis was found on the final plain radiographs in both groups.

DISCUSSION

This study revealed that both types of highly cross-linked polyethylene have excellent linear wear rates and were equally safe to use. However, the difference between the two materials in terms of the long-term wear rate should be further validated.

LEVEL OF EVIDENCE

III; retrospective case control study.

Cup positioning and its effect on polyethylene wear of vitamin E- and non-vitamin E-supplemented liners in total hip arthroplasty: radiographic outcome at 5-year follow-up

BACKGROUND

Aseptic loosening remains a challenging problem after total hip arthroplasty. Accurate cup placement and supplementation of antioxidants in acetabular liners might reduce material failure rates. The aim of this study is to assess the effect of the cup position on the wear behaviour of UHMWPE-XE and UHMWPE-X liners in vivo using virtual radiographs.

METHODS

We conducted a prospective, randomized, controlled, multicenter trial. Clinical data of 372 probands were analyzed. Anteroposterior pelvic X-rays of 324 patients immediately postoperatively and after 1 and 5 years were evaluated by the RayMatch® analysis software regarding cup position and wear behaviour.

RESULTS

Mean cup anteversion was 20.3° (± 7.4) and inclination was 41.9° (± 7.0) postoperatively. 62.3% of all patients had an anteversion and inclination within the Lewinnek safe zone. Anterior and anterolateral approaches led to significantly higher cup anteversion compared to lateral approaches (27.3° ± 5.5; 20.9° ± 7.2; 17.5° ± 6.6; p < 0.001 and p = 0.001, respectively). Mean anteversion increased to 24.6° (± 8.0) after 1 year (p < 0.001). Only one revision occurred because of implant dislocation. Wear rates from UHMWPE-X and UHMWPE-XE did not differ significantly. Anteversion angles ≥ 25° correlated to increased polyethylene wear (23.7 µm/year ± 12.8 vs. 31.1 µm/year ± 22.8, p = 0.012) and this was amplified when inclination angles were ≥ 50° (23.6 µm/year ± 12.8 vs. 38.0 µm/year ± 22.7, p = 0.062).

CONCLUSION

Anterior approaches lead to the highest inaccuracy of cup placement, but cup positioning outside the Lewinnek safe zone does not necessarily cause higher dislocation rates. Moreover, mean anteversion increased by approximately four degrees within the first year after operation, which is expected to be functional due to a regularization of pelvic tilt after intervention. Mid-term wear rates of UHMWPE-X and UHMWPE-XE liners are comparable, but steep cup positions lead to significantly increased polyethylene wear. In summary, a re-evaluation of target zones for intraoperative cup positioning might be considered. In the long-term reduced oxidative embrittlement could lead to superior wear behaviour of vitamin E-blended liners.

In Vivo Performance of Vitamin E Stabilized Polyethylene Implants for Total Hip Arthroplasty: A Review

BACKGROUND

Vitamin E stabilization was introduced to improve the oxidative stability, wear resistance, and mechanical properties of highly crosslinked polyethylene (HXLPE). In this literature review, we asked: (1) How has vitamin E-stabilized HXLPE (VEPE) performed in vivo for total hip arthroplasty (THA) and how does it compare with conventional ultra-high molecular weight polyethylene (UHMWPE) and HXLPE without vitamin E; and (2) Is there an apparent difference in the clinical performance of VEPE created by blending versus diffusion?

METHODS

We performed a systematic search of the literature according to the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines using PubMed and Embase. Included studies reported the in vivo behavior of VEPE in THA. We reviewed 41 studies.

RESULTS

For all studies that compared polyethylene with and without VE stabilization, outcomes for VEPE were either equivalent or superior to the control group (for HXLPE without VE and conventional UHMWPE controls, respectively). Hip insert wear rates were generally less than 0.1 mm/year and in most cases were less than 0.05 mm/year. No VEPE components were revised for osteolysis or adverse outcomes specific to VE incorporation.

CONCLUSION

Across the literature, we found that VEPE was reported to be clinically effective for THA applications, with much of the research indicating positive clinical outcomes and lower or equivalent wear rates compared to conventional UHMWPE and HXLPE controls without VE. Instances of early component fracture were reported, but have multiple potential causes. There is a gap in the literature for comparison of blended and diffused components, so the in vivo impact of VE incorporation method remains to be seen. Overall, this study provides a comprehensive summary of VEPE clinical performance for THA and may serve as a resource for future investigations.

Sterilization of Polymeric Implants: Challenges and Opportunities

Degradable and environmentally responsive polymers have been actively developed for drug delivery and regenerative medicine applications, yet inadequate consideration of their compatibility with terminal sterilization presents notable barriers to clinical translation. This Review discusses industry-established terminal sterilization methods and aseptic processing and contrasts them with innovative approaches aimed at preserving the integrity of polymeric implants. Regulatory guidelines, fiscal considerations, and potential pitfalls are discussed to encourage early integration of sterility regulatory considerations in material designs.

Imaging joint infections using D-methyl-11C-methionine PET/MRI: initial experience in humans

PURPOSE

Non-invasive imaging is a key clinical tool for detection and treatment monitoring of infections. Existing clinical imaging techniques are frequently unable to distinguish infection from tumors or sterile inflammation. This challenge is well-illustrated by prosthetic joint infections that often complicate joint replacements. D-methyl-11C-methionine (D-11C-Met) is a new bacteria-specific PET radiotracer, based on an amino acid D-enantiomer, that is rapidly incorporated into the bacterial cell wall. In this manuscript, we describe the biodistribution, radiation dosimetry, and initial human experience using D-11C-Met in patients with suspected prosthetic joint infections.

METHODS

614.5 ± 100.2 MBq of D-11C-Met was synthesized using an automated in-loop radiosynthesis method and administered to six healthy volunteers and five patients with suspected prosthetic joint infection, who were studied by PET/MRI. Time-activity curves were used to calculate residence times for each source organ. Absorbed doses to each organ and body effective doses were calculated using OLINDA/EXM 1.1 with both ICRP 60 and ICRP 103 tissue weighting factors. SUVmax and SUVpeak were calculated for volumes of interest (VOIs) in joints with suspected infection, the unaffected contralateral joint, blood pool, and soft tissue background. A two-tissue compartment model was used for kinetic modeling.

RESULTS

D-11C-Met was well tolerated in all subjects. The tracer showed clearance from both urinary (rapid) and hepatobiliary (slow) pathways as well as low effective doses. Moreover, minimal background was observed in both organs with resident micro-flora and target organs, such as the spine and musculoskeletal system. Additionally, D-11C-Met showed increased focal uptake in areas of suspected infection, demonstrated by a significantly higher SUVmax and SUVpeak calculated from VOIs of joints with suspected infections compared to the contralateral joints, blood pool, and background (P < 0.01). Furthermore, higher distribution volume and binding potential were observed in suspected infections compared to the unaffected joints.

CONCLUSION

D-11C-Met has a favorable radiation profile, minimal background uptake, and fast urinary extraction. Furthermore, D-11C-Met showed increased uptake in areas of suspected infection, making this a promising approach. Validation in larger clinical trials with a rigorous gold standard is still required.

Large Femoral Heads in Total Hip Arthroplasty With Vitamin E Highly Cross-Linked Polyethylene: Head Penetration Rates Compared to Highly Cross-Linked Polyethylene

BACKGROUND

Highly cross-linked polyethylene with vitamin E (VE-HXLPE) has shown superior tribological properties and has been rapidly adopted in total hip arthroplasty. However, the majority of studies compare VE-HXLPE to conventional or moderately cross-linked polyethylene using standard femoral head sizes. This study's purpose was 2-fold: (1) compare radiographic femoral head penetration (FHP) between VE-HXLPE and HXLPE and (2) evaluate FHP in large femoral heads ≥40 mm.

METHODS

One hundred forty-two consecutive primary total hip arthroplasties using ceramic femoral heads (n = 84 VE-HXLPE; n = 58 HXLPE) in a single implant system were retrospectively reviewed. FHP was measured radiographically utilizing Martell method at 4-week, 1-year, and latest radiographs. FHP, cup position, and demographic variables were compared between VE-HXLPE and HXLPE liners.

RESULTS

Median linear FHP was lower for VE-HXLPE compared to HXLPE during the initial "bedding-in" period between 4-week and 1-year (0.383 vs 0.551 mm, P = .650) and between 1-year and latest follow-up (0.131 vs 0.270 mm/y, P = .636) although without statistical significance. Acetabular cup inclination and anteversion did not influence linear or volumetric FHP (P ≥ .204). Large femoral heads (≥40 mm) were predictive of higher FHP during the early bedding-in period (P ≤ .025) but did not have an effect beyond 1 year in multivariate regression with numbers available. No radiographic osteolysis was observed in any case.

CONCLUSION

These findings support others that VE-HXLPE is the optimal polyethylene bearing surface to minimize FHP during the bedding-in period and beyond. Surprisingly, large ceramic femoral heads appear to influence FHP during the initial bedding-in period but do not increase FHP beyond 1 year. Further longer term follow-up remains warranted.

LEVEL OF EVIDENCE

III.

Revision Risk of Total Hip Arthroplasty With Vitamin E Doped Liners: Results From the Danish Hip Arthroplasty Register

BACKGROUND

Vitamin E-doped cross-linked polyethylene (VEPE) liners were introduced in total hip arthroplasty (THA) to reduce wear and risk of aseptic loosening and liner fracture. We report this nationwide population-based study to investigate the safety of VEPE liners for THA compared to cross-linked annealed or remelted polyethylene (XLPE).

METHODS

We included THAs from The Danish Hip Arthroplasty Register from January 1, 2008 to June 30, 2019, with uncemented cup, VEPE or XLPE liner, and metal or ceramic head. The outcome was revision due to (1) polyethylene-related endpoints (aseptic loosening, granuloma, osteolysis, or liner fractures) and (2) other endpoints.

RESULTS

A total of 110,803 THAs were assessed for eligibility and 53,842 THAs (46,645 patients) were included in the study: 5069 (9.4%) THAs with a VEPE liner and 48,773 (91.6%) with a XLPE liner. Median observation time was 5.48 (interquartile range 3.80-7.15) years for VEPE and 4.85 (interquartile range 2.68-7.76) for XLPE. VEPE had a lower risk of revision for polyethylene-related endpoints compared to XLPE (hazard ratio [HR] 0.60, 95% confidence interval 0.36-0.98) during complete follow-up. THAs with VEPE liners were associated with increased risk of any revision within the first 3 months (HR 1.62, 1.36-1.94), revision recorded as aseptic loosening within 3 months (HR 4.46, 2.26-8.80), and periprosthetic fracture within 3 months (HR 2.57, 1.98, 3.33).

CONCLUSION

VEPE liners had a lower risk of revision due to polyethylene-related endpoints, but a higher risk of all-cause revision within 3 months.

Fatigue wear test comparing vitamin-E-blended crosslinked polyethylene and conventional polyethylene in a Posterior Dynamic Stabilization System of the spine in the laboratory

BACKGROUND

Although artificial joints using polyethylene have been developed for various joints, the development of Posterior Dynamic Stabilization system of the spine using polyethylene has proceeded at a much slower pace. There are no studies which compare the abrasion resistance of vitamin-E-blended crosslinked polyethylene (VE) and conventional polyethylene (Virgin) in the spinal region. The purpose of this study was to compare the wear resistance of VE and Virgin in a Posterior Dynamic Stabilization System of the spine.

METHODS

Posterior Dynamic Stabilization System of the spine uses a polyethylene ball as a sliding surface. A fatigue wear test was repeated up to 1 million cycles at a speed of ±5°, 1 Hz while the rod was being pulled at a load of 50 N. Balls were compared using VE and Virgin in 6 samples each. Ti-6AL-4 V (Ti 64) and Co-Cr-Mo (CoCr) rods were used. Abrasion loss and shape change of the polyethylene balls were compared.

RESULTS

When Ti 64 was used as the rod, the average wear amount was -0.01 mg (0.02 mg, 0.01 mg, -0.06 mg) for VE, and 0.23 mg (0.18 mg, 0.13 mg, 0.38 mg) for Virgin. When CoCr was used as the rod, the average wear amount was 0.42 mg (0.71 mg, -0.06 mg, 0.61 mg) for VE, and 0.73 mg (0.72 mg, 0.70 mg, 0.76 mg) for Virgin. Most polyethylene samples showed indentations of 0.1 m or less at the contact point with the set screw. In the combination of Virgin and CoCr, a white patch was observed on the inner side of the polyethylene samples, with a maximum depression of 0.1 mm.

CONCLUSIONS

A fatigue wear test showed VE to be more efficient in abrasion resistance than Virgin in a Posterior Dynamic Stabilization System of the spine in the laboratory.

Safety of vitamin E-infused highwall liners for routine use in primary total hip arthroplasty: single centre, short-term follow-up of 1221 cases

BACKGROUND

Introduction of new implants should be monitored closely to capture any signs of compromising patient safety. Vitamin E infused highly-crosslinked polyethylene liners (VEPE) offer the potential for reduced wear. Highwall liners have been hypothesised to result in increased wear and potential liner fractures. The aim of this study was to determine the 3-7-year follow-up of highwall VEPE for primary total hip arthroplasty (THA), focusing on liner-related complications.

METHODS

We included 1221 consecutive THA operations from July 2010 to May 2014 with minimum follow-up of 3 (3.1-6.8) years Data collected included demographics, implant data, complications, reoperations, and deaths. Data were cross-referenced with the Danish Hip Arthroplasty Registry in order to ensure validity and completeness. Acetabular shell position was measured using Martell Hip Analysis Suite in a subgroup of 931 THAs.

RESULTS

Cumulative stem revision and shell revision at 3-year follow-up was 3.4% and 0.4% respectively. There were no revisions due to liner failure. Reason for revision included 11 dislocations, 15 soft-tissue revisions for infection, 44 stem revisions of which 34 were periprosthetic fractures and 13 shell revisions of which 6 were combined shell and stem revisions.

CONCLUSION

Early follow-up of VEPE liners for primary THA have not shown any revisions associated with liner failure. Continued monitoring of new materials are necessary to capture any signs of compromised patient safety.

Vitamin E-Enhanced Liners in Primary Total Hip Arthroplasty: A Systematic Review and Meta-Analysis

Objective

Adding vitamin E to highly cross-linked polyethylene liners is frequently performed in clinical practice, aiming at reducing liner wear, increasing liner survival, and delaying revision surgery. This study is aimed at evaluating the revision rate, total femoral head penetration, and postoperative clinical function of highly cross-linked polyethylene liners with and without vitamin E in total hip arthroplasty.

Methods

We conducted a systematic literature search to identify the use of highly cross-linked vitamin E liners compared to other liners in patients who received total hip arthroplasty (THA) before April 2021. The study quality assessment and data collection were conducted by two independent reviewers. Studies were artificially grouped, and vitamin E-enhanced liners (VE-PE) were compared with vitamin E-free liners (non-VE-PE). Analyses were executed using Review Manager version 5.4.1.

Results

From the preliminary screening of 568 studies, fourteen studies met the research criteria. Compared to non-VE-PE, using VE-PE reduced the all-cause revision rate (odds ratio = 0.54; 95% confidence interval (CI) 0.40, 0.73; P < 0.0001). The total femoral head penetration of the VE-PE was lower than that of the non-VE-PE (mean difference = −0.10; 95% CI -0.17, -0.03; P = 0.007). However, there was no difference in clinical function, including the Harris Hip Score and EuroQol Five-Dimension Questionnaire scores.

Conclusion

Compared to the liners without vitamin E, the addition of vitamin E to liners could reduce the all-cause revision rate by approximately 46% in the short-term follow-up. In addition, even though addition of vitamin E could also slow down femoral head penetration, there is no contribution to clinical function.

Vitamin E highly cross-linked polyethylene reduces mid-term wear in primary total hip replacement: a meta-analysis and systematic review of randomized clinical trials using radiostereometric analysis

Vitamin E incorporation into highly cross-linked polyethylene (HXLPE) has been introduced to improve wear resistance, and vitamin E incorporated HXLPE (VEPE) has been used in total hip arthroplasty.

The aim of this meta-analysis was to investigate the wear properties of VEPE in clinical practice by synthesizing the data provided in randomized clinical trials.

The effects on implant stability, functional outcomes and revision rate of VEPE were also compared with those of HXPLE or ultra-high molecular weight polyethylene (UHMWPE).

Literature searches were conducted on 1 January 2020 using MEDLINE, EMBASE, Cochrane and ClinicalTrials.gov databases. Randomized controlled trials (RCTs) comparing the aforementioned parameters between VEPE and standard HXPLE/UHMWPE liners were included.

Methodological quality and the bias of the included studies were analysed. Meta-analyses were performed using the Review Manager software.

Nine RCTs met the eligibility criteria and were included. At early and mid-term follow-up, the vertical penetration and the total penetration of the femoral head were both significantly reduced in the VEPE group. The steady state wear rate of the VEPE group was also remarkably lower.

However, at two-year follow-up, significantly increased cup migration was observed in the VEPE group. Moreover, the mid-term clinical outcomes of the VEPE group were worse, while the total revision rates between the two groups were not significantly different.

The limited number of included studies may compromise our conclusion regarding clinical outcomes of the VEPE bearing surface. More RCTs with longer follow-up periods are needed to further investigate the effects of VEPE in total hip arthroplasty.

Cite this article: EFORT Open Rev 2021;6:759-770. DOI: 10.1302/2058-5241.6.200072

Femoral head penetration in Vitamin-E polyethylene liner versus conventional liners in total hip arthroplasty: systematic review and meta-analysis of randomised control trials

BACKGROUND

Debate encompasses the use of Vitamin E Polyethylene or conventional Polyethylene liner in primary hip arthroplasty. Does the Inclusion of Vitamin E in PE give adequate protection from oxidation and maintains lower rates of wear?

PATIENTS AND METHODS

We performed this study following the Preferred Reporting Items for Systematic Reviews and Meta-analyses Statement (PRISMA) and the Cochrane Handbook for systematic reviews and meta-analysis. Studies were included from any region, written in any language. We had only the randomised control trials comparing the femoral head penetration between Vitamin-E diffused highly cross-linked polyethylene (VEPE) liner and conventional liners in primary total hip arthroplasty.

RESULTS

We included 10 studies in this meta-analysis. We conducted them using Review Manager V.5.0. We computed the risk ratio to measure the treatment effect, considering the heterogeneity. We used Random-effect models. VEPE had insignificant marginal advantages for FHP within three months post-operative. Additionally, VEPE showed significantly less FHP after two and five years. After one year, it showed significantly less FHP with the VEPE group versus the UHMWPE cohort and a non-significant difference between the VEPE and XLPE group.

CONCLUSIONS

In terms of FHP, this metanalysis shows less FHP for the VEPE than conventional PE. A longer follow-up period is required to evaluate whether the oxidation protection gained by Vitamin E results in lower wear rates, less osteolysis, and aseptic loosening compared to the conventional PE in the long term.

Does the use of the largest possible metal head increase the wear of vitamin E-doped cross-linked polyethylene? Two-year results from a randomized controlled trial

AIMS

We aimed to investigate if the use of the largest possible cobalt-chromium head articulating with polyethylene acetabular inserts would increase the in vivo wear rate in total hip arthroplasty.

METHODS

In a single-blinded randomized controlled trial, 96 patients (43 females), at a median age of 63 years (interquartile range (IQR) 57 to 69), were allocated to receive either the largest possible modular femoral head (36 mm to 44 mm) in the thinnest possible insert or a standard 32 mm head. All patients received a vitamin E-doped cross-linked polyethylene insert and a cobalt-chromium head. The primary outcome was proximal head penetration measured with radiostereometric analysis (RSA) at two years. Secondary outcomes were volumetric wear, periacetabular radiolucencies, and patient-reported outcomes.

RESULTS

At two years, 44 patients in each group were available for RSA assessment. The median total two-year proximal head penetration was -0.02 mm (IQR -0.09 to 0.07; p = 0.548) for the largest possible head and -0.01 mm (IQR -0.07 to 0.10; p = 0.525) for 32 mm heads. Their difference was not statistically significant (p = 0.323). Neither group demonstrated a bedding-in period. The median steady-state volumetric wear rates were 6.1 mm³/year (IQR -59 to 57) and 3.5 mm³/year (-21 to 34) respectively, and did not differ between the groups (p = 0.848). There were no statistically significant differences in periacetabular radiolucencies or patient-reported outcomes.

CONCLUSION

The use of the largest possible metal head did not increase vitamin E-doped cross-linked polyethylene wear compared with 32 mm heads at two years. Linear wear was negligible and volumetric wear rates were very low in both head size groups. There was a tendency towards higher values of volumetric wear in large heads that warrants longer-term evaluation before any definite conclusions about the association between head size and wear can be drawn. Cite this article: Bone Joint J 2021;103-B(7):1206-1214.

Implant survival of 2,723 vitamin E-infused highly crosslinked polyethylene liners in total hip arthroplasty: data from the Finnish Arthroplasty Register

Background and purpose - The use of crosslinked polyethylene in total hip arthroplasty (THA) has decreased wear remarkably. It has been suggested that the antioxidative effects of vitamin E may enhance the wear properties of polyethylene even further. This study evaluates revision rates between vitamin E-infused polyethylene liners (E1 and E-poly, ZimmerBiomet, Warsaw, IN, USA) versus moderately crosslinked polyethylene (ModXLPE) liners from the same manufacturer used in primary THA.Patients and methods - We conducted a study based on data from the Finnish Arthroplasty Register. The study group consisted of 2,723 THAs with a vitamin E-infused liner and a reference group of 2,707 THAs with a moderately crosslinked polyethylene liner. Survivorship, revision risk, and re-revision causes were compared between groups.Results - The 7-year survival of the vitamin E-infused polyethylene liner group and of the reference group with revision for any reason as the endpoint was comparable (94% [95% CI 92.9-94.9] and 93% [CI 91.9-93.9], respectively). The adjusted hazard ratio (HR) for any revision was similar between the groups (0.7 [CI 0.4-1.1]). When revision for aseptic loosening was studied as the endpoint, the survival for the study group was 99% (CI 98.6-99.4) and for the reference group 99% (CI 98.7-99.5), and the risk of revision was comparable between the study groups (HR 1.3 [CI 0.7-2.5]).Interpretation - After an observation period of 7 years vitamin E-infused liners shows results equal to results obtained with crosslinked polyethylene liners.

Reduced wear in vitamin E-infused highly cross-linked polyethylene cups: 5-year results of a randomized controlled trial

Background and purpose - Vitamin E-infused polyethylene is a relatively new material in joint arthroplasty; there are no long-term reports, and only few mid-term results. Using radiostereometric analysis (RSA), we primarily determined whether vitamin E-infused highly cross-linked polyethylene (HXLPE/VitE) acetabular cups show less wear than ultra-high molecular weight polyethylene (UHMWPE) acetabular cups at 5 years after total hip arthroplasty (THA). We also assessed whether wear rates correlate with increasing cup inclination angles or cup sizes.Patients and methods - This is a 5-year follow-up of our previously reported randomized controlled trial of 62 patients with 3 years' follow-up, who received THA with either an HXLPE/VitE or a UHMWPE acetabular cup. At 5 years, 40 patients were analyzed (22 in the HXLPE/VitE and 18 in the UHMWPE group).Results - HXLPE/VitE cups continued to show less cumulative femoral head penetration than UHMWPE cups (HXLPE/VitE: 0.24 mm, UHMWPE: 0.45 mm; p < 0.001). Distribution of wear was also more even with HXLPE/VitE cups than with UHMWPE cups (p = 0.002). Moreover, the difference in PE wear between 1 and 5 years in both groups showed no statistically significant correlation with increasing cup inclination angles or cup sizes. Finally, no osteolysis and implant loosening occurred, and no revision surgeries were required.Interpretation - Wear rates continue to be lower in HXLPE/VitE cups than in UHMWPE cups at 5 years of follow-up without correlation with increasing cup inclination angles or cup sizes. Finally, HXLPE/VitE cups may have the potential to prevent osteolysis and implant loosening.

Vitamin E-blended versus conventional polyethylene liners in prostheses : Prospective, randomized trial with 3-year follow-up

BACKGROUND

Despite continuous technical improvements, polyethylene wear debris induced periprosthetic osteolysis remains the main cause for failure of hip arthroplasty. Progressive oxidation of polyethylene was identified as another risk factor for material failure. To overcome this problem, antioxidants such as vitamin E (alpha-tocopherol) were supplemented by diffusion into the latest generation of polyethylene liners.

OBJECTIVE

The purpose of the present study was to investigate the clinical outcome of patients treated with vitamin E blended highly cross-linked ultra-high molecular weight polyethylene liners (UHMWPE-XE) in comparison with conventional UHMWPE‑X liners by evaluating patient-reported outcome measures (PROM's) at 3‑year follow-up.

METHODS

A total of 143 patients were recruited into this prospective, randomized trial in our academic center. Three years after implantation, 101 patients were examined in the outpatient clinic for follow-up. Of these, 51 (50.5%) received UHMWPE-XE and 50 (49.5%) UHMWPE‑X liners. Clinical outcome was evaluated using Harris-Hip-Score (HHS) UCLA-Score and Hip Disability and Osteoarthritis Outcome Score (HOOS).

RESULTS

There was a significant improvement in all PROM's at one- and three-year follow-up compared to the status before implantation. PROM's did not differ significantly between the first and third year follow-up. Both liner groups showed an equal clinical outcome.

CONCLUSION

The present study demonstrates that the supplementation of vitamin E to polyethylene liners is reliable and safe without showing higher complication rates compared with conventional polyethylene liners. The shortterm clinical outcome of vitamin E-blended (UHMWPE‑XE) is equivalent to those of conventional highly cross-linked polyethylene liners.

Identification of Key Candidate Genes Related to Inflammatory Osteolysis Associated with Vitamin E-Blended UHMWPE Debris of Orthopedic Implants by Integrated Bioinformatics Analysis and Experimental Confirmation

PURPOSE

This study aims to identify differentially expressed genes (DEGs) in macrophages exposed to ultra-high-molecular-weight polyethylene (UHMWPE) or vitamin E-blended UHMWPE (VE-UHMWPE) particles, thereby providing potential targets for the treatment of inflammatory osteolysis.

METHODS

The GSE104589 dataset of genome expression in macrophages exposed to UHMWPE and VE-UHMWPE was downloaded from the Gene Expression Omnibus database to identify DEGs. Functional enrichment analysis was performed using DAVID, and the corresponding protein-protein interaction (PPI) network was constructed from the STRING database. Important modules were selected using the molecular complex detection algorithm, and hub genes were identified in cytoHubba. MicroRNAs targeting these DEGs were obtained from the TarBase, miRTarBase, and miRecords databases, while transcription factors (TFs) targeting DEGs were predicted from the ENCODE database. Finally, the top five DEGs were validated by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

A total of 112 DEGs (44 upregulated and 68 downregulated DEGs) were screened. Immune and inflammatory responses were significantly related in gene ontology analysis, and 18 signaling pathways were enriched according to Kyoto Encyclopedia of Genes and Genomes pathway analysis. The PPI network involving 85 nodes and 266 protein pairs indicated that IL1β, CXCL1, ICAM1, CCL5 and CCL4 showed higher degrees. qRT-PCR analysis of the top five DEGs revealed a decreasing trend in the VE-UHMWPE group compared with the UHMWPE group. Key microRNAs (hsa-miR-144, hsa-miR-21, and hsa-miR-221) and TFs (RELA and NFKB1) were predicted to be correlated with the pathogenesis of inflammatory osteolysis through microRNA-TF regulatory network analysis.

CONCLUSION

The present study helps shed light on the molecular mechanisms underlying the changes in the wear-induced inflammatory process after blending vitamin E with UHMWPE. Hub genes including IL1β, CXCL1, ICAM1, CCL5, and CCL4, key microRNAs (hsa-miR-144, hsa-miR-21, and hsa-miR-221) and TFs (RELA and NFKB1) may serve as prognostic and therapeutic targets of inflammatory osteolysis.

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.

A vitamin E blended highly cross-linked polyethylene acetabular cup results in less wear: 6-year results of a randomized controlled trial in 199 patients

Background and purpose - Survivorship of total hip arthroplasty (THA) with the ultra-high molecular weight polyethylene (UHMWPE) monoblock cup has been limited due to periprosthetic osteolysis and aseptic loosening, secondary to wear of the UHMWPE. In response, a vitamin E blended highly cross-linked polyethylene (HXLPE) cup was developed. This study set out to compare the wear and clinical 6-year outcomes of vitamin E blended HXLPE with UHMWPE in an isoelastic monoblock cup in patients with hip osteoarthritis who underwent uncemented THA. The 2-year results have been reported previously. Patients and methods - For this randomized controlled trial 199 patients were included. 102 patients received the vitamin E blended HXLPE uncemented acetabular cup and 97 patients the uncemented UHMWPE monoblock cup. Clinical and radiographic parameters were obtained preoperatively, directly postoperatively, and at 3, 12, 24, and 72 months. Wear rates were compared using the femoral head penetration (FHP) rate. Results - 173 patients (87%) completed the 6-year follow-up. The mean NRS scores for rest pain, load pain, and patient satisfaction were 0.3 (SD 1), 0.6 (SD 1), and 8.6 (SD 1) respectively. The mean Harris Hip Score was 93 (SD 12). The FHP rate was lower in the vitamin E blended HXLPE cup (0.028 mm/year) compared with the UHMWPE cup (0.035 mm/year) (p = 0.002). No adverse reactions associated with the clinical application of vitamin E blended HXLPE were observed. 15 complications occurred, equally distributed between the two cups. The 6-year survival to revision rate was 98% for both cups. There was no aseptic loosening. Interpretation - This study shows the superior performance of the HXLPE blended with vitamin E acetabular cup with clinical and radiographic results similar to the UHMWPE acetabular cup.

Vitamin E-doped total hip arthroplasty liners show similar head penetration to highly cross-linked polyethylene at five years: a multi-arm randomized controlled trial

Aims

The most frequent indication for revision surgery in total hip arthroplasty (THA) is aseptic loosening. Aseptic loosening is associated with polyethylene liner wear, and wear may be reduced by using vitamin E-doped liners. The primary objective of this study was to compare proximal femoral head penetration into the liner between a) two cross-linked polyethylene (XLPE) liners (vitamin E-doped (vE-PE)) versus standard XLPE liners, and b) two modular femoral head diameters (32 mm and 36 mm).

Methods

Patients scheduled for a THA were randomized to receive a vE-PE or XLPE liner with a 32 mm or 36 mm metal head (four intervention groups in a 2 × 2 factorial design). Head penetration and acetabular component migration were measured using radiostereometric analysis at baseline, three, 12, 24, and 60 months postoperatively. The Harris Hip Score, University of California, Los Angeles (UCLA) Activity Score, EuroQol five-dimension questionnaire (EQ-5D), and 36-Item Short-Form Health Survey questionnaire (SF-36) were assessed at baseline, three, 12, 36, and 60 months.

Results

Of 220 screened patients, 127 were included in this study. In all, 116 received the allocated intervention, and 94 had their results analyzed at five years. Head penetration was similar between liner materials and head sizes at five years, vE-PE versus XLPE was -0.084 mm (95% confidence interval (CI) -0.173 to 0.005; p = 0.064), and 32 mm versus 36 mm was -0.020 mm (95% CI -0.110 to 0.071; p = 0.671), respectively. No differences were found in acetabular component migration or in the patient-reported outcome measures.

Conclusion

No significant difference in head penetration was found at five years between vE-PE and XLPE liners, nor between 32 mm and 36 mm heads.

Cite this article: Bone Joint J 2020;102-B(10):1303–1310.

Does vitamin E highly-crosslinked polyethylene convey an advantage in primary total hip replacement? A systematic review and meta-analysis

BACKGROUND

Vitamin E highly cross-linked polyethylene (HXLPE) was developed to reduce wear in total hip replacement (THR). This formal systematic review and meta-analysis aimed to provide independent synthesis of wear characteristics of Vitamin E treated HXLPE compared to HXPLE/UHMWPE. Secondary outcome measures were differences in revision rates and functional scores.

METHODS

We performed a formal systematic review as per PRISMA guidelines; literature searches were conducted on 14 November 2017 (MEDLINE, Embase on Ovid, and the Cochrane Library). We included randomised controlled trials, analyses of joint registries, and case-controlled studies of primary THR comparing cups with a vitamin E HXLPE bearing with bearing surfaces made from other types of polyethylene. Initial screening was performed by 2 independent assessors; disagreement resolved in discussion with a third reviewer. Studies were evaluated using the Cochrane risk of bias tool. Data extraction permitted meta-analysis.

RESULTS

372 studies were identified on initial screening, 5 studies met the eligibility criteria. There was no significant heterogeneity between studies. There was variable risk of bias. At a mean of 35 (range 20-60) months, Vitamin E HXLPE had significant advantages over highly cross-linked polyethylene with regards total femoral head penetration (p = 0.004). Given the RSA measurement errors this may not be clinically significant.There were neither significant differences in revision rates nor Harris Hip Scores (p = 0.06).

CONCLUSION

At a minimum of 3 years follow-up there was reduced total femoral head penetration for vitamin E HXLPE over HXLPE. This bearing surface does not, as yet, have clinically significant advantages in terms of revision rates or patient function over HXLPE.

2-year results of an RCT of 2 uncemented isoelastic monoblock acetabular components: lower wear rate with vitamin E blended highly cross-linked polyethylene compared to ultra-high molecular weight polyethylene

Background and purpose - The long-term survival of arthroplasty components may be limited by polyethylene wear-related problems such as periprosthetic osteolysis and aseptic loosening. Highly cross-linked polyethylene (HXLPE) blended with vitamin E was introduced to improve oxidative stability and to avoid long-term embrittlement. This study clinically compares the tribological behavior and clinical outcome of vitamin E blended HXLPE with ultra-high molecular weight polyethylene (UHMWPE) in an isoelastic monoblock cup for uncemented total hip arthroplasty.Patients and methods - In this randomized controlled trial (RCT), 199 patients were included: 102 patients received the vitamin E blended HXLPE cup, 97 patients the UHMWPE cup. Clinical and radiographic parameters were obtained preoperatively, directly postoperative and at 3, 12, and 24 months. Wear rates were compared using the mean linear femoral head penetration (FHP) rate.Results - 188 patients (94%) completed the 2-year follow-up. Mean patient satisfaction was higher in the vitamin E blended HXLPE group (8.9 [1]) than in in the control group (8.5 [2], p = 0.03). The Harris Hip Score (HHS) was higher in the vitamin E blended HXLPE group (95 [8]) than in the control group (92 [11], p = 0.3). The FHP rate was lower in the vitamin E blended HXLPE group: 0.046 mm/year compared with 0.056 mm/year in the control group (p = 0.05). No adverse reactions associated with the clinical application of vitamin E blended HXLPE were observed during follow-up, with an excellent 2-year survival to revision rate of 98% for both cups.Interpretation - This study shows the superior performance of the HXLPE blended with vitamin E acetabular cup with lower linear femoral head penetration rates and better clinical results compared with the UHMWPE acetabular cup after 2 years.

The Survivorship of the Uncemented Iso-Elastic Monoblock Acetabular Component at a Mean of 6-Year Follow-up

BACKGROUND

Aseptic loosening, caused by wear and osteolysis, is the most frequent reason for hip replacement revision in the UK. To prevent aseptic loosening, an acetabular component with vitamin E added to irradiated highly cross-linked polyethylene (HXLPE) was developed to reduce oxidative degradation.

QUESTIONS/PURPOSES

A prior study of the vitamin E-blended HXLPE acetabular component after 2 years of follow-up reported no adverse reactions or abnormal mechanical behavior. To further examine this hypothesis of reducing wear and osteolysis, we sought to evaluate outcomes after 6-year follow-up.

METHODS

A cohort of 95 of the 112 initial patients (84.2%) completed the 6 years of follow-up after receiving a vitamin E-blended HXLPE acetabular component. Evaluation was performed in terms of clinical (visual analog scale [VAS] score, VAS score with weight-bearing, VAS score for satisfaction, and Harris Hip Score) and radiological (inclination, polar gap, radiolucencies, migration, and 2-D linear femoral head penetration rate) assessment.

RESULTS

The mean VAS score for patient satisfaction was 8.75 and the mean Harris Hip Score was 91.8. There were two revisions because of deep infections and one because of a peri-prosthetic femoral fracture. Two acetabular components migrated initially; however, delayed acetabular stabilization occurred. Both patients had good clinical scores at 72 months. The mean femoral head penetration rate was 0.036 mm/year.

CONCLUSIONS

This prospective cohort study has shown no adverse reactions concerning the vitamin E additive, promising wear rates, no signs of osteolysis, a 100% survival rate for aseptic loosening, and an all-cause survivorship percentage of 97.4% at 6 years of follow-up.

Reasons for Revision, Oxidation, and Damage Mechanisms of Retrieved Vitamin E-Stabilized Highly Crosslinked Polyethylene in Total Knee Arthroplasty

BACKGROUND

In order to improve oxidation resistance, antioxidants such as vitamin-E are added to polyethylene used in the bearing surfaces of orthopedic components. Currently, little is known about the efficacy of this treatment in vivo. This study therefore reports on the reasons for revision, surface damage mechanisms, and oxidation of retrieved vitamin E-stabilized highly crosslinked polyethylene (HXLPE) for total knee arthroplasty.

METHODS

We examined 103 retrieved knee inserts fabricated from vitamin E (VE)-stabilized HXLPE and 67 fabricated from remelted HXLPE as a control. The implantation times were 1.2 ± 1.3 and 1.5 ± 1.3 years for the VE and control cohorts, respectively. The inserts were evaluated for 7 surface damage mechanisms using a semiquantitative scoring method and analyzed for oxidation using Fourier-transform infrared spectroscopy. Reasons for revision were also assessed using operative notes created at time of retrieval.

RESULTS

Both groups were revised primarily for instability, infection, and loosening. Burnishing, pitting, and scratching were the most common damage mechanisms observed, with the VE cohort demonstrating less surface damage than the control. Measured oxidation for the cohort was low, with a median oxidation index of 0.09 ± .05 for the articulating surface, 0.05 ± 0.06 for the backside, 0.08 ± 0.06 for the anterior/posterior surfaces, and 0.08 ± 0.05 for the stabilizing post. As compared to the control cohort, oxidation tended to be less for the VE group at the articulating (P < .001) and backside (P = .003) surfaces, although the median differences were minimal and may not be clinically significant.

CONCLUSION

The results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.

The current role of robotics in total hip arthroplasty

Robotic total hip arthroplasty (THA) improves accuracy in achieving the planned acetabular cup positioning compared to conventional manual THA.

Robotic THA improves precision and reduces outliers in restoring the planned centre of hip rotation compared to conventional manual THA.

Improved accuracy in restoring hip biomechanics and acetabular cup positioning in robotic THA have not translated to any differences in early functional outcomes, correction of leg-length discrepancy, or postoperative complications compared to conventional manual THA.

Limitations of robotic THA include substantive installation costs, additional radiation exposure, steep learning curves for gaining surgical proficiency, and compatibility of the robotic technology with a limited number of implant designs.

Further higher quality studies are required to compare differences in conventional versus robotic THA in relation to long-term functional outcomes, implant survivorship, time to revision surgery, and cost-effectiveness.

Cite this article: EFORT Open Rev 2019;4:618-625. DOI: 10.1302/2058-5241.4.180088

A randomized double-blind noninferiority trial, evaluating migration of a cemented vitamin E-stabilized highly crosslinked component compared with a standard polyethylene component in reverse hybrid total hip arthroplasty

AIMS

Radiostereometric analysis (RSA) studies of vitamin E-doped, highly crosslinked polyethylene (VEPE) liners show low head penetration rates in cementless acetabular components. There is, however, currently no data on cemented VEPE acetabular components in total hip arthroplasty (THA). The aim of this study was to evaluate the safety of a new cemented VEPE component, compared with a conventional polyethylene (PE) component regarding migration, head penetration, and clinical results.

PATIENTS AND METHODS

We enrolled 42 patients (21 male, 21 female) with osteoarthritis and a mean age of 67 years (sd 5), in a double-blinded, noninferiority, randomized controlled trial. The subjects were randomized in a 1:1 ratio to receive a reverse hybrid THA with a cemented component of either argon-gas gamma-sterilized PE component (controls) or VEPE, with identical geometry. The primary endpoint was proximal implant migration of the component at two years postoperatively measured with RSA. Secondary endpoints included total migration of the component, penetration of the femoral head into the component, and patient-reported outcome measurements.

RESULTS

In total, 19 control implants and 18 implants in the VEPE group were analyzed for the primary endpoint. We found a continuous proximal migration of the component in the VEPE group that was significantly higher with a difference at two years of a mean 0.21 mm (95% confidence interval (CI) 0.05 to 0.37; p = 0.013). The total migration was also significantly higher in the VEPE group, but femoral head penetration was lower. We found no difference in clinical outcomes between the groups.

CONCLUSION

At two years, this cemented VEPE component, although having a low head penetration and excellent clinical results, failed to meet noninferiority compared with the conventional implant by a proximal migration above the proposed safety threshold of RSA. The early proximal migration pattern of the VEPE component is a reason for continued monitoring, although a specific threshold for proximal migration and risk for later failure cannot be defined and needs further study. Cite this article: Bone Joint J 2019;101-B:1192-1198.

[Total hip arthroplasty in young patients : Bearings and custom-made prostheses]

BACKGROUND

Carefully and correctly implanted components are the prerequisite for the lifespan of a prosthesis. Whether higher levels of activity lead to prior failure of total hip arthroplasty in young patients is controversially discussed. The right choice of bearings is still of great relevance.

BEARINGS

Ceramic-on-ceramic as well as polyethylene-on-ceramic bearings achieve comparable results, although ceramic-on-ceramic bearings should be avoided in patients with high demands on their range of motion. Polyethylene-on-metal bearings also show good clinical results, if corrosion between head and stem is absent. Metal-on-metal bearings lead to adverse systemic effects due to metal wear and should be implanted in individual cases only, e. g. as hip resurfacing. Alternative bearings have to give proof of effectivity first. Custom-made prostheses constitute an option for young patients with special conditions of hip anatomy. Planning and study results of these prostheses are elucidated in this review article.

Evaluation of vitamin E-diffused highly crosslinked polyethylene wear and porous titanium-coated shell stability: a seven-year randomized control trial using radiostereometric analysis

AIMS

Vitamin E-diffused, highly crosslinked polyethylene (VEPE) and porous titanium-coated (PTC) shells were introduced in total hip arthroplasty (THA) to reduce the risk of aseptic loosening. The purpose of this study was: 1) to compare the wear properties of VEPE to moderately crosslinked polyethylene; 2) to assess the stability of PTC shells; and 3) to report their clinical outcomes at seven years.

PATIENTS AND METHODS

A total of 89 patients were enrolled into a prospective study. All patients received a PTC shell and were randomized to receive a VEPE liner (n = 44) or a moderately crosslinked polyethylene (ModXLPE) liner (n = 45). Radiostereometric analysis (RSA) was used to measure polyethylene wear and component migration. Differences in wear were assessed while adjusting for body mass index, activity level, acetabular inclination, anteversion, and head size. Plain radiographs were assessed for radiolucency and patient-reported outcome measures (PROMs) were administered at each follow-up.

RESULTS

In total, 73 patients (82%) completed the seven-year visit. Mean seven-year linear proximal penetration was -0.07 mm (sd 0.16) and 0.00 mm (sd 0.22) for the VEPE and ModXLPE cohorts, respectively (p = 0.116). PROMs (p = 0.310 to 0.807) and radiolucency incidence (p = 0.330) were not different between the polyethylene cohorts. The mean proximal shell migration rate was 0.04 mm per year (sd 0.09). At seven years, patients with radiolucency (34%) demonstrated greater migration (mean difference: 0.6 mm (sd 0.2); p < 0.001). PROMs were lower for patients with radiolucency and greater proximal migration (p = 0.009 to p = 0.045). No implants were revised for aseptic loosening.

CONCLUSION

This is the first randomized controlled trial to report seven-year RSA results for VEPE. All wear rates were below the previously reported osteolysis threshold (0.1 mm per year). PTC shells demonstrated acceptable primary stability through seven years, as indicated by low migration and lack of aseptic loosening. However, patients with acetabular radiolucency were associated with higher shell migration and lower PROM scores. Cite this article: Bone Joint J 2019;101-B:760-767.

Evaluation of in vivo wear of vitamin E-diffused highly crosslinked polyethylene at five years

Aims

The primary aim of this study was to compare the wear properties of vitamin E-diffused, highly crosslinked polyethylene (VEPE) and one formulation of moderately crosslinked and mechanically annealed ultra-high molecular weight polyethylene (ModXLPE) in patients five years after primary total hip arthroplasty (THA). The secondary aim was to assess the clinical results of patients treated with VEPE by evaluating patient-reported outcome measures (PROMs), radiological evidence of fixation, and the incidence of mechanical failure.

Patients and Methods

A total of 208 patients (221 THAs) from four international centres were recruited into a prospective study involving radiostereometric analysis (RSA) and the assessment of clinical outcomes. A total of 193 hips (87%) were reviewed at the five-year follow-up. Of these, 136 (70%) received VEPE (vs ModXLPE) liners and 68 (35%) received ceramic (vs metal) femoral heads. PROMs and radiographs were collected preoperatively and at one, two, and five years postoperatively. In addition, RSA images were collected to measure PE wear postoperatively and at one, two, and five years after surgery.

Results

We observed similar bedding in one year postoperatively and wear two years postoperatively between the two types of liner. However, there was significantly more penetration of the femoral head in the ModXLPE cohort compared with the VEPE cohort five years postoperatively (p < 0.001). The only variables independently predictive of increased wear were ModXLPE (vs VEPE) liner type (β = 0.22, p = 0.010) and metal (vs ceramic) femoral head (β = 0.21, p = 0.013). There was no association between increased wear and the development of radiolucency (p = 0.866) or PROMs. No patient had evidence of osteolysis.

Conclusion

Five years postoperatively, patients with VEPE (vs ModXLPE) and ceramic (vs metal) femoral heads had decreased wear. The rates of wear for both liners were very low and have not led to any osteolysis or implant failure due to aseptic loosening.

Effects of vitamin E incorporation in polyethylene on oxidative degradation, wear rates, immune response, and infections in total joint arthroplasty: a review of the current literature

Highly cross-linked ultrahigh molecular weight polyethylene (UHMWPE) was introduced to decrease wear debris and osteolysis. During cross-linking, free radicals are formed, making highly cross-linked polyethylene vulnerable to oxidative degradation. In order to reduce this process, anti-oxidant vitamin E can be incorporated in polyethylene. This review provides an overview of the effects of vitamin E incorporation on major complications in total joint arthroplasty: material failure due to oxidative degradation, wear debris and subsequent periprosthetic osteolysis, and prosthetic joint infections. Secondly, this review summarizes the first clinical results of total hip and knee arthroplasties with vitamin E incorporated highly cross-linked polyethylene. Based on in vitro studies, incorporation of vitamin E in polyethylene provides good oxidative protection and preserves low wear rates. Incorporation of vitamin E may have the beneficial effect of reduced inflammatory response to its wear particles. Some microorganisms showed reduced adherence to vitamin E-incorporated UHMWPE; however, clinical relevance is doubtful. Short-term clinical studies of total hip and knee arthroplasties with vitamin E-incorporated highly cross-linked UHMWPE reported good clinical results and wear rates similar to highly cross-linked UHMWPE without vitamin E.

ARTICULATION AND BACKSIDE WEAR ANALYSIS AFTER LONG-TERM IN VITRO WEAR SIMULATION OF VITAMIN E STABILIZED POLYETHYLENE ACETABULAR LINERS WITH A PRESS-FIT LOCKING MECHANISM

A previous retrieval study analyzed the backside wear of short-term implanted liners against in vitro tested liners of similar life in service and showed comparable results among both groups, with no significant backside wear due to micro-motion.

The purpose — to obtain a picture of the overall wear (articulation and backside surfaces) of 0.1% vitamin e blended polyethylene liners, with a locking mechanism based on a press-fit cone in combination with a rough titanium conical inner surface in the fixation area, under a 20 million cycles hip wear simulation.

Materials and Methods. A semi-quantitative method was used in order to assess the damage on the backside of the liners and a 3d measuring machine to assess the creep and wear at the articulation surface.

Results. The total average backside wear score was 22.00±2.59 from a maximum total score of 147 after 5 million cycles (mc), increased to 31.92±5.57 after 10 mc, but showed no further increment after 15 and 20 mc. The reference liners (subjected only to axial load) showed similar wear scores and modes as the liners under wear simulation (axial load and movement). Small scratches produced during insertion and removal were clearly seen at the rim (fixation) area and no considerable abrasion was observed. The machining marks on the convex surface were always visible. Regarding the articulation surface, a steady state wear rate of 7 µm/year was measured.

Conlusion. These results determined that most of the backside wear produced on the liners occurred during their insertion and removal rather than during their life in service. Moreover, the wear at the articulation surface was similar to that seen in vivo at short- and mid-term on highly cross-linked polyethylene liners with and without vitamin e content.

Bearing surfaces in primary total hip arthroplasty

Total hip arthroplasty (THA) is widely considered one of the most successful surgical procedures in orthopaedics. It is associated with high satisfaction rates and significant improvements in quality of life following surgery. On the other hand, the main cause of late revision is osteolysis and wear, often a result of failure of bearing surfaces.Currently, several options are available to the surgeon when choosing the bearing surface in THA (ceramic-on-ceramic (CoC), ceramic-on-polyethylene (CoPE), metal-on-polyethylene (MoPE)), each with advantages and drawbacks.Very few studies have directly compared the various combinations of bearings at long-term follow-up. Randomized controlled trials show similar short- to mid-term survivorship among the best performing bearing surfaces (CoC, CoXLPE and MoXLPE). Selection of the bearing surface is often 'experience-based' rather than 'evidence-based'.The aim of this paper is therefore to evaluate the main advantages and drawbacks of various types of tribology in THA, while providing practical suggestions for the surgeon on the most suitable bearing surface option for each patient. Cite this article: EFORT Open Rev 2018;3 DOI: 10.1302/2058-5241.3.180300.