Polyethylene In Total Knee Arthroplasty Research Articles

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

BackgroundThe 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.MethodsThis 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.DiscussionThe 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 registrationClinicalTrials.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.

Registries Tell Us What We Are Actually Doing: Commentary on an article by Jamil Kendall, MD, et al.: "Revision Risk for Total Knee Arthroplasty Polyethylene Designs in Patients 65 Years of Age or Older. An Analysis from the American Joint Replacement Registry".

Registries Tell Us What We Are Actually Doing: Commentary on an article by Jamil Kendall, MD, et al.: "Revision Risk for Total Knee Arthroplasty Polyethylene Designs in Patients 65 Years of Age or Older. An Analysis from the American Joint Replacement Registry".

Revision Risk for Total Knee Arthroplasty Polyethylene Designs in Patients 65 Years of Age or Older: An Analysis from the American Joint Replacement Registry.

Polyethylene bearing design may influence the risk of revision after total knee arthroplasty (TKA). Previous investigations from outside of the United States have suggested the potential for an increased risk of all-cause revision and revision for infection with the use of posterior-stabilized bearings. We examine the risk of revision based on the polyethylene bearing design selection for primary TKA. An analysis of the American Joint Replacement Registry (AJRR) data from 2012 to 2019 was performed. We identified all primary TKAs over the study period and linked cases to supplemental U.S. Centers for Medicare & Medicaid Services (CMS) data where available. Patient demographic characteristics, polyethylene characteristics, procedure dates, and cause for revision were recorded. Analysis was performed to compare minimally stabilized implants (cruciate-retaining, anterior-stabilized, or pivot bearing designs) with posterior-stabilized implants. Cumulative incidence function (CIF) curves and Cox proportional hazard ratios (HRs) were created for all-cause revision and revision for infection in each group. We identified 305,279 cases with reported minimally stabilized or posterior-stabilized implant characteristics. There were 161,486 cases (52.9%) that utilized posterior-stabilized bearings compared with 143,793 cases (47.1%) with minimally stabilized bearings. For minimally stabilized bearings, 1,693 cases (1.18%) had all-cause revision and 334 cases (0.23%) had revision for infection. For posterior-stabilized bearings, 2,406 cases (1.49%) had all-cause revision and 446 cases (0.28%) had revision for infection. The use of posterior-stabilized bearings had HRs of 1.25 (95% confidence interval [CI], 1.2 to 1.3; p < 0.0001) for all-cause revision and 1.18 (95% CI, 1.0 to 1.4; p = 0.02) for revision for infection. Similar to investigations from international registries, we found an increased risk of all-cause revision and revision for infection when using posterior-stabilized bearings in TKA in the United States. Surgeons should consider this finding when considering bearing selection for primary TKA. Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Vitamin E-enriched polyethylene bearings are not inferior to Arcom bearings in primary total knee arthroplasty at medium-term follow-up.

The release of wear particles can be responsible for periprosthetic osteolysis, which can in turn, lead to aseptic loosening. Vitamin E-infused polyethylene (HXLPE Vit-E) has been shown, in vitro, to be more resistant to wear than conventional polyethylene (UHMWPE) by its crosslinking (HXLPE) and its higher resistance to oxidation. After reading a case report of a fracture of a vitamin E-enriched HXLPE bearing, the aim of this retrospective study was to evaluate fracture risk and clinical inferiority or not of vitamin-E HXLPE compared to conventional polyethylene in total knee arthroplasty (TKA). Three hundred and forty-nine patients (403 TKAs) were contacted, to find out whether they had undergone revision surgery for any reason after a mean (SD) of 7 (1.5) years. Follow-up control radiographs were analyzed for periprosthetic radiolucent lines (RLL) and loosening. Two different Patient Reported Outcome Measurements Scores (PROMS), KOOS and FJS-12, were utilized to assess the daily functionality and identify potential problems. No statistically significant difference in revision rate, occurrence of aseptic loosening or RLL nor outcome as measured with PROMS was observed. No bearing fractures or clinical inferiority was observed for vitamin E-enriched HXLPE at medium-term follow-up (7years) compared to conventional Arcom polyethylene. Level III, therapeutic study.

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

BackgroundIn 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. MethodsWe 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. ResultsBoth 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. ConclusionThe results indicate positive fatigue damage resistance and oxidation resistance for the retrieved VE-stabilized total knee arthroplasty inserts.

Polyethylene in total knee arthroplasty: Where are we now?

Polyethylene (PE) remains the gold standard for the articulating surface in hip and knee arthroplasty. To increase arthroplasty longevity and improve wear resistance, newer versions of PE have been designed with resultantly different wear properties. Highly cross-linked polyethylene (HXLPE) is used in total hip arthroplasty with excellent outcomes; however, its use in total knee arthroplasty (TKA) remains conflicting. This review summarizes biomechanical and wear properties, clinical outcomes, and cost of polyethylene inserts in TKA. Simulation studies have convincingly shown decreased wear and oxidation rates with HXLPE when compared to conventional polyethylene (CPE). Registry results have been conflicting, and short- to midterm clinical studies have not demonstrated a significant difference between HXLPE and CPE. The cost of HXLPE inserts is higher than CPE. Long-term clinical data are lacking and further studies are warranted to evaluate the role of HXLPE in TKA.

Is Cross-Linked Polyethylene an Improvement Over Conventional Ultra-High Molecular Weight Polyethylene in Total Knee Arthroplasty?

BackgroundReducing polyethylene (PE) wear by increasing the cross-linking encouraged surgeons to hope for increased total knee arthroplasty (TKA) survival rates. Different methods of manufacturing cross-linked polyethylene (XLPE) were introduced, following promising in vitro results. Is there a measurable effect of cross-linking on TKA survival? MethodsA registry study was conducted, focusing on fixed tibial inserts in primary TKA. Conventional PE represented 87% of the liners, 10% were cross-linked and 2% were antioxidant PE. Sixty-four percent of the liners were posterior-stabilized (PS). Survival of the different PE groups and survival of the main XLPE available were successively compared. We also looked for differences in the same brand implant groups with regard to PE type, as well as differences between cruciate retaining and PS knees. ResultsNo differences were found when looking at survival for any cause or for aseptic loosening only (P = .96). When comparing the XLPE available, X3 was found to have a better survival than Prolong or Smith & Nephew XLPE (P = .036). When the same implants and X3 or conventional PE were used, no difference could reach a statistical significance. With Zimmer LPS Flex, Prolong XLPE was even associated with a lower survival compared with conventional PE. On Stryker implants, only the Cox regression model allowed highlighting a difference between X3 XLPE and conventional PE, only in PS knees. ConclusionIncreasing the cross-linking seems to only have a low effect, if any, on knee arthroplasty survival. Differences between brands could be found; the manufacturing process could play a role.

Oxidation, Damage Mechanisms, and Reasons for Revision of Sequentially Annealed Highly Crosslinked Polyethylene in Total Knee Arthroplasty

BackgroundSequentially annealed, highly crosslinked polyethylene (HXLPE) has been used clinically in total knee arthroplasty (TKA) for over a decade. However, little is known about the revision reasons; its surface damage mechanisms; or its in vivo oxidative stability relative to conventional polyethylene. We asked whether retrieved HLXPE tibial inserts exhibited: (1) similar revision reasons; (2) improved resistance to surface damage; and (3) improved oxidative stability, when compared with conventional gamma inert sterilized polyethylene inserts. MethodsA total of 456 revised tibial inserts were collected in a multicenter retrieval program between 2000 and 2016. The implantation time for the HXLPE components was 1.8 ± 1.8 years, and for the control inserts it was 3.4 ± 2.7 years. Revision reasons were assessed based on medical records, radiographs, and examinations of the retrieved components. Surface damage was assessed using a semi-quantitative scoring method. Oxidation was measured using Fourier transform infrared spectroscopy. ResultsThe tibial inserts in both cohorts were revised most frequently for loosening, infection, and instability. The most commonly observed surface damage modes were burnishing, pitting, and scratching. Oxidation of the HXLPE inserts was, on average, low and similar to the control inserts at the bearing surface and the stabilizing post. ConclusionsWe observed evidence of in vivo oxidation in both HXLPE and control tibial inserts. We found no association between the levels of oxidation and the clinical performance of the HXLPE tibial components. The findings of this study document the revision reasons, surface damage modes, and oxidative behavior of sequentially annealed HXLPE for TKA.

The use of highly crosslinked polyethylene in total knee arthroplasty.

Advances in polyethylene (PE) in total hip arthroplasty have led to interest and increased use of highly crosslinked PE (HXLPE) in total knee arthroplasty (TKA). Biomechanical data suggest improved wear characteristics for HXLPE inserts over conventional PE in TKA. Short-term results from registry data and few clinical trials are promising. Our aim is to present a review of the history of HXLPEs, the use of HXLPE inserts in TKA, concerns regarding potential mechanical complications, and a thorough review of the available biomechanical and clinical data. Cite this article: Bone Joint J 2017;99-B:996-1002.

Conventional and Highly Crosslinked Polyethylene in Total Knee Arthroplasty—A Design-Independent Wear Investigation

Introduction: Improvement of total knee arthroplasty (TKA) materials is one promising approach for extending the lifetime of endoprostheses. The target of this study was to evaluate the sufficiency of TKA-design-independent rolling–sliding screening tests. Additionally, this study attempted to assess the relevance of the design of TKA systems for wear performance by comparison with a simulator study. Materials and Methods: A TKA-design-independent rolling–sliding testing machine was employed at ISO (the International Organization for Standardization) 14243-near conditions and physiologic level unidirectional rolling–sliding. Contact surfaces were generalized into elementary forms at curvatures of real endoprostheses: CoCr-cylinders on flat UHMWPE (ultra-high-molecular-weight-polyethylene) cuboids. Materials varied in resin and crosslinking. One conventional UHMWPE and three highly crosslinked polyethylenes were charged with an axial load of 2.5 kN for 5 million cycles. Wear was determined gravimetrically and the ranking was compared to a simulator study. Results: No statistically significant differences between either material were found. This was inconsistent with the results of a simulator survey. Conclusions: The results of the study indicate that this type of screening test is not able to correctly rank UHMWPE for use in TKA systems. The use of a UHMWPE plate in the test setup with a rolling–sliding cylinder is capable of producing visible wear marks in the bearing area, but the setup followed by a gravimetric measurement does not show reliable results. As the tested materials did not significantly vary in wear performance, it can be concluded that for differences in TKA wear-production, the design of TKR-systems can matter.

Multicenter Study of Highly Cross-linked vs Conventional Polyethylene in Total Knee Arthroplasty

BackgroundDespite substantial interest and use of highly cross-linked polyethylene (HXLPE) in total knee arthroplasty (TKA), outcomes remain largely unknown. The purpose of this study is to compare HXLPE and conventional polyethylene at 4- to 5-year follow-up. MethodsA prospective multicenter study of 307 posterior-stabilized TKAs (168 conventional and 139 HXLPE) was performed. Short-Form-6D, Short-Form 36, Knee Society Score, Lower Extremity Activity Score, health-related quality of life outcomes, and radiographs were collected preoperatively and at routine postoperative intervals. ResultsTwo hundred twenty-four patients obtained a minimum 4- to 5-year follow-up for analysis. There were no osteolysis or polyethylene failures in either group. Although both conventional and HXLPE poly groups showed significant improvements in all measures from preoperative baselines (P < .05), the XLPE group had slightly greater mean Knee Society Score function (P = .04), Lower Extremity Activity Score (P = .03), and Short-Form 36 Physical Composite Score (P = .03) scores and a greater improvement in Short-Form 6D health-related quality of life of 0.16 points (d = 1.02, 95% CI: 0.01-1.11) at latest follow-up. ConclusionThe study findings support comparative safety and outcomes of HXLPE related to mechanical failure or osteolysis in the midterm. However, longer-term follow-up is warranted to assess whether wear and mechanical properties of HXLPE are maintained in vivo.

Lower prosthesis-specific 10-year revision rate with crosslinked than with non-crosslinked polyethylene in primary total knee arthroplasty

Background and purpose — While highly crosslinked polyethylene has shown reduced in vivo wear and lower rates of revision for total hip arthroplasty, there have been few long-term studies on its use in total knee arthroplasty (TKA). We compared the rate of revision of non-crosslinked polyethylene to that of crosslinked polyethylene in patients who underwent TKA for osteoarthritis.Patients and methods — We examined data from the Australian Orthopaedic Association National Joint Replacement Registry on 302,214 primary TKA procedures with non-crosslinked polyethylene and 83,890 procedures with crosslinked polyethylene, all of which were performed for osteoarthritis. The survivorship of the different polyethylenes was estimated using the Kaplan-Meier method and was compared using proportional hazard models.Results — The 10-year cumulative revision rate for non-crosslinked polyethylene was 5.8% (95% CI: 5.7–6.0) and for crosslinked polyethylene it was 3.5% (95% CI: 3.2–3.8) (> 6.5-year HR = 2.2 (1.5–3.1); p < 0.001). There was no effect of surgical volume or method of prosthesis fixation on outcome. There were 4 different TKA designs that had a minimum of 2,500 procedures in at least 1 of the polyethylene groups and a follow-up of ≥ 5 years. 2 of these, the NexGen and the Natural Knee II, had a lower rate of revision for crosslinked polyethylene. The Scorpio NRG/Series 7000 and the Triathlon Knee did not show a lower rate of revision for crosslinked polyethylene.Interpretation — There is a lower rate of revision for crosslinked polyethylene in TKA, and this appears to be prosthesis-specific and when it occurs is most evident in patients < 65 years of age. The difference in revision rates was mainly due to revisions because of lysis and loosening.

Case report: Total knee arthroplasty polyethylene liner disengagement identified by arthrography

We report a case of total knee arthroplasty polyethylene liner disengagement identified by plain film arthrography and CT arthrography.

Biological activity and migration of wear particles in the knee joint: an in vivo comparison of six different polyethylene materials

Wear of polyethylene causes loosening of joint prostheses because of the particle mediated activity of the host tissue. It was hypothesized that conventional and crosslinked polyethylene particles lead to similar biological effects around the knee joint in vivo as well as to a similar particle distribution in the surrounding tissues. To verify these hypotheses, particle suspensions of six different polyethylene materials were injected into knee joints of Balb/C mice and intravital microscopic, histological and immunohistochemical evaluations were done after 1 week. Whereas the biological effects on the synovial layer and the subchondral bone of femur and tibia were similar for all the polyethylenes, two crosslinked materials showed an elevated cytokine expression in the articular cartilage. Furthermore, the distribution of particles around the joint was dependent on the injected polyethylene material. Those crosslinked particles, which remained mainly in the joint space, showed an increased expression of TNF-alpha in articular cartilage. The data of this study support the use of crosslinked polyethylene in total knee arthroplasty. In contrast, the presence of certain crosslinked wear particles in the joint space can lead to an elevated inflammatory reaction in the remaining cartilage, which challenges the potential use of those crosslinked polyethylenes for unicondylar knee prostheses.

Fracture of the Anterior Locking Flange of a Total Knee Arthroplasty Polyethylene Liner Presenting with Pain following Knee Replacement.

Introduction:Fracture of the modern polyethylene insert of a total knee arthroplasty is rare. We describe the first case of a fractured anterior locking flange of the commonly used Depuy Press-fit Condylar (PFC) Sigma prosthesis.Case Report:The 80 year old Caucasian gentleman presented 8 years following previously uncomplicated and successful primary total knee replacement with pain, swelling and symptoms of instability of the knee. He was able to sublux his knee posteriorly using his hamstrings. Dissociation of the liner was evident on radiographs. He underwent revision of the polyethylene liner. It was evident during the revision that the anterior locking flange of the polyethylene liner had fractured allowing it to dissociate from the tibial tray. At 12 months following this revision he continues to do well and has similar range of movement and function to prior to the episode. This cause of the failure is not clear.Conclusion:Surgeons should be aware of this rare complication when assessing a painful or unstable total knee replacement.

Does Vitamin E–Stabilized Ultrahigh-Molecular-Weight Polyethylene Address Concerns of Cross-Linked Polyethylene in Total Knee Arthroplasty?

Concerns about reduced strength, fatigue resistance, and oxidative stability of highly cross-linked and remelted ultrahigh-molecular-weight polyethylene (UHMWPE) have limited its clinical acceptance for total knee arthroplasty. We hypothesized that a highly cross-linked UHMWPE stabilized with vitamin E would have less oxidation and loss of mechanical properties. We compared the oxidation, in vitro strength, fatigue-crack propagation resistance, and wear of highly cross-linked UHMWPE doped with vitamin E to γ-inert–sterilized direct compression-molded UHMWPE (control). After accelerated aging, the control material showed elevated oxidation, loss of small-punch mechanical properties, and loss of fatigue-crack propagation resistance. In contrast, the vitamin E–stabilized material had minimal changes and exhibited 73% to 86% reduction in wear for both cruciate-retaining and posterior-stabilized total knee arthroplasty designs. Highly cross-linked vitamin E–stabilized UHMWPE performed well in vitro.

The Use of Highly Cross-linked Polyethylene in Total Knee Arthroplasty

Polyethylene wear, with resultant particle-induced osteolysis, is a cause of late failure of total knee arthroplasty. The causes of both wear and osteolysis are multifactorial; still, improvements in the polyethylene liner have been investigated. Available highly cross-linked polyethylene tibial liners and patellar prostheses differ greatly in the amount and method of irradiation, thermal treatments, and sterilization techniques they undergo. Several varieties of highly cross-linked polyethylene reduce the gravimetric and volumetric wear of tibial liners in knee simulator studies. However, reduced fracture toughness and the generation of smaller and possibly more reactive particles also have been reported with some varieties of polyethylene. Clinical studies of the use of highly cross-linked polyethylene in total knee arthroplasty are limited. Two nonrandomized trials of highly cross-linked polyethylene in total knee arthroplasty have reported a nonsignificant decrease in radiolucent lines at 2 and 5 years, respectively. The risks of using highly cross-linked polyethylene include fracture of the liner or of a posterior-stabilized tibial post, liner dislodgement or locking mechanism disruption, and possibly more osteolysis. Highly cross-linked polyethylene tibial liners may be considered for younger, more active patients. However, until additional clinical results are available, a cautious approach is warranted to the widespread use of highly cross-linked polyethylene in total knee arthroplasty.

Retrieval Analysis of Femoral Zirconium Components in Total Knee Arthroplasty: Preliminary Results

Safety of oxidized zirconium (OxZr) in total knee arthroplasty (TKA) has been supported by biomechanical, clinical, and radiologic data. Retrieved OxZr femoral components and corresponding polyethylene (PE) inserts were examined to rule out patterns leading to early failure. Sixteen retrieved TKA with an OxZr femoral component were included. The PE inlays were analyzed applying an established scoring system for wear and surface damage. Femoral components were screened for scratching, pitting, delamination, and striations. The prostheses were in situ for 16.4 ± 11.9 months. The average wear and damage score for the tibial PE inserts was 36.0 ± 12.7. The average score in the visual analysis of the OxZr femoral components was 1.3 ± 1.3. The data presented in this study did not show major wear of the PE in TKA using OxZr components. In this cohort, there were no failures directly related to this implant.

Comparison between highly cross-linked and conventional polyethylene in total knee arthroplasty

The use of highly cross-linked polyethylene in total knee prostheses is still controversial. The aim of the present study was to compare radiographic and clinical results of using conventional and highly cross-linked polyethylene in cruciate retaining total knee prostheses of completely the same design. Two hundred and two consecutive total knee arthroplasties (NexGen CR, Zimmer) were performed using the same procedure. The first consecutive 113 knees had conventional polyethylene insert and following consecutive 89 knees had highly cross-linked polyethylene insert (Prolong, Zimmer). Differences in the age, gender, and diagnosis between two groups were not statistically significant. Preoperative range of motion (ROM) of the knee, and Knee Society Score (KSS) was better in highly cross-linked polyethylene group. Clinical and radiographic results were evaluated at two years after operation. The difference of ROM and KSS between groups was not statistically significant. There was no revision surgery. No knee exhibited osteolysis, aseptic loosening, or polyethylene failure. There was no early catastrophic clinical failure due to use of the new material.

Cross-Linked Polyethylene in Total Knee Arthroplasty: In Opposition

Highly cross-linked polyethylene has been used with success in total hip arthroplasty. The reduction of femoral head penetration has been a uniform finding among researchers at 5 to 7 years of follow-up. However, there have also been newly highlighted modes of failure, as increased brittleness of the material can adversely affect the integrity of the acetabular locking mechanism; and some materials can oxidize in vivo, with additional alterations in mechanical properties and early delamination. The mechanics of articulation in a knee arthroplasty are markedly different and will impose more severe stresses on the polyethylene material than hip arthroplasties. Each change that is made to improve polyethylene wear comes with mechanical trade-offs. It is not clear that the gains in wear that have been shown in hips will translate to knees without adverse ramifications from the altered mechanical properties.