Cross-linked Polyethylene Liners Research Articles

The Lawrence D. Dorr Surgical Techniques & Technologies Award: Using Big Heads and Small Acetabular Components With Highly Cross-Linked Polyethylene in Total Hip Arthroplasty: Is It Safe?

BackgroundContemporary total hip arthroplasty (THA) employs larger femoral heads to optimize hip stability. However, the combination of large femoral heads and comparatively small acetabular components poses a potential risk for implant failure secondary to polyethylene (PE) liner fracture or dissociation. The purpose of this study was to evaluate the incidence of liner fracture or dissociation, implant survivorship, and PE wear rates in primary THAs using large femoral heads and small acetabular components. MethodsBetween 2000 and 2017, we retrospectively identified 882 primary THAs with 36 mm femoral heads and acetabular components ≤52 mm with highly cross-linked polyethylene liners. Mean age was 66 years, 88% were females, and mean body mass index was 30 kg/m2. We evaluated the cumulative incidences of dislocation, any revision, and any reoperation utilizing a competing risk model. Osteolysis and femoral head penetration were assessed with a validated radiographic technique at minimum 10-year follow-up (n = 18). Mean follow-up was 4 years. ResultsThere were no liner fractures or dissociations in the entire cohort. The 10-year cumulative incidences of dislocation, any revision, and any reoperation were 3.2%, 5.6%, and 9.3%, respectively. Mean linear femoral head penetration was 0.042 mm/y and mean volumetric wear rate was 44 mm3/y. No THAs demonstrated evidence of osteolysis or component loosening at long-term follow-up. ConclusionIn a large cohort of primary THAs pairing large femoral heads with small acetabular components, there was no evidence of liner fracture or dissociation. Cumulative incidences of dislocation, any revision, and any reoperation were low at mid-term. Level of EvidenceIV.

Short-term clinical and radiographic outcomes of total hip arthroplasty with PMPC-grafted highly cross-linked polyethylene liners against 32-mm femoral heads

We evaluated the clinical and radiographic outcomes of femoral head penetration and total hip arthroplasties with untreated and poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC)-grafted highly cross-linked polyethylene (HXLPE) acetabular liners against 26-, 28-, and 32-mm cobalt–chromium alloy femoral heads 3 years after the index surgery. Three combinations of the articulating surfaces were evaluated in the present study: untreated or PMPC-grafted HXLPE liner against 26- or 28-mm femoral heads (n = 16, 24) [control (26 or 28 mm) and PMPC (26 or 28 mm)] and PMPC-grafted HXLPE liner against 32-mm femoral heads (n = 64) [PMPC (32 mm)]. The clinical outcomes improved at 3 years postoperatively for the groups. No periprosthetic osteolysis or acetabular component migration was detected, and no revision surgery was performed among the groups. The steady-state wear rate of the PMPC (26 or 28 mm) group (0.021 mm/year) was lower than that of the control (26 or 28 mm) group (− 0.015 mm/year); the steady-state wear was under the clinical threshold. In contrast, the steady-state wear rate of the PMPC (32 mm) group (-0.006 mm/year) showed no significant difference when compared to that of the PMPC (26 or 28 mm) group (p < 0.01). The results obtained in the present study clearly demonstrate that PMPC-grafting onto an HXLPE surface improved the wear resistance of acetabular liners, even when coupled with larger femoral heads. Although further follow-up evaluations are required, PMPC-grafted HXLPE acetabular liners may be a promising approach to extend the longevity of artificial joints.

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.

Satisfactory Outcomes in Patients Operated With Primary Total Hip Arthroplasty for Perthes-like Deformities: Results From a Surgical Technique Utilizing a Conical Stem, an Elevated Hip Center, and No Shortening Femoral Osteotomy.

BackgroundTotal hip arthroplasty (THA) performed on patients with Perthes-like deformities are technically challenging because of the patient’s abnormal hip anatomy. Patients with Perthes-like deformities are at a higher risk of revision, aseptic loosening, nerve injury, and intraoperative fracture after THA, especially if shortening osteotomies are performed. This analysis sought to examine the clinical and radiographic outcomes of a patient cohort with Perthes-like deformities receiving THA with a conical stem, an elevated hip center, and no shortening femoral osteotomy.MethodsTwenty-six patients (27 hips) received THA with MODULUS femoral stems, ceramic or metal femoral heads, and highly cross-linked polyethylene liners between April 2011 and March 2016. All patients were treated at a single center by 4 participating surgeons. Patients completed 2 questionnaires preoperatively and at the final follow-up visit (between 1 and 5 years postoperatively): Harris Hip Score and Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire. Differences in patient-reported outcome measures (PROM) scores were measured by paired t-tests. Preoperative and postoperative anteroposterior radiographs were analyzed to monitor patient outcomes.ResultsSignificant clinical improvements were observed in all individual subcategories of the Harris Hip Score and of the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire; the largest magnitude improvements were observed in the subcategory of pain relief for both questionnaires. No complications, including intraoperative and postoperative femoral fractures, nerve palsy, dislocations, or deep venous thrombosis, were observed.ConclusionThis study found that patients treated with an elevated hip center and low stem-positioning technique using a conical, modular implant system had good clinical outcomes and did not suffer complications at the mean follow-up from surgery of 2.8 years (range: 1-5 years).

Cementation of the highly cross-linked polyethylene liner into a well-fixed acetabular shell to treat patients with recurrent dislocation after total hip arthroplasty.

Cementation of a highly cross-linked polyethylene liner into a well-fixed acetabular shell provided a good durability for liner wear. However, its efficacy in treating recurrent instability due to malposition cup is less reported. The aim of this study is to evaluate the outcome of this surgical technique to treat hip instability. From 2009 to 2019, we have identified 38 patients who had been surgically treated for recurrent instability, including cementation liner (N=20) and revision cup (N=18) procedures. Patients were followed for a mean of 45.66months. We have recorded and analyzed all causes of implant failure including recurrent instability. Clinical outcomes were assessed including complication and Harris Hip Score (HHS) preoperatively and at the latest follow-up. Revision-free survivorship for any cause was 95.0% at 1year, and 84.4% at 5years in cementation liner group and 88.9% at 1year and 5years in revision cup group. Mean Harris hip score improved from 48.3 points preoperatively to 79.5 points at the last follow-up in cementation liner group and mean HHS improved from 43.3 points preoperatively to 77.2 points in revision cup group. There were two implant failures in each group, including one is due to persistent hip instability and the other is due to periprosthetic joint infection in the cementation liner group and two implant failure are due to persistent hip instability in the revision cup group. Functional scores and implant survival were similar in both groups. We demonstrated that orientation correction via the cementation of the polyethylene liner into well-fixed acetabular shell is a promising option to treat and prevent instability. Level of Evidence: Therapeutic Level IV.

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.

AimsThe 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).MethodsPatients 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.ResultsOf 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.ConclusionNo 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.

Three Femoral Stem Designs Without Corrosion: A Review of 2095 Stems.

IntroductionCorrosion at the head–neck interface of modular components in total hip arthroplasty (THA) has been reported as a cause of failure of modern total hip replacement implants. While this method of failure has been well described, it remains poorly understood. The purpose of this study is to review the three most commonly used uncemented femoral stems at our institution over the last fifteen years and to correlate any established risk factors with rates of revision, particularly corrosion.MethodsWe reviewed 2095 patients from March 2000 to September 2015 who underwent total hip arthroplasty with one of three uncemented femoral stem designs. All stems were made of a Ti6Al4V alloy with a 12/14 taper design. We included only those stems coupled with a CoCr head and a highly crosslinked polyethylene liner. We evaluated age, gender, body mass index (BMI), femoral head size, head length, neck angle and offset and correlated these to the incidence of all cause revision, as well as revision excluding infection.ResultsThere were no recognized corrosion-related revisions identified. There was no association between age, BMI, gender, head length, neck angle and offset to all cause revision or revision with infection excluded (p>0.05). Femoral head size less than 32mm was associated with higher all cause revision rates (OR 4.60 (95% CI 1.8, 11.8)) and when excluding infection as a reason for revision (OR 4.94 (95% CI 1.7, 14.41)).ConclusionOver the last fifteen years, we have not identified any cases of corrosion with the three most commonly used femoral stems used at out institution. While we acknowledge that no femoral stem is immune to corrosion, certain femoral stem designs may be uniquely resistant to this mode of failure.Level of EvidenceIII.

Incidence and Characteristics of Osteolysis in HXLPE THA at 16-Year Follow up in Patients 50 Years and Less

IntroductionYoung patients present a challenge for total hip arthroplasty (THA) survivorship. Highly cross-linked polyethylene (HXLPE) liners have decreased the prevalence of osteolysis; however, concerns exist regarding the biologic activity of wear particles. The purpose of this study was to determine the incidence and characteristics of osteolytic lesions in young HXLPE THA patients at an average 16-year follow up and determine the ability to detect osteolysis. MethodsWe performed a retrospective study involving 22 patients (26 THA) under age 50 at primary THA receiving HXLPE liners coupled with cobalt-chrome (CoCr) femoral heads. Computed tomography (CT) scans were reviewed for osteolysis. Chi-squared analysis was used for categorical variables and unpaired Kruskal-Wallis rank-sum test for continuous variables. Logistic regression was used to compare wear rates between those patients with and without osteolysis. ResultsThe mean age at surgery was 38.5 years. The mean time from surgery to CT scan was sixteen years (range 14.25–19.5 years). Nine of the 26 THA showed osteolysis. The mean volume of the lesions was 2.8 cm3. Linear (mean 0.008 mm/y) and volumetric (mean 4.5 mm3/year) wear rates were negligible. One-third of osteolytic lesions were visible on radiographs. Logistic regression failed to demonstrate a correlation between wear rates or UCLA activity score and osteolysis. ConclusionWe observed osteolysis in 35% of HXLPE THA in young patients at mean 16-year follow up despite zero revisions for wear-related problems and clinically insignificant wear rates. Level of EvidenceIV.

Titanium acetabular cementless cups combined with highly crosslinked polyethylene liner have very low rates of aseptic loosening.

There is a clear tendency towards cementless acetabular components in primary total hip arthroplasty. The aim of this study was to assess the long-term clinical and radiological outcome of titanium cementless acetabular cups when combined with a highly crosslinked polyethylene liner. This study is a retrospective follow-up of 67 cups in 64 patients. Clinical outcomes were assessed using the Harris Hip Score. Radiolucent lines, osteolysis and loosening were assessed radiologically. Implant survival was determined using the Kaplan-Meier analysis. The average Harris Hip Score at follow-up was 80.3 ± 14.5. Signs of osteolysis were observed in 7.1% of the radiographs. No aseptic loosening of the cup was reported. Survival of the cup with aseptic loosening as an endpoint was 100%. A comparison with 19 other studies using the same material combination demonstrated very similar results. All manufacturers with available studies have at least one report of 100% survivorship at 10-year follow-up for their titanium cup and highly crosslinked polyethylene acetabular component combination with aseptic loosening as an endpoint. The data suggests that the rate of aseptic loosening of a titanium cup combined with a highly-crosslinked polyethylene liner at 10-year follow-up could be as low as 0%.

Intermediate to Long-Term Follow-up of Cementing Liners into Well-Fixed Acetabular Components.

The cementation of a new liner into a well-fixed acetabular component is common during revision total hip arthroplasty (THA) for many indications, but most commonly for lack of a modern, compatible, highly cross-linked polyethylene (HXLPE) liner. However, little is known about the intermediate-term to long-term durability of this strategy. The purpose of this study was to evaluate the implant survivorship, risk of complications, clinical outcomes, and radiographic results of cementing a new HXLPE liner into a well-fixed acetabular component. We retrospectively identified 323 revision THAs in which a nonconstrained HXLPE liner was cemented into a well-fixed acetabular component. The mean age at the time of the revision THA was 63 years, and 50% of patients were female. The most common indications for revision THA were polyethylene wear and osteolysis (48%), aseptic femoral loosening (35%), and hip instability (8%). The mean follow-up was 9 years. Polyethylene liner failure occurred in 11 cases (3%). In all cases, the cemented liner dissociated from the acetabular component. At 10 years, the survivorship free from any revision was 80% (95% confidence interval [CI], 75% to 84%) and the survivorship free from any reoperation was 77% (95% CI, 72% to 82%). The most common reason for re-revision was dislocation (45% of reoperations). A dislocation occurred in 17% of cases. Hips that underwent revision for instability were significantly more likely to dislocate compared with hips that underwent revision for liner wear (hazard ratio [HR], 2.3 [95% CI, 1.2 to 4.5]; p = 0.02). Elevated rim or face-changing liners were significantly more likely to dissociate than flat liners (HR, 9.0 [95% CI, 1.2 to 70.6]; p = 0.04). Cementation of a nonconstrained HXLPE liner into a well-fixed acetabular component during revision THA provided durable fixation with only a small number of failures at the cement interface (3%). Instability after this procedure remains a concern, but this is multifactorial in nature. These data support the continued use of this technique, when necessary, during revision THA. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Third-Generation Medium Cross-Linked Polyethylene Demonstrates Very Low Wear in Total Hip Arthroplasty.

BackgroundCross-linked polyethylene (XLPE) liners have shown lower wear rates than conventional polyethylene liners in total hip arthroplasty. The primary aim of our study was to report our most recent analysis of wear rates and clinical outcomes of a third-generation XLPE liner. Secondary aims were to investigate the rate of adverse events related to mechanical failure or oxidation of this liner.MethodsA series of 266 total hip arthroplasties using a specific XLPE liner were retrospectively reviewed. Radiographs were examined to determine linear and volumetric wear rates and presence of osteolysis. Clinical outcomes, revision rates, mechanical failures, and risk factors for accelerated polyethylene wear were additionally investigated.ResultsThe mean age at the time of surgery was 65.8 years and the mean follow-up was 5.5 years. The mean linear wear rate was 0.003 mm/year and the mean volumetric wear rate was 0.42 mm3/year, and there was no evidence of osteolysis. Harris hip scores increased from 50.9 preoperatively to 96.0 at the latest follow-up. The revision rate was 0.4%, with no liner rim fractures and no liner dissociations/loosenings. Femoral head material, head size, age, body mass index, and time since implantation had no effect on wear rates.ConclusionWear rates for this third-generation XLPE liner were low at mid-term follow-up, and no adverse sequelae of oxidation or deleterious mechanical properties were observed. This remained true regardless of femoral head size and material or patient age and body mass index. Further analysis will be necessary to ensure continued wear resistance, oxidative stability, and mechanical strength at long-term follow-up.

Total hip arthroplasty in patients with fibrous dysplasia: a modern update.

Fibrous dysplasia (FD) results from an abnormality in lamellar bone formation and most frequently involves the proximal femur. This can lead to the development of osteoarthritis requiring total hip arthroplasty (THA). Such cases are challenging, and there is a lack of information guiding best management. As such, we devised a study assessing the outcomes and complications in patients with FD undergoing THA with modern implant technology, and we outlined our preferred surgical technique. A search of our institutional arthroplasty database was performed to identify patients who underwent THA for FD between January 2001 and July 2018 at Mount Sinai Hospital in Toronto, Canada. Data regarding implants used and the use of allograft material or metal augments or both were obtained. Complications and revision requirements were noted. Radiographic and clinical leg length discrepancies were assessed. A total of 10 hips in 9 patients who underwent THA for FD were identified. Mean follow-up time was 6.0 years (range 0.5 to 10.3 yr). The majority of patients underwent THA using uncemented femoral and acetabular components with large femoral heads on highly cross-linked polyethylene liners. Most cases (80% of hips) required allograft to the proximal femur. A single complication requiring revision was noted. In 90% of hip surgeries, the patient required transfusion of packed red blood cells. Mean radiographic and clinical leg length discrepancies were 0.9 cm (range -2.4 to 2.4 cm) and 0.9 cm (range -4 to 0 cm), respectively. Contrary to previous reports, low complication and revision rates were observed with cementless components and routine use of allograft material. The challenging nature of such cases warrants use of an experienced arthroplasty treatment team.

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

BackgroundIt is proposed that highly porous coatings on acetabular components, such as a porous tantalum coating, provide adequate fixation without ancillary screw fixation in primary total hip arthroplasty (THA). However, tantalum acetabular components have been associated with higher rates of revision than other uncemented components in national registries. The aim of this randomized controlled trial is to determine whether the early migration of a solid-backed tantalum acetabular component was no greater than that of a titanium acetabular component with ancillary screw fixation that has proven good clinical results. MethodsSixty-six patients aged 40 to 64 years, with osteoarthritis and Charnley grade A or B activity grade and who underwent primary THA, were recruited into the trial. Patients were randomized intraoperatively to receive either the tantalum or titanium acetabular component. All patients received the same cemented polished tapered femoral stem, 28-mm cobalt-chromium femoral head, and highly cross-linked polyethylene liner. Acetabular component migration was measured using radiostereometric analysis at 4-6 days postoperatively and at 6 weeks, 3 months, 1 and 2 years following THA. ResultsThe mean proximal migration at 2 years for the tantalum cohort was 0.17 mm (95% confidence interval, 0.09-0.24) which was no greater than that of the titanium cohort which was 0.19 mm (0.07-0.32). Harris hip scores and functional activity scores were similar between groups. ConclusionThese results demonstrate that early stability can be achieved without ancillary screw fixation through the use of a highly porous high friction coating on a solid-backed modular acetabular component. Level of EvidenceLevel I.

Highly Cross-Linked Polyethylene in Cementless Total Hip Arthroplasty in Patients with Previous Acetabular Fractures: A Minimum 5-Year Follow-Up Study.

Outcomes of THA after acetabular fracture are generally less favorable than those of the nontraumatic arthritis due to a higher rate of cup loosening and osteolysis. We, therefore, investigated whether highly cross-linked polyethylene liners positively impact outcomes of THA in patients with posttraumatic osteoarthritis after acetabular fracture. We retrospectively evaluated 39 patients with previous acetabular fracture who underwent THA using highly cross-linked polyethylene liner after a mean 8.5year follow-up. All procedures were performed at a single institution by a single surgeon using the same type of THA implants. Wear measurements were performed using a computer-assisted PolyWare software. Osteolysis was evaluated with use of radiography and computed tomography. The mean preoperative Harris hip score was 44.4 points, which improved to 93.1 points at final follow-up. Neither femoral nor acetabular components displayed mechanical loosening and no components had been revised. Radiographs and CT scans did not demonstrate osteolysis. The mean linear wear was 0.043mm/y (range 0-0.098mm/y). With the data available, univariate regression analysis suggests that age, gender, weight, initial fracture type, the duration of follow-up, activity level, liner thickness, acetabular cup inclination, and the necessity of bone graft had no influence on liner penetration. While the long-term effects of the polyethylene particles from highly cross-linked polyethylene remain unknown, implant survivorship and wear data in this study are promising for this high-risk population. Our encouraging results support the continued use of this type of polyethylene in patients after acetabular fractures. Level IV Therapeutic study.

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.

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. 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 5years postoperatively. The radiographs were analyzed using the observer-independent analysis software RayMatch® (Raylytic GmbH, Leipzig, Germany). The mean wear rate was measured to be 23.6μm/year (SD 13.7; range 0.7-71.8μm). There were no significant differences between the two cohorts (UHMWPE-X: 23.2μm/year vs. UHMWPE-XE: 24.0μm/year, p = 0.73). Cup anteversion significantly changed within the 1styear 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)]. 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 Comparison of Risk of Dislocation and Cause-Specific Revision Between Direct Anterior and Posterior Approach Following Elective Cementless Total Hip Arthroplasty

BackgroundUse of the direct anterior approach (DAA) for total hip arthroplasty (THA) has increased over the last decade. We sought to investigate whether (1) a difference exists in dislocation risk for DAA compared with posterior THA, (2) a difference exists in risk for specific revision reasons, and (3) the likelihood of adverse 90-day postoperative events differs. MethodsWe conducted a cohort study using data from Kaiser Permanente’s Total Joint Replacement Registry. Patients aged ≥18 years who underwent primary cementless THA for osteoarthritis with a highly cross-linked polyethylene liner were included (2009-2017). Multivariable Cox proportional hazards regression was used to evaluate dislocation and cause-specific revision risks, and multivariable logistic regression was used to evaluate 90-day emergency department visits, 90-day unplanned readmissions, and 90-day complications (including deep infection, deep vein thrombosis, and pulmonary embolism). ResultsOf 38,399 primary THA, 6428 (16.7%) were DAA. All-cause revision at 2-years follow-up was 1.78% (95% confidence interval [CI] = 1.46-2.17) for DAA and 2.28% (95% CI = 2.11-2.45) for posterior. After adjusting for covariates, DAA had a lower risk of dislocation (hazard ratio [HR] = 0.39, 95% CI = 0.29-0.53), revision for instability (HR = 0.33, 95% CI = 0.18-0.58), revision for periprosthetic fracture (HR = 0.57, 95% CI = 0.34-0.96), and readmission (odds ratio = 0.82, 95% CI = 0.67-0.99) compared with posterior approach but a higher risk of revision for aseptic loosening (HR = 2.26, 95% CI = 1.35-3.79). ConclusionWhile the DAA associated with lower risks of dislocation and revision for instability and periprosthetic fracture, it is associated with a higher revision risk for aseptic loosening. Surgeons should discuss these risks with their patients.

Effect of inward-outward rotation on hip wear simulation

The ISO 14242-1 standard specifies a three-axis motion for the wear testing of prosthetic hips. Multidirectionality of the relative motion and serum-based lubrication are known to be necessary for the reproduction of clinical wear mechanisms. For multidirectionality however, biaxial motion has been shown to be sufficient. To a biaxial hip joint simulator that incorporated flexion-extension (FE, range 46°) and abduction-adduction (AA, range 12°), a third motion component, inward-outward rotation (IOR, range 12°) was added according to the ISO 14242-1 standard. Due to the addition of the IOR, the wear rate of vitamin E stabilized, extensively cross-linked polyethylene (VEXLPE) liners decreased by 50 per cent. This was probably attributable to the increased linearity of the relative motion in the stance phase, caused by the simplified motion waveforms and their relative phases specified in the standard. In order not to underestimate the wear rate, the established biaxial motion is preferred.

Early Polyethylene Failure in a Modern Total Hip Prosthesis: A Note of Caution

BackgroundHistorically, there has been excellent survivorship of total hip arthroplasty with newer implants expected to outperform prior generations. Review of our institutional database identified problems with one particular cross-linked polyethylene liner in mid-term follow-up, which has not been reported in the literature. We report on the technical aspects of this liner, as well as the clinical and radiographic factors associated with early failure of this bearing in our practice. MethodsA retrospective review of our institutional database was performed from January 2009 to June 2019 of patients who presented with significant osteolysis in the setting of prior total hip arthroplasty with a contemporary polyethylene liner. Demographic and radiographic measures were collected for all patients. ResultsTwelve patients were identified, with nine undergoing revision surgery. All patients demonstrated radiographic osteolysis at the time of revision surgery. The average time to diagnosis of failure was 55.9 months (range: 12-120 months). Average cup position preoperatively was 44 degrees inclination (range: 36-53 degrees) and 21 degrees anteversion (range: 10-34 degrees). Nine patients underwent revision of the acetabular component, with two also undergoing femoral component revision. The Manufacturer and User Facility Device Experience database revealed 22 reported cases of wear-related failure from 2009 to 2019. ConclusionsConsidering that no identifiable risk factors related to patient demographics or implant position were identified, the Exactech Connexion GXL liner may be prone to a high rate of early failure from wear and severe secondary osteolysis. We recommend close surveillance of patients with this bearing surface.

Effects of component position on cross-linked polyethylene liner wear after total hip arthroplasty

Effects of component position on cross-linked polyethylene liner wear after total hip arthroplasty

High survivorship of highly cross-linked polyethylene in revision Total hip Arthroplasty: a minimum 10-year follow-up study

PurposeHighly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation. However, few long-term data on revision total hip arthroplasty (THA) using highly cross-linked polyethylene liners are available. The objective of this study was to determine long-term outcomes of a highly cross-linked polyethylene liner in revision THA.Materials & methodsWe evaluated 63 revision THAs performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up. Thus, the final study cohort consisted of 50 patients (50 hips), including 26 males and 24 females with a mean age of 53 years (range, 27–75 years). Mean follow-up was 11 years (range, 10–14 years).ResultsThe mean Harris hip score improved from 44 points preoperatively to 85 points at the final follow-up. No radiographic evidence of osteolysis was found in any hip. The mean rate of polyethylene liner wear was 0.029 mm/year (range, 0.003 to 0.098 mm/year). A total of 5 hips (10%) required re-revision arthroplasty, including one cup loosening, one recurrent dislocation, and three deep infections. Kaplan-Meier survivorship with an end point of re-revision for any reason was 91.1% and for aseptic cup loosening was 97.9% at 11 years.ConclusionAt a minimum of 10 years, the highly cross-linked polyethylene liners showed excellent clinical performance and implant survivorship, and were not associated with osteolysis in our patients with revision THAs.