Aims. Highly cross-linked polyethylene (HXLPE) greatly reduces wear in total hip arthroplasty, compared to conventional polyethylene (CPE). Cross-linking is commonly achieved by irradiation. This study aimed to compare the degree of cross-linking and in vitro wear rates across a cohort of retrieved and unused polyethylene cups/liners from various brands. Methods. Polyethylene acetabular cups/liners were collected at one centre from 1 April 2021 to 30 April 2022. The trans-vinylene index (TVI) and oxidation index (OI) were determined by Fourier-transform infrared spectrometry. Wear was measured using a pin-on-disk test. Results. A total of 47 specimens from ten brands were included. The TVI was independent of time in vivo. A linear correlation (R. 2. = 0.995) was observed between the old and current TVI standards, except for vitamin E-containing polyethylene. The absorbed irradiation dose calculated from the TVI corresponded to product specifications for all but two products. For one electron beam-irradiated HXLPE, a mean dose of 241% (SD 18%) of specifications was determined. For another, gamma-irradiated HXLPE, a mean 41% (SD 13%) of specifications was determined. Lower wear was observed for higher TVI. Conclusion. The TVI is a reliable measure of the absorbed irradiation dose and does not alter over time in vivo. The products of various brands differ by manufacturing details and consequently cross-linking characteristics. Absorption and penetration of electron radiation and gamma radiation differ, potentially leading to higher degrees of cross-linking for electron radiation. There is a non-linear, inverse correlation between TVI and in vitro wear. The wear resistance of the HXLPE with low TVI was reduced and more comparable to CPE. Cite this article: Bone Joint Res 2024;13(11):682–693

In total hip arthroplasty (THA), cementless cup without screw holes has the putative benefits of maximizing host bone contact and reducing osteolysis by eliminating channels to backside wear particles. However, supplemental trans-acetabular screws cannot be used. 74 hips in 60 patients receiving same model of cementless cup without screw holes (Depuy Duraloc 100 HA cup) from 6/1999 to 3/2003 were prospectively followed up. All patients were allowed to have immediate full weight bearing. Age at THA was 53 ± 13 (range 24–74) years. Osteonecrosis was the leading hip disease (45% of hips). Survivorship was assessed using revision of the cup as the end point. Radiological parameters, including lateral opening angle, vertical and horizontal migration distances of the cups were measured. Paired t-test was used to compare between the measurements in early postoperative period and at final follow up. 51 hips were assessed at minimum 20 years follow-up. The mean follow-up was 22.6 (range 21 – 25) years. All the cups were well fixed. There were two cup revisions. Conventional polyethylene (PE) was used in both hips; osteolysis occurred 17 and 18 years later. Both cups were well fixed but were revised, one due to cup mal-positioning, one due to need in upsizing the articulation. 14 other hips were revised but these cups were well fixed and not revised; 9 loosened stems (most were cemented Elite plus stems), 5 PE wear and osteolysis (all were conventional PE). At 20 years, the survivorship of cups was 96.1%. Changes in lateral opening angle, vertical and horizontal migration distances were 0.44±1.59°, 0.01±1.52mm and -0.32±1.47mm respectively, without statistical significance. This study provided evidence of excellent long-term survivorship of cementless cup without screw holes. Immediate postoperative weight-bearing also did not lead to cup migration in the long-term

The purpose of this randomized controlled trial was to evaluate serum metal levels in patients undergoing total hip arthroplasty (THA) with a conventional compared to a modular dual-mobility bearing. Patients undergoing primary THA for osteoarthritis were randomized to receive either a modular dual-mobility or conventional polyethylene bearing. All patients received the same titanium acetabular and femoral component and a ceramic femoral head. Serum metal levels were drawn pre-operatively then annually for a minimum of two years postoperatively. An a priori power analysis determined that 40 patients (20 per cohort) were needed to identify a clinically relevant difference in serum cobalt of 0.35 ng/ml (ppb) at 90% power. Forty-six patients were randomized to a modular dual-mobility (n=25) or conventional bearing (n=21) with 40 at a minimum follow-up of two years. No differences in serum cobalt (mean 0.14 ppb [range, 0.075–0.29] vs. 0.20 ppb [range, 0.075–0.57], p=0.39) or chromium levels (mean 0.14 ppb [range, 0.05–0.50] vs. 0.12 ppb [range, 0.05–0.35], p=0.65) were identified between the modular dual-mobility and conventional cohorts, respectively. There was no statistically significant difference in serum Co or Cr at two years postoperatively in subjects implanted with a ceramic head and this particular dual mobility bearing in comparison to a ceramic head and a conventional acetabular component. While modest expected elevations in serum Co and Cr were observed in the dual mobility group, in no case did the Co level exceed the laboratory reference range nor the threshold of one part per billion that has been associated with adverse local tissue reactions to mechanically-assisted crevice corrosion

We present minimum 20 year results of a randomized, prospective double blinded trial (RCT) of cross-linked versus conventional polyethylene (PE), using a computer assisted method of PE wear measurement. After Ethics Committee approval, 122 patients were enrolled into an RCT comparing Enduron (non cross-linked PE) and highly cross-linked Marathon PE (DePuy, Leeds, UK). Other than the PE liners, identical components were used, a Duraloc 300 metal shell with one screw, a 28mm CoCr femoral head and a cemented Charnley Elite femoral stem. All patients were followed with anteroposterior (A∼P) and lateral radiographs at 3 days, 6 weeks, 3 months, 6 months, 1, 2, 3, 4, 5, 10 and 20 years. PE wear was measured with PolyMig, which has a phantom validated accuracy of ± 0.09mm. At minimum 20 year follow-up, 47 patients had died, 5 of which had been revised prior to their death. Another 32 patients were revised and alive, leaving 43 patients unrevised and alive (15 Enduron, 28 Marathon). No patients were lost to follow-up, but 2 were not able to be radiographed (dementia), leaving 41 patients (15 Enduron, 26 Marathon) available for PE wear measurement. After the bedding-in period, Enduron liners had a wear rate of 0.182 mm/year, and Marathon liners had a wear rate of 0.028 mm/year. At 20 years follow-up, 37 patients had required revision. Patients with conventional PE had three times the revision rate (28/37) of those who received XLPE (9/37). This is the longest term RCT showing substantially improved clinical and radiological results when XLPE is used as the bearing surface

Aims. The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients. Methods. A double-blinded randomized controlled trial was conducted including 96 TKAs. The migration of the femoral component was measured with radiostereometry (RSA) at three and six months and one, two, and five years postoperatively. PROMs were collected preoperatively and at all periods of follow-up. Results. There was no clinically relevant difference in terms of migration of the femoral component or PROMs between the HXLPE and PE groups. The mean difference in migration (maximum total point motion), five years postopeatively, was 0.04 mm (95% CI -0.06 to 0.16) in favour of the PE group. Conclusion. There was no clinically relevant difference in migration of the femoral component, for up to five years between the two groups. These findings will help to establish a benchmark for future studies on migration of femoral components in TKA. Cite this article: Bone Joint J 2024;106-B(8):826–833

Aims

Oxidized zirconium (OxZi) and highly cross-linked polyethylene (HXLPE) were developed to minimize wear and risk of osteolysis in total hip arthroplasty (THA). However, retrieval studies have shown that scratched femoral heads may lead to runaway wear, and few reports of long-term results have been published. The purpose of this investigation is to report minimum ten-year wear rates and clinical outcomes of THA with OxZi femoral heads on HXLPE, and to compare them with a retrospective control group of cobalt chrome (CoCr) or ceramic heads on HXLPE.

Aims

Radiostereometric analysis (RSA) is the most accurate radiological method to measure in vivo wear of highly cross-linked polyethylene (XLPE) acetabular components. We have previously reported very low wear rates for a sequentially irradiated and annealed X3 XLPE liner (Stryker Orthopaedics, USA) when used in conjunction with a 32 mm femoral heads at ten-year follow-up. Only two studies have reported the long-term wear rate of X3 liners used in conjunction with larger heads using plain radiographs which have poor sensitivity. The aim of this study was to measure the ten-year wear of thin X3 XLPE liners against larger 36 or 40 mm articulations with RSA.

Aims

The Birmingham Hip Resurfacing (BHR) arthroplasty has been used as a surgical treatment of coxarthrosis since 1997. We present 20-year results of 234 consecutive BHRs performed in our unit.

Aims. The primary objective of this study was to compare the five-year tibial component migration and wear between highly crosslinked polyethylene (HXLPE) inserts and conventional polyethylene (PE) inserts of the uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary objectives included clinical outcomes and patient-reported outcome measures (PROMs). Methods. A double-blinded, randomized study was conducted including 96 TKAs. Tibial component migration and insert wear were measured with radiostereometric analysis (RSA) at three, six, 12, 24, and 60 months postoperatively. PROMS were collected preoperatively and at all follow-up timepoints. Results. There was no clinically relevant difference in terms of tibial component migration, insert wear, and PROMs between the HXLPE and PE groups. The mean difference in tibial component migration (maximal total point migration (MTPM)) was 0.02 mm (95% confidence interval (CI) -0.07 to 0.11), which is below the value of 0.2 mm considered to be clinically relevant. Wear after five years for HXLPE was 0.16 mm (95% CI 0.05 to 0.27), and for PE was 0.23 mm (95% CI 0.12 to 0.35). The mean difference in wear rate was 0.01 mm/year (95% CI -0.02 to 0.05) in favour of the HXLPE group. Wear is mainly present on the medial side of the insert. Conclusion. There is no clinically relevant difference in tibial component migration and insert wear for up to five years between the HXLPE conventional PE inserts. For the implant studied, the potential advantages of a HXLPE insert remain to be proven under clinical conditions at longer-term follow-up. Cite this article: Bone Joint J 2023;105-B(5):518–525

Results in patients undergoing total hip arthroplasty (THA) for femoral head osteonecrosis (ON) when compared with primary osteoarthritis (OA) are controversial. Different factors like age, THA type or surgical technique may affect outcome. We hypothesized that patients with ON had an increased revision rate compared with OA. We analysed clinical outcome, estimated the survival rate for revision surgery, and their possible risk factors, in two groups of patients. In this retrospective cohort analysis of our prospective database, we assessed 2464 primary THAs implanted between 1989 and 2017. Patients with OA were included in group 1, 2090 hips; and patients with ON in group 2, 374 hips. In group 2 there were more men (p<0.001), patients younger than 60 years old (p<0.001) and with greater physical activity (p<0.001). Patients with lumbar OA (p<0.001) and a radiological acetabular shape type B according to Dorr (p<0.001) were more frequent in group 1. Clinical outcome was assessed according to the Harris Hip Score and radiological analysis included postoperative acetabular and femoral component position and hip reconstruction. Kaplan-Meier survivorship analysis was used to estimate the cumulative probability of not having revision surgery for different reasons. Univariate and multivariate Cox regression models were used to assess risk factors for revision surgery. Clinical improvement was better in the ON at all intervals. There were 90 hips revised, 68 due to loosening or wear, 52 (2.5%) in group 1, and 16 (4.3%) in group 2. Overall, the survival rate for revision surgery for any cause at 22 years was 88.0 % (95% CI, 82-94) in group 1 and 84.1% (95% CI, 69 – 99) in group 2 (p=0.019). Multivariate regression analysis showed that hips with conventional polyethylene (PE), compared with highly-cross linked PEs or ceramic-on-ceramic bearings, (p=0.01, Hazard Ratio (HR): 2.12, 95% CI 1.15-3.92), and cups outside the Lewinnek´s safe zone had a higher risk for revision surgery (p<0.001, HR: 2.57, 95% CI 1.69-3.91). Modern highly-cross linked PEs and ceramic-on-ceramic bearings use, and a proper surgical technique improved revision rate in patients undergoing THA due to ON compared with OA

The 2021 Australian Orthopaedic Association National Joint Replacement Registry report indicated that total shoulder replacement using both mid head (TMH) length humeral components and reverse arthroplasty (RTSA) had a lower revision rate than stemmed humeral components in anatomical total shoulder arthroplasty (aTSA) - for all prosthesis types and diagnoses. The aim of this study was to assess the impact of component variables in the various primary total arthroplasty alternatives for osteoarthritis in the shoulder. Data from a large national arthroplasty registry were analysed for the period April 2004 to December 2020. The study population included all primary aTSA, RTSA, and TMH shoulder arthroplasty procedures undertaken for osteoarthritis (OA) using either cross-linked polyethylene (XLPE) or non-cross-linked polyethylene (non XLPE). Due to the previously documented and reported higher revision rate compared to other anatomical total shoulder replacement options, those using a cementless metal backed glenoid components were excluded. The rate of revision was determined by Kaplan-Meir estimates, with comparisons by Cox proportional hazard models. Reasons for revision were also assessed. For a primary diagnosis of OA, aTSA with a cemented XLPE glenoid component had the lowest revision rate with a 12-year cumulative revision rate of 4.7%, compared to aTSA with cemented non-XLPE glenoid component of 8.7%, and RTSA of 6.8%. The revision rate for TMH was lower than aTSA with cemented non-XLPE, but was similar to the other implants at the same length of follow-up. The reason for revision for cemented aTSR was most commonly component loosening, not rotator cuff deficiency. Long stem humeral components matched with XLPE in aTSA achieve a lower revision rate compared to shorter stems, long stems with conventional polyethylene, and RTSA when used to treat shoulder OA. In all these cohorts, loosening, not rotator cuff failure was the most common diagnosis for revision

We report the outcome of 320 primary Total Hip Arthroplasties (THA) with minimum 10-year follow-up (range 10–17 years, mean 12.6 years), performed by a single surgeon in Tauranga New Zealand, with the Exeter Contemporary Flanged all-polyethylene cup and Exeter femoral stem via a posterior approach. The aim of the study is to compare the results with the published results from the design centre and create a baseline cohort for further outcomes research in this centre.

All patients were prospectively followed at 6 weeks, 1 year, 5 years, 10 years, (and 15 years when available). Of 333 cases that matched the inclusion criteria, 13 procedures in 12 patents were excluded because of concomitant bone grafting and/or supplementary cage fixation, leaving 320 primary THA procedures in 280 patients, including 26 bilateral procedures in 13 patients.

Mean follow-up of the surviving cases was 12.6 (range 5.0-17.1) years. There were 12 revisions – 2 for fracture, 5 for instability, 1 for impingement pain and 4 for infection. There were no revisions for aseptic cup loosening. Kaplan-Meier survivorship with revision for aseptic loosening as the endpoint was 100% at 15.0 years (with minimum 40 cases remaining at risk). All-cause acetabular revision in 12 cases result in a Kaplan-Meier survival of 95.9% (95% CI: 93.5 to 98.3%).

Cemented THA with the Exeter Contemporary Flanged cup and the Exeter stem is a durable combination with results that can be replicated outside of the design centre. The Exeter Contemporary Flanged cup has excellent survivorship at 15 years when used with the Exeter stem. Cemented THA with well-proven components should be considered the benchmark against which newer designs and materials should be compared.

The benefits of HXLPE in total knee arthroplasty (TKA) have not been as evident as total hip arthroplasty (THA). A systematic review and meta-analysis to assess the impact of highly-crosslinked polyethylene (HXLPE) on TKA outcomes compared to conventional polyethylene (CPE) is described. All studies comparing HXLPE with CPE for primary TKA were included for analysis. The minimum dataset included revision rates, indication for revision, aseptic component loosening and follow-up time. The primary outcome variables were all-cause revision, aseptic revision, revision for loosening, radiographic component loosening, osteolysis and incidence of radiolucent lines. Secondary outcome measures included postoperative functional knee scores. A random-effects meta-analysis allowing for all missing data was performed for all primary outcome variables. Six studies met the inclusion criteria. In total, there were 2,234 knees (1,105 HXLPE and 1,129 CPE). The combined mean follow-up for all studies was 6 years. The aseptic revision rate in the HXLPE group was 1.02% compared to 1.97% in the CPE group. There was no difference in the rate of all-cause revision (p = 0.131), aseptic revision (p = 0.298) or revision for component loosening (p = 0.206) between the two groups. Radiographic loosening (p = 0.200), radiolucent lines (p = 0.123) and osteolysis (p = 0.604) was similar between both groups. Functional outcomes were similar between groups. The use of HXLPE in TKA yields similar results for clinical and radiographic outcomes when compared to CPE at midterm follow-up. HXLPE does not confer the same advantages to TKA as seen in THA

Aims

A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade.

Aims

This study reports the ten-year wear rates, incidence of osteolysis, clinical outcomes, and complications of a multicentre randomized controlled trial comparing oxidized zirconium (OxZr) versus cobalt-chrome (CoCr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) and highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA).

Aims

The aim of this study was to evaluate the performance of first-generation annealed highly cross-linked polyethylene (HXLPE) in cementless total hip arthroplasty (THA).

Aims

This study investigates head-neck taper corrosion with varying head size in a novel hip simulator instrumented to measure corrosion related electrical activity under torsional loads.

The purpose of this study was to compare oxinium versus metal-on-polyethylene wear in two consecutive prospective randomized series of low friction total hip arthroplasty at a minimum 10-year follow-up.

A total of 100 patients with a median age of 60.9 years were randomized to receive either oxinium (50 hips) or metal (50 hips) femoral head. The polyethylene socket was EtO sterilized in the first 50 patients, whereas it was highly cross-linked and remelted (XLPE) in the following 50 patients. The primary criterion for evaluation was linear head penetration measurement using the Martell system by an investigator blinded to the material. Also, a survivorship analysis was performed using wear related loosening revised or not as the end point.

Complete data were available for analysis in 40 hips at a median follow-up of 12.9 years (11 to 14), and in 36 hips at a median follow-up of 12.3 years (10 to 13) in the EtO sterilized and XLPE series, respectively.

In the EtO sterilized series, the mean steady-state wear rate was 0.245 ± 0.080 mm/year in the oxinium group versus 0.186 ± 0.062 mm/year in the metal group (p = 0.009). In the XLPE series, the mean steady-state wear rate was 0.037±0.016 mm/year in the oxinium group versus 0.036±0.015 mm/year in the metal group (p = 0.94). The survival rate at 10 years was 100% in both XLPE series, whereas it was 82.9% (IC 95%, 65–100) and 70.5% (IC95%, 50.1–90.9) in the metal-EtO and oxinium-EtO series, respectively.

This RCT demonstrated that up to 14-year follow-up, wear was significantly reduced when using XLPE, irrespective of the femoral head material. Also, no osteolysis related complication was observed in the XLPE series. In the current study, oxinium femoral heads showed no advantage over metal heads and therefore their continued used should be questioned related to their cost.

Aims

We aimed to evaluate the long-term outcome of highly cross-linked polyethylene (HXLPE) cemented acetabular components and assess whether any radiolucent lines (RLLs) which arose were progressive.

Aims

The aim of our study was to investigate the effect of asymmetric crosslinked polyethylene liner use on the risk of revision of cementless and hybrid total hip arthroplasties (THAs).