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.

Aims

Isolated acetabular liner exchange with a highly crosslinked polyethylene (HXLPE) component is an option to address polyethylene wear and osteolysis following total hip arthroplasty (THA) in the presence of a well-fixed acetabular shell. The liner can be fixed either with the original locking mechanism or by being cemented within the acetabular component. Whether the method used for fixation of the HXLPE liner has any bearing on the long-term outcomes is still unclear.

Aims

This study reports the results of 38 total hip arthroplasties (THAs) in 33 patients aged less than 50 years, using the JRI Furlong hydroxyapatite ceramic (HAC)-coated femoral component.

Aims. Biofilm infections are among the most challenging complications in orthopaedics, as bacteria within the biofilms are protected from the host immune system and many antibiotics. Halicin exhibits broad-spectrum activity against many planktonic bacteria, and previous studies have demonstrated that halicin is also effective against Staphylococcus aureus biofilms grown on polystyrene or polypropylene substrates. However, the effectiveness of many antibiotics can be substantially altered depending on which orthopaedically relevant substrates the biofilms grow. This study, therefore, evaluated the activity of halicin against less mature and more mature S. aureus biofilms grown on titanium alloy, cobalt-chrome, ultra-high molecular weight polyethylene (UHMWPE), devitalized muscle, or devitalized bone. Methods. S. aureus-Xen36 biofilms were grown on the various substrates for 24 hours or seven days. Biofilms were incubated with various concentrations of halicin or vancomycin and then allowed to recover without antibiotics. Minimal biofilm eradication concentrations (MBECs) were defined by CFU counting and resazurin reduction assays, and were compared with the planktonic minimal inhibitory concentrations (MICs). Results. Halicin continued to exert significantly (p < 0.01) more antibacterial activity against biofilms grown on all tested orthopaedically relevant substrates than vancomycin, an antibiotic known to be affected by biofilm maturity. For example, halicin MBECs against both less mature and more mature biofilms were ten-fold to 40-fold higher than its MIC. In contrast, vancomycin MBECs against the less mature biofilms were 50-fold to 200-fold higher than its MIC, and 100-fold to 400-fold higher against the more mature biofilms. Conclusion. Halicin is a promising antibiotic that should be tested in animal models of orthopaedic infection. Cite this article: Bone Joint Res 2024;13(3):101–109

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).

Majority of ultra-high molecular weight polyethylene (UHMWPE) medical devices used in total joint arthroplasty are crosslinked using gamma radiation to improve wear resistance. Alternative methods of crosslinking are urgently needed to replace gamma radiation due to rapid decline in its supply. Peroxide crosslinking is a candidate method with widespread industrial applications. Oxidative stability and biocompatibility, which are critical requirements for medical device applications, can be achieved using vitamin-E as an additive and by removing peroxide by-products through high temperature melting, respectively. We investigated compression molded UHMWPE/vitamin-E/di-cumyl peroxide blends followed by high-temperature melting in inert gas as a material candidate for tibial knee inserts. Wear resistance increased and mechanical properties remained largely unchanged. Oxidation induction time was higher than most of the other clinically available formulations. The material passed the local-end point biocompatibility tests per ISO 10993. Compounds found in exhaustive extraction were of no concern with margin-of-safety values well above the accepted level, indicating a desirable toxicological risk profile. Peroxide crosslinked, vitamin-E stabilized, and high temperature melted UHMWPE has recently been cleared for clinical use in tibial knee inserts. With all the salient characteristics needed in a material that can provide superior long-term performance in total joint patients, peroxide crosslinking can replace gamma radiation crosslinking of UHMWPE for use in all total joint replacement implant including acetabular liners

Periprosthetic joint infection (PJI) remains an extremely challenging complication. We have focused on this issue more over the last decade than previously, but there are still many unanswered questions. We now have a workable definition that everyone should align to, but we need to continue to focus on identifying the organisms involved. Surgical strategies are evolving and care is becoming more patient-centred. There are some good studies under way. There are, however, still numerous problems to resolve, and the challenge of PJI remains a major one for the orthopaedic community. This annotation provides some up-to-date thoughts about where we are, and the way forward. There is still scope for plenty of research in this area.

Cite this article: Bone Joint J 2022;104-B(11):1193–1195.

Aims

A functional anterior cruciate ligament (ACL) or posterior cruciate ligament (PCL) has been assumed to be required for patients undergoing unicompartmental knee arthroplasty (UKA). However, this assumption has not been thoroughly tested. Therefore, this study aimed to assess the biomechanical effects exerted by cruciate ligament-deficient knees with medial UKAs regarding different posterior tibial slopes.

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). Methods. Patients undergoing primary THA were recruited from four institutions and prospectively allocated to the following treatment groups: Group A, CoCr femoral head with XLPE liner; Group B, OxZr femoral head with XLPE liner; and Group C, OxZr femoral head with UHMWPE liner. All study patients and assessors recording outcomes were blinded to the treatment groups. The outcomes of 262 study patients were analyzed at ten years’ follow-up. Results. Patients in Group C were associated with increased mean liner wear rates compared to patients in Group A (0.133 mm/yr (SD 0.21) vs 0.031 mm/yr (SD 0.07), respectively; p < 0.001) and Group B (0.133 mm/yr (SD 0.21) vs 0.022 mm/yr (SD 0.05), respectively; p < 0.001) at ten years’ follow-up. Patients in Group C were also associated with increased risk of osteolysis and aseptic loosening requiring revision surgery, compared with patients in Group A (7/133 vs 0/133, respectively; p = 0.007) and Group B (7/133 vs 0/135, respectively; p = 0.007). There was a non-statistically significant trend towards increased mean liner wear rates in Group A compared with Group B (0.031 mm/yr (SD 0.07) vs 0.022 mm/yr (SD 0.05), respectively; p = 0.128). All three groups were statistically comparable preoperatively and at ten years’ follow-up when measuring normalized Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.410), 36-Item Short Form Health Survey (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p = 0.451). Conclusion. The use of UHMWPE was associated with progressively increased annual liner wear rates after THA compared to XLPE. At ten years’ follow-up, the group receiving UHMWPE demonstrated an increased incidence of osteolysis and aseptic loosening requiring revision surgery compared to XLPE. Femoral heads composed of OxZr were associated with trend towards reduced wear rates compared to CoCr, but this did not reach statistical significance and did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two femoral head components. Cite this article: Bone Joint J 2022;104-B(7):833–843

This study reports the ten-year polyethylene liner wear rates, incidence of osteolysis, clinical outcomes and complications of a three-arm, multicentre randomised controlled trial comparing Cobalt-Chrome (CoCr) and Oxidised Zirconium (OxZr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and XLPE liner; Group B received an OxZr femoral head and XLPE liner; and Group C received an OxZr femoral head and UHMWPE liner. Blinded observers recorded predefined outcomes in 262 study patients at regular intervals for ten years following THA. At ten years follow-up, increased linear wear rates were recorded in group C compared to group A (0.133 ± 0.21 mm/yr vs 0.031 ± 0.07 mm/yr respectively, p<0.001) and group B (0.133 ± 0.21 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p<0.001). Patients in group C were associated with increased risk of osteolysis and aseptic loosening requiring revision surgery compared with group A (7/133 vs 0/133 respectively, p=0.007) and group B (7/133 vs 0/135 respectively, p=0.007). There was a non-significant trend towards increased liner wear rates in group A compared to group B (0.031 ± 0.07 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p=0.128). All three groups were statistically comparable preoperatively and at ten years follow-up when measuring normalised Western Ontario and McMaster Universities Osteoarthritis Index(p=0.410), short-form-36 (p = 0.465 mental, p = 0.713 physical), and pain scale scores (p=0.451). The use of UHMWPE was associated with progressively increased annual liner wear rates after THA. At ten years follow-up, this translated to UHMWPE leading to an increased incidence of osteolysis and aseptic loosening requiring revision THA, compared with XLPE. Femoral heads composed of OxZr were associated with a non-significant trend towards reduced wear rates compared to CoCr, but this did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two treatments groups

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).

This study reports the ten-year outcomes of a three-arm, multicentre randomised controlled trial comparing Cobalt-Chrome (CoCr) and Oxidised Zirconium (OxZr) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly cross-linked polyethylene (XLPE) liners in total hip arthroplasty (THA). Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and XLPE liner; Group B received an OxZr femoral head and XLPE liner; and Group C received an OxZr femoral head and UHMWPE liner. The outcomes of 262 study patients were analysed at ten years follow-up. At ten years, increased linear wear rates were recorded in group C compared to group A (0.133 ± 0.21 mm/yr vs 0.031 ± 0.07 mm/yr respectively, p<0.001) and group B (0.133 ± 0.21 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p<0.001). Patients in group C had increased risk of osteolysis and aseptic loosening requiring revision surgery compared with group A (7/133 vs 0/133 respectively, p=0.007) and group B (7/133 vs 0/135 respectively, p=0.007). There was a non- significant trend towards increased liner wear rates in group A compared to group B (0.031 ± 0.07 mm/yr vs 0.022 ± 0.05 mm/yr respectively, p=0.128). All three groups were statistically comparable preoperatively and at ten years follow-up from a clinical score perspective. The use of UHMWPE was associated with progressively increased annual liner wear rates. At ten years follow-up, this translated to an increased incidence of osteolysis and aseptic loosening requiring revision, compared with XLPE. Femoral heads composed of OxZr were associated with a non-significant trend towards reduced wear rates compared to CoCr, but this did not translate to any differences in osteolysis, functional outcomes, or revision surgery between the two treatments groups

Aims

The aims of this study were to evaluate wear on the surface of cobalt-chromium (CoCr) femoral components used in total knee arthroplasty (TKA) and compare the wear of these components with that of ceramic femoral components.

Abstract. Objectives. Ultra-High Molecular Weight Polyethylene (UHMWPE) can be made radiopaque through the diffusion of an oil-based contrast agent (Lipiodol Ultra-fluid). A similar process is used for Vitamin E incorporated polyethylene, which has a well-established clinical history. This study aimed to quantify the leaching of Lipiodol and compare to vitamin E polyethylene. Method. GUR 1050 polyethylene (4 mm thickness) was cut into squares, 10 mm. 2. Samples (n=5) were immersed in 25 ml Lipiodol (Guerbet, France), or 15 ml Vitamin E (L-atocopherol, Sigma-Aldrich, UK). To facilitate diffusion, samples were held at 105°C for 18 hours. After treatment, all samples were immersed in DMEM (Sigma-Aldrich, UK) with Penicillin Streptomycin (Sigma-Aldrich, Kent, UK) at 4%v/v and held at 37°C in an incubator. Untreated polyethylene samples were included as controls. Leaching was quantified gravimetrically at weeks 2, 4 and 8. The radiopacity of the Lipiodol-diffused samples was investigated from µCT images (162kV, resolution 0.2 mm, X Tec, XT H 225 ST, Nikon Metrology, UK). Results. The leaching of Lipiodol and Vitamin E followed the same trend and reached a steady state after week 2. At this point there was a 20% decrease in the Hounsfield Unit and droplets of radiopaque oil were visible in the DMEM solution; these were not evident in subsequent scans. Over 8 weeks of 20% Lipiodol leached out of the polyethylene, which was greater than of 10% Vitamin E. Conclusion. After 8 weeks the radiopaque polyethylene was still identifiable in CT scan images, even though 20% of leaching occurred. The leaching of Lipiodol may be mitigated through cross-linking, which has been shown to reduce leaching of Vitamin E; this will be investigated as future work. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Orthopedic implants are subject to wear and release ultra-high molecular weight polyethylene (UHMWPE) debris. Analysis of UHMWPE wear particles is critical in determining the safety and effectiveness of novel orthopedic implants. Complete digestion of periprosthetic tissue and wear fluid is necessary to ensure accurate morphological and quantitative particle analysis. Acid digestion methods are more effective than enzymatic and base digestion approaches [Baxter+ 2009]. However, optimal digestion times, quantity, and type of acid are unclear for particle isolation. In addition, imaging and analysis techniques are critical to ensure accurate reporting of particle characteristics. Here, we 1) compared the efficacy of three acid-based digestion methods in isolating particles from a) bovine serum and b) animal/human tissue, and 2) analyzed the effects of imaging location on particle quantity/morphology results. Methods. 1a) UHMWPE (GUR 150) particles were generated by Mode I knee wear testing for 1 million cycles in bovine serum. Serum was digested in one of four solutions: 12.2M HCl, 15.8M HNO. 3. , a 1:1 volume ratio of HNO. 3. :HCl (aqua regia), or filtered H. 2. O (control). The serum:solution volume ratio was 1:5 [Niedzwiecki+ 2001, ISO 17853:2011]. Digestion occurred for 60min on a stir plate at 60°C. Each digest was combined with MeOH at a 1:5 digest:MeOH volume ratio and filtered using a 100 nm polycarbonate membrane. The particle-containing membranes were imaged (12 images/membrane) using scanning electron microscopy (SEM) to determine particle characteristics, including quantity, equivalent circular diameter (ECD) and aspect ratio (AR). 1b) Based on 1a, HNO. 3. was used to digest porcine and human tissue at concentrations of 1:40, 1:60, or 1:80 tissue:HNO. 3. volume ratios for either 1, 12, or 24 hours, followed by SEM analysis. 2) Particle characteristics were compared at nine locations (20 images/location) across a particle-containing membrane to determine the effects of imaging location. Results. 1a) HNO. 3. and aqua regia methods successfully digested the bovine serum, whereas the HCl and H. 2. O methods were unsuccessful (Fig.1A). Comparing HNO. 3. and aqua regia groups, particle characteristics and ECD frequency distribution were nearly identical (Fig.1B). 1b) Nitric acid did not fully digest porcine or human tissues. 2) Similar particle characteristics were observed in all nine locations analyzed across the polycarbonate membrane. The particle quantity, ECD, and AR for a representative center vs. intermediate location were 808 vs. 780 particles, 0.33±0.28 vs. 0.35±0.29 µm, and 1.57±0.56 vs. 1.51±0.4, respectively (Fig.2). Conclusions. Nitric acid and aqua regia are capable of digesting bovine serum using low quantities of acid for short duration, allowing precise analysis of UHMWPE particle debris from orthopedic implants. However, further optimization of digestion techniques for animal/human tissue is warranted. In addition, an accurate representation of particle distribution can be achieved without analyzing hundreds of images, because membrane location does not strongly influence particle results. Finally, ASTM F1877-16 – Standard Practice for Characterization of Particles – could benefit from adding software-based automated particle characterization as an optional method. An automated approach that uses k-means clustering image segmentation to identify particles and computer vision tools to extract relevant morphological features is under development and validation

Aims

We present the results, in terms of survival, clinical outcome, and radiological appearance at 20 years, in a cohort of 225 cemented Exeter Universal femoral components (Stryker, Newbury, UK) implanted in 207 patients, at a district general hospital.

The purpose of this investigation is to assess the rate of wear the effect once the “bedding in period”/ poly creep had been eliminated. Creep is the visco-elastic deformation that polyethylene exhibits in the first 6–12 weeks. We also assessed the wear pattern of four different bearing couples in total hip arthroplasty (THA): cobalt-chrome (CoCr) versus oxidized zirconium (OxZir) femoral heads with ultra-high molecular weight polyethylene (UHMWPE) versus highly-crosslinked polyethylene (XLPE) acetabular liners. This was a randomized control study involving 92 patients undergoing THA. They were randomized to one of four bearing couples: (1) CoCr/UHMWPE (n= 23), (2) OxZir/UHMWPE (n=21), (3) CoCr/XLPE (n=24), (4) OxZir/XLPE (n=24). Patients underwent a posterior approach from one of three surgeons involved in the study. All patients received a porous-coated cementless acetabular shell and a cylindrical proximally coated stem with 28 mm femoral heads. Each patient was reviewed clinically and radiographically at six weeks, three and 12 months, two, five and 10 years after surgery. Standardized anteroposterior and lateral radiographs were taken. All polyethylene wear was measured by an independent blinded reviewer. Linear and volumetric wear rates were measured on radiographs using a validated computer software (Polyware Rev. 5). Creep was defined as the wear at 6 or 12 weeks, depending on if there was a more than 10% difference between both measurements. If a greater than 10% difference occurred than the later period's wear would be defined as creep. 72 hips were included in analysis after exclusion of seven revisions, three deaths and 10 losses to follow-up. The annual linear wear rates (in mm/y) at 10 years were (1) 0.249, (2) 0.250, (3) 0.074 and (4) 0.050. After adjusting for creep these rates become were (1) 0.181, (2) 0.142, (3) 0.040 and (4) 0.023. There is statistical differences between raw and adjusted linear wear rates for all bearing couples. The percentage of the radiographically measured wear at 10 years due to creep is (1) 30% (2) 44%, (3) 58.5% and (4) 51.5% with significant differences in couples with XLPE versus those with UHMWPE. There was no significant correlation between age, gender, cup size, tilt, planar anteversion and the linear or volumetric wear rates. The linear wear rate of both UHMWPE and XLPE are even lower thxdsxzan previously described when creep is factored out. XLPE has again demonstrated far superior linear wear rates at 10 years than UHMWPE. There were no significant differences in wear rate at 10 years between CoCr and OxZir, this may be due to an underpowered study. XLPE exhibits proportionally more creep than UHMWPE within the first 6–12 weeks and accounts for more of the total wear at 10 years as measured radiographically at the end period

Polyethylene wear-debris induced inflammatory osteolysis is known as the main cause of aseptic loosening and long term revision total hip arthroplasty. Although recent reports suggest that antioxidant impregnated ultra-high molecular weight polyethylene (UHMWPE) wear-debris have reduce the osteolytic potential in vivo when compared to virgin UHMWPE, little is known about if and/or how PE rate of oxidation affects osteolysis in vivo. We hypothesized that oxidized UHMWPE particles would cause more inflammatory osteolysis in a murine calvarial bone model when compared to virgin UHMWPE. Male C57BL/6 eight weeks old received equal amount of particulate debris overlaying the calvarium of (n=12/group): sham treatment (no particles), 2mg (6,75×107 particles/mg) of endotoxin-free UHMWPE particles (PE) or of endotoxin-free highly oxidized-UHMWPE (OX) particles. In vivo osteolysis was assessed using high resolution micro-CT and inflammation with L-012 probe dependent luminescence. At day 10, calvarial bone was examined using high resolution micro-CT, histomorphometric, immunohistochemistry analyses and qRT-PCR to assess OPG, RANK, RANK-L, IL-10, IL-4, IL-1b and TRAP genes expression using the protocol defined by individual TaqManTM Gene Expression Assays Protocol (Applied Biosystems). In vivo inflammation was significantly higher in the OX (1.60E+06 ± 8.28E+05 photons/s/cm2) versus PE (8.48E+05 ± 3.67E+05) group (p=0.01). Although there was a statistically significant difference between sham (−0.27% ± 2.55%) and implanted (PE: −9.7% ± 1.97%, and OX: − 8.38% ± 1.98%) groups with regards to bone resorption (p=0.02), this difference was not significant between OX and PE (p = 0.14). There was no significant difference between groups regarding PCR analyses for OPG, RANK, RANK-L, IL-10, IL-4, IL-1b and TRAP (p = 0.6, 0.7, 0.1, 0.6, 0.3, 0.4, 0.7 respectively). Bone volume density was significantly decreased in PE (13.3%±1.2%) and OX (12.2%±1.2%) groups when compared to sham (15%±0.9%) (p < 0 .05). Histomorphometric analyses showed a significantly decreased Bone Thickness/Tissue Thickness ratio in the implanted group (0.41±0.01 mm and 0.43±0.01 mm) compared to sham group (0.69± 0.01) (p < 0 .001). However, there were no significant difference between OX and PE (p = 0.2). Our findings suggest that oxidized UHMWPE particles display increased inflammatory potential. Results were not significant regarding in vivo or ex vivo osteolysis. As antioxidant-diffused UHMWPE induce less inflammation activity in vivo, the mechanism by which they cause reduced osteolysis requires further investigation

Aims. We propose a state-of-the-art temporary spacer, consisting of a cobalt-chrome (CoCr) femoral component and a gentamicin-eluting ultra-high molecular weight polyethylene (UHMWPE) tibial insert, which can provide therapeutic delivery of gentamicin, while retaining excellent mechanical properties. The proposed implant is designed to replace conventional spacers made from bone cement. Methods. Gentamicin-loaded UHMWPE was prepared using phase-separated compression moulding, and its drug elution kinetics, antibacterial, mechanical, and wear properties were compared with those of conventional gentamicin-loaded bone cement. Results. Gentamicin-loaded UHMWPE tibial components not only eradicated planktonic Staphylococcus aureus, but also prevented colonization of both femoral and tibial components. The proposed spacer possesses far superior mechanical and wear properties when compared with conventional bone cement spacers. Conclusion. The proposed gentamicin-eluting UHMWPE spacer can provide antibacterial efficacy comparable with currently used bone cement spacers, while overcoming their drawbacks. The novel spacer proposed here has the potential to drastically reduce complications associated with currently used bone cement spacers and substantially improve patients’ quality of life during the treatment. Cite this article: Bone Joint J 2020;102-B(6 Supple A):151–157

Aims

A retrospective longitudinal study was conducted to compare directly volumetric wear of retrieved polyethylene inserts to predicted volumetric wear modelled from individual gait mechanics of total knee arthroplasty (TKA) patients.