Aims. Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening. Methods. A systematic search was undertaken using the Cochrane methodology in three online databases: MEDLINE, Embase, and CINAHL. Studies were screened against predetermined criteria, and data were extracted. Available National Joint Registries in the Network of Orthopaedic Registries of Europe were also screened. A random effects model meta-analysis was undertaken. Results. Of 263 studies, 12 were included with a total of 3,861 TKAs. Meta-analysis of ten studies showed high rates of overall tibial or femoral RLLs for the cemented original design of the ATTUNE TKA. The overall rate was 21.4% (95% confidence interval (CI) 12.7% to 33.7%) for all types of design but was higher for certain subgroups: 27.4% (95% CI 13.4% to 47.9%) for the cruciate-retaining type, and 29.9% (95% CI 15.6% to 49.6%) for the fixed-bearing type. Meta-analysis of five studies comparing the ATTUNE TKA with other implants showed a significantly higher risk of overall tibial or femoral RLLs (odds ratio (OR) 2.841 (95% CI 1.219 to 6.623); p = 0.016) for the ATTUNE. The rates of loosening or revision for loosening were lower, at 1.2% and 0.9% respectively, but the rates varied from 0% to 16.3%. The registry data did not report specifically on the original ATTUNE TKA or on revision due to loosening, but ‘all-cause’ five-year revision rates for the cemented ATTUNE varied from 2.6% to 5.9%. Conclusion. The original cemented ATTUNE TKA has high rates of RLLs, but their clinical significance is uncertain given the overall low associated rates of loosening and revision. However, in view of the high rates of RLLs and the variation in the rates of loosening and revision between studies and registries, close surveillance of patients who have undergone TKA with the original ATTUNE system is recommended. Cite this article: Bone Joint J 2023;105-B(6):610–621

Abstract. Introduction. Choosing a hinged implant in the revision knee arthroplasty (rTKA) setting is challenging and limited data on implant performance exists. We present the survivorship and reason for failure in rTKA performed at our institution using the LINK hinge prosthesis, predominantly the cemented modular Endo-Model prosthesis. Methodology. 260 consecutive revision knee cases performed between 2012 and 2020 were reviewed retrospectively. Mean follow up was 27 months (range 0 to 107). Survivorship was analysed in Stata using a Log Rank test to compare performance in patients stratified according to age (≥80 years old (76 cases), 70–79 years (104 cases) and ≤70 years (80 cases). Results. 53 patients died and 48/207 (23%) cases in 40 patients underwent re-revision. Reasons for re-revision were aseptic loosening (21), infection (12), instability (4), extensor failure (1), stiffness (1), fracture (1) and other (8). Loosening was seen in the femur (8), tibia (5), and both the femur and tibia (8). Sub-group analysis of patients according to age showed a significantly higher failure rate in younger patients (6 failures (8%) in patients ≥80, 27 failures (26%) in 70–79 and 15 (19%) in ≤70 (p = 0.02). Failure in patients ≤70 was predominantly due to aseptic loosening (8/15). Conclusion. Here we report a significantly higher rate of LINK hinge prostheses failure in patients <70 undergoing rTKA. Consent should consider the risk of re-revision in this patient group

Introduction & Aims. In other medical fields, smart implantable devices are enabling decentralised monitoring of patients and early detection of disease. Despite research-focused smart orthopaedic implants dating back to the 1980s, such implants have not been adopted into regular clinical practice. The hardware footprint and commercial cost of components for sensing, powering, processing, and communicating are too large for mass-market use. However, a low-cost, minimal-modification solution that could detect loosening and infection would have considerable benefits for both patients and healthcare providers. This proof-of-concept study aimed to determine if loosening/infection data could be monitored with only two components inside an implant: a single-element sensor and simple communication element. Methods. The sensor and coil were embedded onto a representative cemented total knee replacement. The implant was then cemented onto synthetic bone using polymethylmethacrylate (PMMA). Wireless measurements for loosening and infection were then made across different thicknesses of porcine tissue to characterise the sensor's accuracy for a range of implantation depths. Loosening was simulated by taking measurements before and after compromising the implant-cement interface, with fluid influx simulated with phosphate-buffered saline solution. Elevated temperature was used as a proxy for infection, with the sensor calibrated wirelessly through 5 mm of porcine tissue across a temperature range of 26–40°C. Results. Measurements for loosening and infection could be acquired simultaneously with a duration of 4 s per measurement. For loosening, the debonded implant-cement interface was detectable up to 10 mm with 95% confidence. For temperature, the sensor was calibrated with a root mean square error of 0.19°C at 5 mm implantation depth and prediction intervals of ±0.38°C for new measurements with 95% confidence. Conclusions. This study has demonstrated that with only two onboard electrical components, it is possible to wirelessly measure cement debonding and elevated temperature on a smart implant. With further development, this minimal hardware/cost approach could enable mass-market smart arthroplasty implants

Introduction. Aseptic loosening of the acetabular cup in total hip replacement (THR) remains a major problem. Current diagnostic imaging techniques are ineffective at detecting early loosening, especially for the acetabular component. The aim of this preliminary study was to assess the viability of using a vibration analysis technique to accurately detect acetabular component loosening. Methods. A simplified acetabular model was constructed using a Sawbones foam block into which an acetabular cup was fitted. Different levels of loosening were simulated by the interposition of thin layer of silicon between the acetabular component and the Sawbones block. This included a simulation of a secure (stable) fixation and various combinations of cup zone loosening. A constant amplitude sinusoidal excitation with a sweep range of 100–1500 Hz was used. Output vibration from the model was measured using an accelerometer and an ultrasound probe. Loosening was determined from output signal features such as the number and relative strength of the observed harmonic frequencies. Results. Both measurement methods were capable of measuring the output vibration. Preliminary findings show different patterns in the output signal spectra were visible when comparing the stable cup with the 1mm of simulated spherical loosening at driving frequencies 1050 Hz, 1100 Hz and 1150 Hz (p < 0.05) using the accelerometer, whereas for ultrasound at frequencies 950 Hz and 1350 Hz (p < 0.05). Conclusions. Experimental testing showed that vibration analysis could be used as a potential detection method for acetabular cup component loosening using either an accelerometer or ultrasound probe to detect the vibration. However, the capacity of ultrasound to overcome the attenuating effect of the surrounding soft tissues and its high signal to noise ratio suggest it has the best potential for clinical use

The incidence of loosening of a cemented glenoid component in total shoulder arthroplasty, detected by means of radiolucent lines or positional shift of the component on true antero-posterior radiographs, has been reported to be between 0% to 44%. These numbers depend on the criteria used for loosening and on the length of follow-up. Radiolucent lines are however difficult to detect and to interpret, because of the mobility of the shoulder girdle and the obliquity of the glenoid, which hinder standardisation of radiographs. After review of radiolucencies around cemented glenoid components with a mean follow-up of 5. 3 years in 48 patients we found progressive changes to be present predominantly at the inferior pole of the component. This may hold a clue for the mechanism behind loosening of this implant. Since loosening is generally defined as a complete radiolucent line around the glenoid component and is difficult to assess as a result of the oblique orientation of the glenoid, an underestimation of the loosening rate using radiological data was suspected. Therefore a pilot study using Roentgen Stereophotogrammatric Analysis (RSA) was performed. In five patients an additional analysis of glenoid component loosening using digital Roentgen Stereophotogrammetric Analysis (RSA) was performed. The relative motion of the glenoid component with respect to the scapula was assessed and the length of this translation vector was used to represent migration. Loosening was defined as a migration of the component, exceeding the pessimistic estimate of the accuracy of RSA 0. 3 mm for this study. After three years of follow-up, three out of five glenoid components had loosened (1. 2 – 5. 5 mm migration). In only one patient with a gross loosened glenoid, the radiological signs were consistent with the RSA findings. It was concluded that when traditional radiographs are used for assessment of early loosening, the loosening rate is underestimated. We recommend that RSA be used for this

This systematic review of the literature summarises the clinical experience with ceramic-on-ceramic hip bearings over the past 40 years and discusses the concerns that exist in relation to the bearing combination. Loosening, fracture, liner chipping on insertion, liner canting and dissociation, edge-loading and squeaking have all been reported, and the relationship between these issues and implant design and surgical technique is investigated. New design concepts are introduced and analysed with respect to previous clinical experience

Introduction: High-flexion (HF) TKA designs were introduced in order to achieve greater flexion than with conventional TKA designs. Although early clinical results are promising, recent literature raises concerns about fixation and risk for early loosening of the femoral component during high demanding activities. This study’s aim was to measure the loosening force of the femoral component of several PS-TKA designs in a deep flexion configuration. Methods: The loosening force of the femoral component of ten contemporary PS-TKAs, including five HF and five conventional designs from the major orthopaedic companies were evaluated. To simulate a deep flexion configuration, each TKA was implanted in a femoral bone model and placed in a loading frame in 135° of flexion, with the tibia vertically. Loosening of the femoral component was induced by raising the tibial insert with constant displacement rate, maintaining the same flexion angle. The resisting force was recorded continuously. A stereo-photogrammetric system registered the relative motion between the femoral component and the bone model. The loosening force was determined when a gap of 2 mm was observed. The influence of pegs on the loosening force was also investigated. Results: Generally, conventional femoral designs required higher forces before loosening occurred compared to HF designs (p< 0.001). In the group of the HF designs there was a statistically significant difference between the designs (p=0.015) due to the shape of the internal box cut. For some designs, the presence of pegs induced a statistically significant change in loosening force. Discussion and Conclusion: Several design characteristics of the femoral component can alter its resistance to loosening. In this in vitro study, it was shown that the shape of the internal box cut and the presence of pegs, as well as the geometry of the pegs, are important factors for the loosening force. In the group of the HF components there was a statistically significant difference between the designs with an open and a closed box

The purpose of the present study was to identify risk factors for femoral loosening and neck fracture for Conserve+ metal-on-metal hybrid surface atrhroplasty. The first 500 hips (of over 700 implanted by the senior author) in 436 patients were reviewed. Mean age was 48.6 with 74% of males patients. 16 hips were converted to THR secondary to aseptic failure on the femoral side (11 femoral component loosenings and 5 femoral neck fractures). 14 hips showed radiolucencies around the short metaphyseal stem at last follow-up. A retrieval analysis was performed and analyzed specimens compared with the intra operative photos of the prepared femoral head and the post-op X-rays. The cause of neck fractures is multifactorial. Risk factors include: uncovered reamed bone, leaving the component proud, notching the neck, impingement, osteopenia and cysts, and trauma. Avoidance of technical deficiencies and proper patient selection can eliminate neck fractures. Loosening is also multifactorial. Risk factors for loosening included: cysts > 1 cm, small femoral head size, female gender, early cases (before improved acrylic fixation including femoral suctioning measures were instituted) and reduced stem shaft angle. Meticulous initial preparation of the femoral bone surfaces, drying with suctioning, and maximizing the fixation area are critical when the fixation area is small, especially with osteopenia and cystic degeneration. These techniques have dramatically diminished the incidence of loosening and radiolucencies. Cementing the femoral metaphyseal stem is a meaningful technical improvement towards the prevention of early femoral failure in patients with risk factors

The goal of the study was to describe the features of the aseptic loosening of the cup in CoC THR and to determine factors that affect the time to revision.

It is a retrospective study including all patients who had a revision of CoC THR for aseptic failure fixation of the cup, between 2007 and 2017. 55 patients (27 women, 28 men) (56 hips) were included in the study. Eight hips (13 %) had also a stem exchange. At the primary T HR, the mean age of the patients was 47.9 years (17–72), 28 press fit cups had screws, the mean diameter of the cup was 51.2 mm (46–62) and the mean inclination was 52° (37–67). Clinical and radiological data were retrospectively recorded by an observer different to the initial operators.

The mean age of the patients at the revision was 55.4 years (26–84). The mean time to revision was 90.1 months (14–240), and was significantly greater in patients aged less than 52 years, in cups without screws and with a 28mm head. The trend curve of the time to cup revision showed a bimodal distribution at three and ten years. 20 cups had migrated (33%). Bone loss was rated type 1 in 41 hips (73.0%), type 2 in 12 hips and type 3 in three hips). The mean diameter of the new cup was 52.3 mm (46–64). It was inferior to that of the initial cup in 26 hips (46.4%). 31 cups were impacted (55.5%) and 25 needed to be cemented (45.5%). No macroscopic wear was detected on the ceramic implant.

Aseptic loosening of the cup in CoC THA does not appear to increase over time, supporting the fact that the failure is unrelated to wear and is not due to a biological mechanism. The occurrence of two peaks of frequency over time may suggest that different mechanisms occur.

Purpose: Loosening remains a problem with semi-constrained total elbow prostheses. The trend in recent years has been to improve prosthesis design to achieve stability of the humeral implant. We report a small series of nine Coonrad-Morrey total elbow prostheses where three early loosenings were observed in the ulnar implant. We attempt to analyse the causes and present a review of the recent literature. Material and methods: Nine patients, mean age 60 years, age range 57–63 years, underwent total elbow arthroplasty with a Coonrad-Morrey prosthesis for rheumatoid disease (n=5), stiff degenerative joints after trauma (n=3, flexion-extension 20°), floating joint after trauma (n=1). The posterolateral approach described by Bryan and Morrey was used for eight elbows and the posterior approach for one. Clinical and radiological results were assessed with the performance index and the Mayo clinic score respectively. Results: Mean follow-up was 3.6 years (1.5–4.7). Outcome was very good or good for seven elbows (score > 75 and > 50), fair for one (< 50) and poor for one (< 25). Three elbows were pain free, two presented pain during movement against force. Flexion was greater than 120° in four elbows (all four rheumatoid polyarthritis). Radiologically, we observed three cases of ulnar implant loosening with two type IV lucent lines, and one type III line. There was one humeral implant with a lucent line which did not change over time (type I). The two cases of type IV lines were associated with radial and anterior translation migration of the prosthetic stem with effraction or lysis of the ulnar cortical. The three ulnar loosenings appeared between the second and third postoperative year on two post-trauma stiff degenerative elbows (flexion-extension < 20°) and one rheumatoid elbow. At last follow-up, there was one poor result requiring revision surgery, one fair result, and one very good result (totally asymptomatic type 4 lucent line). Discussion: The causes of these loosenings were studied: difficult cementing technique in a tight canal, mediocre primary stability of the ulnar implant opposing the excellent fit of the humeral implant with an encased graft under the anterior wing, excessive constraint. Our results are similar to those reported by Hilebrand who had 30% evolving ulnar lucent lines and suggest that we should reserve this prosthesis for unstable elbows

High-flexion total knee replacement (TKR) designs have been introduced to improve flexion after TKR. Although the early results of such designs were promising, recent literature has raised concerns about the incidence of early loosening of the femoral component. We compared the minimum force required to cause femoral component loosening for six high-flexion and six conventional TKR designs in a laboratory experiment. Each TKR design was implanted in a femoral bone model and placed in a loading frame in 135° of flexion. Loosening of the femoral component was induced by moving the tibial component at a constant rate of displacement while maintaining the same angle of flexion. A stereophotogrammetric system registered the relative movement between the femoral component and the underlying bone until loosening occurred. Compared with high-flexion designs, conventional TKR designs required a significantly higher force before loosening occurred (p < 0.001). High-flexion designs with closed box geometry required significantly higher loosening forces than high-flexion designs with open box geometry (p = 0.0478). The presence of pegs further contributed to the fixation strength of components. We conclude that high-flexion designs have a greater risk for femoral component loosening than conventional TKR designs. We believe this is attributable to the absence of femoral load sharing between the prosthetic component and the condylar bone during flexion

Prosthetic joint infection (PJI) is a complex disease that causes significant damage to the peri-implant tissue. Developing an animal model that is clinically relevant in depicting this disease process is an important step towards developing novel successful therapies. In this study, we have performed a thorough histologic analysis of peri-implant tissue harvested post Staphylococcus aureus (S. aureus) infection of a cemented 3D-printed titanium hip implant in rats.

Sprague-Dawley rats underwent left hip cemented 3D-printed titanium hemiarthroplasty via posterior approach under general anesthesia. Four surgeries were performed for the control group and another four for the infected group. The hip joint was inoculated with 5×10⁹ CFU/mL of S. aureus Xen36 prior to capsule closure. The animals were scarified 3 weeks after infection. The femur was harvested and underwent micro-CT and histologic analysis. Hematoxylin and eosin (H&E), as well as Masson's trichrome (MT) stains were performed. Immunohistochemistry (IHC) using rabbit antibody for S. aureus was also used to localize bacterial presence within femur and acetabulum tissue .

The histologic analysis revealed strong resemblance to tissue changes in the clinical setting of chronic PJI. IHC demonstrated the extent of bacterial spread within the peri-implant tissue away from the site of infection. The H&E and MT stains showed 5 main features in infected bone: 1) increased PMNs, 2) fibrovascular inflammation, 3) bone necrosis, and 4) increased osteoclasts 5) fibrosis of muscular tissue and cartilage. Micro CT data showed significantly more osteolysis present around the infected prosthesis compared to control (surgery with no infection).

This is the first clinically relevant PJI animal model with detailed histologic analysis that strongly resembles the clinical tissue pathology of chronic PJI. This model can provide a better understanding of how various PJI therapies can halt or reverse peri-implant tissue damage caused by infection.

Total joint replacement (TJR) was one of the most revolutionary breakthroughs in joint surgery. The majority studies had shown that most implants could last about 25 years, anyway, there is still variation in the longevity of implants. In US, for all the hip revisions from 2012 to 2017 in the United States, 12.0% of the patients were diagnosed as aseptic loosening. Variable studies have showed that any factor that could cause a systemic or partial bone loss, might be the risk of periprosthetic osteolysis and aseptic loosening.

Breast cancer is the most frequent malignancy in women, more than 2.1 million women were newly diagnosed with breast cancer, 626,679 women with breast cancer died in 2018. It's been reported that the mean incidence of THA was 0.29% for medicare population with breast cancer in USA, of which the incidence was 3.46% in Norwegian. However, the effects of breast cancer chemotherapy and hormonotherapy, such as aromatase inhibitors (AI), significantly increased the risk of osteoporosis, and had been proved to become a great threat to hip implants survival.

In this case, a 46-year-old female undertook chemotherapy and hormonotherapy of breast cancer 3 years after her primary THA, was diagnosed with aseptic loosening of the hip prosthesis. Her treatment was summarized and analyzed.

Breast cancer chemotherapy and hormonotherapy might be a threat to the stability of THA prosthesis. More attention should be paid when a THA paitent occurred with breast cancer. More studies about the effect of breast cancer treatments on skeleton are required.

Elderly patients with a high mortality risk for revision surgery are severely handicapped by a loosened hip prosthesis. Loosening is mainly caused by particle-induced osteolysis leading to the formation of a synovium-like interface tissue. As an alternative to revision surgery we have investigated the possibility of removing the tissue using a gene therapy approach and thereafter stabilizing the prosthesis with percutaneous cement injection. First we demonstrated that transduction of interface cells with a gene coding for E.coli nitroreductase (NTR) resulted in a 60-fold increase in sensitivity to the prodrug CB1954 that is converted to a toxic metabolite by NTR. Given these in-vitro data, we explored if intra-articular administration of this adenoviral vector encoding NTR followed by the prodrug was able to kill sufficient tissue in-vivo to allow refixation of the prosthesis by cement. We report the first three patients from a phase 1 study of 12 patients with a loosened hip who are experiencing debilitating pain and have significant comorbidity. On day 1 the vector is injected into the hip joint and on day 3 the prodrug is injected. On day 10 three holes are drilled in the femur and one in the acetabulum. Biopsies are taken from the periprosthetic space and low viscosity cement (Osteopal, Biomet Merck, Sjöbo, Sweden) is injected under fluoroscopic guidance. The first three patients have been included in the study and five more are planned for treatment before June 2005. The patients are females of 86, 72, and 79 years old. There were no adverse effects from vector injection (3x10 exp 9 particles). Six hours after prodrug injection the patients experienced nausea, (WHO grade 1) a commonly reported reaction to this prodrug. There was vomiting in two patients. Hip pain increased, but this was anticipated as this therapy will increase prosthesis loosening. 16 ml of cement was subsequently injected into the periprosthetic space in the first patient and 18 ml in the second. The patients were ambulated the day after surgery. The first two patients have a follow-up of twelve and six weeks. There was no pain in the hip. The maximum walking distance had increased from 5 to 30 meters in the first patient. The current study is the first to use in vivo intra-articular adenoviral mediated gene transfer in a clinical setting. Our preliminary results suggest that gene therapy and cement injection for hip prosthesis refixation is clinically feasible

It has been suggested that occult infection of joint prostheses contributes to a proportion of aseptic loosening. The aims of the study were to determine the incidence of occult infection in a sample of patients undergoing revision surgery for aseptic loosening and examine the role of ultrasound sonication in its detection. A prospective trial was conducted at Christchurch and Burwood Hospitals. At the time of revision surgery, intra-operative tissue and fluid samples were taken. The removed prosthesis was immersed in saline solution in a sterile plastic container, and then sonicated. The sonicate fluid underwent prolonged routine cultures (14 days) to increase the rate of detection of slow growing organisms. The cases were patients undergoing revision surgery for aseptic loosening or infection. The control group was comprised of patients having revision surgery for any other indication. These implants were subjected to the same protocol as the study group. A total of 122 patients were included in the study; 54 in the Aseptic Loosening [AL] group, 15 Infections and 53 controls. There were significantly more smokers in the AL group and less smokers in the control group (p=0.04 and p=0.04 respectively). The mean age for revision in the Infection and Periprosthetic fracture groups was less than those of other groups (p=0.007 and p=0.02) respectively. There were 18 cases with positive intra-operative cultures. Eight of those were in the aseptic group (i.e. 14.8% of the group). Conventional sampling techniques were positive in 17 of 18 cultures (94%). Sonication was only positive in 10 out of the 18 cultures (56%). Sonication was concordant with the conventional sampling techniques in half of the positive cultures in the AL group and overall. The only bacteria to be isolated from sonicate cultures were Staphylococcus Aureus and Coagulase Negative Staphylococci. Diabetes Mellitus was the only risk factor to have a significant association with having a positive culture result (p=0.03). There was also a significant association with having raised pre-operative Neutrophil differential count or inflammatory markers with having a positive culture (p=0.0001). However this association was not present when the AL group was examined separately. There was a significant rate of positive culture results in the aseptic loosening group of around 15%. Ultrasound sonication was less sensitive than current sampling techniques with no apparent added benefit. This paper does not support the hypothesis that occult infection is a significant driver of aseptic loosening

Abstract

Increasing femoral offset in total hip replacement (THR) has several benefits including improved hip abductor strength and enhanced range of motion. Biomechanical studies have suggested that this may negatively impact on stem stability. However, it is unclear whether this has a clinical impact. Using data from the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), the aim of this study was to determine the impact of stem offset and stem size for the three most common cementless THR prostheses revised for aseptic loosening.

The study period was September 1999 to December 2020. The study population included all primary procedures for osteoarthritis with a cementless THR using the Corail, Quadra-H and Polarstem. Procedures were divided into small and large stem sizes and by standard and high stem offset for each stem system. Hazard ratios (HR) from Cox proportional hazards models, adjusting for age and gender, were performed to compare revision for aseptic loosening for offset and stem size for each of the three femoral stems.

There were 55,194 Corail stems, 13,642 Quadra-H stem, and 13,736 Polarstem prostheses included in this study. For the Corail stem, offset had an impact only when small stems were used (sizes 8-11). Revision for aseptic loosening was increased for the high offset stem (HR=1.90;95% CI 1.53–2.37;p<0.001).

There was also a higher revision risk for aseptic loosening for high offset small size Quadra-H stems (sizes 0-3). Similar to the Corail stem, offset did not impact on the revision risk for larger stems (Corail sizes 12-20, Quadra-H sizes 4-7). The Polarstem did not show any difference in aseptic loosening revision risk when high and standard offset stems were compared, and this was irrespective of stem size.

High offset may be associated with increased revision for aseptic loosening, but this is both stem size and prosthesis specific.

In a recent phase 2 superiority clinical trial we demonstrated that a single dose of 60mg of the human monoclonal antibody denosumab inhibits osteolytic lesion activity in patients undergoing revision total hip arthroplasty (THA), demonstrating proof of biological efficacy for this clinical application. Here, we examined the effect that denosumab has on disease biology at the osteolysis tissue level.

Osteolytic tissue taken from the prosthesis-bone lesion interface at revision surgery in patients with osteolysis (n=10 participants that had received a single 60 mg dose of denosumab 8 weeks prior to revision surgery and n=10 that had received placebo) was examined for total genetic message activity and protein levels using whole genome sequencing and mass spectrometry, respectively.

The top five upregulated enriched pathways with denosumab treatment included inflammatory response, myeloid cell activation, myeloid leukocyte migration, neutrophil and granulocyte activation (p<6.26 × 10⁻²⁸). Cell morphogenesis was amongst the most downregulated pathways (p<3.42 ×10⁻²³). Finally, comparison of the trial mRNA and protein data versus mouse single cell RNA sequencing data of the same pathway blockade in mouse tibia showed the same direction of effect, suggesting that giving the drug causes then cells responsible for osteolysis to disperse into a more immature form (128 of 189 genes (z=4.87, P<0.0001) disease and functional pathways at the mRNA level and 10 of 11 (z=2.72, P=0.0065) at the protein level).

In this first-in-man study we identify multiple genes and pathways within periprosthetic osteolysis tissue that are affected by denosumab treatment. The dominant pathways involved upregulation of innate inflammatory signaling and downregulation of cell morphogenesis. We also found enrichment of similar disease and functional pathways at both the mRNA and protein levels versus mRNA pathway enrichment found in mouse osteomorphs. These data provide the first human data of the mechanistic effect of denosumab treatment on inflammatory osteolytic lesion activity after joint replacement that is necessary to support its clinical application.

∗Winner of The Bone & Joint Journal prize∗

Aims

The aim of this study was to determine if uncemented acetabular polyethylene (PE) liner geometry, and lip size, influenced the risk of revision for instability or loosening.

Aims

The aim of this study is to report the implant survival and factors associated with revision of total elbow arthroplasty (TEA) using data from the Dutch national registry.

Aims

The current evidence comparing the two most common approaches for reverse total shoulder arthroplasty (rTSA), the deltopectoral and anterosuperior approach, is limited. This study aims to compare the rate of loosening, instability, and implant survival between the two approaches for rTSA using data from the Dutch National Arthroplasty Registry with a minimum follow-up of five years.

Aims

The objective of this study was to compare the two-year migration and clinical outcomes of a new cementless hydroxyapatite (HA)-coated titanium acetabular shell with its previous version, which shared the same geometrical design but a different manufacturing process for applying the titanium surface.

Introduction and Objective

The patients with a total hip arthroplasty is growing in world manly in Europe and USA, and this solution present a high success at 10years in several orthopaedic registers. The application of total press-fit hip fixation presents the most used solution, but presents some failures associated to the acetabular component fixation, associated to the load transfer and bone loss at long term. The aim of this work is to investigate the influence of different acetabular bone loss in the strain distribution in iliac bone. To evaluate implant fixation, an experimental study was performed using acetabular press-fit component simulating different acetabular bone loss and measuring the strain distribution.

For patients who took joint replacement, one of the complications, aseptic joint loosening, could cause a high risk of revision surgery. Studies have shown that MSCs have the ability of homing and differentiating, and also have highly effective immune regulation and anti-inflammatory effects. However, few studies had focused on the stem cells in preventing the occurrence and development of aseptic loosening. In this research, we aimed to clarify whether human umbilical cord mesenchymal stem cells could inhibited the aseptic joint loosening caused by wear particles.

A Cranial osteolysis mice model was established on mice to examine the effect of hUC-MSCs on the Titanium particles injection area through micro-CT. The amount of stem cells injected was 2 × 10 5 cells. One week later, the mouse Cranial were obtained for micro-CT scan, and then stained with HE analysis immunohistochemical analysis of TNF-α, CD68, CCL3 and Il-1β.

All mice were free of fever and other adverse reactions, and there was no death occurred. Titanium particles caused the osteolysis at the mice cranial, while local injection of hUC-MSCs did inhibit the cranial osteolysis, with a lower BV/TV and a higher porosity. Immunohistochemical results suggested that the expression of TNF-α, CD68, CCL3 and Il-1β in the cranial in Titanium particles mice increased significantly, but was significantly reduced in mice injected with hUC-MSCs. The inhibited CD68 expression indicated that the number of macrophage was lower, which might be a result of the inhibition of CCL3.

According to the studies above, HUC-MSCs treatment of mouse cranial osteolysis model can significantly reduce osteolysis, inhibit macrophage recruitment, alleviate inflammatory response, without causing adverse reactions. It may become a promising treatment of aseptic joint loosening.

Previous work has demonstrated increased implant failure in patients with DDH compared to osteoarthritis with historic methods and implants. This study examines outcomes of modern total hip arthroplasty (THA) techniques using uncemented fixation and cross-linked PE (XLPE) bearings for DDH.

A consecutive series of 879 patients with DDH who underwent primary THA with uncemented components and a XLPE bearing at a single institution between 1999 and 2016 were identified. Mean age at index arthroplasty was 51 years, with 78% females. Mean follow-up was 8 years.

5- and 10-year survivorships free of revision were 98.4% and 98%, respectively. 5- and 10-year survivorships free of reoperation for any reason were 97% and 96%, respectively. Survivorship free of acetabular revision for aseptic loosening was 99.8% at 5 and 10 years, while survivorships free of femoral revision for aseptic loosening were 99.7% at 5 years and 99.5% at 10 years. Survivorship free of reoperation for PE damage (2 liner fractures, 2 rim damage from impingement) was 99.3% at 10 years. There were no revisions for bearing surface wear or osteolysis. 13% of patients experienced complications (4% dislocation, 3.3% wound complication rate). Ten-year survivorship free of reoperation for instability was 99.2%. 8 patients developed infection requiring operation (<1%). 100 patients had a prior pelvic osteotomy (11%), which did not increase rate of complications (p=0.22) or reoperations (p=0.51).

Fixation with modern uncemented implants has dramatically reduced implant loosening in patients with DDH, and the use of XLPE bearings has markedly reduced revision for PE wear/osteolysis in this young patient population, leading to dramatically improved mid/long-term survivorship compared to historic series.

Mortality following revision hip surgery for periprosthetic fracture (PPF) has been reported to be as high as 60% at 5 years. The aim of this study was to determine the mortality rate for PPF revisions, compared to revision for aseptic loosening or infection at our tertiary referral centre.

Revision arthroplasty procedures performed for PPF, aseptic loosening or infection between January 2014 and December 2015 at our institution were identified using a prospectively collected PPF referral database and locally collected NJR data. Comparisons were made between the 3 groups for baseline demographics, admission to higher-level care, length of stay, complications, and Kaplan-Meier failure (mortality) at 1 & 5 years post-operative (with log-rank test for equality).

There were 37 PPF, 71 infected and 221 aseptic revisions. PPF had a higher proportion of females (65% vs. 39% in infection and 53% in aseptic; p = 0.031) and grade 3 and 4 ASA patients (p = 0.006). Median time to surgery from injury for PPF was 8 days (95% CI, 6–16). Single-stage procedures were performed in 84% of PPF, 42% of infection and 99% of aseptic revisions (p < 0.001). 19% of PPF revisions required HDU admission, 1% in the aseptic group and none in the infection group (p<0.001). Median length of stay was significantly different (PPF 10; infection 14; aseptic 8 days (p < 0.001). The Kaplan-Meier estimate of 1-year mortality were: PPF = 0%; infection = 2.8% (0.7–11.1%); aseptic = 0.9% (0.2–3.5%). 5-year mortality estimates were: PPF = 17.1% (8–34%), infection = 8.7% (4–18.3%), aseptic = 12% (8.4–17%). Log-rank test of equality was not significant, p=0.833.

Despite the PPF group having an average delay to surgery of 8 days, higher ASA grades and more admissions to HDU there was no significant difference in mortality rates between the groups at 1 and 5 years postoperatively. Using a coherent MDT approach with dedicated healthcare professionals this service demonstrates a low post operative mortality rate which merits further investment and development.

This study evaluates the association between consultant and hospital volume and the risk of re-revision and 90-day mortality following first-time revision of primary hip replacement for aseptic loosening.

We conducted a cohort study of first-time, single-stage revision hip replacements (RHR) performed for aseptic loosening and recorded in the National Joint Registry (NJR) data for England, Wales, Northern Ireland, and the Isle of Man between 2003 and 2019. Patient identifiers were used to link records to national mortality data, and to NJR data to identify subsequent re-revision procedures. Multivariable Cox proportional hazard models with restricted cubic splines were used to define associations between volume and outcome.

Among 12,676 RHR there were 513 re-revisions within two years, and 95 deaths within 90 days of surgery. The risk of re-revision was highest for a consultant's first RHR (Hazard Ratio (HR) 1·58 (95%CI 1·16 to 2·15)) and remained significantly elevated for their first 26 cases (HR 1·26 (95%CI 1·00 to 1·58)). Annual consultant volumes of five/year were associated with an almost 30% greater risk of re-revision (HR 1·28 (95%CI 1·00 to 1·64)) and 80% greater risk of 90-day mortality (HR 1·81 (95%CI 1·02 to 3·21)) compared to volumes of 20/year. RHR performed at hospitals which had cumulatively undertaken fewer than 168 RHR were at up to 70% greater risk of re-revision (HR 1·70 (95% CI 1·12 to 2·60)), and those having undertaken fewer than 309 RHR were at up to three times greater risk of 90-day mortality (HR 3·06 (95% CI 1·19 to 7·86)).

This study found a significantly higher risk of re-revision and early postoperative mortality following first-time single-stage RHR for aseptic loosening when performed by lower-volume consultants and at lower-volume institutions, supporting the move towards the centralisation of such cases towards higher-volume units and surgeons.

Purpose: Loosening of glenoid components in total shoulder arthroplasty is a common clinical problem which can necessitate revision surgery. The mechanism of loosening is poorly understood and may relate to implant design, component fixation techniques, and interfacial tensile stresses. We are unaware of any studies that have examined the fundamental aspects of load transfer to bone for various joint loading configurations. Hence, the objective of this study was to investigate the effect of joint loading on bone strain adjacent to a poly-ethylene glenoid implant. Method: Five specimens (4 males; avg age: 59.5 yrs) implanted with a cemented, all polyethylene component (Anatomical Shoulder; Zimmer) were tested using an apparatus capable of producing loading vectors with various angles, magnitudes and directions. Each specimen was tested using a ramp load of 0–150 N (at 10N/sec) in two directions (superior and inferior) and with six angles of load application. A uniaxial strain gauge was placed in each of the four quadrants of the glenoid, approximately 1 mm medial to the glenoid rim. The primary axis of each strain gauge was oriented medio-laterally to record bone strains. The humeral head was simulated by a custom steel ball with a radius of curvature consistent with a nonconforming humeral prosthesis. Results: The relationship between strain and applied force was not linear (superior quadrant at 40o: linear fit R2=0.96; quadratic fit R2=0.999; p< 0.0005), and was dependent on the loading angle. During pure compressive loading, tension was observed in the superior and inferior quadrants of the glenoid; while less consistent results in the anterior and posterior quadrants revealed variable tension and compression. Superior and inferior loading each caused increasing ipsilateral tension, occurring from 0–30o and 0–20o, respectively. Conclusion: The current study is thought to be the first to directly measure load transfer at the implant-bone interface. We demonstrated load transfer nonlinearities between a surgically implanted glenoid component and the underlying bone in all locations and for a wide range of loading conditions. This has important implications towards the modeling of these constructs using finite element analyses. The results also illustrate tensile loading during compressive and small eccentricity loading cases. These results suggest a polyethylene flexure, causing the periphery of the glenoid implant to flex upwards placing the cement mantle and underlying bone in tension. Tensile loads that are linked to cement mantle fracture and implant loosening are produced under loading conditions associated with activities of daily living. This study has provided insight into the mechanisms of load transfer between a cemented polyethylene glenoid implant and the underlying bone. Reduction or elimination of these interfacial tensile stresses around the glenoid periphery should be considered when developing novel methods for component fixation

Introduction

Recent total knee arthroplasty (TKA) designs have featured more anatomic morphologies and shorter tibial keels. However, several reports have raised concerns regarding the impact of these modifications on implant longevity. This study's purpose is to report the early performance of a modern, cemented TKA design.

The aim of this study is the comparative assessment of long term clinical (subjective and objective), functional and quality of life outcome data between primary and revision THA.

122 patients (130 hips) who underwent cementless revision THA of both components (TMT cup, Wagner SL stem, Zimmer Biomet) for aseptic loosening only (Group A) were compared to a matched group of 100 patients (100 hips) who underwent cementless primary THA for osteoarthritis (Synergy stem, R3 cup, Smith & Nephew) (Group B). Outcomes were evaluated with survival analysis curves, Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Oxford hip score (OHS), Short form-12 health survey (SF-12) and EQ-5D-5L scales. Mobility was assessed with walking speed, timed up and go test (TUG), Parker mobility, Lower extremity function score (LEFS) and UCLA scores.

At a mean follow up of 14.4 years (10 to 20) a cumulative success rate of 96% (95% CI 96 to 99%) in Group A and 98% (95% CI 97 to 99%) in Group B with operation for any reason as an end point was recorded. Statistically significant differences between groups were developed for WOMAC (Mann-Whitney U test, p= 0.014), OHS (Mann-Whitney U test, p= 0.020) and physical component of SF-12 scores (Mann-Whitney U test, p= 0.029) only. In Group A, in multiple regression analysis, patients’ cognition (p=0.001), BMI (p=0.007) and pain (p=0.022) were found to be independent factors influencing functional recovery (WOMAC). Similarly, pain (p=0.03) was found to influence quality of life (EQ-5D-5).

In the long term, revision THA shows satisfactory but inferior clinical, functional, and quality of life outcomes when compared to primary THA. Residual pain, BMI and cognitive impairment independently affect functional outcomes.

Introduction

Tibial component loosening is a frequent cause of failure in primary total knee arthroplasty (TKA). Management options include isolated tibial component revision or full component revision. A full component revision is frequently selected by surgeons who are unfamiliar with the existing implant or have a “let's just start over attitude.” This option adds morbidity versus isolated tibial exchange. While isolated tibial exchange has lower morbidity, it is technically more challenging with regard to exposure and maintaining prosthetic stability. This study was designed to compare these two reconstructive options.

Objectives

Investigate the incorporation of an antibiotic in bone cement using liposomes (a drug delivery system) with the potential to promote osseointegration at the bone cement interface whilst maintaining antibiotic elution, anti-microbiological efficacy and cement mechanical properties.

Prosthetic joint infection and aseptic loosening are associated with significant morbidity. Antibiotic loaded bone cement is commonly used and successfully reduces infection rates; however, there is increasing resistance to the commonly used gentamicin.

Previous studies have shown gentamicin incorporated into bone cement using liposomes can maintain the cement's mechanical properties and improve antibiotic elution.

The phospholipid phosphatidyl-l-serine has been postulated to encourage surface osteoblast attachment and in a liposome could improve osseointegration, thereby reducing aseptic loosening.

Preliminary clinical isolate testing showed excellent antimicrobial action with amoxicillin therefore the study aims were to test amoxicillin incorporated into bone cement using liposomes containing phosphatidyl-l-serine in terms of antibiotic elution, microbiological profile and mechanical properties.

INTRODUCTION

Mechanical loosening of total hip replacement (THR) is primarily diagnosed using radiographs, which are diagnostically challenging and require review by experienced radiologists and orthopaedic surgeons. Automated tools that assist less-experienced clinicians and mitigate human error can reduce the risk of missed or delayed diagnosis. Thus the purposes of this study were to: 1) develop an automated tool to detect mechanical loosening of THR by training a deep convolutional neural network (CNN) using THR x-rays, and 2) visualize the CNN training process to interpret how it functions.

INTRODUCTION

Joint replacement is one of the most common orthopaedic procedures, with over 2 million surgeries performed each year across the globe. Loss of implant fixation, or aseptic loosening, is the leading cause of revision following primary joint replacement, accounting for ∼25% of all revision cases [1]. However, diagnosis of aseptic loosening and its underlying causes remain challenging due to the low sensitivity and specificity of plain radiographs. To address this, we propose a novel approach inspired by [2] involving the use of a self-sensing bone cement (by imparting strain-dependent electrical conductivity or piezoresistivity) combined with electrical impedance tomography (EIT). Piezoresistivity is imparted to cement via incorporation of micro/nanoscale conductive fillers. Therefore mechanical effects such as loosening and cracks will manifest as a conductivity change of the cement. This work explores if EIT is able to detect strains and cracks within the bone cement volume.

Surgical treatment of fragility sacrum fractures with percutaneous sacroiliac (SI) screw fixation is associated with high failure rates in terms of screw loosening, cut-through and turn-out. The latter is a common cause for complications, being detected in up to 20% of the patients. The aim of this study was to develop a new screw-in-screw concept and prototype implant for fragility sacrum fracture fixation and test it biomechanically versus transsacral and SI screw fixations.

Twenty-seven artificial pelves with discontinued symphysis and a vertical osteotomy in zone 1 after Denis were assigned to three groups (n = 9) for implantation of their right sites with either an SI screw, the new screw-in-screw implant, or a transsacral screw. All specimens were biomechanically tested to failure in upright position with the right ilium constrained. Validated setup and test protocol were used for complex axial and torsional loading, applied through the S1 vertebral body. Interfragmentary movements were captured via optical motion tracking. Screw motions in the bone were evaluated by means of triggered anteroposterior X-rays.

Interfragmentary movements and implant motions in terms of pull-out, cut-through, tilt, and turn-out were significantly higher for SI screw fixation compared to both transsacral screw and screw-in-screw fixations. In addition, transsacral screw and screw-in-screw fixations revealed similar construct stability. Moreover, screw-in-screw fixation successfully prevented turn-out of the implant, that remained at 0° rotation around the nominal screw axis unexceptionally during testing.

From biomechanical perspective, fragility sacrum fracture fixation with the new screw-in-screw implant prototype provides higher stability than with the use of one SI screw, being able to successfully prevent turn-out. Moreover, it combines the higher stability of transsacral screw fixation with the less risky operational procedure of SI screw fixation and can be considered as their alternative treatment option.

Background

Implant loosening is a common cause of a poor outcome and pain after total knee arthroplasty (TKA). Despite the increase in use of expensive techniques like arthrography, the detection of prosthetic loosening is often unclear pre-operatively, leading to diagnostic uncertainty and extensive workup. The objective of this study was to evaluate the ability of a machine learning (ML) algorithm to diagnose prosthetic loosening from pre-operative radiographs, and to observe what model inputs improve the performance of the model.

Considerable evidence exists that aseptic loosening is initiated by wear particles that recruit macrophages and stimulate their production of pro-inflammatory cytokines. The cytokines primarily act indirectly by inducing production of RANKL, which stimulates osteoclast differentiation, osteolysis, and inflammatory bone loss. There is also considerable evidence that activation of macrophage Toll-like Receptors (TLRs) contributes to this cascade of events. It is however controversial whether bacterially-derived immunostimulatory molecules known as Pathogen-Associated Molecular Patterns (PAMPs) can contribute to aseptic loosening by stimulating their cognate TLRs on macrophages. Priming and subsequent activation of the NLRP3 inflammasome is essential for macrophage production of mature, active IL-1β in response to wear particles. We recently confirmed that wear particles can activate pre primed NLRP3 inflammasomes in the absence of PAMPs. Thus, activation of the NLRP3 inflammasome is the only macrophage-based event in the aseptic loosening cascade that we have found to date is independent of PAMPs. In contrast, priming of the NLRP3 inflammasome by wear particles requires PAMPs as well as their cognate TLRs. These results add to the growing body of evidence that bacterially-derived PAMPs can contribute to aseptic loosening.

Introduction

A search of the literature indicates several constrained total knee arthroplasty (TKA) systems are at risk for articular surface lockdown bolts backing out. The backing out of a lockdown bolt may lead to an unstable and/or painful knee and may necessitate revision. Upon backing out, the bolt may damage implant components and surrounding tissues. To date, studies in the literature have not simulated or replicated loosening of bolts in TKA. Therefore, the objectives of this study were to 1) develop a set of physiological loading parameters that challenge bolted articular surfaces; 2) evaluate whether significant bolt torque is lost during application of this loading to a CCK device with a bolt as a secondary locking mechanism.

Aim

The aim of our study was to evaluate culture-negative prosthetic joint infections in patients who were pre-operatively evaluated as aseptic failure.

Background

The modern modular implants allow surgeons to combine different combinations of components within the same brand of which some may have completely different design.

During 1999–2012 the same cemented femur component was used together with a cemented stemmed tibia baseplate and also against a cemented pegged tibia baseplate. We decided to compare the revision rate of total knee arthroplasties (TKAs) using these two tibia baseplates.

Background

Mechanisms underlying implant failure remain incompletely described, though the presence of macrophage-mediated inflammatory reactions is well documented. Hypoxia has a critical role in many diseases and is known to be interdependent with inflammation. Metals used for joint replacements have also been reported to provoke hypoxia-like conditions. In view of this, we aim to investigate hypoxia-associated factors in aseptic loosening and osteoarthritis with a focus on macrophages.

Non-large head Metal-on-metal (MoM) hip replacements were seen as a solution to concerns about implant wear in younger patients. Mid-term loosening of once well-fixed hydroxyapatite (HA) coated femoral stems was recently observed in select MoM patients upon revision surgery. Accordingly, an implant retrieval study was undertaken to examine the incidence of aseptic loosening of in HA-coated femoral stems with MoM, ceramic on ceramic (CoC) and metal on polyethylene (MoP) bearing couples.

A single-centre implant retrieval lab reviewed 44 hydroxyapatite (HA)-coated titanium wedge taper stems of the same design retrieved over a period of 9 years. Ten were MoM articulations, 23 MoP and 11 CoC. Head sizes ranged from 28 to 40 with only four 40mm heads, all of which were MoM. Reason for revision, duration of implantation, femoral head size, patient age and body mass index was recorded for each retrieval. Goldberg corrosion scores were determined for the taper surfaces of each retrieval, with ‘0’ indicating no corrosion and ‘3’ indicating severe corrosion. Logistic regression analysis, Wilcoxan Rank Sum and Fischer's exact test were used for statistical analysis.

Aseptic loosening was the listed reason for revision in 18 of 44 cases. MoM bearing was associated with increased probability of aseptic loosening (Odds ratio 7.1 (95%CI 1.1–47.0) p=0.042). Severity of corrosion was also associated with aseptic loosening (Odds ratio 2.75 (95%CI 1.1–6.6) p=0.02). Head size and patient age had no correlation. Median time to revision of implants for aseptic loosening was 4.5 years (range: 4.2–7.0 years) for MoM versus 1.4 years (range: 0.3–3.0) for other bearing couples (p=0.004). Aseptic loosening was categorised as early (<=2 years) or mid-term (>2 years). No MoM hips were revised for aseptic loosening in the first 2 years while 8 of the 11 mid-term revisions had MoM articulations (p=0.004). Taper corrosion was more severe in mid-term aseptic loosing cases (p=0.049).

MoM HA-coated hip replacements appear to be associated with increased mid-term aseptic loosening compared to other bearing couples. Patients with MoM HA-coated hip replacements should be monitored regularly beyond the initial 1 to 2 years following surgery. Future analyses will examine the presence and progression of femoral radiolucency prior to revision surgery to determine an approximate timeline of stem loosening in this patient cohort. This research highlights the importance of implant retrieval programs to assess post-revision implant characteristics for early identification of possible device issues.

We describe a technique for the diagnosis of loosening of the femoral component of the Oxford Unicompartmental Knee Replacement using accurately aligned lateral radiographs in extension and flexion. If gaps are present between the component and cement on one radiograph and not on the other, the component is loose.

Cemented acetabular components commonly have a long posterior wall (LPW). Alternative components have a hooded or offset reorientating geometry, theoretically to reduce the risk of THR instability. We aimed to determine if cemented acetabular component geometry influences the risk of revision surgery for instability or loosening.

The National Joint Registry for England, Wales and Northern Ireland (NJR) dataset was analysed for primary THAs performed between 2003 – 2017. A cohort of 224,874 cemented acetabular components were identified. The effect of acetabular component geometry on the risk of revision for instability or for loosening was investigated using binomial regression adjusting for age, gender, ASA grade, diagnosis, side, institution type, operating surgeon grade, surgical approach, polyethylene crosslinking and head size. A competing risk survival analysis was performed with the competing risks being revision for other indications or death.

Among the cohort of subjects included, the distribution of acetabular component geometries was: LPW – 81.2%, hooded – 18.7% and offset reorientating – 0.1%. There were 3,313 (1.47%) revision THAs performed, of which 815 (0.36%) were for instability and 838 (0.37%) were for loosening. Compared to the LPW group, the adjusted subhazard ratio of revision for instability in the hooded group was 2.29 (p<0.001) and 4.12 (p=0.047) in the offset reorientating group. Likewise, the subhazard ratio of revision for loosening was 2.43 (p<0.001) in the hooded group and 11.47 (p<0.001) in the offset reorientating group. A time-varying subhazard ratio of revision for instability (hooded vs LPW) was found, being greatest within the first 6 months.

This Registry based study confirms a significantly higher risk of revision THA for instability and for loosening when a cemented hooded or offset reorientating acetabular component is used, compared to an LPW component. Further research is required to clarify if certain patients benefit from the use of hooded or offset reorientating components, but we recommend caution when using such components in routine clinical practice.

Background

Hard-on-hard bearings showed advantages of reduction of wear rates, osteolysis and aseptic loosening in total hip arthroplasty (THA). A new combination of ceramic-on-metal (COM) was developed to compensate the disadvantages of MOM and COC. COM showed good short-term results in vitro and in vivo studies. There was no report of stripe wear and metal ion level elevation. Our study was designed to evaluate the wear pattern of this bearing in early loosening THA.

Background

Inflammation and chemokines play a pivotal role in aseptic loosening (AL) and prosthetic joint infection (PJI) of total joint arthroplasty (TJA). Recently, the Duffy antigen receptor for chemokines (DARC) on erythrocytes was identified as a potent chemokine receptor able to bind and carry without deactivating a wide range of CXC and CC chemokines from circulation to tissues. The role of DARC and its functional polymorphism (SNP) influencing the number of the DARC molecules on the erythrocytes in AL/PJI has not been studied yet.

The protective effect of lipped polyethylene uncemented acetabular liners against revision THA for instability has been reported. However, the effect of lip size has not been explored, nor has the effect on revision THA for loosening. We aimed to determine if uncemented acetabular liner geometry, and lip size, influences the risk of revision THA for instability or loosening.

202511 primary THAs with uncemented polyethylene acetabular components were identified from the NJR dataset (2003 – 2017). The effect of acetabular liner geometry and lip size on the risk of revision THA for instability or loosening was investigated using binomial regression and competing risks survival analyses (competing risks were revision for other causes or death) adjusting for age, gender, ASA grade, diagnosis, side, institution type, surgeon grade, surgical approach, head size and polyethylene crosslinking.

The distribution of acetabular liners was: neutral – 39.4%, offset neutral – 0.9%, 10-degree – 34.5%, 15-degree – 21.6%, 20-degree – 0.8%, offset reorientating – 2.82%. There were 690 (0.34%) revision THAs for instability and 604 (0.3%) for loosening. Significant subhazard risk ratios were found in revision THA for instability with 10-degree (0.63), 15-degree (0.48) and offset reorientating (1.6) liners, compared to neutral liners. There was no association found between liner geometry and risk of revision THA for loosening.

This Registry based study confirms a significantly lower risk of revision THA for instability when a lipped liner is used, compared to neutral liners, and a higher risk with the use of offset reorientating liners. Furthermore, 15degree liners seem to have a lower risk than 10degree liners. We did not find an association between acetabular liner geometry and revision THA for loosening.

10- and 15-degree lipped polyethylene liners seem to offer a lower revision risk over neutral liners, at least at medium term followup. Further studies are required to confirm if this benefit continues into the long-term.

Background

The process of osteolysis is well studied both in vivo and in vitro. Although multiple pathways have been implicated in osteolytic change and animal models have been developed there are few human tissue studies. There are no extensive human tissue studies comparing osteoarthritic hips to well fixed and loose prostheses.

Introduction

Computer Tomography (CT) imaging has been limited to beam hardening artefacts until now. Literature has failed to describe sensitivity and specifity for loosening of endoprothesis in CTs, as metal artefacts have always influenced the diagnostic value of CTs.

In recent years a new technology has been developed, the Dual Energy CT. Dual Energy CT scanners simultaneously scan with two tubes at different energy levels, most commonly 100kVp and 140kVp. Furthermore pictures gained from Dual Energy CTs are post-processed with monoenergetic reconstruction, which increases picture quality while further reducing metal artefacts.

This promising technology has increased the diagnostic value preventing more radiation for the patients, for example in detection of kidney stones or to map lung perfusion. In the musculoskeletal imaging it has not been established yet and further clinical investigations are necessary.

Thus the aim of this study is to describe sensitivity and sensibility for endoprothesis loosening of this novel technology.

Aseptic loosening is a major cause of failure of total hip arthroplasty. The adverse tissue response to prosthetic wear particles, with activation of cytokine and prostanoid production, contributes to bone loss around the implants. We have investigated the possibility that inducible nitric oxide synthase (iNOS) and cyclo-oxygenase-2 (COX-2) are expressed in macrophages in the pseudomembrane at the bone-implant interface, thereby contributing to the periprosthetic bone resorption.

We also assessed whether peroxynitrite, a nitric oxide (NO)-derived oxidant associated with cellular injury, is generated in the membrane. Enzymatic activity of iNOS was measured using the arginine-citrulline assay technique and prostaglandin E₂ (PGE₂), as an indicator of COX-2 activity, was measured using an enzyme immunoassay.

Cellular immunoreactivity for iNOS, nitrotyrosine (a marker of peroxynitrite-induced cellular injury) and COX-2 was assessed by quantitative peroxidase immunocytochemistry while immunofluorescence methods were used for subsequent co-localisation studies with CD68⁺ macrophages.

The presence of calcium-independent iNOS activity and PGE₂ production was confirmed in the homogenized interface membrane. Immunocytochemistry showed that periprosthetic CD68⁺ wear-debris-laden macrophages were the most prominent cell type immunoreactive for iNOS, nitrotyrosine and COX-2. Other periprosthetic inflammatory and resident cell types were also found to immunolocalise nitrotyrosine thereby suggesting peroxynitrite-induced protein nitrosylation and cellular damage not only in NO-producing CD68⁺ macrophages, but also in their neighbouring cells. These data indicate that both iNOS and COX-2 are expressed by CD68⁺ macrophages in the interface membrane and peroxynitrite-induced cellular damage is evident in such tissue. If high-output NO and peroxynitrite generation were to cause macrophage cell death, this would result in the release of phagocytosed wear debris into the extracellular matrix. A detrimental cycle of events would then be established with further phagocytosis by newly-recruited inflammatory cells and subsequent NO, peroxynitrite and prostanoid synthesis. Since both NO and have been implicated in the induction and PGE₂ maintenance of chronic inflammation with resulting loss of bone, and peroxynitrite in the pathogenesis of disease states, they may be central to the pathogenesis of aseptic loosening.

A longitudinal study was done assessing the latest radiographs available in a series of collarless Corail uncemented stems which have reported survival rates of 95% at 20 years. Parameters scored included the degree of “Ghosting” or delamination, the Gruen, the stem fit in the femoral canal and the degree of calcar resorption. Patient and implant demographics were noted.

At 3 years the loosening rate was 23% reaching 64% at 6 years after the index procedure. It was present in all age groups, with a peak in the 24 to 49 year age group. Males and females had the same occurrence. When it was present this was always in zone 1. It was present in 6% of patients in zone 7, but then always associated with zone 1 changes. High and standard off-set stems had the same loosening rates. The looser fit of the stem the higher the incidence of loosening. There was no correlation to the type of bearing surface or the degree of calcar resorption. Those patients with a BMI of 25 – 35 had lower loosening rates compared to those with higher or lower BMI's.

We postulate that cancellous bone on-growth onto the hydroxyapatite coating associated with loading flexural micro-motion leads to hydroxyapatite being pulled off the smooth stem substrate in zone 1. Progressive delamination of the hydroxyapatite then occurs. The triple-tapered design though imparts continued stability.

We report high loosening rates in the Corail stem and suggest a mechanism for its development.

Aseptic loosening is the single most important long-term complication of total joint arthroplasty. Wear debris induced inflammation stimulates osteoclastic resorption of bone. Cellular mechanisms involved in osteoblast viability in PWD induced inflammation is poorly understood.

Wear induced inflammation increases osteoblast necrosis and susceptibility to death by apoptosis. PMMA cement has a detrimental effect on osteoblast resistance to apoptosis, and that this is via an receptor mediated pathway. Osteoblast cell cultures (Human and MG63) were grown with and without PMMA cement and assessed for apoptosis and necrosis. TNF-α or Fas antibody simulated inflammation. Viability and apoptosis with PI exclusion, flow cytometry and western blotting assessed response.

Cement induced osteoblast necrosis up to 1 hour. This effect was negated after 24 hours. Culture of osteob1asts on cement had no direct effect on spontaneous apoptosis but susceptibility to inflammation was increased.

Polymerised cement has no direct effect on osteoblast cell death. Effects are mediated by inhibiting expression of anti-apoptotic protein (Bcl-2), and increasing susceptibility to inflammatory. Osteoblast resistance to death may represent a novel and important factor in aseptic loosening. The role of gene therapy is explored.

Introduction and Aims: Accumulating evidence suggests that bacterially derived endotoxins may contribute to aseptic loosening. This study determined whether lipopolysaccharide (LPS), the classical endotoxin from Gram-negative bacteria, can be detected in periprosthetic tissue from patients with aseptic loosening. We utilised an assay that detects all forms of LPS and is unaffected by beta-glucan-like molecules.

Method: Periprosthetic tissue from revision total hip arthroplasty and synovia from primary total joint arthroplasty were homogenised in PBS in endotoxin-free conditions. Non-specific amidases in the homogenates were inactivated at 100 degrees C. LPS was measured using the Endospecy assay (Associate of Cap Cod). Multiple dilutions of the homogenates were assayed to maximise sensitivity, while avoiding assay inhibition assessed by spike recovery determinations. Results were corrected for colour and spike recovery. Assay results were considered positive if the absorbances were higher than the lowest standard and the LPS level was significantly greater (p< 0.05) than the PBS control. Statistical analysis was by ANOVA with Bonferroni-Dunn (Control) post-hoc tests.

Results: Samples from 13 patients have been studied to date. Multiple assays of four of these samples showed no detectable LPS while nine of these samples resulted in both positive and negative assays. This inter-assay variability prevents measurement of the concentration of LPS in the samples. Nonetheless, many of the samples contain detectable amount of LPS. Thus, six out of eight samples from revision THA patients with aseptic loosening had positive assays, as did two of four primary TJA patients. LPS was also detected in a sample from a revision control. These results demonstrate that samples from THA patients with aseptic loosening and from primary TJA contain detectable amounts of LPS derived from Gram-negative bacteria.

Conclusion: This conclusion is consistent with numerous studies, showing that human serum contains LPS derived from minor infections, gut flora, or dental procedures. It is likely that many of these samples also contain molecules derived from Gram-positive bacteria that have very similar biological effects as LPS. However, detection of these Gram-positive molecules await further improvements in assay specificity and sensitivity.

Background

Polyethylene wear in both cemented and uncemented total hip arthroplasty (THA) lead to generation of particles with their access to the interface which has been responsible for periprosthetic osteolysis and subsequent loosening of cup and stem. Many studies have been published studying the pattern of polyethylene wear and its relation to the type of implant (cemented/ uncemented cup or ceramic/metal head) used. No study in our knowledge has strictly focused on the effect of cemented versus uncemented stem on the polyethylene wear rates. We tried to compare the polyethylene wear rates reckoned with software (Poly Ware REV 7) of ultra high molecular weight polyethylene (UHMWPE) in hybrid and uncemented THA and its effect on complications of total hip replacements.

Early revision after total knee arthroplasty (TKA) is fortunately uncommon. However, instability and lack of fixation are common early failure mechanisms. Cement techniques utilizing lavage and multiple drill hole interdigitation of the resected tibial surface can reduce micromotion and produce reliable tibial component fixation. This study looks at clinical failure mechanisms, cement technique and polyethylene damage in patients needing early revision of cemented TKA.

PCL-retaining TKA with cement fixation was performed on > 1000 patients at a single institution. Cement techniques varied with surgeon, with some using lavage and drill hole preparation of the resected surface and others electing to cement the surface “as cut”. Seventeen patients were revised within three years of follow-up. Revision reasons included loosening (41%), instability (18%), infection (24%), pain (12%), and malposition (6%). Prospective outcome scores, radiographic data, revision reasons, and polyethylene wear were compared.

Pre-revision pain and function scores gradually decreased back to pre-operative levels. Leg alignment averaged 7° varus (nine patients) and 12° valgus (eight patients) pre-operatively and 5° valgus at pre-revision. Tibial radiolucent lines were present medially only in nine knees and medially and laterally in four knees. The majority of patients revised for loosening had a tibial component cemented onto the “as cut” bone without additional preparation. Damage covered 32%-85% of the polyethylene articular surface. Scratching and pitting were significantly correlated (p< 0.05) with shorter in-situ time and revision for instability and loosening. Alignment and outcome scores were not correlated with damage.

In this series of cemented TKA, loosening and instability accounted for 59% of the early failure, similar to the incidence previously reported for cementless TKA. Cement technique and component positioning, not polyethylene wear, were the primary contributing factors. Attention to ligament balancing and achieving better tibial component fixation is needed to further limit the incidence of early failure after cemented TKA.

Aims: To determine the usefulness of preoperative CRP, ESR, WCC and joint aspirate in the diagnosis of infective loosening before revision TKA.

Methods and Materials: Retrospective review of patients undergoing revision TKA for the period May 1998 to May 2008 was performed, examining the results of preoperative CRP, ESR, WCC, joint aspirate and intra-operative microbiological samples. Positive results were CRP ≥10 mg/dL, ESR ≥ 22mm/hr, WCC ≥11 g/dL and positive growth on culture unless stated as contaminant. The data was analysed to determine sensitivity, specificity, negative and positive predictive values of the tests for single stage and staged revisions.

Results: 51 patients underwent single stage revision with 10 positive cultures. CRP and WCC were highly specific for infection (84%, 98%) with low sensitivities (10%). ESR was 66% specific and 25% sensitive. All had high negative predictive values (76–86%).

23 patients underwent staged revision. 17 cases had positive cultures at 1st stage and 8 at 2nd stage. 1st stage CRP, ESR and WCC had low sensitivity (67%, 59%, 17%). WCC was 80% specific whereas CRP and ESR had low specificity (25%, 20%). All had high positive predictive value (71–80%). 2nd stage CRP and ESR were specific for infection (71%) but had low sensitivities (22 and 44%). WCC was 0% sensitive but 87% specific. Negative predictive values of CRP, ESR and WCC were 63, 71 and 62%.

For both single stage and 1st stage staged revisions, pre-operative joint aspirate was 100% specific with sensitivities of 0% for single stage and 50% in staged revisions.

Conclusion: All patients undergoing both staged and single stage revision arthroplasty should routinely have preoperative inflammatory markers and joint aspirate. However, positive intraoperative cultures may still be obtained despite negative preoperative investigations.

The presence of microdamage in bone and its targeted repair by activating bone remodelling has been controversial partly because it is difficult to locate and difficult to quantify. A number of studies have now validated techniques to locate and quantify microdamage and microdamage repair in human cortical and trabecular bone samples. The purpose of this study is to determine if microcracks accumulate in the cancellous bone of the intertrochanteric region of the proximal femoral shaft and influence the strength of bone. We have used en bloc basic fuchsin staining to identify in vivo microcracks in 70 micron sections. Trabecular bone was sampled in 33 patients undergoing total hip replacement for primary osteoarthritis. The study sample had a median age of 73 years and included 18 women (aged 49 to 84 years) and 15 men (aged 45 to 85 years). Histomorphometry was used to quantify the number of cracks in each case. In a selection of 12 cases the bone sample was also biomechanically tested to determine the cancellous bone strength. We found that microcracks accumulate with age, particularly after the age of about 60 years. This indicates that the bone from the elderly is more susceptible to fatigue damage than bone from the young. In addition, an increased number of microcracks in the cancellous bone significantly reduced the ultimate failure stress of the bone. Bone screws or pins placed in cortical or trabecular bone create microdamage adjacent to an implant, and the area in which this microdamage occurs is the same as that which subsequently remodels. Microdamage may be the result primarily of procedures during prosthetic implantation, but bone screws or pins can create stress concentrations that can be sites for initiation of new cracks. Therefore, if bone remodelling targets bone microdamage for repair then accumulation of microdamage around prosthetic implants may be responsible for the biologic responses which lead to implant loosening. This phenomenon is understudied in orthopaedic research and is an area requiring further investigation.

Aseptic loosening has become the single most important long-term complication of total joint replacements. The pathophysiology of this loosening is multifactorial in origin ranging from mechanical wear, poor surgical technique, thermal damage and the inflammatory response to particulate wear debris. Cytokines are released in response to macrophage activation by particulate wear debris (PWD), the resultant inflammatory cascade stimulates osteoclastic resorption of bone. The failure of remodelling and repair mechanisms may be as a result of Osteonecrosis from cement (PMMA).

Hypothesis: That PMMA increases Osteoblast susceptibility to necrosis and apoptosis following inflammatory challenge.

Materials and Methods: Osteoblast cell cultures were grown on PMMA cement plates and assessed for apoptosis and necrosis by PI exclusion staining, morphological changes on light and electron microscopy and flow cytometry.

Results: PMMA induced osteonecrosis is highest at 1 hour (34.45) in comparison to control levels (4.55). There is no significant change in Apoptosis at 24 hours. Culture of the Osteoblasts on cement and delayed stimulation with TNF-α causes increased Apoptosis and Necrosis.

Conclusion: PMMA cement causes Osteoblast necrosis in the early stages of polymerisation, after 24 hours there is little increase in apoptosis/necrosis. However Osteoblasts that grow in contact with cement are more susceptible to apoptosis and necrosis following TNFα challenge. This may prove to be an important step in the pathogenesis of Aseptic loosening.

We reviewed 40 cementless Porous Coated Anatomic knee replacements in 34 consecutive patients. The average follow-up was 12.9 months (range 6 to 36 months). At review, loose beads were identified in 23 knees, in 11 on the femoral side and in 16 on the tibial side (in five knees on both sides). One loose bead was adjacent to the patella. In four knees there were intra-articular beads. Radiolucent lines at the interface between bone and prosthesis were seen in 19 knees, in six on the femoral side and in 16 on the tibial side (in three knees on both sides). In relation to the tibial component loose beads were associated with a radiolucent line in all except one case. Progressive loosening with an increasing number of loose beads was seen in three knees. At this early stage of follow-up there was no correlation between the clinical results and the presence of loose beads.

Introduction: A retrospective audit to evaluate the results of Austin Moore hemiarthroplasty conversion to Total hip arthroplasty for suspected aseptic loosening.

Materials and Methods: A consecutive cohort of patients who had conversion of Austin-Moore hemiarthroplasty to Total hip arthroplasty performed at our district general hospital between August 2000 and May 2006 were included in the study.

The total of 41 patients were divided into two groups depending on the duration between the primary hemiarthroplasty procedure and its revision to total hip arthroplasty – (1) Less than one year (16 patients) and (2) More than one year (25 patients).

The data collected included: age, sex, classification of the fracture, date of primary operation, surgical approach, inflammatory markers, indication and date of revision to total hip arthroplasty, and the final outcome.

Results: The rate of infection after the revision to total hip arthroplasty was found to be 25% (4/16 patients) in patients who underwent the revision operation within 1 year after the primary operation, whereas the infection rate was 8% (2/25 patients) for those who had the revision operation more than a year after the primary operation. The difference in infection rates between the two groups was found to be statistically significant despite the small numbers.

Discussion: The patients who have early loosening of the Austin-Moore hemiarthroplasty within the 1 year of the primary procedure should raise a suspicion of occult infection. Despite near normal inflammatory markers, a two-staged conversion to total hip arthroplasty should be seriously considered.

Purpose of the study: This series included 50 consecutive cases of titanium hydroxyapatite coated cups impacted directly on live bone of the neoacetabulum after removal of a loosened cup implanted and reviewed at more than ten years.

Material and methods: The goal was to insert a titanium hydroxyapatite-coated cup on the largest quantity of healthy cancellous bone in the neocavity without using a graft and without worrying about the future height of the center of rotation nor the medial offset. The shortened impaction related to the neoacetabulum formed by the loosening could be compensated for by descending the femoral stem a bit further. This method of acetabular revision was performed for 75 hips before 1993. At more than ten years follow-up, four hips were lost to follow-up, 20 patients had died, and one case of early suppuration was noted. The series thus included 50 cups in 48 patients (22 men and 26 women, mean age 67 years at revision surgery). The Charnley classification was: A:21, B:22, C:7. Mean follow-up was 11 years. The SOFCOT staging was: I=0, II=33, III=14, IV=3. AAOS I=0, II=32, III=18, IV=0. The number of prior cup replacements: 0=46, 1=4. Approach: trochanterotomy (n=44), femorotomy (n=0), posterolateral alone (n=6). Mean cup diameter 60 (range 48–68). Femoral stems changed = 20. Preoperative PMA = 12 and postoperative PMA = 16.

Results: Among the 50 hips, 48 exhibited optimal fixation without lucent line or bone defect. One patient presented a partial lucent line and one had revision at nine years. At five years, all cups (100%) were in place and at ten years 98%. There were no cases of pelvic fracture and only three stage IV hips.

Discussion: The advantages of this method are to avoid the use of a graft or frozen head, and the generally immediate/rapid weight bearing. This series raises the question of whether it is advisable to replace the new cup in the position of the paleoacetabulum. These implants can be improved with screwed cups onto which a double-mobility cup can be press-fit. This technique has enabled weight-bearing in conditions which otherwise would not have been possible for these frail elderly patients.

Conclusion: In light of this consecutive series reviewed at more than ten years, we have decided to continue this approach.

Purpose: We report our results of revision procedures for severe acetabular loosening with saddle prostheses. The series concerned six patients, mean age 67 years age range 58–82 years, who initially presented rheumatoid disease (n=3), degenerative hip disease (n=3, one secondary to trauma), and radiation-induced hip disease (n=1). These patients had undergone one to three procedures for reconstruction with a bone graft and metal implants.

Material and methods: Failure was the indication for salvage with a saddle prosthesis due to massive loss of acetabular bone stock, complicated in five cases by an unstable hemipelvis due to transverse nonunion. An allograft was screw fixed in the iliac wing in two cases to stabilise the saddle prosthesis. Weight bearing was allowed early after surgery in all cases except two. The hip was immobilised in four cases for three to six weeks in a bermuda cast or with traction (n=4). Follow-up was 2 to 5 years.

Results: There was only one complication: stress fracture of the iliac bone at two years which did not heal. Bone graft with ostheosynthesis was proposed. Pain relief was nearly total in all cases. Four patients could walk without crutches and two walked with two crutches or an ambulator due to associated disease or alar fracture. The fixation was at 60 – 95° with abduction at 10–30°. All patients were satisfied and two felt the result was very superior to simple ablation of the prosthesis which they had experienced. Radiograpically, there was no evidence of ascension of the saddle but the risk remains at this short follow-up due to the rates described in the literature. One major migration was observed as was one stress fracture of a weak iliac bone which required removal of the implant.

Discussion: This difficult technique provides a better result and thus would be indicated for young patients able to sustain the intervention. It would be logical to associate a supporting bone graft on the iliac bone to prevent stress fracture and migration of the saddle. The saddle prosthesis appears to be the last resort after failure or insufficient results after prior reconstruction. The leading cause of failure is nonunion with hemipelvis mobility. This suggests the intervention should be considered before reaching this stage of well tolerated ace-tabular loosening.

The early diagnosis of aseptic loosening of a total hip replacement by plain radiography, scintigraphy and arthrography has been shown to be unreliable. It has been suggested that it may be possible to distinguish between a secure and a loose prosthesis using a vibration technique. We have assessed the use of this technique in vitro using models of early and late loosening. Late loosening with an unstable prosthesis can be reliably detected by vibration analysis, but this method was shown to have a very poor diagnostic sensitivity in early loosening when there is no obvious prosthetic instability.

1. Prosthetic acetabular cups of the Charnley and McKee-Farrar designs were cemented into cadaveric pelves using different procedures for preparing the acetabulum.

2. The torsional moments needed to loosen these cups were measured.

3. The torsional moments so measured were found to be from about four to more than twenty times higher than the frictional moments measured in independent tests on the two designs of prosthesis.

4. It is argued that late looseness of the acetabular component after total hip replacement, in the absence of infection, seems most likely to be due to thermal damage to the bone occurring at the time of polymerisation of the cement, and to subsequent bone resorption.

5. Surgical preparation of the acetabulum should include removal of all the articular cartilage and cleaning of the acetabular fossa, but the drilling of additional holes in the floor of the acetabulum seems unimportant.

6. The possibility of fatigue fracture in bone as a factor contributing to late loosening is an argument in favour of metal-on-polyethylene prostheses with their lower frictional moments, although the importance of this factor cannot be estimated.

The experience that we gathered using uncemented stems for revisions with diaphyseal anchorage gave us satisfactory outcomes both for survival curve

(94% of cases – 15 yrs follow-up) and for clinical results in the aseptic mobilisations.

Thus, we extended this technique in the re-implant of septic prostheses.

We treated 43 cases of septic hip prostheses from 2003 to 2006. The treatment of choice has been the two-stage revision with the implant of temporary spacer, utilising the one-stage treatment just in few cases selected from needle-aspiration positive culture. The technique foresees the utilisation of Wagner uncemented revision stems in 98% of cases and 2% using a first implant prosthesis. Accompaniment antibiotic protocol has been protracted for 3 – 6 months till the negativity of the inflammation index.

Average follow-up of 26 months shows good clinical and radiographical results with percentage of a new revision of the two-stage in 2.32% (1 case).

The uncemented components are confirmed to be the best presidia for the implant stability retrieval in the immediate and long-term either, the two-stage strategy appears sure enough for the re-infections control especially associated with an adequate antibiotic treatment. Therefore, the choice strategy proposed by us favours the uncemented implants in combination with the two-stage.

Aims

Radial head arthroplasty (RHA) may be used in the treatment of non-reconstructable radial head fractures. The aim of this study was to evaluate the mid-term clinical and radiographic results of RHA.

We have demonstrated that erythromycin (EM) inhibits wear debris-induced macrophage activation and osteo-clastogenesis (both in vitro and in vivo) through targeting NF-κB signalling. Our clinical trial further verified that oral EM can be efficiently delivered to periprosthetic tissue and improve local inflammation. The purpose of this study was to assess the efficacy of periprosthetic EM delivery in a rat osteolysis model.

The PA coated titanium (Ti) pin (Stryker) was loaded with EM (8 μl = 2.8 mg/pin). Drug release assay showed around 25% of loaded EM was remained in the PA layer 24 hours after loading. Rats were divided into three groups:

saline control (n=5);

Uncoated Ti pins were pressfit inserted into right tibia following the injection 200 μl of either UHMWPE particles (5 mg/ml) or saline (control). The revision surgeries were performed 6 weeks after the first surgery. The previous implanted pins were replaced with new Ti pins either with or without EM coating. Rats were then sacrificed one month after “revision surgery”, and the knee joint samples were collected for μCT and histology analysis.

μCT analysis showed that the value of bone volume (bv/tv) in the group treated with EM (0.26 ± 0.07) was significantly higher than the group untreated (0.14 ± 0.04), while there was no significant difference between EM treated group and the saline control group (0.15 ± 0.11). The parameters of cancellous bone structure all pointed a trend of better structure in EM treated group than other two groups. However, this difference did not reach statistical significance. Histology analysis (H& E staining) demonstrated that in the saline control the tibia retained a smooth endocortical surface with a prominent periprosthetic membrane. In the EM-treated group, endocortical erosion was reduced and the peri-prosthetic tissue appeared thinner than uncoated pins.

The overall cellularity of periprosthetic membranes from the EM-treated group was decreased compared to the untreated group. Analysis of membrane thickness revealed a significantly thinner membrane in EM-treated group compared with untreated group and saline control (p< 0.05).

The results of this study seem to indicate that an EM coated Ti pin provided a sufficient drug source to effectively treat wear debris-induced periprosthetic inflammation and osteolysis.

Aseptic loosening arises when periprosthetic bone loss results in mechanical failure at the host-implant interface, and is the main factor limiting implant survival after total hip arthroplasty (THA). The aims of this study were to determine whether genetic variation is a risk factor for loosening, explore the metabolic mechanisms of periprosthetic bone loss, and determine whether bisphosphonates may prevent bone loss and enhance implant mechanical stability after THA. In a genetic association study (J Bone Mineral Res2003; 18:1995–2001) we found that carriage of the −238A allele within the promoter region of the TNF gene was an independent risk factor for aseptic loosening. A subsequent reporter gene assay showed differential TNF gene responsiveness between the –238A and –238G alleles to polyethylene particule stimulation (Calcified Tissue Int 2003; 72: 251-273). In a cross-sectional study (J Orthop Res 2003; 214: 691–696) we found that subjects with aseptic loosening had lower bone mineral density (BMD) in the region of the femoral calcar and higher urinary excretion of cross-linked collagen breakdown products than their counterparts with fixed femoral implants. In a randomised controlled trial we found that a single dose infusion of a bisphosphonate (pamidronate) reduced femoral bone loss over 2 years after THA, but did not affect pelvic bone loss or implant migration (J Bone Miner Res2002; 17: 1328). Transient increases in bone turnover markers occurred after surgery and were highly predictive of later femoral BMD change. The main predictor of early implant migration was patient age, but not periprosthetic BMD change. In summary, genetic as well as environmental factors affect implant survival after THA. Aseptic loosening is associated with regional changes in bone mass and turnover as well as focal osteolytic lesions. Bisphosphonate therapy is well tolerated after THA and has a clear biological effect. However, the impact of preventing early bone loss on late aseptic loosening remains unclear and awaits long term study.

[Winner, Robert Jones Gold Medal and Association Prize, 2003]

Aims: The symptoms of aseptic and septic prosthetic joint loosening may be similar, and identification of low-grade prosthetic infection based only on clinical history and physical examination has a reported low sensitivity. In a prospective study we explored to what extent a thorough examination of the patient’s history of sickness and a standardized preoperative clinical examination could help the surgeon to identify cases of septic loosening.

Methods: We included 54 patients undergoing revision surgery due to loosening of a total hip or knee prosthesis. Preoperatively a standardized form which included data regarding the patient’s history of sickness was obtained and a physical examination was performed.

Postoperatively a final diagnose was made based on microbiological testing, which in addition to routine culture, included sonication of the prosthesis and nucleic acid based diagnostics (PCR). Data from the preoperative examination was evaluated in relation to the final diagnose (chi-square test and Student’s t-test), and the sensitivity and specificity for diagnosing a septic loosening was calculated for each preoperative finding.

Results: According to the final diagnose, 21 patients had a septic loosening and 33 patients had an aseptic loosening. In the septic group and aseptic group the following anamnestic data was registered: Pain during rest: 16/21 vs. 7/33 (p < 0.001). Prior history of soft tissue debridement: 11/21 vs. 4/33 (p = 0.001). Prior prosthetic revision surgery: 13/21 vs. 8/33 (p = 0.006). Time from index operation to revision: 45 (5 – 144) moths vs. 159 (22–390) moths, (p = 0.02). Time from index operation to debut of prosthetic assosiated dyscomfort: 10 (0–110) moths vs. 120 (0–240) moths, (p < 0.001). The calculated sensitivity (se) and spesifisity (sp) for the pre-operative findings were: Existence of prosthetic related pain during rest: 79% se, 79% sp; history of soft tissue revision in the affected joint 52% se, 88% sp; history of prior exchange prosthetic revision in the affected joint 62% se, 76% sp, respectively.

Conclusion: We advise a carefully obtained history from every patient presenting with loosening of implanted prosthetic components for identification of a potential low grade infection. In particular, pain during rest has a notable sensitivity and specificity. A prior history of soft tissue revision also strongly indicates a septic prosthetic loosening.

Hip simulator studies with ceramic-on-metal (COM) predicted less wear than metal-on-metal (MOM: Isaac. 2009). While clinical evidence is scant, two COM case reports described pseudotumors with adverse cup positioning (Deshmukh 2012, Koper 2014). It would appear that our Korean case report is the first to describe pseudotumor formation in well-positioned COM arthroplasty and including detailed failure analysis. A 50-year old female (active salesperson) had bilateral avascular necrosis of her femoral heads. A left metal-on-polyethylene (MPE) hip was performed at outside institution in 2003. At our 3-yrs evaluation, radiographs showed well-functioning MPE hip. Five years later she complained of gradual left-hip pain (2011). Radiographs and CT scan demonstrated wear, osteolysis and loosening of both components. The revision in 2011 was by COM (Fig. 1), using S-ROM stem/sleeve, 36mm ceramic head (Biolox-delta), a CoCr liner and 54mm shell (Pinnacle: Depuy Inc). Cup inclination and anteversion were considered appropriate at 45° and 20° respectively; femoral anteversion of 15° was also appropriate.

At 1-yr follow-up patient complained of mild discomfort in left COM hip (2012). Range of motion was painless and normal. Examination revealed a soft, non-tender swelling (2×3cm) in left inguinal region with no inflammation and radiographs were normal (Fig. 1a). One month later the patient complained of left hip pain, the previously noted swelling had increased in size, and she started to limp. Radiographs showed cup migration with increased inclination. CT scans showed a circumscribed lesion extending into iliopsoas region (Fig 2). Serum cobalt and chromium levels were high at 2.4 and 22.5µg/ L, respectively.

At revision the pseudotumor and surrounding inflamed synovium was excised. The cystic soft-tissue swelling (stained black) extended into the joint (Fig. 2a). The ceramic head showed a large “black stripe” across the dome (Fig 2b). The cup was loose while the femoral stem was well fixed. Operative cultures of soft tissues and joint fluid were negative for infection while histopathology was consistent for metallosis (Fig. 3). Aggressive debridement was carried out, acetabular defects were filled with bone graft. Revision incorporated 32mm ceramic head (Biolox-delta), highly cross-linked liner and 52mm trabecular-metal shell (Depuy). Functionally the patient has continued to improve. By 6 months, serum ion concentrations decreased to Co:1.3 and Cr:2.54µg/ L with most recent ion levels lower still (Co:0.66 and Cr:0.42µg/ L).

Ceramic head surfaces showed normal wear appearance. The large gray stripe identified on the highly polished dome contained Co and Cr metal-transfer from the CoCr liner (Fig. 2b). Thin gray stripes on equatorial head regions (x4 rougher than dome) represented contamination by Ti, Al and V, typical of adverse impingement against Ti6Al4V neck (Clarke 2013). There was a 100–150um defect on rim of CoCr liner as a result of impingement. Cup out-of-roundness was 476um compared to only 7um for ceramic head, thus cup wear dominated at 25–30mm³ volume. This case report was illustrative of the unpredictable and seldom diagnosed risk of habitual cup-to-neck impingement and the risk of relying on pristine simulator studies to predict outcomes in novel THA bearings.

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Introduction: The biological processes underlying osteolysis in aseptic loosening are not completely understood, but are believed to include factors such as hydrostatic pressure and wear debris. Characterisation of the pseudosynovial membrane from failed implants has revealed numerous cell types with well characterised roles in osteoclastogenesis and bone resorption. More recent work has demonstrated the presence of immunomodulatory cells, including T cells. IL-17 is a T cell product that is believed to be capable of inducing bone resorption. The aims of our study were to characterise the effects of IL-17 on the expression of RANKL and OPG by synovial fibroblasts and to evaluate its role in supporting osteoclastogenesis in vitro.

Materials and Methods: Synovial fibroblasts (SFB) were isolated from tissue obtained at joint replacement surgery. SFB were expanded in culture and used in experiments between passage 4 and 5. Human SFB, and for comparison the human osteosarcoma cell line MG63, were treated with IL-17 (5 and 50ng/ml) for up to 48 hours. The expression and production of RANKL and OPG at 6, 24 and 48hours was assessed by RT-PCR, quantiative real-time PCR, Northern blot and Western blot analyses. To investigate osteoclastogenesis, peripheral blood mononuclear cells (PBMCs) were cultured with IL-17 (5 and 50ng/ml) either alone or with M-CSF (25 ng/ml). After 14–21 days, cultures were fixed and stained for tartrate-resistant acid phosphatase (TRAP) and multinucleated, TRAP positive cells counted. Experiments were repeated on ivory slices and resorption evaluated.

Results: RT-PCR and QT-PCR analysis demonstrated that RANKL mRNA levels in SFB (4 of 5 patients) are enhanced by IL-17 in a biphasic manner. RANKL expression was elevated at 6 hours, returned to near control values at 24 hours before demonstrating increased levels at 48 hours. The expression of RANKL in MG63 cells was enhanced by IL-17 (5ng/ml) at 6 and 24 hours, and by IL-17 (50ng/ml) at 48 hours. The expression of OPG by SFB was upregulated by IL-17 (5 and 50ng/ml) at 6, 24 and 48 hours. The elevated expression of OPG in MG63 cells by IL-17 was time dependent, and this elevated expression was confirmed by Western blot. In cultures of PBMCs, IL-17 alone increased the numbers of TRAP+ve multinucleate cells dose-dependently. Similar levels of TRAP+ve cells were observed in the cultures treated with RANKL and M-CSF, but numbers of multinucleated cells were further increased when M-CSF was supplemented with IL-17. Resorption of ivory wafers was also observed in cultures treated with IL-17.

Conclusions: These results suggest that IL-17 induced osteoclast formation could contribute to the bone loss associated with a wide range of pathological states involving osteolysis and aseptic loosening.

Despite all gain of knowledge, septic and aseptic loosening of endoprostheses still remain unsolved problems. In loosening of joint arthroplasty a periprosthetic membrane is found between the bone and the loosened implant. The characteristics of the membrane are influenced by the process that leads to the loosening of the endoprosthesis. The aim of the study was to introduce a classification system that enables a standardized diagnostic evaluation and helps to determine the aetiology of the loosening process.

Based on histomorphological criteria and polarized light microscopy, four types of periprosthetic membranes were defined: periprosthetic membranes of the wear particle type (type I), periprosthetic membranes of the infectious type (type II), periprosthetic membranes of the combined type (type III), and periprosthetic membranes of the indifferent type (type IV). Periprosthetic membranes of 268 patients were analyzed according to the defined criteria.

The interobserver reproducibility was sufficient (95%). The correlation between histopathological and microbiological diagnosis was high (89%, p< 0,001). The four types of periprosthetic membranes showed a significantly different time of revision.

This classification system enables a standardized diagnostic procedure. It therefore is a basis for further studies concerning the etiology and pathogenesis of prosthesis loosening. The reliability of this histomorphological examination in diagnosing infections is currently reviewed.

Purpose: We report a prospective series of 70 explantations of the femoral pivot via a transfemoral approach required due to septic and aseptic loosening.

Material and methods: Aseptic loosening was observed in 61 cases, septic loosening in 9. The extended posterolateral approach was used to remove the implant in all cases and a femoral segment (Wagner method). Reconstruction of the femur was achieved with locked stems without cement (65 patients) or a long stem without cement (1 patient). Reimplantation was not attempted in four patients. Bone grafts were not used. Mean follow-up in this series was 3.5 years. The PMA score was used for clinical assessment. Radiographic assessment of segment healing and bone regrowth around the implant was done by measuring the cortical index.

Results: We observed a significant gain in the PMA score of more than 9 points. We had one intraoperative fracture of the femoral segment and two episodes of early dislocation. All femoral segments healed. Osteogenesis failed in three cases with fracture of the locking screw. There were also two cases of late fracture of the trochanter. At one year, bone regrowth measured from the cortical index was greater than 10% on the average.

Discussion: We discuss the characteristic features of this type of surgery in comparison with other solutions for femoral revision: operative time, blood loss, choice of implants, later weight bearing. We also found that this technique allows easier implant removal and more effective cleaning of the femoral shaft in the event of septic surgery with fewer cases of intraoperative accidents (malposition, femoral fractures). We were able to demonstrate that this method of femur reconstruction without bone graft provides a stimulation of osteogenesis in the floating segment. Stem locking provides primary stability in 100% of the cases. Secondary stability was achieved in 90% due to the quality of the newly formed bone.

Aseptic loosening of orthopaedic implants has a major financial impact on the Health Service. The process is thought to be caused by wear particles that are phagocytosed by macrophages and hence stimulate bone resorption via a cytokine response. Previous work suggests that factors inhibiting or enhancing bone resorption act through regulation of the OPG and RANK-L mechanism. The objective of this study was to identify the role of RANK-L and OPG within the cytokine response leading to orthopaedic implant loosening.

Ten samples of cellular membrane obtained during revision arthroplasty surgery were analysed with basic histological staining, immunohistology and polymerase chain reaction (PCR). In vitro studies were also carried out using explanted cancellous bone, to which PMMA particles were added and bone resorbing osteoclastic cells were identified by their Tartrate-Resistant Acid Phosphatase (TRAP) activity.

PCR identified the presence of OPG in all of the periprosthetic samples, with RANK-L shown in 40% of the specimens. Immunoreactivity was shown for CD3, CD68 and RANK-L. In vitro studies confirm that there is an initial burst of inflammatory cytokine activity that then subsequently plateaus.

A balance of RANK-L and OPG regulates bone resorption at the bone/implant interface of implants by stimulating a significant initial inflammatory response which leads to loosening.

The role of matrix metalloproteinases (MMPs) in the aseptic loosening of hip prostheses is well established. Gelatinase MMPs have been identified in the interface membranes and the pseudosynovial tissues in the hips. Little data are available on gelatinase MMPs and their major regulators, including specific tissue inhibitors of matrix metalloproteinases (TIMPs) in the loosening of shoulder prostheses. The objectives of this study were to determine whether A) gelatinase MMPs and their regulators (MMP14, TIMP-1,-2) are produced by periprosthetic tissues in cases of aseptic loosening of shoulder prostheses, and, B) to identify which cell types, in both interface and synovial tissues, localize the enzymes.

Interface tissues and synovial tissues were obtained during revision surgery for loose shoulder implants. In 9 patients (6-Total Shoulder Replacement, 3-Hemiarthro-plasty (Bipolar), 9 samples of interface tissues and 8 samples of synovial tissues were obtained. Of the interface tissues 2 were from the interface of the bipolar and the unresurfaced glenoid. Formalin-fixed paraffin embedded sections were stained using primary antibodies for MMP2 (Neomarkers), MMP9 (Oncogene Ltd), TIMP1, TIMP2 & MMP14 (Chemicon Ltd). Antigen retrieval required pressure cooker treatment for MMP2 and MMP9 and trypsin for TIMP1. Visualisation used a standard DAB chromagen technique (Envision, Dako Ltd.). Appropriate control sections ensured reproducibility of the staining. The antibodies selected bind to both active and inactive forms of the MMPs.

Both HDPE and metal debris were seen in both the synovial and interface tissues. Transformation of macrophages to giant cells was associated with PE debris, and was not observed with metal debris alone.

The presence of gelatinase MMPs in both interface and synovial tissues in aseptic loosening of shoulder prostheses was demonstrated. Differences between the MMP content of macrophages and giant cells between the tissues was detected, positivity was associated with the presence of metallic and/or HDPE debris. Activation of endothelial MMP2 by both MMP14 and low levels of TIMP2 would support the development of a vascular network.

Aseptic loosening is generally associated with the presence of wear particle-associated macrophages in the pseudomembrane commonly formed around failed prosthetic implants. The extent of the macrophage response evoked by the wear particles has been shown to correlate with the amount of periprosthetic osteolysis. Numerous studies have shown that wear particle-associated macrophages contribute to osteolysis by (i) releasing inflammatory cytokines and/or (ii) differentiating into bone resorbing osteoclasts. Although macrophages and macrophage polykaryons are the main inflammatory cells found in periprosthetic tissues, numerous fibroblasts are also present in the connective tissue pseudomembrane. The recently identified molecule, RANKL has been shown to play a central role in the osteoclast formation and bone resorption observed in aseptic loosening. We have shown that arthroplasty macrophages, which express RANK, the receptor for RANKL, are capable of osteoclast differentiation; this process is inhibited by osteoprotegerin (OPG), the soluble decoy receptor for RANKL. As fibroblasts are known to express RANKL, the aim of the present study was to determine whether fibroblasts isolated from periprosthetic tissues could induce the generation of bone resorbing osteoclasts that would contribute to the osteolysis commonly seen in the periprosthetic loosening.

Fibroblast-like cells were isolated from pseudomembrane from patients (n=5) undergoing hip revision due to aseptic loosening, by routine collagenase enzyme digestion. The isolated cells were seeded in flasks for 2–4 weeks before being passaged for a further 3–4 times. Generated fibroblast-like cells (10⁴) were then co-cultured with 5x10⁵ normal human peripheral blood monocytes (n=5) on glass coverslips and dentine slices in the presence of (i) no added factors, (ii) macrophage colony stimulating factor (M-CSF) and (iii) M-CSF plus OPG. All cultures were maintained for 1,17 and 21 days. The extent of osteoclast differentiation was then determined by the expression of specific osteoclast markers including tartrate-resistant acid phosphatase (TRAP) and vitronectin receptor (VNR) and evidence of lacunar resorption.

In the absence M-CSF, no osteoclast formation was noted in 24 hours, 17 or 21 days in fibroblast/monocyte cultures. However, in the presence of M-CSF alone, large numbers of TRAP⁺ and VNR⁺ multinucleated cells capable of lacunar resorption were noted in these co-cultures. The addition of OPG, which is known to inhibit RANKL-mediated osteoclast formation, significantly reduced the extent of osteoclast formation and lacunar resorption in these co-cultures.

These results indicate that one means whereby peri-prosthetic osteolysis may occur is by fibroblasts in the arthroplasty pseudomembrane inducing macrophage-osteoclast differentiation. Fibroblasts express RANKL and interact with arthroplasty macrophages, which express RANK and function as osteoclast precursors. These findings indicate that suppression of osteoclast formation by OPG may be a possible form of therapy for reducing prosthetic loosening.

The longevity of the fixation of implants in a formerly dysplastic hip is compromised by several risk factors:

Young age.

Preoperative planning is mandatory. Procedure, choice of method, and availability of appropriate equipment and endoprosthetic implants must be ensured. Computerised tomography with 3-D reconstruction is recommended for more complex anatomical situations.

Introduction

High-flexion knee implants have been developed to accommodate a large range of motion (ROM > 120°) after total knee arthroplasty (TKA). In a recent follow-up study, Han et al. [1] reported a disturbingly high incidence of femoral loosening for high-flexion TKA. The femoral component loosened particularly at the implant-cement interface. Highly flexed knee implants may be more sensitive to femoral loosening as the knee load is high during deep knee flexion [2], which may result in increased tensile and/or shear stresses at the femoral implant fixation.

The objective of this study was to analyse the load-transfer mechanism at the femoral implant-cement interface during deep knee flexion (ROM = 155°). For this purpose, a three-dimensional finite element (FE) knee model was developed including high-flexion TKA components. Zero-thickness cohesive elements were used to model the femoral implant-cement interface. The research questions addressed in this study were whether high-flexion leads to an increased tensile and/or shear stress at the femoral implant-cement interface and whether this would lead to an increased risk of femoral loosening.

Pain relief in hip arthroplasty plays an important role in the intra/post operative stages in order to achieve an almost pain free post operative recovery period to mobilise the patient as early and safely as possible and avoid undesirable post surgical complications.

A consecutive series of 99 total hip arthroplasties in 93 patients performed by a single surgeon between December 1996 and January 2006 were assessed for signs of clinical or radiological loosening.

Intra-operative local anaesthetic mixture (Ropivacaine-Ketorolac (30mg) -Adrenaline or RKA mixture) was infiltrated into the joint capsule and surrounding tissue around the acetabular component, and into the different muscle layers in the thigh around the femoral component. A total of 150–200 mls of this mixture was injected and a further 50 mls (with 30mg ketorolac) injected through a catheter left in-situ before discharge 12 to 24 hours later. Radiographic analysis was carried out using the Hodgkinson criteria to predict acetabular component loosening and the Gruen method to determine femoral component loosening.

Of the 99 hybrid hips, 57 were right and 42 were left hip arthroplasties and 6 patients had bilateral consecutive hips done. 5 were performed for revision of fractured necks of femur in Birmingham hip resurfacings and one total hip arthroplasty revised to a hybrid and the remaining 92 were primary hybrid hip arthroplasties. The arthroplasties were performed for Osteoarthritis (89), Rheumatoid arthritis (4), and others (6). At mean follow up of 4.2 years, no aseptic loosening was noted radiologically or clinically, no components have been revised for failure or loosening and no components have dislocated.

The use of high dose local infiltration NSAIDs in the intraoperative and early post operative phase does not seem to affect prosthetic fixation at-least during short to mid term follow up of total hip joint arthroplasties.

We have compared prospectively the incidence of loosening of 20 femoral stems with a matt surface with that of 20 polished stems of an otherwise identical tapered, non-modular design of Exeter hip replacement. The stems were inserted using the same technique at operation and radiographs showed no difference in the adequacy of the cement mantle or of fixation. All the patients were reviewed regularly and none was lost to follow-up.

After a minimum follow-up of nine years, four matt but no polished stems had been revised for aseptic loosening. Polished stems subsided slightly within the cement mantle early, but did not loosen.

We have studied aseptic loosening of the femoral component in 76 patients with primary total hip replacement using the Capital prosthesis. The mean follow-up was 26 months (10 to 37).

Twelve femoral components (16%) were definitely and eight (10%) were possibly loose. They were characterised by a thin cement mantle (p < 0.001) and excessive residual cancellous bone in the proximomedial region (p < 0.01).

We recommend that the cement mantle around the prosthesis should be 2 to 3 mm and that further long-term studies are needed to evaluate the wear properties of titanium-nitride-coated titanium femoral heads.

Aseptic loosening is seen in a significant proportion of cemented total hip replacements (THR). In a small subgroup of patients who suffer early loosening polyethylene debris is unlikely to be responsible. We recently reported one case of allergic contact dermatitis to N,N-dimethylparatoluidine (DMT), an accelerator used in bone cement. We have therefore investigated this using skin-patch tests to a variety of substances including metals, polyethylene and the separated individual components of Simplex cement.

We studied 70 patients, 15 with aseptic loosening less than two years after THR, 25 with satisfactory long-term cemented fixation, five with infected loosening of cemented THRs and 25 awaiting hip arthroplasty. We found seven positive reactions to DMT, all of them in patients with the rapid onset of aseptic loosening.

Allergy to DMT is recognised in the dental profession in respect of the ‘denture sore mouth’ syndrome, and could also be an occupational hazard since some industrial glues contain DMT. Our results suggest the need for awareness of possible previous dental or occupational exposure to the constituents of bone cement. We recommend the use of skin-patch testing in high-risk cases.

We report a prospective study of gait and tibial component migration in 45 patients with osteoarthritis treated by total knee arthroplasty (TKA). Migration was measured over two years using roentgen stereophotogrammetry. We used the previously established threshold of 200 μm migration in the second postoperative year to distinguish two groups: a risk group of 15 patients and a stable group of 28 patients.

We performed gait analysis before operation and at six months and at two years after TKA. On all three occasions we found significant differences between the two groups in the mean sagittal plane moments of the knee joint. The risk group walked with higher peak flexion moments than the stable group. The two groups were not discriminated by any clinical or radiological criteria or other gait characteristics.

The relationship which we have found between gait with increased flexion moments and risk of tibial component loosening warrants further study as regards the aetiology of prosthetic loosening and possible methods of influencing its incidence.

Lungs exposed to particulate debris may be damaged by proteolytic enzymes during phagocytosis. Damage is worse if patients are deficient in α1-antitrypsin (A1AT) which helps neutralise these enzymes. We investigated the possibility that A1AT deficiency contributes to aseptic loosening following total hip replacement (THR) when wear particles are phagocytosed.

Method: A1AT level and phenotype were measured in patients attending for revision THR within 15 years of implantation. Periprosthetic lysis was graded from X-rays by 3 hip surgeons with an interest in revision, blinded to history and A1AT results. Patients were grouped according to presence of high or low levels of lysis radiologically. Mean A1AT levels were calculated for the two groups.

Results: 17 patients were recruited, mean age 69.5, mean interval between surgery and onset of pain 8.3 years (2–12). 2 were heterozygotes for the less active S form of A1AT and therefore mildly deficient. Time to onset of pain in both was 12 years. X-rays were available for 12 patients. For all reviewers, the mean A1AT level in the high lysis group was raised and greater than that of the low lysis group. For 1 reviewer this reached statistical significance (P< 0.01). Mean A1AT level in the high lysis group was 2.5 (raised) and in the low lysis 1.6 (normal). Both A1AT deficient patients were classified as high lysis by all reviewers despite normal A1AT levels.

Conclusions: The incidence of A1AT deficiency is only marginally higher in this group than in the general population therefore A1AT deficiency is unlikely to be a common cause of failure of hip replacements. Elevated levels of A1AT in the presence of lysis suggests that A1AT may play a role in the aetiology of aseptic loosening. Further work is needed to evaluate this and to assess vulnerability of A1AT deficient patients to lysis.

Purpose of the study: Because of the growing number of aseptic loosening of total hip arthroplasty (THA), a reliable biological marker would be useful to diagnosis osteolysis early and non-invasively while avoiding the risk of false positives. The purpose of this study was to analyse the value of the interleukin-10(IL10)-alphaTNF ratio in serum and synovial fluid as a marker of THA aseptic loosening.

Material and methods: Blood synovial fluid samples were collected in 27 volunteers with a cemented THA (group THA) and 30 healthy subjects comparable for age and gender who were programmed for total hip arthroplasty because of primary osteoarthritis (group OA). We analysed: locally by the level of alphaTNF and IL10 in the supernate of differentiated THP-1 with and without adjunction of synovial fluid (SF); in the bloodstream the production of alphaTNA and IL10 by monocytes; the correlation between serum and SF levels and the presence or not of loosening.

Results: In the THA group, SF induced a relative decrease in IL10 strangly not associated with an increase in alphaTNF. However, the IL10/alphaTNF ratio was significantly lower in the OA group. Circulating monocytes produced more alphaTNF in the THA group while there was no significant difference in the production of IL10 by the two groups. However, the IL10/alphaTNF ratio was significantly higher (2-fold) in the THA group. Regarding serum cytokine levels, there was a local accumulation of alphaTNF in the THA group and IL10 in the OA group.

Discussion: The IL10/alphaTNF ratio alone was significantly correlated with aseptic loosening, locally and in the general bloodstream. IL10 or alphaTNF did not alone correlate in all conditions. These results show that use of this ratio appears to be more effective than assay of a single proinflammatory cytokine for the early diagnosis of aseptic loosening. The validity of this ratio is supported by its local and general correlation. A comparative prospective study in healthy subjects using a non-invasive method (except for the blood samples) should be conducted to confirm the clinical pertinence of this marker.

Introduction: Activated peri-prosthetic macrophages release pro-inflammatory cytokines, including interleukin-6 (IL-6), that stimulate osteoclast activation and aseptic loosening. Natural sequence variations (polymorphisms) within the IL-6 gene promoter region are associated with diseases characterised by increased osteoclast activity, including osteoporosis, and affect IL-6 production in-vitro. We tested whether polymorphisms in the IL-6 gene promoter influence the risk of aseptic loosening after total hip arthroplasty (THA).

Methods: 614 Caucasians, 292 men and 322 women, mean age 75.8 years who had undergone primary cemented THA for idiopathic osteoarthritis a mean of 13.4 years previously were recruited. Peripheral blood was taken and DNA extracted using standard techniques. Subjects were genotyped for the IL-6 -174, -572, and -597 promoter single nucleotide polymorphisms using the Taqman 5′ nuclease method.

Results: The allele frequencies and carriage rates for both alleles at promoter positions −174, −572, and −597 were similar between controls and aseptic loosening subjects (Table, χ² P> 0.05 all comparisons).

Discussion: Although Il-6 has been implicated in the pathogenesis of aseptic loosening and the −174, −572, and −597 polymorphisms are associated with bone loosing pathologies, they do not appear to play a major role in aseptic loosening after THA.

The aim of the study to analyze the circulating white blood cells including the intensity expression of surface receptors and cytoplasmic molecules in patients underwent total hip replacement, with either aseptic or septic loosening of hip prostheses in order to identify cell-surface and cytoplasmic markers that could be indicative of early loosening. Flow cytometry was performed in whole peripheral blood samples of 20 patients with loosening (10 septic and 10 aseptic). Ten healthy individuals served a control group. The CD62L, CD18, CD11a, CD11b and CD11c expressions were evaluated. The mean fluorescence intensity (MFI) of CD 18 was decreased on all leukocytes subsets compared to control group. For patients with aseptic loosening we demonstrated an increase of MFI for CD11b in granulocytes and for CD11c in monocytes and granulocytes compared to control group. In patients with septic loosening an increase of MFI for CD 11c was observed in monocytes compared to control group. The comparison between aseptic and septic loosening showed a statistically significant lower CD18 MFI value in granulocytes for aseptic loosening. A trend towards lower MFI values of CD 62L in lymphocytes and granulocytes were observed in aseptic but not in septic loosening patients compared to control group. The present study is the first study in published literature to demonstrate cell surface and cytoplasmic markers in peripheral blood indicative of loosening of THAs by means of flow cytometry.

Frontal and lateral plain radiographs are the first choice for follow-up observations of the osteotomy boundary that faces the femoral and tibial components of a TKA. However, as plain radiographs provide no information in the image depth direction, it is difficult to determine the exact position of early-stage bone radiolucent lines. A new tomosynthesis technique, which uses both iterative reconstruction and metal extraction methods, has recently attracted attention. We report that this technique provides multi-slice images of the boundary between the metallic implant and the osteotomy surface, which is difficult to observe using conventional multi-slice imaging methods such as CT and MRI, and permits semi-three-dimensional evaluations of polyethylene wear.

Aim: To assess the results of aseptic and aseptic cases using the PFC/TC3 system, and to correlate this with the restoration of joint line height.

Method: 148 patients underwent revision TKR using the PFC/TC3 system. No re-revision cases were included in this series. Data was prospectively collected (using the Bristol Knee Score) pre-operatively and at a mean of 4.2 years post-revision. 31 revisions were for infection and 53 revisions were for aseptic loosening. Revision for infection was done as a two-stage procedure and aseptic as a single operation. Measurements of the joint line height were made pre and post-operatively using Figgie’s method. The cases were divided into 3 groups on the basis of joint line restoration:

Lowered by more than 5 mm

Results: The mean pre-op total score for the infection group was 35/100 and 40/100 for the aseptic loosening group. The total score post-operatively was 67 for the infection group and 73 for the aseptic loosening group. The joint line was restored in 50% of infected cases and in 60% of aseptic loosening cases.

Conclusion: although the overall results were slightly less satisfactory for the infected revision group, there was no significant difference between the two groups either in total BKS scores or in reproduction of the joint line. The average outcome was much less good than for primary TKR.

Background/Aims

The development of extendable prostheses has permitted limb salvage surgery in paediatric patients with bone tumours in proximity to the physis. Prostheses are extended to offset limb length discrepancy as the child grows. Aseptic loosening (AL) is a recognised complication. The implant stem must fit the narrow paediatric medullary canal and remain fixed while withstanding growth and increasing physical demands. Novel designs incorporate a hydroxyapatite (HA) coated collar that manufacturers claim improves bony ongrowth and stability, providing even stress distribution in stem and shoulder regions and providing a bone-implant seal, resulting in decreased AL and prolonged survival. This study aims to assess whether there is a relationship between bony ongrowth onto a HA collar and AL. Hypothesis: Bone ongrowth onto the HA collar of extendable prostheses is associated with more stable fixation and less AL despite patient growth.

Between December 1998 and December 1999 twenty-one patients with painful knee arthroplasties underwent assessment by radionuclide arthrography. There were eleven female and ten male patients, with an average age of 60 years at the time of the index procedure. The index procedure was a primary total knee arthroplasty, primary medial unicompartmental knee arthroplasty and revision medial UKA in seventeen, three and one patients respectively. Nineteen arthroplasties were uncemented and two were hybrids. All patients had previously been investigated by clinical examination, serological testing, fluoroscopic AP and lateral radiographs, and Tc99 bone scan with equivocal results. The presence of radionuclide about the tibial stem was considered diagnostic of tibial loosening. Nine patients underwent revision knee arthroplasty. The presence of radionuclide about the tibial stem correctly predicted a loose tibial component in four of five cases. Similarly, the absence of radionuclide about the tibial stem correctly predicted a stable tibial component in four of four cases. In the single misdiagnosed case the tibial component did not have a large central stem, had focal osteolysis about several screws, but remained stable. Radionuclide arthrogram is a useful tool in the investigation of painful knee arthroplasty. Radionuclide about the tibial stem is the key predictor of tibial component loosening.

Introduction: Aseptic loosening is the leading cause of failure in total hip arthroplasty. We present our long-term results of cemented revision of failed total hip replacements.

Materials And Methods: All patients requiring revision for aseptic loosening were prospectively followed up to assess the patterns of failure as well as the clinical and radiological outcomes of revision. There were 102 cases between 1992 and 2000. The mean age at revision was 67.4 (36–88). There were 60 male and 42 female patients. At the time of the final follow-up 26 patients had died and 10 had further surgery. Of the remainder, 64 patients attended the final assessment and 2 could not be traced.

Results: The mean time to follow-up was 6.8 years (5–13 years).

53 patients required revision of both components. There were 49 stem only revisions.

4 patients were re-revised for recurrent loosening and 2 for infection.

There were 14 dislocations. Of these, 4 required secondary stabilisation and 2 underwent Girdlestone’s excision arthroplasty for recurrent dislocation.

46 of the 64 patients who attended final follow-up had no changes in their X-ray appearances compared to the immediately post-operative films. 9 of the stems and 9 of the cups had signs of progressive lucent lines around the cement mantle.

This gives a survivorship of 89% at ten years with reoperation for any cause as the end-point.

Discussion: Initial reported results of cemented revisions were variable. These have been improving with more recent publications including those from the Scandinavian hip registries. Our results confirm the latter findings of excellent survivorship in cemented revisions.

Purpose: Instrumentation and cementoplasty have been used individually or synergistically to augment screw fixation for better stabilization. A pilot study was performed to develop a new way to use this relationship to solve problematic screw loosening in both healthy and osteoporotic bone. Results show there may be indication to use the following characterized method.

Methods: In 12 cases of patients, pedicle fixation was used for complex decompression. The ages range from 70–85 years and included 8 females and 4 males. All patients underwent a bone tamp bolus formation in cancellous bone through each pedicle at the superior level of construct (3–4 cc. in each site, injected under low pressure) followed by pedicle screw insertion into the bolus, and subsequent levels were fixated by only pedicle screws.

Results: The preoperative, postoperative, and 3 month follow-up plain x-ray films were evaluated for stable bone tamp implantation, cement leakage, and screw placement. In all 12 cases there was no evidence of screw migration, pull-out, fracture, spinal cord compression, nerve root compression, or complication with cement placement. There was no example of cement extrusion into spinal canal. All patients had uneventful recoveries which included physical therapy, mild analgesics, and bracing.

Conclusion: This new technique may solve the problem of loosening of screws in healthy and osteoporotic bone by providing a more secure anchorage system not yet seen in previous studies. Further study is needed to develop more specific outcomes to determine the best technique using the balloon bone tamp system.

Purpose of the study: to demonstrate a mechanism of loosening of the Souter-Strathclyde Total Elbow Replacement (TER) using evidence from revision surgery.

Methods: nine Souter-Strathclyde humeral and ulnar components retrieved from revision surgery for aseptic loosening were examined macroscopically and then microscopically under low power magnification. The wear patterns were compared and photographed.

Results and conclusion: inspection of the retrieved cobalt chrome steel humeral components revealed no evidence of surface wear. However on examination of the polyethylene ulnar components six of the nine exhibited macroscopic wear taking the form of deep linear grooves on either the medial or lateral articulating surface. Microscopic examination revealed wear exhibited as complete disruption of the polyethylene machining lines on the medial and lateral articular surfaces, but almost complete preservation on the central gliding ridge. The findings are best explained in the context of normal elbow kinematics and congruence of the Souter-Strathclyde components. The normal elbow joint is not a simple hinge joint. In addition to flexion/extension, axial rotation and abduction/adduction motion patterns occur. However articulating surfaces of the Souter-Strathclyde components are highly congruent and thus resist the elbow’s normal translational and rotational movements. Our wear patterns are the result of humeral component rocking during flexion and extension as a result of this resistance. The central gliding ridge is preserved because the humeral component is not always in contact with it as it rocks out of its articulation in the coronal plane. Furthermore as the humeral component rocks, the sharp edge of its articulating surface makes contact with the articulating surface of the ulna causing abrasion and in the extreme circumstance the deep linear grooves observed. The biomechanics eventually lead to component loosening.

To determine socket survivorship in DDH based on the severity of hip dysplasia, we carried out a retrospective study of 283 cemented total hip replacements carried out at Wrightington. The hips were classified according to the Crowe and Hartofilakidis classifications. Revision was used as the end point for prosthetic survivorship. The results were analysed statistically using SPSS for Windows

The mean age at time of surgery was 42.6 years with a mean follow-up of 15.7 years. The acetabulum was grafted in 46 cases. The commonest cause for revision was aseptic loosening of the acetabular component (88.3%). 254 procedures were carried out through a transtrochanteric approach with a direct lateral approach used for the remaining mildly dysplastic hips. At 10 years 5.3% of dysplastic, 14.8% of low dislocation and 51.1 % of high dislocation hips were revised.. At 10years 6% of Crowe Type1, 8.5% of Type2, 25.5% of Type3 and 39.2% of Type4 hips were revised. At 20 years 24% of dysplastic, 45% of low dislocation and 88% of high dislocation hips were revised. At 20years 27.3% of Crowe Type1, 29.3% of Type2, 63.3% of Type3 and 84.4% of Type4 hips were revised. The 20 year survival of patients less than 50 years of age at the time of surgery was 61% as compared to 92% survival in patients more than 50 years of age. The mean age of patients in the revised group was 35 years as compared to 45 years in the non-revised group.

Conclusion: This study demonstrates satisfactory results in dysplastic hips following cemented total hip replacements. With increasing severity of hip dysplasia there is a higher rate of premature failure of the acetabular component. There is adverse correlation between age and survival of the acetabular component. There is a dramatic increase in cup failure between 10 and 20 years.

Background: The commonest cause of long term failure of total joint arthroplasty is aseptic loosening. As a result, many patients will require complex revision surgery that is not only technically challenging but associated with poorer results. Revisions procedures are also associated with higher morbidity and costs.

Aim: To quantify osteolysis in a small animal model of aseptic loosening. This model can then be utilised for screening therapeutic agents to inhibit aseptic loosening.

Materials and Methods: 7 time mated female mice were injected with radioactive calcium 45 on day 14 of gestation. The 52 offsprings were divided into 2 equal groups and subjected to either the implantation of clinically relevant ceramic particles or sham surgery into their femora. The non-operated femora were used as control. Animals were killed 4 weeks following surgery. Femora were retrieved, dissolved and radioactivity measured as outcome (CPM/mg = Counts Per Minute per milligram). A Linear mixed effects model was utilised to examine the difference in outcome between the 2 groups.

Results: The mean scintillation count for sham surgery was 388 CPM/mg compared to 449 CPM/mg in the control femora. The mean scintillation count for ceramic particles was 351 CPM/mg compared to 420 CPM/mg in the control femora. The mean effect on outcome of surgery with ceramic particles relative to sham surgery was estimated at 16.7 CPM/mg (95CI%: 0.9 to 32.5 CPM/mg; p = 0.025).

Conclusion: We have successfully shown that this model can quantify osteolysis. However, the difference detected between sham surgery and ceramic particles was biologically small displaying the inert properties of ceramic. Extending the post surgery interval might show a larger difference between sham surgery and ceramic particles and permit quantitative analysis of therapeutic agents to be screened to inhibit aseptic loosening.