Aim. Vascular compromise following supracondylar fractures is frequently described. Near Infra-red Spectrometry (NIRS) is a technique through which real-time data can be gathered non-invasively on the oxygenation status of tissues. The drive now is to gain knowledge on how NIRS data can be interpreted and to validate its use in the clinical setting. Methods. This ethically approved prospective study looks at volar forearm compartment oxygen saturation (StO2) in 20 patients with supracondylar fractures requiring operative intervention. Both the injured limb and the contra-lateral, uninjured limb were monitored. 20 patients from a cohort of 29 had full data sets and are thus presented. Results. 12 patients were neurovascularly intact. Eight patients showed some neurovascular compromise. There was no difference (P=0.3475) between the StO2 of the injured and non-injured arms of the neurovascularly intact patients. Of the eight arms with an altered neurovascular status, four were pink and pulseless. We encountered no compartment syndromes in this series. Comparing the StO2 from the neurovascularly altered limbs (mean 66.84% range 45.43–89.53% SD 15.90) and the neurovascularly intact limbs (mean 81.62% range 64.21–98.89% SD 9.523) there was a significant difference (P=0.039). There was quick return to normal values after operation in those that were operated upon to release neurovascular compression. An improvement of 13.44% ± 8.769. Conclusion. NIRS data is shown to be valid in this model. Further studies are needed to delineate the normal values for StO2 and further investigate the indications for intervention. NIRS measurements of muscle tissue oxygenation can identify patients with clinical neurovascular compromise, and can identify the return of adequate perfusion following operative correction of supracondylar fractures. NIRS based tissue oxygenation monitoring may be a useful adjunct to clinical assessment, particularly in paediatric patients and those with altered consciousness

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

Aims. This study aimed to investigate the role and mechanism of meniscal cell lysate (MCL) in fibroblast-like synoviocytes (FLSs) and osteoarthritis (OA). Methods. Meniscus and synovial tissue were collected from 14 patients with and without OA. MCL and FLS proteins were extracted and analyzed by liquid chromatography‒mass spectrometry (LC‒MS). The roles of MCL and adenine nucleotide translocase 3 (ANT3) in FLSs were examined by enzyme-linked immunosorbent assay (ELISA), flow cytometry, immunofluorescence, and transmission electron microscopy. Histological analysis was performed to determine ANT3 expression levels in a male mouse model. Results. We discovered for the first time that MCL was substantially enriched in the synovial fluid of OA patients and promoted the release of inflammatory cytokines from FLSs through MCL phagocytosis. Through LC‒MS, ANT3 was identified and determined to be significantly upregulated in MCL and OA-FLSs, corresponding to impaired mitochondrial function and cell viability in OA-FLSs. Mitochondrial homeostasis was restored by ANT3 suppression, thereby alleviating synovial inflammation. Furthermore, elevated ANT3 levels inhibited ERK phosphorylation. Specifically, silencing ANT3 prevented inhibition of ERK phosphorylation and significantly reduced the elevation of reactive oxygen species (ROS) and JC1 membrane potential in MCL-induced synovial inflammation. Conclusion. This study revealed the important roles of MCL and ANT3 in FLS mitochondria. Silencing ANT3 rescued ERK phosphorylation, thereby restoring mitochondrial homeostasis in FLSs and alleviating synovitis and OA development, offering a potential target for treating synovitis and preventing early-stage OA. Cite this article: Bone Joint Res 2023;12(4):274–284

Osteoarthritis (OA) is a disabling disease depriving the quality of life of patients. Mesenchymal stem cells (MSCs) are recently used to modify the inflammatory and degenerative cascade of the disease. Source of MSCs could change the progression and symptoms of OA due to their different metabolomic activities. We asked whether MSCs derived from the infrapatellar fat (IPF), synovium (Sy) and subcutaneous (SC) tissues will decrease inflammatory and degenerative markers of normal and OA chondrocytes and improve regeneration in culture. Tissues were obtained from three male patients undergoing arthroscopic knee surgery due to sports injuries after ethical board approval. TNFa concentration decreased in all MSC groups (Sy=156,6±79, SC=42,1±6 and IPF=35,5±3 pg/ml; p=0,036) on day 14 in culture. On day seven (Sy=87,4±43,7, SC=23±8,9 and IPF=14,7±3,3 pg/ml, p=0,043) and 14 (Sy=29,1±11,2, SC=28,3±18,5 and IPF=20,3±16,2 pg/ml, p=0,043), MMP3 concentration decreased in all groups. COMP concentration changes however were not significant. Plot scores of tissues for PC2-13,4% were significantly different. Based on the results of liquid chromatography-mass spectrometry (LC-MS) metabolomics coupled with recent data processing strategies, clinically relevant seven metabolites (L-fructose, a-tocotrienol, coproporphyrin, nicotinamide, bilirubin, tauro-deoxycholic acid and galactose-sphingosine) were found statistically different (p<0.05 and fold change>1.5) ratios in tissue samples. Focusing on these metabolites as potential therapeutics could enhance MSC therapies. Acknowledgment: Hacettepe University, Scientific Research Projects Coordination Unit (#THD-2020-18692) and Turkish Society of Orthopedics and Traumatology (#TOTBID-89) funded this project. Feza Korkusuz MD is a member of the Turkish Academy of Sciences (TÜBA)

Aim. Prosthetic joint infections pose a major clinical challenge. Developing novel material surface technologies for orthopedic implants that prevent bacterial adhesion and biofilm formation is essential. Antimicrobial coatings applicable to articulating implant surfaces are limited, due to the articulation mechanics inducing wear, coating degradation, and toxic particle release. Noble metals are known for their antimicrobial activity and high mechanical strength and could be a viable coating alternative for orthopaedic implants [1]. In this study, the potential of thin platinum-based metal alloy coatings was developed, characterized, and tested on cytotoxicity and antibacterial properties. Method. Three platinum-based metal alloy coatings were sputter-coated on medical-grade polished titanium discs. The coatings were characterized using optical topography and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Ion release was measured using inductively coupled plasma optical emission spectrometry (ICP-OES). Cytotoxicity was tested according to ISO10993-5 using mouse fibroblasts (cell lines L929 and 3T3). Antibacterial surface activity, bacterial adhesion, bacterial proliferation, and biofilm formation were tested with gram-positive Staphylococcus aureus ATCC 25923 and gram-negative Escherichia coli ATCC 25922. Colony forming unit (CFU) counts, live-dead fluorescence staining, and SEM-EDS images were used to assess antibacterial activity. Results. Three different platinum-based metal alloys consisting of platinum-iridium, platinum-copper, and platinum-zirconium. The coatings were found 80 nm thick, smooth (roughness average < 60 nm), and non-toxic. The platinum-copper coating showed a CFU reduction larger than one logarithm in adherent bacteria compared to uncoated titanium. The other coatings showed a smaller reduction. This data was confirmed by SEM and live-dead fluorescence images, and accordingly, ICP-OES measurements showed low levels of metal ion release from the coatings. Conclusions. The platinum-copper coating showed low anti-adhesion properties, even with extremely low metal ions released. These platinum-based metal alloy coatings cannot be classified as antimicrobial yet. Further optimization of the coating composition to induce a higher ion release based on the galvanic principle is required and copper looks most promising as the antimicrobial compound of choice. Acknowledgments. This publication is supported by the DARTBAC project (with project number NWA.1292.19.354) of the research program NWA-ORC which is (partly) financed by the Dutch Research Council (NWO); and the AMBITION project (with project number NSP20–1-302), co-funded by the PPP Allowance made available by Health-Holland, Top Sector Life Sciences & Health to ReumaNederland

Aim. A novel anti-infective biopolymer implant coating was developed to prevent bacterial biofilm formation and allow on-demand burst release of anti-infective silver (Ag) into the surrounding of the implant at any time after surgery via focused high-energy extracorporeal shock waves (fhESW). Method. A semi-crystalline Poly-L-lactic acid (PLLA) was loaded with homogeneously dissolved silver (Ag) applied onto Ti6Al4V discs. A fibroblast WST-1 assay was performed to ensure adequate biocompatibility of the Ag concentration at 6%. The prevention of early biofilm formation was investigated in a biofilm model with Staphylococcus epidermidis RP62A after incubation for 24 hours via quantitative bacteriology. In addition, the effect of released Ag after fhESW (Storz DUOLITH SD1: 4000 impulses, 1,24 mJ/mm. 2. , 3Hz, 162J) was assessed via optical density of bacterial cultures (Escherichia coli TG1, Staphylococcus epidermidis RP62A, Staphylococcus aureus 6850) and compared to an established electroplated silver coating. The amount of released Ag after the application of different intensities of fhESW was measured and compared to a control group without fhESW via graphite furnace atomic absorption spectrometry (GF-AAS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Results. The coating with 6% Ag reduced Staphylococcus epidermidis biofilm formation by 99.7% (mean±SD: 2.1×10^5 ± 3,9×10^5 CFU/µL) compared to uncoated controls (6.8×10^7 ± 4.9×10^7 CFU/µL); (p=0.0001). After applying fhESW the commercially available electroplated silver coating did not prevent the growth of all tested bacterial strains. Bacterial growth is delayed with 4% Ag and completely inhibited with 6% Ag in the novel coating, except for a small increase of S. aureus after 17 hours. SEM and EDS confirmed a local disruption of the coating after fhESW. Conclusions. This novel anti-infective implant coating has the potential to prevent bacterial biofilm formation. The on-demand burst release of silver via fhESW could be an adjunctive in the treatment of implant related infection and is of particular interest in the concept of single stage revision surgery

The aim of this study is to compare the release of titanium (Ti) and zirconium (Zr) into the tissue surrounding Ti- and ZrO. 2. -implants. Methyl methacrylate embedded mini pig maxillae with 6 Ti-implants and 4 ZrO2-implants were analysed after 12-weeks of implantation. The spatial distribution of elemental Ti and Zr in maxillae near implants was assessed with laser ablation (LA)-inductively coupled plasma (ICP)-mass spectrometry (MS). From each maxilla two bone slices adjacent to the implants were measured. The contents of Ti and Zr in these bone slices were determined by ICP-MS and ICP-optical emission spectrometry. Increased intensity of Ti and Zr could be detected in bone tissues at a distance of 891±398 µm (mean ± SD) from Ti-implants and 927±404 µm from ZrO2-implants. The increased intensity was mainly detected near implant screw threads. The average Ti content detected in 11 bone slices from samples with Ti-implants was 1.67 mg/kg, which is significantly higher than the Ti content detected in 8 slices from samples with ZrO. 2. -implants. The highest Ti content detected was 2.17 mg/kg. The average Zr content in 4 bone slices from samples with ZrO. 2. -implants is 0.59 mg/Kg, the other 4 bone slices showed Zr contents below the detection limit (. After 12-weeks of implantation, increased intensity of Ti and Zr can be detected in bone tissues near Ti- and ZrO. 2. -implants. The results show that Ti content released from Ti-implants is higher than the Zr content released from ZrO. 2. -implants

Introduction and Objective. Individuals with type 2 diabetes (T2D) have a 3-fold increased risk of bone fracture compared to non-diabetics, with the majority of fractures occurring in the hip, vertebrae and wrists. However, unlike osteoporosis, in T2D, increased bone fragility is generally not accompanied by a reduction in bone mineral density (BMD). This implies that T2D is explained by poorer bone quality, whereby the intrinsic properties of the bone tissue itself are impaired, rather than bone mass. Yet, the mechanics remain unclear. The objective of this study is to (1) assess the fracture mechanics of bone at the structural and tissue level; and (2) investigate for changes in the composition of bone tissue along with measuring total fluorescent advanced glycation end products (fAGEs) from the skin, as T2D progresses with age in Zucker diabetic fatty (ZDF (fa/fa)) and lean Zucker (ZL (fa/+)) rats. Materials and Methods. Right ulnae and skin sections were harvested from ZDF (fa/fa) (T2D) and ZL (fa/+) (Control) rats at 12 and 46 weeks (wks) of age (n = 8, per strain and age) and frozen. Right ulnae were thawed for 12 hrs before micro-CT (μCT) scanning to assess the microstructure and measure BMD. After scanning, ulnae were loaded until failure via three-point bending. Fourier transform-infrared microspectroscopy (FTIR) was used to measure various bone mineral- and collagen-related parameters such as, mineral-to-matrix ratio and nonenzymatic cross-link ratio. Finally, fAGEs were measured from skin sections using fluorescence spectrometry and an absorbance assay, reported in units of ng quinine/ mg collagen. Results. At 12 and 46 wks bone size was significantly smaller in length (p < 0.01), cortical area (p < 0.001) and cross-sectional moment of inertia (p < 0.001) in T2D rats compared to age-matched controls. A slight reduction in BMD was observed in T2D rats compared to controls at both ages, however, this was not significant. Structural properties of T2D bone were significantly altered at 12 and 46 wks, with bending rigidity increasing approximately 2.5-fold and 1.5-fold in control and T2D rats with age, respectively (p < 0.0001). Similarly, yield and ultimate moment significantly reduced in T2D rats with age in comparison to controls (p < 0.0001). Energy absorbed to failure was significantly reduced in T2D rats at 46 weeks of age compared to controls (p < 0.01). The amount of energy absorbed to failure increased approximately 1.4-fold from 12 to 46 wks in control rats, however, in T2D rats a reduction was seen with age, although not significant. At 12 wks, there was no significant deficits in tissue material properties, whereas, at 46 wks a significant reduction in yield stress, yield strain and ultimate stress was observed for T2D rats in comparison to controls (p < 0.05). Conclusions. These findings show that longitudinal growth is impaired as early as 12 wks of age and by 46 wks bone size is significantly reduced in T2D rats compared to controls. The reduction in T2D structural properties is likely attributed to the bone geometry deficits. At 12 wks of age, the tissue material properties are not altered in T2D bone versus controls. However, at 46 wks, bone strength is reduced in T2D, leading to the conclusion that tissue properties are altered as the disease progresses

Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, with cumulative treatment costs for all prosthetic joint infections estimated to be ∼ $1 billion per annum (UK and North America). Its ability to develop resistance or tolerance to a diverse range of antimicrobial compounds, threatens to halt routine elective implant surgery. One strategy to overcome this problem is to look beyond traditional antimicrobial drug therapies and investigate other treatment modalities. Biophysical modalities, such as ultrasound, are poorly explored, but preliminary work has shown potential benefit, especially when combined with existing antibiotics. Low intensity pulsed ultrasound is already licensed for clinical use in fracture management and thus could be translated quickly into a clinical treatment. Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, biofilms were challenged with gentamicin +/− low-intensity ultrasound (1.5MHz, 30mW/cm2, pulse duration 200µs/1KHz) for 180 minutes and 20 minutes, respectively. The primary outcome measures were colony-forming units/mL (CFU/mL) and the minimum biofilm eradication concentration (MBEC) of gentamicin. The mean number of S. aureus within control biofilms was 1.04 × 109 CFU/mL. Assessment of cellular metabolism was conducted using a liquid-chromatography-mass spectrometry, as well as a triphenyltetrazolium chloride assay coupled with spectrophotometry. There was no clinically or statistically significant (p=0.531) reduction in viable S. aureus following ultrasound therapy alone. The MBEC of gentamicin for this S. aureus strain was 256 mg/L. The MBEC of gentamicin with the addition of ultrasound was reduced to 64mg/L. Metabolic activity of biofilm-associated S. aureus was increased by 25% following ultrasound therapy (p < 0 .0001), with identification of key biosynthetic pathways activated by non-lethal dispersal. Low intensity pulsed ultrasound was associated with a four-fold reduction in the effective biofilm eradication concentration of gentamicin, bringing the MBEC of gentamicin to within clinically achievable concentrations. The mechanism of action was due to partial disruption of the extracellular matrix which led to an increase of nutrient availability and oxygen tension within the biofilm. This metabolic stimulus was responsible for the reversal of gentamicin tolerance in the biofilm-associated S. aureus

Hydrogels are hydrated 3-dimensional (3D) polymer networks that can be chemically or physically crosslinked. Interest in the use of hydrogels for tissue engineering applications has been growing in the past few decades due to their excellent biocompatibility and biodegradability. One of the major drawbacks of the use of hydrogels in such applications is their lack of structural strength. To address this, in this work, we have combined two hydrogel types, namely gelatin and alginate. In this work, a 1 ml volume of gelatin alginate hydrogel was molded in each well of a 24 well-plate and crosslinked with different concentrations of calcium chloride (CaCl. 2. ) (20, 40, 60, 80, and 100 mM) to investigate the influence of concentration on hydrogel properties and cell viability. The hydrogel was characterized using Fourier transform infrared (FTIR) spectrometry, environmental scanning electron microscopy (ESEM), and an Alamar blue assay to assess the chemical structure, the surface morphology, and the epithelial cell viability of the hydrogel, respectively. The FTIR analysis shows that network formation improved with increasing concentration; decreased ion-polymer interactions have been noted for concentrations ≤ 60 mM. This appears to be in agreement with ESEM images that show an evolution from a smooth, featureless surface to the appearance of surface pore structure for concentrations ≥ 80 mM. Perhaps as ion concentration increases and network formation improves, the effect is evidenced as surface porosity; low concentrations result in swelling and a smooth surface. In terms of cell viability, viability has been found to increase with increasing concentration. The cell viability is 90 % at 100 mM CaCl. 2. , in contrast to 50 % for a concentration of 20 mM after 9 days of incubation. It is possible that the reduced viability can be attributed to the high proportion of uncrosslinked polymer chains at low concentrations. Overall, these results provide useful information about the role of crosslinking concentration on hydrogel properties, knowledge that may be applied to 3D bioprinting

Aims

Pigment epithelium-derived factor (PEDF) is known to induce several types of tissue regeneration by activating tissue-specific stem cells. Here, we investigated the therapeutic potential of PEDF 29-mer peptide in the damaged articular cartilage (AC) in rat osteoarthritis (OA).

Aims

Biofilm-related infection is a major complication that occurs in orthopaedic surgery. Various treatments are available but efficacy to eradicate infections varies significantly. A systematic review was performed to evaluate therapeutic interventions combating biofilm-related infections on in vivo animal models.

Increased failure rates due to metallic wear particle-associated adverse local tissue reactions (ALTR) is a significant clinical problem in resurfacing and total hip arthroplasty. Histological analysis and particle characterization are important elements for understanding the biological mechanisms of the reaction and different histological subtypes may have unique needs for longitudinal clinical follow-up and complication rates after revision arthroplasty. Consecutive patients (N=285 cases) presenting with ALTR from three major hip implant classes, metal-on-metal resurfacing and total hip arthroplasty (THA) and non-metal-on-metal THA with dual modular neck were identified from our prospective Osteolysis Tissue Database and Repository and 53 cases were selected for wear particle nano-analysis. Conventional histology: Tissue samples taken from multiple regions around the hip with extensive sampling performed at macroscopic examination were examined by light microscopy. Particle analysis: Tissue samples selected after frozen section evaluation for cellularity and particle content were examined by scanning electron microscopy (SEM), backscatter scanning electron microscopy (BSEM), BSEM-energy-dispersive X-ray spectroscopy (EDS) element mapping examination, transmission electron microscopy (TEM), TEM-EDS element mapping, and X-ray diffraction spectrometry (XRD) examination. ALTR encompasses three main histological patterns: 1) macrophage predominant, 2) mixed lymphocytic and macrophagic, and 3) predominant sarcoid-like granulomas. Duration of implantation and composition of periprosthetic cellular infiltrates was significantly different among the three implant types examined. Distinct differences in the size, shape, and element composition of the metallic particulate material were detected in each implant class, with correlation of the severity of the adverse reaction with element complexity of the particles. ALTR encompasses a diverse range of histological patterns, which are reflective of both the implant configuration independent of manufacturer and clinical features such as duration of implantation. Distinct differences in the metallic particulate material can contribute to explain the histological features of the ALTR and variability of performance of the implants. ALTR exhibits different histological patterns and is dependent on the characteristics of the wear particulate material of each implant class and host immunological reaction

Hip resurfacing offers an attractive alternative to conventional total hip arthroplasty in young active patients. It is particularly advantageous for bone preservation for future revisions. Articular Surface Replacement (ASR) is a hip resurfacing prosthesis manufactured by DePuy Orthopaedics Inc. (Warsaw, IN). The manufacturer voluntarily recalled the ASR system in 2010 after an increasing number of product failures. The present study aimed to determine the long-term results in a large cohort of patients who received the ASR prosthesis. Between February 2004 and August 2010, 592 consecutive hip resurfacings using the ASR (DePuy Orthopaedics Inc., Warsaw, IN) resurfacing implant were performed in 496 patients (391 males and 105 females). The mean age of the patients at the time of the surgery was 54 (range: 25 to 74) years. Osteoarthritis was the most common diagnosis in 575 hips (97.1%). The remaining patients (2.9%) developed secondary degenerative disease from ankylosing spondylitis, avascular necrosis, developmental hip dysplasia, and rheumatoid arthritis. Clinical and radiographic information was available for all patients at the last follow up. Cobalt (Co) and chromium (Cr) levels were measured in 265 patients (298 hips) by inductively coupled plasma-mass spectrometry (ICP-MS). The average follow up of the study was 8.6 years (range: 5.2 to 11.6 years). The mean Harris hip and UCLA scores significantly improved from 44 and 2 pre-operatively to 85.3 and 7.1 respectively. The median Co and Cr ion level was 3.81 microgram per liter and 2.15 microgram per liter respectively. Twenty-seven patients (5.4%) were found to have blood levels of both Co and Cr ions that were greater than 7 microgram per liter. Fifty-four patients (9.1%) were revised to a total hip arthroplasty. Kaplan-Meier survival analysis showed a survival rate of 87.1% at 8.6 years with revision for any cause and 87.9% if infection is removed. A significantly higher survival rate was observed for the male patients (90.2%, p <0.0001) and for the patients with ASRs with femoral heads diameters larger than 52 mm (90.1%, p=0.0003). This study confirms that patient selection criteria are of great importance to the overall survivorship of hip resurfacing arthroplasty. Improved clinical results have been reconfirmed with the use of larger diameter femoral heads

Aims

This study aimed to demonstrate the promoting effect of elastic fixation on fracture, and further explore its mechanism at the gene and protein expression levels.

Introduction: Over the past decade metal-on-metal bearings in the form of hip resurfacings have been increasing in popularity and with it, an associated interest in the potential side effects of elevated serum metal ion levels. Method: We prospectively measured the cobalt and chromium serum levels of 20 patients over a two-year period following Birmingham hip resurfacing. Cobalt was measured with inductively coupled plasma mass spectrometry and chromium using graphite furnace atomic absorption spectrometry. Results: For serum cobalt there was an initial increase, to a peak at six months then a gradual decline. A similar pattern was observed for chromium, although the peak occurred slightly later at nine months. Conclusion: One-off single measurements of metallic ion levels is of minimal clinical use, when the actual pattern of ion elevation and fall is not known. This study allows us to expect a peak at certain times following a hip resurfacing and a gradual decline thereafter

Corrosion in modular taper connections of total joint replacement has become a hot topic in the orthopaedic community and failures of modular systems have been reported. The objective of the present study was to determine in vivo titanium ion levels following cementless total hip arthroplasty (THA) using a modular neck system. A consecutive series of 173 patients who underwent cementless modular neck THA and a ceramic on polyethylene bearing was evaluated retrospectively. According to a standardized protocol, titanium ion measurements were performed on 67 patients using high-resolution inductively coupled plasma-mass spectrometry. Ion levels were compared to a control group comprising patients with non-modular titanium implants and to individuals without implants. Although there was a higher range, modular-neck THA (unilateral THA: 3.0 μg/L (0.8–21.0); bilateral THA: 6.0 μg/L (2.0–20.0)) did not result in significant elevated titanium ion levels compared to non-modular THA (unilateral THA: 2.7 μg/L (1.1–7.0), p = 0.821; bilateral THA: 6.2 μg/L, (2.3–8.0), p = 0.638). In the modular-neck THA group, patients with bilateral implants had significantly higher titanium ion levels than patients with an unilateral implant (p < 0.001). Compared to healthy controls (0.9 μg/L (0.1–4.5)), both modular THA (unilateral: p = 0.029; bilateral p = 0.003) and non-modular THA (unilateral: p < 0.001; bilateral: p < 0.001) showed elevated titanium ion levels. The data suggest that the present modular stem system does not result in elevated systemic titanium ion levels in the medium term when compared to non-modular stems. However, more outliner were seen in modular-neck THA. Further longitudinal studies are needed to evaluate the use of systemic titanium ion levels as an objective diagnostic tool to identify THA failure and to monitor patients following revision surgery

Introduction: Over the past decade metal on metal bearings in the form of hip resurfacings have been increasing in popularity and with it an associated interest in the potential side effets of elevated serum metal ion levels. Methods: We prospectively measured the cobalt and chromium serum levels of 20 patients over a 2 year period following Birmingham hip resurfacing. Cobalt was measured with inductively coupled plasma mass spectrometry and chromium using graphite furnace atomic absorption spectrometry. Results: For serum cobalt there was an initial increase to a peak at 6 months then a gradual decline. A similar pattern was observed for chromium, although the peak occurred slightly later at 9 months. Conclusions: One off single measurements of metallic ion levels are of minimal clinical use, when the actual pattern of ion elevation and fall is not known. This study allows us to expect a peak at certain times following a hip resurfacing and a gradual decline thereafter

An experimental study was performed in order to investigate methods of preparation and mechanical properties of a potential bone graft substitute. This new composite material consists of porous hydoxyapatite coated with oxidised cellulose. Porous hydoxyapatite has excellent osteoconductive properties and promising strength characteristics. Drawbacks include its lack of osteoinductive properties and its brittle nature. Oxidised cellulose can be functionalised to provide binding sites for proteins, drugs and cells, which would allow for increased osteoinductive activity. It has good tensile strength. By creating a composite of these two substances, it was proposed that a graft substitute could be created. Hydroxyapatite samples were formed by processing and sintering bovine cancellous bone. A method was devised by which cellulose was brought into solution and infiltrated into hydoxyapatite samples. The cellulose was then regenerated (cured) and oxidised. Infrared spectrometry confirmed the desired chemical reactions took place and that oxidised cellulose was formed. Scanning electron microscopy confirmed that the three-dimensional structure of the hydroxyapatite was satisfactorily coated. Crush testing showed that infiltrated samples were less brittle and more likely to hold their shape than control samples. Further development and testing is required to assess this composite material for its biological activity and potential as a bone graft substitute

In a randomized study of 60 patients allergic reactions are evaluated in three joint prosthesis groups, a resurfacing arthroplasty (ReCap), a non-cemented, large metal-on-metal head (Bimetric Magnum) and a non-cemented, alumina ceramic-on-ceramic bearing in a titanium shell (Bimetric C2a). The inclusion criteria were osteoarthritis, ASA I–II, MRI-scan without caput necrosis, DXA-scan without osteoporosis. The exclusion criteria were short neck (<2cm.), large cysts (>1cm.), medical treatment affecting the bone metabolism, severe deformity of the femoral head, impaired kidney function and inability to co-operate. Blood samples were drawn prior to and 6 weeks, 6 months, 1 year, and 3 years after surgery; two tubes from which plasma was prepared, and two tubes for serum. From the last included 20 patients in each group was also taken blood one and three years after surgery for an in vitro lymphocyte assay for scoring of possible hypersensitivity to prosthesis metals. The isolated lymphocytes were subjected to measurement of proliferation and expression of CD69 by flow cytometry and measurement of the Migration Inhibitory Factor (MIF) by ELISA. Plasma concentrations of the cytokines IL-1, IL-4, IL-6, IL-8, IL-12p70, IL-15, interferon-and osteoprotegerin were determined by multiplex-immunoassay. Serum concentrations of chromium and cobalt were determined by graphite furnace atomic absorption spectrometry. The serum concentrations of chromium and cobalt were lowest in patients with the C2a implant and highest with Magnum, some of these differences were significant at 6 weeks, 6 months, and 1 year after surgery. No patient had a very high serum metal concentration. The values of the variables measured in the in vitro lymphocyte assay mainly changed in the expected direction depending on the concentration of the same metal in the serum sample drawn at the same time, but no significant correlation was seen. One patient had uncertain symptoms of metal hypersensitivity and relatively high serum metal concentrations 3 years after arthroplasty with a Magnum prosthesis and was assessed extraordinarily, and elicited the marginally highest MIF responses in the lymphocyte assay. A strong correlation was found between the plasma concentrations of most cytokines, but the cytokine concentrations were not correlated to contemporary metal concentrations