Aims. Patients receiving cemented hemiarthroplasties after hip fracture have a significant risk of deep surgical site infection (SSI). Standard UK practice to minimize the risk of SSI includes the use of antibiotic-loaded bone cement with no consensus regarding type, dose, or antibiotic content of the cement. This is the protocol for a randomized clinical trial to investigate the clinical and cost-effectiveness of high dose dual antibiotic-loaded cement in comparison to low dose single antibiotic-loaded cement in patients 60 years and over receiving a cemented hemiarthroplasty for an intracapsular hip fracture. Methods. The WHiTE 8 Copal Or Palacos Antibiotic Loaded bone cement trial (WHiTE 8 COPAL) is a multicentre, multi-surgeon, parallel, two-arm, randomized clinical trial. The pragmatic study will be embedded in the World Hip Trauma Evaluation (WHiTE) (ISRCTN 63982700). Participants, including those that lack capacity, will be allocated on a 1:1 basis stratified by recruitment centre to either a low dose single antibiotic-loaded bone cement or a high dose dual antibiotic-loaded bone cement. The primary analysis will compare the differences in deep SSI rate as defined by the Centers for Disease Control and Prevention within 90 days of surgery via medical record review and patient self-reported questionnaires. Secondary outcomes include UK Core Outcome Set for hip fractures, complications, rate of antibiotic prescription, resistance patterns of deep SSI, and resource use (more specifically, cost-effectiveness) up to four months post-randomization. A minimum of 4,920 patients will be recruited to obtain 90% power to detect an absolute difference of 1.5% in the rate of deep SSI at 90 days for the expected 3% deep SSI rate in the control group. Conclusion. The results of this trial will provide evidence regarding clinical and cost-effectiveness between low dose single and high dose dual antibiotic-loaded bone cement, which will inform policy and practice guidelines such as the National Institute for Health and Care Excellence guidance on management of hip fractures. Cite this article: Bone Jt Open 2021;2(2):72–78

Antimicrobial resistance (AMR) is projected to result in 10 million deaths every year globally by 2050. Without urgent action, routine orthopaedic operations could become high risk and musculoskeletal infections incurable in a “post-antibiotic era.” However, current methods of studying AMR processes including bacterial biofilm formation are 2D in nature, and therefore unable to recapitulate the 3D processes within in vivo infection. Within this study, 3D printing was applied for the first time alongside a custom-developed bioink to bioprint 3D bacterial biofilm constructs from clinically relevant species including Staphylococcus aureus (MSSA), Methicillin-resistant staphylococcus aureus (MRSA), Escherichia coli and Pseudomonas aeruginosa. Bacterial viability and biofilm formation in bioprinted constructs was excellent, with confocal laser scanning microscopy (CSLM) used to demonstrate biofilm production and maturation over 28 days. Bioprinted 3D MRSA and MSSA biofilm constructs had greater resistance to antimicrobials than corresponding two-dimensional (2D) cultures. Thicker 3D E.coli biofilms had greater resistance to tetracycline than thinner constructs over 7 days of treatment. Raman spectroscopy was also adapted in a novel approach to non-invasively diagnose 3D bioprinted biofilm constructs located within a joint replacement model. In conclusion, mature bacterial biofilm constructs were reproducibly 3D bioprinted for the first time using clinically relevant bacteria. This methodology allows the study of antimicrobial biofilm penetration in 3D, and potentially aids future antimicrobial research, replicating joint infection more closely than current 2D culture models. Furthermore, by deploying Raman spectroscopy in a novel fashion, it was possible to diagnose 3D bioprinted biofilm infections within a joint replacement model

Kirschner wires are commonly used in paediatric fractures, however, the requirement for removal and the possibility of pin site infection provides opportunity for the development of new techniques that eliminate these drawbacks. Bioabsorbable pins that remain in situ and allow definitive closure of skin at the time of insertion could provide such advantages. Three concurrent studies were performed to assess the viability of bioabsorbable pins across the growth plate. (1) An epidemiological study to identify Kirschner wire infection rates. (2) A mechanical assessment of a bioabsorbable pin compared to Kirschner wires in a simulated supracondylar fracture. (3) The insertion of the implants across the physis of sheep to assess effects of the bioabsorbable implant on the growth plate via macroscopic, pathohistological and micro-CT analysis. An infection rate of 8.4% was found, with a deep infection rate of 0.4%. Mechanically the pins demonstrated comparable resistance to extension forces (p=) but slightly inferior resistance to rotation (p=). The in vivo component showed that at 6 months: there was no leg length discrepancy (p=0.6), with micro-CT evidence of normal physeal growth without tethering, and comparable physeal width (p=0.3). These studies combine to suggest that bioabsorbable pins do not represent a threat to the growth plate and may be considered for physeal fracture fixation

Introduction. Femoral neck fractures are a large clinical and economical problem. One of the most common fixation options for femoral neck fractures are multiple cancellous screws. A previous clinical study has shown the lack of washers to be the single largest predictor of fixation failure in the treatment of femoral neck fractures with cancellous screws. This finding was somewhat surprising as washers do not prevent the screws from backing out and do not provide any increase resistance to varus collapse. Therefore a follow-up biomechanical study was designed to test this observation. The purpose was to evaluate the maximal insertional torque of screws in osteoporotic bone with and without washers. We hypothesized that the lateral cortex of an osteoporotic proximal femur does not provide sufficient counter resistance for the screw heads to obtain maximum torque upon screw insertion in the femoral head and that the use of washers would increase screw purchase by providing a larger rigid surface area and subsequent higher counter resistance thereby allowing a higher maximal screw insertion torque. Methods. We used eight matched pairs of osteoporotic fresh-frozen human cadaveric femurs (age >70 years, all female). Two screws each were inserted in each femur either with or without a washer and maximal insertional torque was measured using a 50 Nm torque transducer. The testing was performed using a customized device which allowed the torque transducer to apply a constant axial force and torque speed to the screws. A paired Student's t-test was used to compare the maximal screw insertional torque of screws with washers versus screws without washers in matched pairs. Results. Fifteen out of 16 times the maximal screw insertional torque was higher when a washer was used. The average maximal torque with a washer was 5.1 Newtonmeter (Nm) compared to 3.1 Nm without a washer (p<0.001). Conclusion. We conclude that the addition of washers increases the maximal insertion torque of cancellous screws in the treatment of osteoporotic femoral neck fractures by providing counter resistance to the screw heads at an otherwise weak lateral cortex. We have demonstrated that the washer prevents the screw heads from penetrating the lateral cortex and provides for an improved purchase of the screws in the femoral head. As a clinical reference value for interpretation of this data, the limit of torque limiting screw drivers used with locking plates is set between 4 and 6 Nm. Therefore the difference in insertion torques likely represents clinically relevant values. Since there is no apparent disadvantage in the use of washers and they are inexpensive and readily available even in less developed countries, we advocate for their routine use until larger clinical studies disprove their efficacy

Objectives. Deep bone and joint infections (DBJI) are directly intertwined with health, demographic change towards an elderly population, and wellbeing. The elderly human population is more prone to acquire infections, and the consequences such as pain, reduced quality of life, morbidity, absence from work and premature retirement due to disability place significant burdens on already strained healthcare systems and societal budgets. DBJIs are less responsive to systemic antibiotics because of poor vascular perfusion in necrotic bone, large bone defects and persistent biofilm-based infection. Emerging bacterial resistance poses a major threat and new innovative treatment modalities are urgently needed to curb its current trajectory. Materials and Methods. We present a new biphasic ceramic bone substitute consisting of hydroxyapatite and calcium sulphate for local antibiotic delivery in combination with bone regeneration. Gentamicin release was measured in four setups: 1) in vitro elution in Ringer’s solution; 2) local elution in patients treated for trochanteric hip fractures or uncemented hip revisions; 3) local elution in patients treated with a bone tumour resection; and 4) local elution in patients treated surgically for chronic corticomedullary osteomyelitis. Results. The release pattern in vitro was comparable with the obtained release in the patient studies. No recurrence was detected in the osteomyelitis group at latest follow-up (minimum 1.5 years). Conclusions. This new biphasic bone substitute containing antibiotics provides safe prevention of bone infections in a range of clinical situations. The in vitro test method predicts the in vivo performance and makes it a reliable tool in the development of future antibiotic-eluting bone-regenerating materials. Cite this article: M. Stravinskas, P. Horstmann, J. Ferguson, W. Hettwer, M. Nilsson, S. Tarasevicius, M. M. Petersen, M. A. McNally, L. Lidgren. Pharmacokinetics of gentamicin eluted from a regenerating bone graft substitute: In vitro and clinical release studies. Bone Joint Res 2016;5:427–435. DOI: 10.1302/2046-3758.59.BJR-2016-0108.R1

Recent findings about UHMWPE oxidation from in vivo stresses lead to the need of a better understanding of which anti-oxidant additivation method is the best option for the use in orthopaedic field. A GUR 1050 crosslinked Vitamin E - blended UHMWPE has been investigated, to provide an accurate outline of its properties. DSC and FTIR measurements, together with ageing and tensile tests were performed on compression moulded blocks, as well as biocompatibility tests, including implantation on rabbits. Moreover, wear simulations on finished components (Delta acetabular liners) have been completed. All the test procedures have been repeated for a reference material, a GUR 1050 crosslinked and remelted standard UHMWPE (commercial name UHMWPE X-Lima), and the outcomes have been compared to the crosslinked Vitamin E - blended UHMWPE ones. On the additivated UHMWPE, we found a ultimate tensile strength of 43 MPa, a yield strength value of 25 MPa, and an elongation to breakage equal to 320%. The degree of cristallinity was 45 ± 2%, and no signal of creation of oxidation products was detected up to 2000 h of permanence in oxidant ambient after the ageing test. The reference material showed comparable mechanical resistance values (∗ = 40 MPa, y = 20 MPa, 350% elongation), a cristallinity of 46 ± 2%, and the creation of oxidation products starting from 700 h in oxidant ambient. The biocompatibility tests indicate that the additivated material is biocompatible, as the reference X-Lima UHMWPE. Wear tests gave a wear rate of 5,09 mg/million cycles against 6,13 mg/million cycles of the reference material, and no sign of run in wear rate. Our results indicate that there is no change in mechanical properties in respect to the reference material. This is confirmed by DSC measurements, that show no change in cristallinity. The blend between polymer and additive assures an uniform concentration of Vitamin E across the whole thickness of the moulded block, and ageing test results on additivated UHMWPE have shown that the material possess a superior resistance to degradation phenomena. Biocompatibility assess that the presence of Vitamin E is not detrimental for the in vivo use of the material, and wear results indicate a better wear resistance of the material, especially in the first stages of the wear process. From these considerations, it can be concluded that the material, in respect to the standard UHMWPE, is highly resistant to oxidation phenomena, therefore it is expected to have superior in vivo endurance performance

Staphylococcus aureus is responsible for 60–70% infections of surgical implants and prostheses in Orthopaedic surgery, costing the NHS £120–200 million per annum. 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. Using a methicillin-sensitive S. aureus reference strain and the dissolvable bead assay, biofilms were challenged by a low-intensity ultrasound (1.5MHz, 30mW/cm2, pulse duration 200µs/1KHz) for 20 minutes and gentamicin. The 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. 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 64mg/L. Further studies confirmed that the mechanism of action was due to incomplete disruption of the extracellular matrix with subsequent metabolic stimulation of the dormant biofilm-associated bacteria due to increased nutrient availability and oxygen tension. Low intensity pulsed ultrasound was associated with a 4-fold reduction in the effective biofilm eradication concentration of gentamicin; bringing the MBEC of gentamicin to within clinically achievable concentrations

Methicillin Resistant Staphylococcus Aureus (MRSA) screening has reduced rates of MRSA infection in primary total hip (THR) and total knee (TKR) replacements. There are reports of increasing methicillin resistance (MR) in Coagulase Negative Staphylococci (CNS) causing arthroplasty infections. We examined microbiological results of all 2-stage THR/TKR revisions in Tayside from 2001–2010. 72 revisions in 67 patients were included; 30 THRs and 42 TKRs. Mean ages at revision were 89 and 72 years respectively. Male: female ratio 1.4:1.2-year survivorship for all endpoints: 96% in THRs and 88% in TKRs. 5-year survival: 83% and 84% respectively. The most common organisms were SA (30%) and CNS (29%). Antibiotic resistance was more common amongst CNS. 72% of CNS were resistant to Methicillin versus 20% of SA. 80% of CNS were resistant to Gentamicin OR Methicillin versus 20% of SA. 32% (8/72 cases or 11% overall) of CNS were resistant to BOTH Gentamicin AND Methicillin, the primary arthroplasty antibiotic prophylaxis in our region, versus 4% of SA. Harris Hip Scores and Knee Society Scores were lower post primary, prior to symptoms of infection in patients who had MR organisms cultured compared with those who had methicillin sensitive organisms. One-year post revision both groups recovered to similar scores. Our data suggest MR-CNS cause significantly more arthroplasty infections than MRSA. Patients developing MR infections tend to have poorer post-primary knee and hip scores before symptoms of infection fully develop. 32% of CNS causing arthroplasty infections in our region are resistant to current routine primary antibiotic prophylaxis

Introduction. Rapid identification of bacteria from extemporaneous samples would greatly help management of prosthesis joint infection. The aim of the present retrospective study was to evaluate a new molecular assay (GeneXpert MRSA-SA SSTI (Cepheid)) for detecting Staphylococcus aureus (SA) and methicillin resistance directly from bone and joint samples in less an hour (58 minutes). Material et method. Retrospective study using 91 frozen samples (76 patients) of joints (n=24), bone biopsies (n=42) and tissue biopsies (n=25):. -. SA positive samples: n=72 (methicillin susceptible SA (MSSA), n=63; methicillin resistant MRSA, n=9). -. SA positive samples: n=19. The results were compared with routine results (culture in solid and liquid medium, identification and susceptibility test) from each participating lab. Results. The 72 SA positive samples gave:. -. 68 concordant positive results comprising:. . 9 MRSA positive samples,. . 56 MSSA positive samples,. . 3 MSSA positive samples, positive for SA but with inconclusive results for methicillin resistance. -. 4 negative discordant results for MSSA positive samples. The 19 SA negative samples gave:. . 16 concordant negative results. . 3 SASM positive results for negative culture of samples obtained from patients with other MSSA positive deep or superficial samples, suggesting a higher sensitivity for the GeneXpert test than culture in these cases. Sensitivity and specificty for bone and joint samples:. Se=68/72=94.4%. Sp=16/16=100%. Conclusion. The GeneXpert MRSA-SA SSTI assay provides 58-minute detection of MSSA and MRSA directly from bone and joint samples. Sensitivity and specificity were excellent in this preliminary study. This test may enable real-time peroperative diagnosis of Staphylococcus aureus, which could be very useful in the field of revision surgery. Further prospective studies should be done to accurately determine the PPV, NPV, and clinical and pharmaco-economic impact of this test in the setting of prosthesis joint infection

Introduction. Osteoporosis is a metabolic disease of the bone responsible for a loss of bone resistance and an increase in fracture risk. World Health Organization (WHO) estimations are about 6.3 millions of femoral neck fractures in the world by 2050. These estimations make osteoporosis a real problem in term of public health. Knowledge in biological tissues mechanical behaviour and its evolution with age are important for the design of diagnosis and therapeutic tools. From the mechanical aspect, bone resistance is dependent on bone density, bone architecture and bone tissue quality. If the importance of bone density and bone architecture has been well explored, the bone tissue quality still remains unstudied because of the lack of biomechanical tools suitable for testing bone at this microscopic dimension. Therefore the goal of this study is to estimate the osteoporotic cancellous bone tissue mechanical behaviour at its microscopic scale, using an approach coupling mechanical assays and digital reconstruction. Materials and methods. The experimental study is based on cancellous bone tissue extracted from human femoral head. Forty 8mm diameters bone cylinders have been removed from femoral head explanted after a femoral neck fracture treated by arthroplasty. These cylinders have been submitted to a digitally controlled compressive trial. Before and after the trials, microscanner analyses with an 8 μm spatial resolution have been realized in order to determine the micro structural parameters. The cylinders have been rebuilt with the digital model-building in order to estimate the mechanical behaviour and the bone quality. Results. The results will be presented from a macroscopic and microscopic point of view and will show the relationship between gender and age of the patients. At the macroscopic scale, we will look at that apparent young modulus heterogeneity and the cracking strength. At the microscopic scale, we will confirm that the cancellous bone tissue mechanical behaviour is close to the Haversian bone tissue mechanical behaviour. Finally, the parametric study will permit us to point out the main microstructural components influencing cancellous bone tissue quality. Conclusion. This study allows a precise estimation of the osteoporotic cancellous bone tissue mechanical behaviour. It seems to be a great step in the understanding of this disease and it could probably lead to great improvements in the diagnosis, prognostic, medical and surgical approaches of osteoporosis

Introduction. In total hip arthroplasty ceramic on ceramic bearing couples are used more and more frequently and on a wordwide basis. The main reason of this choice is reduction of wear debris and osteolysis. The tribological properties and the mechanical behaviour of the implanted ceramic must remain the same throughout the patient's life. The aim of this study was to evaluate the resistance of Alumina Matrix Composite to environmental degradation. Material and method. The alumina matrix composite or BIOLOX ® delta is manufactured in Germany by CeramTec. It is made up of 80 vol.% Al2O3, 17 vol.% Yttria Stabilized ZrO2 and 3vol.% strontium aluminate platelets. The zirconia grains account for 1.3 mol.% of the Yttria content. Accelerated aging tests in water steam at 142°C, 134°C, 121°C, and 105°C were performed to evaluate the aging kinetics of the composite. X-ray diffraction was used to determine the monoclinic phase content on the material surface. Phase transformation is associated with weakness and increase in roughness of zirconia ceramic implants. Results. The data below shows average monoclinic contents before and after aging in water vapour according to the ISO standard test (134°C, 2 bars water steam, 10 h) on the surface and inside the 28 mm taper(12/14 taper) femoral ball heads manufactured in alumina ceramic composite. There are precisions concerning the roughness and the load to failure before and after aging concerning 28mm diameter heads. Before Aging 13%+/-3% of Monoclinic content. After 10 H at 134°C23%+/-3% of Monoclinic content the roughness of the polished surface remain the same (5nm+/− 2). The load to failure of 28 mm heads before aging is 76 kN +/− 5kN, and 72 kN +/− 5kN after aging. The results show that although a rise in monoclinic content is predictable after long aging duration in vivo, the impact of the transformation is quite different to monolithic zirconia. A zirconia femoral head exhibits an important increase of roughness from 2 nm to more than 50 nm when submitted to the same duration of ageing. Other tests with hip simulators under severe micro separation have been done to analyse the impact of aging on wear performance. The main wear zone on femoral heads underwent a phase transformation from tetragonal to monoclinic (23% monoclinic) at 5 milion cycles duration without any change in roughness after 5Mc duration. Conclusion. This experimental testing program has enabled a prediction for the long-term in vivo environmental resistance of prostheses made out of Alumina Matrix Composite. The substantial improvement in mechanical properties and the excellent wear behaviour, even under severe microseparation conditions has been clinically confirmed. Today more than 960,000 ceramic ball heads and more than 450 000 ceramic inserts made of the alumina matrix composite have been implanted. Additionally, due to enhanced mechanical behaviour, new applications in orthopaedics are possible

Introduction. Patients suffering from finger joint pain or dysfunction due to arthritis and traumatic injury may require arthroplasty and joint replacement. Single-part silicone-based implants remain the material of choice and most widely used option, although reports on their long-term clinical performance are variable. For trauma indications, patients have a high expectation of functionality necessitating the use of materials with high wear resistance and mechanical performance. A new proximal inter phalangeal (PIP) joint designed by Zrinski AG (Wurmlingen, Germany), comprising a self-mating carbon fibre reinforced polyetheretherketone (CFR-PEEK) coupling, may provide a suitable alternative. Here we describe the wear performance of the CFR-PEEK components in a PIP joint wear simulator and subsequent characterisation of the wear particles. Methods. Four proximal and distal PIP components were milled (Zrinski AG) from CFR-PEEK (Invibio Ltd, UK) and subjected to wear testing (Endo Lab ® GmbH, Germany). The test was conducted at 37°C over 5 million cycles in 25% bovine serum (refreshed every 0.5 million cycles). The load was a static force of 63N applied at a frequency of 1Hz with a flexion/extension angle of ±40°. Wear rate was determined by mass loss from each component. Pooled serum samples from the wear simulator were subjected to protein digest and the remaining particulate debris isolated by serial filtration through 10μm, 1μm and 0.1μm filters. Particle size and morphology was subsequently determined by scanning electron microscopy (SEM) (Continuum Blue, UK). Results. Both components exhibited high resistance to wear, with the proximal component resulting in a wear rate of 0.09mg/million cycles, whilst that of the distal component was 0.07mg/million cycles. Particle analysis revealed that the majority of debris generated during the wearing in phase (0.5 million cycles) was <0.5μm in diameter. During the steady state phase (0.5–3 million cycles) a large peak in particle size was observed in the 2μm diameter range, whilst in the latter stage (3–5 million cycles) peaks in particle size were seen at 0.4μm and 2μm. During each stage, both the particle count and aspect ratio remained relatively unchanged. Conclusion. Under these test conditions the CFR-PEEK coupling demonstrated a linear and consistently low wear rate over the 5 million cycle test period, with the majority of particles generated being <2μm in diameter. The low wear rate and biocompatibility demonstrated by CFR-PEEK suggests it is a suitable alternative to silicone in PIP joint prostheses. Acknowledgements. The authors would like to thank Zrinski AG, Christian Kaddick at EndoLab GmbH for the wear simulator work and Mark Yeoman at Continuum Blue Ltd. for particle analysis

Cephalasporin antibiotics have been commonly used for prophylaxis against surgical site infection. To prevent Clostridium difficile, the preferential use of agents such as flucloxacillin and gentamicin has been recommended. The aim of this study was to investigate the bone penetration of these antibiotics during hip and knee arthroplasty, and their efficacy against Staphylococcus aureus and S. epidermidis. Bone samples were collected from 21 patients undergoing total knee arthroplasty (TKA) and 18 patients undergoing total hip replacement (THA). The concentration of both antibiotics was analysed using high performance liquid chromatography. Penetration was expressed as a percentage of venous blood concentration. The efficacy against common infecting organisms was measured using the epidemiological cut-off value for resistance (ECOFF). The bone penetration of gentamicin was higher than flucloxacillin. The concentration of both antibiotics was higher in the acetabulum than the femoral head or neck (p=0.007 flucloxacillin; p=0.021 gentamicin). Flucloxacillin concentrations were effective against S. aureus and S. epidermis in all THAs and 20 (95%) TKAs. Gentamicin concentrations were effective against S.epidermis in all bone samples. Gentamicin was effective against S. aureus in 11 (89%) femoral samples. Effective concentrations of gentamicin against S. aureus were only achieved in 4 (19%) femoral and 6 (29%) tibial samples in TKA. Flucloxacillin and gentamicin was found to effectively penetrate bone during arthroplasty. Gentamicin was effective against S. epidermidis in both THA and TKA, while it was found to be less effective against S. aureus during TKA. Bone penetration of both antibiotics was less in TKA than THA

Background. Jumper's knee is the result of violent and repeated contractions of quadriceps muscle caused by rapid acceleration and deceleration, jumping and kicking that load on patellar tendon stressing its mechanical resistance. The porpose of this retrospective study is to analyze the results, after the debridment of the patellar tendon and the patellar apex abrasion performed by arthroscopy, at a mean follow-up of seven years. Methods. From 1996 to 2006, sixty-four patients (seventy-three knees) affected by jumper's knee underwent surgical tretment after failure of nonoperative treatment. All knees were operated on by the same surgeon using the same surgical technique: arthroscopic debridement of the articular face of patellar tendon and arthroscopic abrasion of patellar apex. Pre-operative and post-operative evaluation was made according to IKDC score, Lysholm Knee Scale and VISA-P score. Results. The pre-operative subjective IKDC score was 52,96. This score significantly increased to 94,72 at 12 months post-operation, and has remained nearly constant at 10 years of follow-up. The mean pre-operative Lysholm Knee Scale was 51,57 and significantly increased to 86,48 at 12 months post-operation again remaining nearly constant at 10 years of follow-up. The score according to VISA-P which was pre-operatively 35,32 increased to 69,80 at 12 months post-operation and was 69,35 at 10 years of follow-up. Nineteen of the twenty-seven patients who were involved in competitive sport continued it at the same level and twenty-four were symptoms-free. Conclusions. For these satisfactory results, for the low aggressivity of this surgery, for the short recovery time and the faster return to sport we think that the debridment of the patellar tendon and the patellar apex abrasion performed by arthroscopy is the technique to prefer for surgical treatment of Jumper's Knee

Introduction. Microbiological diagnosis of bone and joint infections (BJIs) currently relies on standard cultures which are time consuming and lack sensitivity. Various molecular approaches have been described and allowed improvement of BJI diagnosis. This study evaluated for the first time the performance of a DNA microarray-based assay (Prove-it™ Sepsis assay, PISA) for the rapid (<6 hours) detection and identification of 50 different species involved in BJI directly from clinical samples. Material and methods. We retrospectively selected 130 bone and joint samples (67 synovial fluids and 63 bone biopsies) including 114 positive and 16 negative samples. The microbiological diagnosis had been previously established either by culture(C+, n=53) or by PCR16S and sequencing when culture was negative (C-/PCR+). The positive samples were selected to match the species targeted on the DNA microarray. DNA extraction was performed before proceeding to PISA amplification and hybridization on every selected sample. Results. Among the 16 negative samples, one was detected positive with S. epidermidis by PISA, result that was secondarily confirmed using specific PCR. Among the 114 positive samples, 62.3% were positive using PISA with highly concordant identification compared to culture and PCR16S/sequencing results. Forty-three samples (37.7%) remained negative, illustrating a defect of sensitivity. However, PISA accurately detected methicillin resistance not only among the 16 C+/PISA+ Staphylococcus species (n=5) but also among the 28 C-/PCR16S+ Staphylococcus species (n=12) offering crucial rapid information to adapt the treatment of staphylococcal BJIs. Seven polymicrobial samples were also identified without extensive experiments. Discussion – Conclusion. Even if the sensitivity deserves to be improved by optimizing DNA extraction and investigating on human DNA interference, these preliminary promising results highlight that this new and simple microarray method could be in the future an alternative to conventional PCR16S for the diagnosis of BJI

Aims

Osteopetrosis (OP) is a rare hereditary disease that causes reduced bone resorption and increased bone density as a result of osteoclastic function defect. Our aim is to review the difficulties, mid-term follow-up results, and literature encountered during the treatment of OP.

Introduction. Cobalt chrome on polyethylene remains a widely used bearing combination in total joint replacement. However wear induced osteolysis, bulk material property degradation of highly cross-linked polyethylene (HXLPE) [1], and oxidation after implantation (thought to be as a result of lipid absorption or cyclic loading [2]) remains a concern. ECIMA is a cold-irradiated, mechanically annealed, vitamin E blended next generation HXLPE developed to maintain mechanical properties, minimise wear and to improve the oxidation resistance in the long-term. The aim of this study was to compare the in-vitro wear rate and mechanical properties of three different acetabular liners; conventional UHMWPE, HXLPE and ECIMA. Methods. Twelve liners (Corin, UK) underwent a 3 million cycle (mc) hip simulation. Three conventional UHMWPE liners (GUR1050, Ø32 mm, 30 kGy sterilised in Nitrogen), three HXLPE liners (GUR1020, Ø40 mm, 75 kGy cross-linking and EtO sterilised) and six ECIMA liners (0.1 wt% vitamin E GUR1020, Ø40 mm, 120 kGy cross-linking, mechanically deformed and annealed, and EtO sterilised) articulated against CoCrMo alloy femoral heads to ASTM F75 (Corin, UK). Wear testing was performed in accordance with ISO 14242 parts 1 and 2, with a maximum force of 3.0 kN and at a frequency of 1 Hz. The test lubricant used was calf serum with a protein content of 30 g/l and 1% (v/v) patricin added as an antibacterial agent. Volumetric wear rate was determined gravimetrically after the first 0.5 mc and every 1 mc thereafter. ASTM D638 type V specimens (3.2 mm thick) were machined from ECIMA material for uniaxial tension testing to ASTM D638. Ultimate tensile strength (UTS), yield strength and elongation values were measured. These values were compared to mechanical data available for the other material types. Results. There was a 94% and a 68% reduction in the wear rate for the ECIMA liners compared to the conventional UHMWPE and HXLPE liners respectively. There was an increase in UTS, yield strength and elongation of 11%, 11% and 15% respectively, for ECIMA compared to HXLPE. Discussion. The wear results reported in this study indicate that ECIMA is a very low wearing material which has the potential to reduce wear related osteolysis in-vivo. Importantly, the mechanical properties were generally maintained unlike the degradation found in many modified polyethylene materials and were more comparable to conventional UHMWPE than HXLPE. The reduced wear rate during in-vitro hip simulation of ECIMA compared to conventional UHMWPE, coupled with improved mechanical properties in comparison to HXLPE, makes ECIMA a promising next generation, advanced bearing material

Introduction. In knee arthroplasty a ceramic component has several advantages: first, there is no ion release implying a risk for potential allergies. Second, the hardness of the material leads to a scratch resistance which ultimately reduces PE wear over time. In the past, ceramic components in knee applications were limited in the variety of design possibilities due to necessary thickness of the component resulting from the associated fracture risk of ceramics. By the development of an alumina matrix composite material with increased mechanical properties it is possible to develop ceramic knee components which have nearly the same design as a metal component and use the same implantation technique as well as the same instruments. This offers the surgeon the opportunity to choose intraoperatively between metal or ceramic knee components. Extensive in-vitro testing shows that ceramic knee components achieve superior mechanical test results. The reliability of the components is proven by two different burst tests and a fatigue test for both a femoral and a tibial ceramic knee component. Material and method. The mechanical proof-test was developed by subsequent steps of numerical load/stress analysis and design of an adequate mechanical test equipment. The procedure was organized as follows:. Oncologic: Analysis of relevant maximum in-vivo loading conditions. Analysis of the “boundary conditions”. Finite Element analysis: Identifying regions of highest stress concentration. Design analysis and accommodation if necessary. Development of an adequate mechanical test equipment which produces stresses comparable to the in-vivo conditions. Performing mechanical tests with ceramic femoral components. Validation of the test concept: comparison of test results and stress analysis. Assign “safety margin”,. Establish “proof test”. Results. Two independent load scenarios have been determined for each type of components as being in-vivo relevant. Hence, the developed proof-test consists of two subsequent load tests, the so-called regular test and the tension test for the femoral components, and the upper side test and the lower side test for the tibial components. In the regular test, the mechanical strength of the polished outer condyles is tested using a force which is equivalent to an in-vivo loading of 16 times bodyweight. In the tension test, the interior sides of the condyles are stressed in the sagittal plane ensuring a mechanically reliable implantation. This test is performed with a force equivalent to 10 times bodyweight. Discussion. The procedure to determine the proof loads using the maximum in-vivo loads together with a safety factor ensures the mechanical safety of the ceramic knee component. Together with the well-known excellent wear and biological behaviour of ceramics, this application provides an alternative to common metallic knee components. Clinical observations in the framework of a multi-centre study in different European countries have been started and show very promising results

Introduction. Vitamin E stabilization of radiation crosslinked UHMWPE is done by (1) blending into the resin powder, consolidating and irradiating or (2) diffusing into already consolidated and irradiated UHMWPE and terminally gamma sterilizing. With blending, a higher radiation dose is required for crosslinking to the same level as virgin UHMWPE. With diffusion, the vitamin E amount used is not limited by the crosslink density, but, vitamin E is exposed to terminal sterilization dose of 25–40 kGy, less than the 100–150 kGy used with blending, which may decrease the grafting of the antioxidant onto the polymer. We investigated the efficiency of grafted vitamin E against squlene-initiated accelerated aging. Methods. Medical grade GUR1050 UHMWPE with vitamin E (0.1 wt%) was irradiated to 150 kGy. Tibial knee insert preforms were irradiated to 100 kGy, diffused with vitamin E using a doping and homogenization procedure. This UHMWPE was used either before or after gamma sterilization. One set of machined blocks (10 × 10 × 6 mm; n = 6) were extracted in boiling hexane for 4 days, then dried. The extracted blocks were doped with squalene at 120°C for 2 hours. One block each was analyzed after doping. The rest were accelerated aged at 70°C and 5 atm. of oxygen for 6 (n = 2) and 14 days (n = 3). Thin sections (150 micron thick) were microtomed and analyzed by Fourier Transform Infrared Spectroscopy to determine a vitamin E index (1245–1275 cm. −1. normalized to 1850–1985 cm. −1. ) and an oxidation index (1700 cm. −1. normalized to 1370 cm. −1. ) after extraction with boiling hexane for 16 hours and drying. Results. After extraction, 92% of the original vitamin E was removed from diffused and sterilized UHMWPE and 99% of the vitamin E was removed from the diffused and unsterilized UHMWPE. Vitamin E content of the blended, irradiated UHMWPEs could not be detected. As a result of accelerated aging in the presence of squalene, all extracted vitamin E-stabilized UHMWPEs showed increased oxidation except diffused, sterilized UHMWPE. The small amount grafted vitamin E in these samples (8%, ∼0.02 wt%) protected irradiated UHMWPE under these conditions. All vitamin E-stabilized, extracted UHMWPEs showed higher oxidative stability than irradiated and melted virgin UHMWPE in the presence of squalene. In the blended, irradiated UHMWPE, there was less effective vitamin E compared to the diffused, sterilized UHMWPE due to the high dose irradiation. Conclusions. Radiation grafting of vitamin E onto UHMWPE was effective against squalene initiated oxidation in accelerated aging. Vitamin E-diffused, sterilized UHMWPE showed no oxidation and diffused, unsterilized UHMWPE and blended, irradiated UHMWPE showed higher oxidative resistance than irradiated/melted UHMWPE

Aims. Infections of bone usually require multiple surgery and prolonged periods of treatment. One reason for problems is found in the presence of stationary phase bacteria embedded in biofilms that show increased resistance against conventional antibiotic therapy (up to 1000x MIC). Biofilms adhere to surfaces of avital material making radical debridement a prerequisite for cure. Osseous defects are common in such conditions and need to be addressed. To avoid re-infection high local antbiotic concentrations are necessary. Allograft bone may be impregnated with high loads of antibiotics using a special incubation technique. The resulting antibiotic bone compound (ABC) provides high and long lasting concentrations at the site of infection and is likely to restore bone stock simultaneously. Based on this technology we have developed a new surgical technique. Methods. 42 patients (10–67yrs) with chronic osteitis were included into a prospective study using a standardized protocol. Infection was at the humerus (1x), femur (10x), tibia (29x) or femur+tibia (2x), respectively. Treatment consisted of removal of foreign material, radical sequestrectomy and soft-tissue debridement followed by pressurized lavage. Surfaces of sclerotic bone were trimmed down to vital areas. The remaining osseous defects were filled with ABC, using an impaction technique resulting in complete dead space management. The allograft was impregnated with vancomycin, in cases with mixed pathogens combinations with tobramycin were used. Internal fixation was performed the same time whenever applicable. Sites were drained and closed immediately; rehabilitation did not differ from uninfected procedures. Results. 1 patient died shortly after surgery from cardiac failure. 41 could be followed for a minimum of 2 and a maximum of 6years (mean 3,1years). In 2 patients wound healing was unsatisfactory requiring additional coverage with a muscle flap. 2 patients showed material failure after intramedullary nailing, requiring exchange of the implant. In those cases no sign of infection was present at the time of revision. There were 3 cases with recurrence of infection, all originating from foci not detected during the index operation and becoming apparent between 3 and 12 months after surgery. Two could successfully be revised using the same technique; one refused revision and shows continuing fistulation. Radiological incorporation of allografts appeared as after conventional bone grafting, union of pseudarthroses was achieved between 2 and 6 months after (re-) stabilization. 40 patients (95,2%) were fully weight bearing, painfree and without any sign of infection at the latest follow up. Conclusion. Using antibiotic impregnated allograft bone eradication of pathogens, grafting of defects, dead space management and insertion of osteosynthetic material may be accomplished in a one stage procedure. Since the graft gradually is replaced by healthy own bone improved long term results may be expected as well as improved conditions in the case of another revision. The new technique provides for quick rehabilitation, improved results and markedly reduced costs of treatment in cases of bone infection