Aims

Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors.

Polymerisation of PMMA results in a volume change resulting from molecular rearrangement. The calculated maximal volume reduction is approximately 7.6%; however, void growth reduces this to 3–6%. The significance of volume reduction is controversial, in particular with reference to void elimination techniques. Whilst the impact of mixing technique on overall volume change is known, little is understood about the dynamic volumetric changes occurring during the crucial time of cement-bone micro-interlock formation. This study aimed to investigate the volumetric behaviour of bone cement during polymerisation.

Polyethylene tubes were modified to simulate the physical and dimensional constraints of the human femoral medullary canal. The tubes were filled with either hand or enhanced vacuum mixed cement and suspended in a water bath. The residual weight of the cement specimen in water was recorded at 60sec intervals for 30 minutes. The dry weight of the cement is known and the immersed weight can be calculated. Archimedes principal allows calculation of the density and thus the volume of the cement mass throughout polymerisation. The specimens were sectioned, stained and analysed to assess sectional porosity.

In no specimen was it possible to demonstrate overall net expansion, however, hand mixed specimens demonstrated a temporary period of expansion during the early exothermic period. Vacuum mixed specimens demonstrated progressive contraction only. Overall volume change correlated closely with sectional porosity.

The overall volume reduction is strongly influenced by porosity. The temporary expansion observed in porous cement specimens must result from temperature driven growth of voids. This expansion occurs during the crucial period of cement-bone micro-interlock formation, and may therefore enhance attempts at pressurisation. Conversely, progressive volume reduction, as seen with low porosity cement, may impede micro-interlock formation. Successful cementation using vacuum mixed cement may therefore be solely dependent on adequate cement pressurisation.

Orthopaedics has been left behind in the worldwide drive towards diversity and inclusion. In the UK, only 7% of orthopaedic consultants are female. There is growing evidence that diversity increases innovation as well as patient outcomes. This paper has reviewed the literature to identify some of the common issues affecting female surgeons in orthopaedics, and ways in which we can address them: there is a wealth of evidence documenting the differences in the journey of men and women towards a consultant role. We also look at lessons learned from research in the business sector and the military. The ‘Hidden Curriculum’ is out of date and needs to enter the 21st century: microaggressions in the workplace must be challenged; we need to consider more flexible training options and support trainees who wish to become pregnant; mentors, both male and female, are imperative to provide support for trainees. The world has changed, and we need to consider how we can improve diversity to stay relevant and effective.

Cite this article: Bone Jt Open 2021;2-10:893–899.

A spine compression fracture is a very common form of fracture in elderly with osteoporosis. Injection of polymethyl methacrylate (PMMA) to fracture sites is a minimally invasive surgical treatment, but PMMA has considerable clinical risks. We develop a novel type thermoplastic injectable bone substitute contains the proprietary composites of synthetic ceramic bone substitute and absorbable thermoplastic polymer. We used thermoplastic biocompatible polymers Polycaproactone (PCL) to encapsulate calcium-based bone substitutes hydroxyapatite (Ca10(PO4)6(OH)2, HA) and tricalcium phosphate (TCP) to form a biodegradable injectable bone composite material. The space occupation ration PCL:HA/TCP is 1:9. After heating process, it can be injected to fracture site by specific instrument and then self-setting to immediate reinforce the vertebral body. The thermoplastic injection bone substitute can obtain good injection properties after being heated by a heater at 90˚C for three minutes, and has good anti-washout property when injected into normal saline at 37˚C. After three minutes, solidification is achieved. Mechanical properties were assessed using the material compression test system and the mechanical support close to the vertebral spongy bone. In vitro cytotoxicity MTT assay (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed and no cell cytotoxicity was observed. In vivo study with three New Zealand rabbits was performed, well bone growth into bone substitute was observed and can maintain good mechanical support after three months implantation. The novel type thermoplastic injection bone substitute can achieve (a) adequate injectability and viscosity without the risk of cement leakage; (b) adequate mechanical strength for immediate reinforcement and prevent adjacent fracture; (c) adequate porosity for new bone ingrowth; (e) biodegradability. It could be developed as a new option for treating vertebral compression fractures

Multiple studies have established an inverse relationship between ambient theatre temperatures and polymethyl methacrylate (PMMA) cement setting times. It is also known that allowing cement to equilibrate to ambient theatre temperatures restores expected setting characteristics. One overlooked entity is the transport and storage conditions of cement. This is important in tropical regions, where extreme temperature and humidity may cause rapid cement setting times, resulting in potentially significant intra-operative complications. This study investigated the relationship between extreme transport and storage conditions of Antibiotic Simplex cement (Stryker), and the effect on setting times at Cairns Hospital, Far North Queensland, Australia. Fifty units of cement were divided evenly into a control arm and four experimental arms. The experimental arms were designed to mimic potential transport and storage conditions. They included seven days of storage in a medication fridge, on the hospital loading dock, in a cane shed, and in a Toyota Landcruiser parked outdoors during January 2022. Humidity and temperature readings were recorded. The samples in each group were evenly distributed to equilibrate to theatre conditions for 1 hour and 24 hours. Setting time was recorded when a no. 15 scalpel blade was unable to mark the surface. All three ‘hot’ exposures setting times were significantly faster for both 1 hour (ρ=0.001) and 24 hours (ρ=0.024) equilibration times. The difference in setting times for the ‘cold’ exposure was not significant for either equilibration times (ρ=1). To our knowledge, this is the first study investigating cement setting times in tropical climates. Further studies are required to address the effect of these conditions on biomechanical strength of PMMA cement. We conclude that extreme heat and humidity during transport and storage have a statistically significant effect on cement setting times

Introduction: Despite a multitude of reports detailing the management of infected hips and knees with or without arthroplasty, only little information is available on how to deal with infected shoulders. Besides primary haematogenous infection, the increasing number of surgical procedures (infiltration, arthroscopy, ORIF, total- or hemi arthroplasty) confront the orthopaedic surgeon increasingly with this devastating complication. Our goal is to present our experience with the use of a cement spacer in the treatment of infected shoulder joints. Material and Methods: Between 1995 and 2005 9 patients were diagnosed with deep shoulder infection. The study includes 5 women and 4 men. The mean age at the time of diagnosis of the infection was 65 years (range, 51–78 years). Only 2 patient had had no prior surgery of the shoulder. 5 patients had an infection of a shoulder arthroplasty and 2 patients had been treated with ORIF for fracture. All of the patients underwent resection the humeral head or retrieval of the arthroplasty with large debridement followed by implantation of an antibiotic impregnated polymethyl methacrylate spacer. After a mean duration of two months of antibiotics and after normalisation of the CRP a delayed reimplantation of a prosthesis was performed in 6 patients. One patient is awaiting arthroplasty, while two patients are satisfied with the functional result obtained with the spacer and do not want further surgery. Results: None of the patients developed recurrent infection at an average follow-up time of 36 months. Shoulder function was judged objectively and subjectively to be at least satisfactory in all of the patients. Conclusions: Staged treatment of infected shoulders using antibiotic impregnated polymethyl methacrylate spacers showed in our small group of patients, good and reproducible results. The individually moulded and fitted spacer filling the joint cavity and restoring the normal anatomy of the shoulder after joint debridement makes secondary procedures much easier. In the cases of exchange prosthetic reconstruction no recurrent infection has been experienced and all of the patients have substantial pain relief and an adequate shoulder function. Based on this experience the authors think that staged treatment and the use of a cement spacer in infected shoulder joints is a valid approach

Shoulder arthroplasty humeral stem design has evolved to accommodate patient anatomy characteristics. As a result, stems are available in numerous shapes, coatings, lengths, sizes, and vary by fixation method. This abundance of stem options creates a surgical paradox of choice. Metrics describing stem stability, including a stem's resistance to subsidence and micromotion, are important factors that should influence stem selection, but have yet to be assessed in response to the diametral (i.e., thickness) sizing of short stem humeral implants. Eight paired cadaveric humeri (age = 75±15 years) were reconstructed with surgeon selected ‘standard’ sized short-stemmed humeral implants, as well as 2mm ‘oversized’ implants. Stem sizing conditions were randomized to left and right humeral pairs. Following implantation, an anteroposterior radiograph was taken of each stem and the metaphyseal and diaphyseal fill ratios were quantified. Each humerus was then potted in polymethyl methacrylate bone cement and subjected to 2000 cycles of 90º forward flexion loading. At regular intervals during loading, stem subsidence and micromotion were assessed using a validated system of two optical markers attached to the stem and humeral pot (accuracy of <15µm). The metaphyseal fill ratio did not differ significantly between the oversized and standard stems (0.50±0.06 vs 0.50±0.10; P = 0.997, Power = 0.05); however, the diaphyseal fill ratio did (0.52±0.06 vs 0.45±0.07; P < 0.001, Power = 1.0). Neither fill ratio correlated significantly with stem subsidence or micromotion. Stem subsidence and micromotion were found to plateau following 400 cycles of loading. Oversizing stem thickness prevented implant head-back contact in all but one specimen with the least dense metaphyseal bone, while standard sizing only yielded incomplete head-back contact in the two subjects with the densest bone. Oversized stems subsided significantly less than their standard counterparts (standard: 1.4±0.6mm, oversized: 0.5±0.5mm; P = 0.018, Power = 0.748;), and resulted in slightly more micromotion (standard: 169±59µm, oversized: 187±52µm, P = 0.506, Power = 0.094,). Short stem diametral sizing (i.e., thickness) has an impact on stem subsidence and micromotion following humeral arthroplasty. In both cases, the resulting three-dimensional stem micromotion exceeded, the 150µm limit suggested for bone ingrowth, although that limit was derived from a uniaxial assessment. Though not statistically significant, the increased stem micromotion associated with stem oversizing may in-part be attributed to over-compacting the cancellous bed during broaching, which creates a denser, potentially smoother, interface, though this influence requires further assessment. The findings of the present investigation highlight the importance of proper short stem diametral sizing, as even a relatively small, 2mm, increase can negatively impact the subsidence and micromotion of the stem-bone construct. Future work should focus on developing tools and methods to support surgeons in what is currently a subjective process of stem selection

Shoulder arthroplasty is effective at restoring function and relieving pain in patients suffering from glenohumeral arthritis; however, cortex thinning has been significantly associated with larger press-fit stems (fill ratio = 0.57 vs 0.48; P = 0.013)1. Additionally, excessively stiff implant-bone constructs are considered undesirable, as high initial stiffness of rigid fracture fixation implants has been related to premature loosening and an ultimate failure of the implant-bone interface2. Consequently, one objective which has driven the evolution of humeral stem design has been the reduction of stress-shielding induced bone resorption; this in-part has led to the introduction of short stems, which rely on metaphyseal fixation. However, the selection of short stem diametral (i.e., thickness) sizing remains subjective, and its impact on the resulting stem-bone construct stiffness has yet to be quantified. Eight paired cadaveric humeri (age = 75±15 years) were reconstructed with surgeon selected ‘standard’ sized and 2mm ‘oversized’ short-stemmed implants. Standard stem sizing was based on a haptic assessment of stem and broach stability per typical surgical practice. Anteroposterior radiographs were taken, and the metaphyseal and diaphyseal fill ratios were quantified. Each humerus was then potted in polymethyl methacrylate bone cement and subjected to 2000 cycles of compressive loading representing 90º forward flexion to simulate postoperative seating. Following this, a custom 3D printed metal implant adapter was affixed to the stem, which allowed for compressive loading in-line with the stem axis (Fig.1). Each stem was then forced to subside by 5mm at a rate of 1mm/min, from which the compressive stiffness of the stem-bone construct was assessed. The bone-implant construct stiffness was quantified as the slope of the linear portion of the resulting force-displacement curves. The metaphyseal and diaphyseal fill ratios were 0.50±0.10 and 0.45±0.07 for the standard sized stems and 0.50±0.06 and 0.52±0.06 for the oversized stems, respectively. Neither was found to correlate significantly with the stem-bone construct stiffness measure (metaphysis: P = 0.259, diaphysis: P = 0.529); however, the diaphyseal fill ratio was significantly different between standard and oversized stems (P < 0.001, Power = 1.0). Increasing the stem size by 2mm had a significant impact on the stiffness of the stem-bone construct (P = 0.003, Power = 0.971; Fig.2). Stem oversizing yielded a construct stiffness of −741±243N/mm; more than double that of the standard stems, which was −334±120N/mm. The fill ratios reported in the present investigation match well with those of a finite element assessment of oversizing short humeral stems3. This work complements that investigation's conclusion, that small reductions in diaphyseal fill ratio may reduce the likelihood of stress shielding, by also demonstrating that oversizing stems by 2mm dramatically increases the stiffness of the resulting implant-bone construct, as stiffer implants have been associated with decreased bone stimulus4 and premature loosening2. The present findings suggest that even a small, 2mm, variation in the thickness of short stem humeral components can have a marked influence on the resulting stiffness of the implant-bone construct. This highlights the need for more objective intraoperative methods for selecting stem size to provide guidelines for appropriate diametral sizing. For any figures or tables, please contact the authors directly

Introduction. The medical field has long held largely anecdotal beliefs that polymethyl methacrylate (PMMA) vapors are dangerous to a growing fetus, and as such, women who are pregnant should avoid exposure. This study investigates the perceptions of female orthopedic surgeons regarding PMMA cement exposure during pregnancy, and if it influences 1) currently held beliefs / practices and 2) clinical and career choices. Methods. A 23-question survey was distributed via e-mail to active members of the Ruth Jackson Orthopaedic Society and a private social media group for women in orthopedics. Questions included demographics, current usage of PMMA, previous exposure during pregnancy and/or breastfeeding, and beliefs regarding current or future willingness of exposure. Additionally, questions were asked regarding PMMA training and whether beliefs influenced specialty choices. Results. There were 278 survey responses received, of which 256 met inclusion criteria. 73% currently utilize PMMA in training/practice, and >90% of survey respondents reported awareness of risks surrounding PMMA in pregnancy. PMMA training was found to have a weak positive correlation with those who remained in the room while pregnant. 43.6% would leave the room in the future if PMMA were being used while they were pregnant, with 26.2% leaving if they were breastfeeding. 24.9% would leave if they were the primary surgeon on the case, and 8.4% admitted that PMMA exposure during pregnancy factored into which subspecialty they chose. Conclusion. This survey demonstrates a lack of consensus amongst female orthopedic surgeons regarding the risks posed by remaining in a room during pregnancy and breastfeeding while PMMA is used. Despite 90% of respondents claiming awareness of the risks of PMMA, beliefs and education practices should be examined to determine if they match the available literature. It is plausible that beliefs regarding this exposure are deterring individuals from pursuing specialties where PMMA is used regularly. For any tables or figures, please contact the authors directly

Experience has demonstrated in the hip and knee, related to total joint replacement arthroplasty, polymethyl methacrylate cement fixation can provide problems in terms of loosening, fragmentation, particulate wear and ultimate failure. These same problems have been recognised in total shoulder arthroplasty related to cement fixation of the glenoid. While cement fixation of the humeral component has proven much less problematic, there has been a swelling towards avoidance of using cement to secure the humeral component for fear of difficulty if revision is required. Surprisingly, with the high incidence of lucent lines, bone resorption and frank loosening, representing the most common source of failure in total shoulder arthroplasty, cementless fixation of the glenoid has not been, until now, embraced. The advent of reverse total shoulder arthroplasty has demonstrated the ability for secure cementless fixation to provide long-lasting secure implant retention in implants which have inherently higher shear and stress forces passing through the implant/bone interface. In anatomic total shoulder arthroplasty a woven tantalum anchor (Trabecular Metal) has proven to demonstrate secure cementless fixation as well. This presentation will discuss the use of trabecular metal anchored glenoid implants with and without additional screw fixation for anatomic and convertible reverse arthroplasty baseplates. Avoidance of complications with successful long-lasting outcomes requires meticulous surgical attention to detail

The Masquelet or induced membrane technique (IMT) is a two-stage surgical procedure used for the treatment of segmental bone defects. In this technique, the defect is first filled with a polymethyl methacrylate (PMMA) spacer, which triggers the formation of a membrane that will encapsulate the defect. During the second surgery, the spacer is carefully removed and replaced by autologous bone graft while preserving the membrane. This membrane is vascularized, contains growth factors, and provides mechanical stability to the graft, all of which are assumed to prevent graft resorption and promote bone healing. The technique is gaining in popularity and several variations have been introduced in the clinical practice. For instance, orthopaedic surgeons now often include antibiotics in the spacer to treat or prevent infection. However, the consequences of this approach on the properties of the induce membrane are not fully understood. Accordingly, in a small animal model, this study aimed to determine the impact on the induced membrane of impregnating spacers with antibiotics frequently used in the IMT. We surgically created a five-mm segmental defect in the right femur of 25 adult male Sprague Dawley rats. The bone was stabilized with a plate and screws before filling the defect with a PMMA spacer. Animals were divided into five equal groups according to the type and dose of antibiotics impregnated in the spacer: A) no antibiotic (control), B) low-dose tobramycin (1.2 g/40 g of PMMA), C) low-dose vancomycin (1 g/40 g of PMMA), D) high-dose tobramycin (3.6 g/40 g of PMMA), E) high-dose vancomycin (3 g/40 g of PMMA). The animals were euthanized three weeks after surgery and the induced membranes were collected and divided for analysis. We assessed the expression of selected genes (Alpl, Ctgf, Runx2, Tgfb1, Vegfa) within the membrane by quantitative real-time PCR. Moreover, frozen sections of the specimens were used to quantify vascularity by immunohistochemistry (CD31 antigen), proliferative cells by immunofluorescence (Ki-67 antigen), and membrane thickness. Microscopic images of the entire tissue sections were taken and analyzed using FIJI software. Finally, we measured the concentration of vascular endothelial growth factor (VEGF) in the membranes by ELISA. No significant difference was found among the groups regarding the expression of genes related to osteogenesis (Alpl, Runx2), angiogenesis (Vegfa), or synthesis of extracellular matrix (Ctgf, Tgfb1) (n = four or five). Similarly, the density of proliferative cells and blood vessels within the membrane, as well as the membrane thickness, did not vary substantially between the control, low-dose, or high-dose antibiotic groups (n = four or five). The concentration of VEGF was also not significantly influenced by the treatment received (n = four or five). The addition of tobramycin or vancomycin to the spacer, at the defined low and high doses, does not significantly alter the bioactive characteristics of the membrane. These results suggest that orthopaedic surgeons could use antibiotic-impregnated spacers for the IMT without compromising the induced membrane and potentially bone healing

Polymethyl methacrylate spacers are commonly used during staged revision knee arthroplasty for infection. In cases with extensive bone loss and ligament instability, such spacers may not preserve limb length, joint stability and motion. We report a retrospective case series of 19 consecutive patients using a custom-made cobalt chrome hinged spacer with antibiotic-loaded cement. The “SMILES spacer” was used at first-stage revision knee arthroplasty for chronic infection associated with a significant bone loss due to failed revision total knee replacement in 11 patients (58%), tumour endoprosthesis in four patients (21%), primary knee replacement in two patients (11%) and infected metalwork following fracture or osteotomy in a further two patients (11%). Mean follow-up was 38 months (range 24–70). In 12 (63%) patients, infection was eradicated, three patients (16%) had persistent infection and four (21%) developed further infection after initially successful second-stage surgery. Above knee amputation for persistent infection was performed in two patients. In this particularly difficult to treat population, the SMILES spacer two-stage technique has demonstrated encouraging results and presents an attractive alternative to arthrodesis or amputation

Aim. The preparation of antibiotic-containing polymethyl methacrylate (PMMA), as spacers generates a high polymerization heat, which may affect their antibiotic activity; it is desirable to use bone cement with a low polymerization heat. Calcium phosphate cement (CPC) does not generate heat on polymerization, and comparative elution testings are reported that vancomycin (VCM)-containing CPC (VCM-CPC) exceeded the antibiotic elution volume and period of PMMA (VCM-PMMA). Although CPC alone is a weak of mechanical property spacer, the double-layered, PMMA-covered CPC spacer has been created and clinically used in our hospital. In this study, we prepared the double-layered spacers: CPC covered with PMMA and we evaluated its elution concentration, antimicrobial activity and antibacterial capability. Method. We prepared spherical, double-layered, PMMA-coated (CPC+PMMA; 24 g CPC coated with 16 g PMMA and 2 g VCM) and PMMA alone (40 g PMMA with 2 g VCM) spacers (5 each). In order to facilitate VCM elution from the central CPC, we drilled multiple holes into the CPC from the spacer surface. Each spacer was immersed in phosphate buffer (1.5 mL/g of the spacer), and the solvent was changed daily. VCM concentrations were measured on days 1, 3, 7, 14, 28, 56, and 84. Antimicrobial activity against MRSA and MSSA was evaluated by the broth microdilution method. After measuring all the concentration, the spacers were compressed at 5 mm/min and the maximum compressive load up to destruction was measured. Results. The VCM concentration of the CPC+PMMA spacer exceeded that of the PMMA spacer at all-time points; in particular, it was approximately 7.3 times (109.30 vs. 15.03 μg/mL) and approximately 9.1 times (54.47 vs. 6.50 μg/mL) greater on days 14 and 28, respectively. Using the broth microdilution method, we found that the CPC+PMMA spacer had higher antimicrobial activity than the PMMA model. On day 56, the PMMA spacer lost the capability to inhibit bacterial growth, but the CPC+PMMA spacer maintained this ability. The average maximum compressive load for the CPC+PMMA was 7.28 kN, and that of PMMA was 16.21 kN. Conclusions. The CPC+PMMA spacer was superior to PMMA alone in VCM elution volume and duration, so CP- C+PMMA may be effective for the treatment of MRSA and MSSA infection. The double-layered, antibiotic-loaded cement spacer may maintain antibacterial capability and sufficient strength

Objectives. The purpose of this study was to refine an accepted contaminated rat femur defect model to result in an infection rate of approximately 50%. This threshold will allow examination of treatments aimed at reducing infection in open fractures with less risk of type II error. Methods . Defects were created in the stablised femurs of anaethetised rats, contaminated with Staphylococcus aureus and then debrided and irrigated six hours later. After 14 days, the bone and implants were harvested for separate microbiological analysis. This basic model was developed in several studies by varying the quantity of bacterial inoculation, introducing various doses of systemic antibiotics with and without local antibiotics. Results . The bacterial inoculation associated with a 50% infection rate was established as 1 × 10. 2. colony forming units (CFU). With an initial bacterial inoculum of 1 × 10. 5. CFU, the dose of systemic antibiotics associated with 50% infection was 5 mg/Kg of cafazolin injected sub-cutaneously every 12 hours, starting at the time of the first debridment and continuing for 72 hours (seven doses). The systemic dose of cafazolin was lowered to 2 mg/Kg when antibiotic polymethyl methacrylate beads were used concurrently with the same amount of bacterial inoculation. Conclusion. This model of open fracture infection has been further refined with potential for local and systemic antibiotics. This is a versatile model and with the concepts presented herein, it can be modified to evaluate various emerging therapies and concepts for open fractures. Cite this article: Bone Joint Res 2014;3:187–92

Introduction. The complex cellular mechanisms of the aseptic loosening of total joint arthroplasties still remain not completely understood in detail. Especially the role of adherent endotoxins in this process remains unclear, as lipopolysaccharides (LPS) are known to be very potent modulators of the cell response on wear particle debris. Contributing factors on the LPS affinity of used orthopedic biomaterials as their surface roughness have to be investigated. The aim of this study was to evaluate the affinity of LPS on the surface roughness of different biomaterials in vitro. The hypothesis of the study was that rough surfaces bind more LPS than smooth surfaces. Materials and methods. Cubes with a side length from ultra-high-molecular-weight-polyethylene (UHMWPE), crosslinked polytethylene (XPE), carbon fibre reinforced poly-ether-ether-ketone (CFR-PEEK), titanium, titanium alloy, Polymethyl methacrylate (PMMA), implant steel (CoCr) and instrument steel (BC) were produced (figure 1). Cubes of each material have been produced with a rough and a smooth surface. Before the testings, all cubes and used materials were treated with E-Toxa-Clean(®) to eliminate pre-existing LPS on the used surfaces. The cubes were then fixed on the cap of a glass that was filled with a LPS solution with a concentration of 5 IE/ml. After 30 minutes the cube was removed and the LPS concentration in the supernatant was measured. The endotoxin content of each sample was evaluated by a Limulus Amoebocyte Lysate (LAL) - Test (Lonza, Verviers, Belgium). The detection level of endotoxin was set at < 0.005 EU/ml diluted 1/10. Results. All tested rough biomaterials showed a higher affinity to LPS compared to the smooth surfaces. Conclusion. The initial hypothesis could be confirmed. The results prove that rough and therefore larger surfaces bind more LPS than smooth surfaces. A rough surfaces correlates with a larger total surface of the used biomaterial. In this context protheses should be avoided that show a large rough surface, as these endoprostheses might bind more LPS and trigger an enhanced inflammatory reaction that results in an early aseptic loosening

The use of polymethyl methacrylate based cement for the fixation of joint replacements although commonly applied, is still limited by interfacial weakness. This study aims to document the effects of a variety of surface treatments on implant/cement bonding and link them to their surface properties. Thirty seven femoral implant analogues of Ti6Al4V rods were given one of six different surface treatments: traditional grit blasting, wet and dry Vaquasheening, acid etching in concentrated sulphuric and hydrochloric acid, anodisation at 150V, and a combination of acid etching and anodisation, before being embedded into a commercially available poly(methyl methacrylate) bone cement. The interfacial strength, energy and stiffness were measured through pushout testing. Surface analysis included examination with scanning electron microscopy, wettability tests and roughness analysis. Results were analysed with a one-way ANOVA with post hoc tests. Overall, the coarse blasted surface created the strongest interface, followed by both etched then anodised, acid etched only, wet Vaquasheened, anodised only and finally dry vaquasheened. While anodised samples showed a weaker bond than etched samples, the combination of etching and anodisation was not different to etching alone. In addition, six different types of interface failure modes were observed, and theories as to explain their mechanism, using experimental evidence were outlined. Coarse blasted surfaces showed the strongest bonding, while other surface modifications may encourage tissue ingrowth and other biological responses, these surface treatments do not strengthen bonding for cemented fixation

Clinical and radiological assessment of results of vertebral body stenting procedure. Introduction: Use of metallic stents along with cement have shown good restoration of the vertebral body in cadaveric spines. We have presented the early results of vertebral body stenting done at Royal Derby Hospitals. Patients and Methods: All patients had a transpedicular approach to the vertebral body. The vertebral body stent was expanded using a balloon as in balloon kyphoplasty. The balloon was removed leaving the stent in place. The resultant cavity was filled with partially cured polymethyl methacrylate in osteoporotic fractures and calcium phosphate cement in traumatic fractures. Radiological assessment included pre operative measurement of vertebral body angle, correction achieved and maintenance of correction at follow up. All patients were assessed using the visual analogue score and oswestry disability index. The procedure was done in 14 fractures (10 patients). 9 fractures were traumatic while 5 were osteoporotic fractures. The mean age of the traumatic fractures was 54.28 years while the mean age of osteoporotic fractures was 82.34 years. Mean follow up was 10 months. All traumatic fractures were type A 3.1. Mean vertebral body angle correction achieved was 8.3° (4° to 14.2°). None of the patients lost the reduction at follow up. The mean VAS for pain at 6 months was 3.8. The mean oswestry disability index was 22% for traumatic fractures, while it was 44% for osteoporotic fractures. Vertebral body stenting is a safe procedure. It was successful in restoring the anterior column with encouraging radiological and clinical results

Introduction: In kyphoplasty and vertebroplasty, polymethyl methacrylate (PMMA) is currently the standard in augmentation materials but it is characterized by a lack of osseointegration and limited biocompatibility. At the same time, calcium phosphate cements are not currently considered an alternative due to their insufficient mechanical stability against shear, compression and extension forces. This prospective study examines the suitability of a new calcium alumiate ceramic (Xeraspine. ®. , Doxa) for augmentation of vertebral fractures treated with balloon-kyphoplasty. Methods: The operation technique follows the standard protocol for a bilateral percutaneous balloon-kypho-plasty (Kyphon). Exclusion criteria were: additional instrumentation, age > 90 years, as well as cardiac arrhythmia. The following clinical and radiological data were collected pre and post op, as well as after 6 weeks: Visual-Analogue-Score, Oswestry-Index, bisegmental endplate angle, and vertebral hight. A CT- scan was provided to show possible cement extrusion and disintegration. Results: 20 vertebrae were included so far. The fractures could be classified as: type A1.3 (n=11), A3.1 (9). They were located at Th9 - L3. All 20 patients reported pain relief immediately post op. Restoration of endplate angles was 6,2° on average. There was no case of cement disintegration. No loss of correction was observed radiologically. Discussion: The calcium aluminate ceramic used in balloon-kyphoplasty is an alternative to PMMA. Due to comparable shear, compression and extension strengths, there is no risk of cment breakage and following loss of correction. On the other hand the calcium aluminate ceramic shows better biocompatibility if compared to PMMA

Limb salvage in musculoskeletal tumor surgery may be complicated by infection. With the advent of modern techniques and medical management limb sparing surgeries can be considered as an alternative to ablation. Between 1992 and 2014, 17 patients were treated for infected megaprostheses after being surgically treated for musculoskeletal tumors. There were nine females and eight males. The mean time from the index procedure until infection was 30 months. Following radical debridement, the resultant skeletal defect averaged 30 cm. Patients were treated with local antibiotics in polymethyl methacrylate (PMMA) spacers and endoprostheses as well as IV antibiotics for a minimum of six weeks followed by oral antibiotics for an additional six weeks. The initial tumor procedure involved the femur in eleven patients, the tibia in two, the acetabulum in one, the humerus in two, and the ulna in one. Patients had repeat cultures before two-stage reimplantation when their WBC, ESR, and CRP returned to normal. Patients were reimplanted when final cultures were negative. Thirteen patients were treated using a two-stage protocol with customized intraoperative antibiotic impregnated PMMA spacers including intramedullary nails for a mean of 10 months and the other four patients had a one-stage procedure. These four patients included two patients with a total femur replacement and two patients with an allograft-prosthetic composite of the proximal humerus and ulna. The organisms cultured were gram positive in 14 cases, mixed gram positive and negative in one case, and two patients had no growth on cultures but histologic evidence of acute infection. Reimplantation was successful in 13 patients after the initial procedure (76%). Four patients had recurrent infections. One of these patients was successfully reimplanted after a one-stage procedure, two had a second two-stage procedure and have retained their spacers, and one had an amputation. Successful limb salvage in regards to infection control occurred in 14/17 patients (82%). One additional patient required an amputation for an oncologic complication (local recurrence), so the overall limb salvage rate was 13/17 (76%). Patients with megaprosthetic infections following limb salvage treatment for musculoskeletal tumors do not have to be uniformly subject to amputation. Radical debridement and appropriate antibiotics in conjunction with custom spacers followed by selective one- and two-stage reimplantation results in successful limb salvage in 82% of patients. This result is similar to other reports despite the large size average defects

When fixing a mid or distal periprosthetic femoral fracture with an existing hip replacement, creation of a stress-riser is a significant concern. Our aim was to identify the degree of overlap required to minimise the risk of future fracture between plate and stem. Each fixation scenario was tested using 4th generation composite femoral Sawbones®. Each sawbone was implanted with a collarless polished cemented stem with polymethyl methacrylate bone cement and cement restrictor. 4.5mm broad Peri-loc™ plates were positioned at positions ½, 1 and 2 shaft diameters (SD) proximal and distal to the tip of the femoral stem. Uni-axial strain gauges (medial and lateral longitudinal gauges, anterior and posterior torsional gauges) measured microstrain at tip of the femoral stem with a standard load of 500N in axial, 3-point lateral and composite torsion/posterior loading using an Instron machine. With axial loading fixation with 2SD proximal resulted in the least amount of strain, in both tension & compression, at the tip of the femoral stem. Fixation with 4 unicortical screws was significantly better than 2 alternating unicortical screws (mean microstrain difference 3.9 to 15.3, p<0.0001). With lateral 3-point loading fixation with 2SD proximal overlap and 2 alternating unicortical screws resulted in the least amount of strain, in both tension and compression, at the tip of the femoral stem (p<0.0001). With torsion & posterior displacement 2SD proximal fixation resulted in the least amount of rotational strain. There was no significant difference between 4 unicortical screws compared to 2 alternating unicortical screws (p>0.05 in 3 of 4 gauges). Fixation of midshaft or distal femoral fractures with a well-fixed total hip arthroplasty should have at least 2 shaft diameters of proximal overlap with a 4.5mm broad plate. It is not clear if 4 unicortical screws or 2 alternating screws are optimal