The purpose of this study is to enhance massive bone allografts osseointegration used to reconstruct large bone defects. These allografts show >50% complication rate requiring surgical revision in 20% cases. A new protocol for total bone decellularisation exploiting the vasculature can offer a reduction of postoperative complication by annihilating immune response and improving cellular colonization/ osseointegration. The nutrient artery of 18 porcine bones - humerus/femur/radius/ulna - was cannulated. The decellularization process involved immersion and sequential perfusion with specific solvents over a course of one week. Perfusion was realized by a peristaltic pump (mean flow rate: 6ml/min). The benefit of arterial perfusion was compared to a control group kept in immersion baths without perfusion. Bone samples were processed for histology (HE, Masson's trichrome and DAPI for cell detection), immunohistochemistry (IHC : Collagen IV/elastin for intraosseous vascular system evaluation, Swine Leukocyte Antigen – SLA for immunogenicity in addition to cellular clearance) and DNA quantification. Sterility and solvent residues in the graft were also evaluated with thioglycolate test and pH test respectively. Compared to native bones, no cells could be detected and residual DNA was <50ng/mg dry weight. Intramedullary spaces were completely cleaned. IHC showed the preservation of intracortical vasculature with channels bounded by Collagen IV and elastin within Haversian systems. IHC also showed a significant decrease in SLA signaling. All grafts were sterile at the last decellularization step and showed no solvent residue. The control group kept in immersion baths, paired with 6 perfused radii/ulnae, showed that the perfusion is mandatory to ensure complete decellularisation. Our results prove the effectiveness of a new concept of total bone decellularisation by perfusion. These promising results could lead to a new technique of Vascularized Composite Allograft transposable to pre-clinical and clinical models

Objectives. Hips with metal-on-metal total hip arthroplasty (MoM THA) have a high rate of adverse local tissue reactions (ALTR), often associated with hypersensitivity reactions. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) measures tissue perfusion with the parameter Ktrans (volume transfer constant of contrast agent). Our purpose was 1) to evaluate the feasibility of DCE-MRI in patients with THA and 2) to compare DCE-MRI in patients with MoM bearings with metal-on-polyethylene (MoP) bearings, hypothesising that the perfusion index Ktrans in hips with MoM THA is higher than in hips with MoP THA. Methods. In this pilot study, 16 patients with primary THA were recruited (eight MoM, eight MoP). DCE-MRI of the hip was performed at 1.5 Tesla (T). For each patient, Ktrans was computed voxel-by-voxel in all tissue lateral to the bladder. The mean Ktrans for all voxels was then calculated. These values were compared with respect to implant type and gender, and further correlated with clinical parameters. Results. There was no significant difference between the two bearing types with both genders combined. However, dividing patients by THA bearing and gender, women with MoM bearings had the highest Ktrans values, exceeding those of women with MoP bearings (0.067 min. −1. versus 0.053 min. −1. ; p-value < 0.05) and men with MoM bearings (0.067 min. −1. versus 0.034 min. −1. ; p-value < 0.001). Considering only the men, patients with MoM bearings had lower Ktrans than those with MoP bearings (0.034 min. −1. versus 0.046 min. −1. ; p < 0.05). Conclusion. DCE-MRI is feasible to perform in tissues surrounding THA. Females with MoM THA show high Ktrans values in DCE-MRI, suggesting altered tissue perfusion kinematics which may reflect relatively greater inflammation. Cite this article: Dr P. E. Beaule. Perfusion MRI in hips with metal-on-metal and metal-on-polyethylene total hip arthroplasty: A pilot stud. Bone Joint Res 2016;5:73–79. DOI: 10.1302/2046-3758.53.2000572

Aims. Continuous local antibiotic perfusion (CLAP) has recently attracted attention as a new drug delivery system for orthopaedic infections. CLAP is a direct continuous infusion of high-concentration gentamicin (1,200 μg/ml) into the bone marrow. As it is a new system, its influence on the bone marrow is unknown. This study aimed to examine the effects of high-concentration antibiotics on human bone tissue-derived cells. Methods. Cells were isolated from the bone tissue grafts collected from six patients using the Reamer-Irrigator-Aspirator system, and exposed to different gentamicin concentrations. Live cells rate, apoptosis rate, alkaline phosphatase (ALP) activity, expression of osteoblast-related genes, mineralization potential, and restoration of cell viability and ALP activity were examined by in vitro studies. Results. The live cells rate (the ratio of total number of cells in the well plate to the absorbance-measured number of live cells) was significantly decreased at ≥ 500 μg/ml of gentamicin on day 14; apoptosis rate was significantly increased at ≥ 750 μg/ml, and ALP activity was significantly decreased at ≥ 750 μg/ml. Real-time reverse transcription-polymerase chain reaction results showed no significant decrease in the ALP and activating transcription factor 4 transcript levels at ≥ 1,000 μg/ml on day 7. Mineralization potential was significantly decreased at all concentrations. Restoration of cell viability was significantly decreased at 750 and 1,000 μg/ml on day 21 and at 500 μg/ml on day 28, and ALP activity was significantly decreased at 500 μg/ml on day 28. Conclusion. Our findings suggest that the exposure concentration and duration of antibiotic administration during CLAP could affect cell functions. However, further in vivo studies are needed to determine the optimal dose in a clinical setting. Cite this article: Bone Joint Res 2024;13(3):91–100

Introduction: Interest in the relationships between subchondral bone pathology and cartilage breakdown has been stimulated by the observations that bone marrow edema (BME) is related to both pain and bone remodeling and that the progression of cartilage lesions is greater in joints with significant BME. The hypothesis of this study is that changes in perfusion in subchondral bone bear a functional relationship to bone remodeling and cartilage degradation and are a part of a physicochemical signaling mechanism to osteoblasts. We have utilized dynamic, contrast-enhanced magnetic resonance imaging (MRI) to assess perfusion and BME in osteoarthritis (OA) and osteonecrosis (ON). Methods: Investigation of marrow perfusion in BME was performed in both the Dunkin-Hartley guinea pig model of OA patients and cohort of 26 control patients. The human study was performed on a 1.5T magnet using a dedicated surface coil and STIR [3500/17/150 (TR/TE/TI)] and VIBE [5.50/2.89 (TR/TE); 10° (flip angle)] pulse sequences. We determined pharmacokinetic parameters of marrow perfusion according to the two compartment model of Brix, which is characterized by rate and volume transfer constants that can be derived mathematically from time-signal intensity curves. Results: In the guinea pig model, inflow slope was similar at all ages; kel was decreased in the affected medial, but not in the normal lateral, tibia indicating reduced perfusion and outflow obstruction. Comparison of BME and perfusion metrics with morphological features (Mankin scores and subchondral bone plate thickness) at the medial tibia demonstrates that changes in perfusion dynamics precede bone remodeling and cartilage breakdown by several months. Compared to normal marrow, kinetic parameters of contrast-enhancement in areas of BME included higher initial slope (p< .001), higher A (p< .001), lower kep (p=.004), and lower kel (p< .001). In areas of BME around ON, there was significantly lower A (p=.009) and lower kel (p=.04) compared to BME adjacent to OA, but no significant difference in either initial slope (p=.06) or kep (p=.26). Discussion: To our knowledge, these are the first reports of the use of dynamic, enhanced-MRI to characterize bone marrow perfusion in BME associated with OA and ON. In the Dunkin-Hartley guinea pig, reduced perfusion in BME temporally precede alterations in bone remodeling and appearance of cartilage lesions, and are spatially localized to bone subjacent to eventual cartilage lesions. We have also demonstrated similar perfusion kinetics associated with BME in human ON and OA. Calculations of intraosseous pressure associated with outflow obstruction and decreased perfusion are consistent with measurements made in end-stage ON and OA. Osteoblasts are known to be responsive to flow, pressure, and pO2. Increased pressure and decreased flow associated with outflow obstruction may constitute physicochemical signals to osteoblasts which result in changes in cytokine expression and contribute to trabecular remodeling and cartilage breakdown

Introduction. Supraspinatus tears comprise most rotator cuff injuries, the leading cause of shoulder pain and an increasing problem with ageing populations. Surgical repair of considerable or persistent damages is customary, although not invariably successful. Tissue engineering presents a promising alternative to generate functional tissue constructs with improved healing capacities. This study explores tendon tissue constructs’ culture in a platform providing physiological mechanical stimulation and reports on the effect of different loading regimes on the viability of human tendon cells. Method. Porcine decellularized tendon scaffolds were fixed into flexible, self-contained bioreactor chambers, seeded with human tenocytes, allocated in triplicates to either static control, low (15±0.8Newtons [N]), medium (26±0.5N), or high (49±2.1N)-force-regime groups, connected to a perfusion system and cultured under standard conditions. A humanoid robotic arm provided 30-minute adduction/abduction stimulation to chambers daily over a week. A metabolic activity assay served to assess cell viability at four time points. Statistical significance = p<0.05. Result. One day after beginning mechanical stimulation, chambers in the medium and high-force regimes displayed a rise in metabolic activity by 3% and 5%, respectively. By the last experimental day, all mechanical stimulation regimes had induced an augment in cell viability (15%, 57% and 39% with low, medium, and high loads, respectively) matched against the static controls. Compared to all other conditions, the medium-force regime prompted an increased relative change in metabolic activity for every time point set against day one (p<0.05). Conclusion. Human tenocytes’ viability reflected by metabolic activity in a physiologically relevant bioreactor system is enhanced by loading forces around 25N when mechanically stimulating using adduction/abduction motions. Knowing the most favourable load regime to stimulate tenocyte growth has informed the ongoing exploration of the distinctive effect of different motions on tendon regeneration towards engineering tissue grafts. This work was supported by the Engineering and Physical Sciences Research Council EP/S003509/1

Near infrared light between the wavelengths of 700 and 950 nanometers has a relatively low absorption in tissue, and light of these wavelengths is able to penetrate several centimetres into tissue. Absorption of light is primarily due to hemoglobin. The absorption spectra for oxy-hemoglobin and deoxy-hemoglobin are different, and therefore comparison of light absorption at different wavelengths allows an assessment of the relative concentrations of these two chromophores. Light penetrates bone as well as soft-tissue, and near infrared spectroscopy (NIRS) is potentially a relatively simple, low-cost technique for assessing perfusion in bone. However, although absorption of light is low, scattering is high, and the spatial resolution of the measurement is poor. Application of the technique to the study of bone perfusion requires consideration of the potential confounding absorption arising from adjacent tissues that may have higher perfusion. A clinical problem of interest in our institute is that of vascular changes occurring in bone of patients with spinal cord injury (SCI), and the relationship of these changes to bone density changes. We have, therefore, concentrated on developing NIRS for measurement of the proximal tibia, which is a common site for fractures in these patients. In order to develop a probe for the measurement of bone, experiments were performed with phantoms containing infrared absorbing dyes. Numerical simulations were also performed using the Monte Carlo technique. One of the most important design considerations is the distance between the optode delivering light to the skin, and the collecting optode which detects light. It was found that a separation of 20 mm between the light source and detector was an optimum compromise for minimizing contributions from overlying skin and surrounding muscle, while still being able to detect light efficiently enough to measure dynamic changes in chromophore concentration. We have now started to apply this technique clinically. Relative changes of oxy- and deoxy-hemoglobin concentration have been measured in response to a range of interventions. Comparison has been made of the effect of different interventions designed to modify perfusion of bone (neuro-muscular stimulation of the calf, intermittent pneumatic compression, low amplitude high frequency vibration, and venous tourniquet). We are studying vascular reactivity in chronic SCI patients and controls and we have also started to investigate the effect of daily neuro-muscular stimulation in acute SCI patients. Preliminary results of these clinical studies will be presented

Bioreactors have been used in articular cartilage tissue engineering (AC-TE) to apply different mechanical stimuli in an attempt to better mimic the native AC microenvironment. However, these systems are often highly complex, costly and not very versatile. In this work, we propose a simple and customizable perfusion bioreactor fabricated by 3D-extrusion to study the effect of shear stress in human bone-marrow mesenchymal stem cells (hBMSC) cultured in 3D porous polycaprolactone (PCL) scaffolds. Prototype models were designed in a CAD-software to perfectly fit the scaffolds and computational fluid dynamics analysis was used to predict the fluid velocities and shear stress forces inside the bioreactor. For the culture studies, hBMSC-PCL constructs were cultured under static expansion for 2 weeks and then transferred to the ABS-extruded bioreactors for continuous perfusion culture (0.2mL/min) under chondrogenic induction for additional 3 weeks. Perfused constructs showed similar cell proliferation and higher sGAG production in comparison to the static counterparts (bioreactor without perfusion). Constructs exposed to shear stress stimuli presented higher expressions of chondrogenic genes (COLII/Sox9/Aggrecan) and reduced expressions of COLI and Runx2 (osteogenic) than static group. However, the higher expression of COLX in the perfused constructs suggests a shear stress role in AC hypertrophy. Both conditions (perfused/static) stained positively for GAG deposition and for the presence of collagen II and aggrecan. Overall, the results provide a proof-of-concept of our customizable extruded bioreactor envisaging applications as a platform for AC-TE repair strategies and in the development of more reliable in vitro models for disease modelling and drug screening

The purpose of this study was to analyze the long-term effect of arterial perfusion of drugs and bone marrow stromal cells (bMSCs) on osteonecrosis of femoral head (ONFH). From Jan 1997 to Mar 2004, one hundred and seventeen patients with ONFH were consecutively enrolled to receive a digital subtraction angiography (DSA) in arteriae circumflexa femoris medialis and arteriae circumflexa femoris lateralis. In DSA, a dosage of drugs (urokinase, salvia injection, and tetramethylpyrazine) and autologous bMSCs or only the drugs were perfused into the arteries. The morphological changes of the arteries in DSA after perfusion were recorded. Symptoms radiographs, and the Harris hip-rating score were determined preoperatively and at each follow-up examination at one month, six months, one year, 2 years and 5 years after the treatment. 83 patients were followed up for more than five years. The median follow-up period was 7.9 years. After the drugs had been perfuse, the arteries became thicker, and more than 2 branches appeared in DSA. Five years after the operation, the Harris hip score of 32 patients (38 hips) treated by arterial perfusion of simplex drugs (group A) increased from 59.24±5.28 to 71.80±6.37 (p< 0.01), and the excellent and good rate of centesimal evaluation was 57.9%. The Harris hip score of 51 patients (59 hips) treated by arterial perfusion of drugs and autologous bMSCs (group B) increased from 59.52±4.85 to 78.29±6.05 (p< 0.01), and the excellent and good rate was 78.0% which was significantly higher than that of group A (p=0.035). Since two years after operation, the Harris hip score of group A was significantly higher than that of group B (p< 0.01). Among the patients in group B, the rate of excellent and good in early stages (˜,˜ a and ˜ b according to Ficat classifying, 50 hips) was 84.0%, which was better than the rate in the terminal stage (Ficat III, 9 hips, the excellent and good rate was 44.4%)(p = 0.028), and the rate of excellent and good in low age group (< 40 years, 33 hips) was also better than that in high age group (≥ 40 years, 26 hips)(p=0.038). We conclude that arterial perfusion of drugs and autologous bMSCs treating osteonecrosis of femoral head is safe and effective. The long-term therapeutic effect is more satisfactory than that of simplex arterial perfusion of drugs

The aim of the study is to compare the postoperative pain relief provided by continuous perfusion of wound by bupivacaine and fentanyl with that of patient controlled analgesia using morphine in elective shoulder surgery. This retrospective case control study included 76 consecutive patients who had elective shoulder surgery. 39 patients had patient controlled analgesic system (PCA) with morphine and 37 patients had a continuous wound perfusion with bupivacaine and fentanyl via a disposable Silicone Balloon Infuser. Patients were also given additional oral NSAIDs or morphine if needed. The pain score measured postoperatively based on a 10 point Visual Analogue Scale (VAS) at 1, 2, 3 and 18 hours was noted. The use of antiemetics and additional painkillers was recorded. The complications of both methods were also noted. We found that the analgesia provided by continuous perfusion of wound by bupivacaine and fentanyl was constant and comparable to that provided by the patient controlled analgesic system using morphine. PCA with morphine was associated with significantly high incidence of nausea and vomiting (p < 0.001). We conclude that continuous perfusion of the wound by bupivacaine and fentanyl appears to be a simple, effective and safe method of providing analgesia following elective shoulder surgery

A high incidence of complications with wound healing in calcaneum fractures treated with open reduction and internal fixation (25 – 33% of cases) has been reported. In one study 80% of those who had wound complications required surgical treatment of these. Two recent studies have shown that the risk factors for wound complications in this injury are single layered closure, high BMI, extended time between injury and surgery, diabetes, open fractures and smoking. In our unit, out of a small sample of 56 patients undergoing calcaneal fracture fixation, all those who developed wound complications were smokers. Transcutaneous oximetry is a technique that has been used routinely to assess oxygen perfusion in neonates and also sometimes in peripheral vascular disease (PVD). It has seen greater use as a research tool in PVD and orthopaedic surgery, being used to look at oxygenation around wounds to assess different surgical approaches. This study was performed to assess whether a difference in the oxygen perfusion around the ankle joint could be measured in smokers and non-smokers. A transcutaneous oximetry probe was used to assess the tissue oxygen perfusion at the ankle (posterior to lateral malleolus where the incision line would be) and on the chest (just to the side of the sternum). A standardised technique was used for each patient. Patients were chosen who had no lower limb orthopaedic problem or known PVD. The groups were matched in terms of sex and average age. The data was analysed after logarithmic transformation using a two-tailed Students t-test. The average pO2 chest/foot ratio was higher in the non-smokers than smokers but this was not significant (p=0.704). The average ankle pO2 was higher in the non-smokers and this was shown to be significant (p=0.026). Although a small sample, these data suggest that tissue oxygenation around the ankle may be significantly lower in smokers. This would help to explain why they are at increased risk of wound healing complications. This work also demonstrates that transcutaneous oximetry can be a useful tool in orthopaedic research. Tissue oxygenation around other joints could also be assessed in relation to position to discover the optimum position for wound healing

The aim of the study is to compare the postoperative pain relief provided by continuous perfusion of wound by bupivacaine and fentanyl with that of patient controlled analgesia using morphine in elective shoulder surgery. This retrospective case control study included 76 consecutive patients who had elective shoulder surgery. 39 patients had patient controlled analgesic system (PCA) with morphine and 37 patients had a continuous wound perfusion(intra bursal) with bupivacaine and fentanyl via a disposable Silicone Balloon Infuser. Patients were also given additional oral NSAIDs or morphine if needed. The pain score measured postoperatively based on a 10 point Visual Analogue Scale (VAS) at 1, 2, 3 and 18 hours was noted. The use of antiemetics and additional painkillers was recorded. The complications of both methods were also noted. We found that the analgesia provided by continuous perfusion of wound by bupivacaine and fentanyl was constant and comparable to that provided by the patient controlled analgesic system using morphine. PCA with morphine was associated with significantly high incidence of nausea and vomiting (p < 0.001).We conclude that continuous perfusion of the wound by bupivacaine and fentanyl appears to be a simple, effective and safe method of providing analgesia following elective shoulder surgery

Aims: The present experiment addressed the question whether lipopolysaccharides (LPS), hip joint tamponade or their combination modulate hip perfusion. Methods: 16 immature Danish Landrace pigs of both genders were treated in 3 groups. 4 animals received LPS from escherichia coli intravenously 4 hours previous to hip joint tamponade. 8 pigs underwent the hip operation without previous medication. 4 animals without treatment served as control group. Blood ßow measurement was done by the Radioactive Tracer Microspheres technique. Results: Femoral head epiphyseal blood ßow decreased signiþcantly during hip joint tamponade. Reperfusion occurred to a level not signiþcantly differing from that before ischemia, whereas epiphyses remained ischemic in 2 pigs. The hip joint capsule showed signiþcant hyperperfusion during and after joint tamponade. No signiþcant difference was revealed comparing the LPS-treated and non-treated groups of pigs in all hip regions (p = 0.79, U-test). In addition, in the LPS-group, none of the femoral head epiphyses remained ischemic. Conclusions: LPS and hip joint tamponade, which have separately been discussed as pathomechanic factors of Non Traumatic Femoral Head Necrosis, have been combined in a bifactorial porcine model. Systemic lipopolysacchrides as bacterial endotoxin have no acute effect on regional hip perfusion which would make a consequent osteonecrosis probable. 6hourly hip joint tamponade alone evoked non reperfusion in 2 out of 8 pigs and a prolongation of the 6 hours ischemia might evoke more cases of non reperfusion

Introduction: Dividing the short external rotators 2 cm from their insertion into the femur should preserve the deep branch of the medial femoral circumflex artery. Our aim was to determine, prospectively, femoral head perfusion during hip resurfacing arthroplasty comparing two posterior approaches. Methods: 20 hip resurfacing arthroplasties were performed in 20 patients by two different surgeons between September 2005 and November 2006. Patients were divided into two equal groups according to approach. One surgeon used the extended posterior approach and the other a modified posterior approach. Intravenous cefuroxime was administered in every case following capsulectomy and relocation of the femoral head. After 5 minutes the femoral head was dislocated and prepared as routine for the operation. Bone from the top of the femoral head and reamings were sent for assay to determine the concentration of cefuroxime. Results: There was no statistical difference between the concentration of cefuroxime in bone when using the modified posterior approach (mean 5.6mg/kg; CI 3.6 – 7.8) compared to the extended posterior approach (mean 5.6; CI 3.5 – 7.8; p=0.95). In one patient, who had the operation through the posterior approach, cefuroxime was undetectable. Discussion: The similarity in femoral head perfusion between approaches suggests the blood supply is further impaired by capsulectomy rather than by damaging the MFCA alone

Current 5-year survival after complete resection of pulmonary metastases is ≈ 30%, and many patients develop pulmonary recurrences. Obviously new treatment options are needed for this indication. Isolated lung perfusion (ILuP) is an experimental technique to deliver high-dose chemotherapy to the lung without systemic exposure. Recently, a phase I trial of ILuP combining 45 mg melphalan followed by pulmonary metastasectomy for resectable lung metastases proved to be feasible and safe. The current 3-center phase II study (including University Hospital Antwerp/P. van Schil and Anthonius Hospital Nieuwegein/F. Schramel) allows patients with resectable lung metastases from colorectal cancer, soft tissue- and osteosarcoma to be treated with ILuP prior to metastasecomy. At Leiden University Medical Center we treated 8 patients: 4 with colorectal cancer (age 54–59 y), 2 osteosarcoma (19–20 y), 1 sarcoma NOS of bone (38 y) and 1 sarcoma NOS (56 y) of soft tissue. The number of metastases was 1–2 and one patient had resection of 9 metastases. The procedure was uncomplicated in 7 cases and 1 patient had reversible pulmonary edema. Hospital admission duration was 6–8 days in the uncomplicated group and 14 days in the one patient with a complication. No long term toxicity was observed with extensive follow-up including lung function tests. With a median follow-up of 7 months (range 2–16), only the patient with 9 metastases had a recurrence and died of disease. Our single center prelimininary data show that ILuP is feasible and does not lead to irreversible or severe toxicity. Compared to retrospective data with metastasectomy alone, perfusion did not add toxicity. Follow-up is too short to draw any conclusions on efficacy

Purpose: To review the MRI findings in transient osteoporosis of the hip (TOH) and to investigate the pattern of perfusion in dynamic studies. Material and Methods: Twenty-seven patients (29 hips), 23–66 years old, were referred for hip pain without history of trauma. In all patients the diagnosis of TOH based on x-rays (decrease bone density of the femoral head) and MRI (bone marrow edema-BME) was confirmed after complete resolution of symptoms and MRI findings after 6–18 months. MRI studies included T1-w SE, T2-w-SPIR-TSE and contrast enhanced T1-w TFE in dynamic mode and delayed SE. Imaging assessment included joint effusion, location and extent of BME (types A–D), sparing of the femoral head, subchondral linear lesions, and collapse. Results: Joint effusion was observed in 28 of 29 hips. The extent of BME in the femoral head was type A in 5/29 hips, B in 2/29, C in 16/29, D in 6/29. Associated BME of the acetabulum was depicted in 6/29 hips. In 12/29 hips the bone marrow edema was sparing the subchondral area. Subchondral line was only found in 2/29 hips. On dynamic T1–w images all hips presented with a delayed pattern of perfusion up to 40 sec. Conclusion: MRI findings are useful in diagnosing TOH and differentiating this entity from early AVN

This is quite an innovative study that should lead to a multicentre validation trial. We have developed an FDG-PET/MRI texture-based model for the prediction of lung metastases (LM) in newly diagnosed patients with soft-tissue sarcomas (STSs) using retrospective analysis. In this work, we assess the model performance using a new prospective STS cohort. We also investigate whether incorporating hypoxia and perfusion biomarkers derived from FMISO-PET and DCE-MRI scans can further enhance the predictive power of the model. A total of 66 patients with histologically confirmed STSs were used in this study and divided into two groups: a retrospective cohort of 51 patients (19 LM) used for training the model, and a prospective cohort of 15 patients (two patients with LM, one patient with bone metastases and suspicious lung nodules) for testing the model. In the training phase, a model of four texture features characterising tumour sub-region size and intensity heterogeneities was developed for LM prediction from pre-treatment FDG-PET and MRI scans (T1-weighted, T2-weighted with fat saturation) of the retrospective cohort, using imbalance-adjusted bootstrap statistical resampling and logistic regression multivariable modeling. In the testing phase, this multivariable model was applied to predict the distant metastasis status of the prospective cohort. The predictive power of the obtained model response was assessed using the area under the receiver-operating characteristic curve (AUC). In the exploratory phase of the study, we extracted two heterogeneity metrics from the prospective cohort: the area under the intensity-volume histogram of pre-treatment DCE-MRI volume transfer constant parametric maps and FMISO-PET hypoxia maps (AU-IVH-Ktrans, AU-IVH-FMISO). The impact of the addition of these two individual metrics to the texture-based model response obtained in the testing phase was first investigated using Spearman's correlation (rs), and lastly using logistic regression and leave-one-out cross-validation (LOO-CV) to account for overfitting bias. First, the texture-based model reached an AUC of 0.94, a sensitivity of 1, a specificity of 0.83 and an accuracy of 0.87 when tested in the prospective cohort. In the exploratory phase, the addition of AU-IVH-FMISO did not improve predictive power, yielding a correlation of rs = −0.42 (p = 0.12) with lung metastases, and a relative change in validation AUC of 0% in comparison with the texture-based model response alone in LOO-CV experiments. In contrast, the addition of AU-IVH-Ktrans improved predictive power, yielding a correlation of rs = −0.54 (p = 0.04) with lung metastases, and a change in validation AUC of +10%. Our results demonstrate that texture-based models extracted from pre-treatment FDG-PET and MRI anatomical scans could be successfully used to predict distant metastases in STS cancer. Our results also suggest that the addition of perfusion heterogeneity metrics may contribute to improving model prediction performance

Short Summary. The present study demonstrated the feasibility of culturing a large number of standardised granular MSC-containing constructs in a packed bed/column bioreactor that can produce sheep MSC-containing constructs to repair critical-size bone defects in sheep model. Introduction. Endogenous tissue regeneration mechanisms do not suffice to repair large segmental long-bone defects. Although autologous bone graft remains the gold standard for bone repair, the pertinent surgical technique is limited. Tissue constructs composed of MSCs seeded onto biocompatible scaffolds have been proposed for repairing bone defects and have been established in clinically-relevant animal models. Producing tissue constructs for healing bone defects of clinically-relevant volume requires a large number of cells to heal an approximately 3 cm segmental bone defect. For this reason, a major challenge is to expand cells from a bone marrow aspirate to a much larger, and sufficient, number of MSCs. In this respect, bioreactor systems which provide a reproducible and well-controlled three-dimensional (3D) environment suitable for either production of multiple or large size tissue constructs are attractive approaches to expand MSCs and obtain MSC-containing constructs of clinical grade. In these bioreactor systems, MSCs loaded onto scaffolds are exposed to fluid flow, a condition that provides both enhanced access to oxygen and nutrients as well as fluid-flow-driven mechanical stimulation to cells. The present study was to evaluate bioreactor containing autologous MSCs loaded on coral scaffolds to repair critical-size bone defects in sheep model. Materials and Methods. Animals: 12 two-year-old, female Pre-Alpes sheep were used and reared in accordance with the European Committee for Care. Three-dimensional, porous scaffolds (each 3×3×3 mm) of natural coral exoskeleton were used as substrates for cell attachment. The packed bed/column bioreactor set-up used in the present study was composed of a vertical column filled with MSC-containing constructs. Sheep MSCs were isolated from sheep bone marrow. MSCs were seeded on scaffolds and cultured overnight under standard cell-culture condition. MSC-containing constructs were r placed into the perfusion bioreactor and were either exposed to a perfusion medium flow rate of 10 mL/min for 7 continuous days. Osteoperiosteal segmental (25 mm) defects were made in the left metatarsal bone of 12 sheep. The defect was either filled with coral scaffolds alone (Group 1; five sheep); or filled with coral scaffolds loaded with MSCs (Group 2; five sheep); or filled with autologous bone graft (Group 3; 2 sheep). Results. At 6 month after implantation, radiographs showed resorption of the coral scaffold in all animals but this process was not complete and not the same in all animal. At 6 month radiographs showed more bone formation in group 2 than in group 1. New bone formation volume in each defect was assessed by micro-computed tomography. Volume of bone healing was higher in group 2 than group 1. Discussion. The potential of MSC-containing constructs in a bioreactor for repairing long segmental critical-sized bone defects in sheep was investigated. In one animal of the group 2 the volume of new bone formation was 2066 mm3 and was similar to the bone volume of group 3 (2300 mm3). Our results may have important implications in bone tissue engineering. We observed that the bone tissue regenerationosteogenic ability of bone constructs processed in bioreactor approached the bone autografts

Introduction: Due to a lack of techniques there is only some data of testing mechanical influence on chondroctyes grown in 3-D tissue-culture over several months. In a new perfusion-chamber these mechanical factors could be studied in in-vitro tissue culture. Experimental Method: Chondrocytes which had been isolated by enzymatic digestion of mature pigs were seeted in Aga-rose on resorpable PDA/PGA (Ethisorb®) implants. These implants were cultured for 2, 6 and 12 weeks with alternating pressures of 0.5 MPa. Beneath a unpressurized control group, pressure was applied for 1 sec with a rest of 1 sec, for 2 sec with a rest of 8 sec and for 20 sec with a rest of 80 sec. Dulbecos medium was used for perfusion. Results and discussion: After 6 weeks the resorbable carrier has dissolved, in the following weeks the different groups showed different cartilage development (Fig. 1). After 12 weeks the 20/80 sec group showed collagen II and also major collagen I production in immunohistology, the 1/1 sec group showed only small traces of collagen I and masses of collagen II production. Further immunochemistry and scaning electron microscopy was able to show typical aspects of differentiated cartilage. Conclusion: The in-vitro differentiation of chondrocytes to mature cartilage is linked to certain mechanical factors. A frequency of 1/1 sec pressure is more favourable than lesser frequencies

Aim: Avascular necrosis of the femoral head is believed to play a role in failure of the femoral component in metal on metal hip resurfacing arthroplasty. The purpose of our study was to determine, prospectively, femoral head perfusion during hip resurfacing arthroplasty in the posterior and anterolateral approaches. Methods: 20 hip resurfacing arthroplasties were performed in 19 patients between September 2005 and April 2006. Patients were divided into two groups according to approach. An equal number of operations were performed by two different surgeons; one using the extended posterior approach and the other an anterolateral approach. Intravenous cefuroxime was administered in every case following capsulectomy and relocation of the femoral head. After 5 minutes the femoral head was dislocated and prepared as routine for the operation. Bone from the top of the femoral head and reamings were sent for assay to determine the concentration of cefuroxime. Results: The concentration of cefuroxime in bone was significantly greater when using the anterolateral approach (mean 15.7mg/kg; CI 12.3 to 19.1) compared to the posterior approach (mean 5.6mg/kg, CI 3.5 to 7.8; p< 0.001). In one patient, who had the operation through a posterior approach, cefuroxime was undetectable. Conclusion: The posterior approach is associated with a significant reduction in the blood supply to the femoral head during hip resurfacing arthroplasty. This may be a cause for avascular necrosis and potential failure of the femoral component in this procedure

Introduction: Avascular necrosis of the femoral head may play a role in failure of the femoral component in metal on metal hip resurfacing arthroplasty. The purpose of our study was to determine, prospectively, femoral head perfusion during hip resurfacing arthroplasty in the posterior and anterolateral approaches. Methods: 20 hip resurfacing arthroplasties were performed in 19 patients between September 2005 and March 2006 by two different surgeons; one using the extended posterior approach and the other an anterolateral approach. There were an equal number of procedures for each approach. 1.5 gms of intravenous cefuroxime was administered following caspsulectomy and relocation of the femoral head. After 5 minutes the femoral head was dislocated and prepared as routine for the operation. Bone from the top of the femoral head and reamings were sent for assay to determine the concentration of cefuroxime. The average time taken to prepare the femur and take samples was 8.5 minutes. Results: The concentration of cefuroxime in bone was significantly greater when using the anterolateral approach (mean 15.7mg/kg; CI 12.3 – 19.1) compared to the posterior approach (mean 5.6mg/kg; CI 3.5 – 7.8; p< 0.001). In one patient, who had the operation through a posterior approach, cefuroxime was undetectable. Discussion: The posterior approach is associated with a significant reduction in the blood supply to the femoral head during hip resurfacing arthroplasty. This may be a cause for avascular necrosis and potential failure of the femoral component in this procedure