Aims. Osteonecrosis (ON) can cause considerable morbidity in young people who undergo treatment for acute lymphoblastic leukaemia (ALL). The aims of this study were to determine the operations undertaken for ON in this population in the UK, along with the timing of these operations and any sequential procedures that are used in different joints. We also explored the outcomes of those patients treated by core decompression (CD), and compared this with conservative management, in both the pre- or post-collapse stages of ON. Methods. UK treatment centres were contacted to obtain details regarding surgical interventions and long-term outcomes for patients who were treated for ALL and who developed ON in UKALL 2003 (the national leukaemia study which recruited patients aged 1 to 24 years at diagnosis of ALL between 2003 and 2011). Imaging of patients with ON affecting the femoral head was requested and was used to score all lesions, with subsequent imaging used to determine the final grade. Kaplan-Meier failure time plots were used to compare the use of CD with non surgical management. Results. Detailed information was received for 85 patients who had developed ON during the course of their ALL treatment. A total of 206 joints were affected by ON. Of all joints affected by ON, 21% required arthroplasty, and 43% of all hips affected went on to be replaced. CD was performed in 30% of hips affected by ON. The majority of the hips were grade 4 or 5 at initial diagnosis of ON. There was no significant difference in time to joint collapse between those joints in which CD was performed, compared with no joint-preserving surgical intervention. Conclusion. There is a high incidence of surgery in young people who have received treatment for ALL and who have developed ON. Our results suggest that CD of the femoral head in this group of patients does not delay or improve the rates of femoral head survival. Cite this article: Bone Joint J 2021;103-B(3):589–596

Paediatric acute leukemia may present with various clinical mifestations that mimic different orthopaedic conditions and can produce diagnostic confusion. In a retrospective study we reviewed the cases of 129 children (average age 6.2 years) affected by acute leukemia who had been seen between 1984 and 1999 at the Paediatric Haemato-Oncology Department of the University of Padova and had complete clinical and radiographic data. Almost all the patients (93.7%) had a variety of general signs and symptoms at presentation: weakness (44.3%); anorexia (32.7%); lethargy (7.8%); fever (64.2%); pallor (79.6%); bleeding (25.3%); lymphoadenopathy (58.8%); hepatosplenomeg-aly (75.6%). Thirty-seven patients (28.6%) had complaints related to the muscoloskeletal system when they were first seen including: pain (92.7%), swelling (29,7%), joint limitation (47.8%), limping (18.8%). Skeletal surveys were made for ninety-two (71.3%) of the patients when the diagnosis of leukemia was made, while the other thirty-seven (28.6%) had radiograms of the symptomatic areas. Seventy-five patients (58.1%) presented normal radiograms and fifty-four (41.9%) showed one or more abnormalities. Osteopenia was diagnosed in eight patients; lytic lesions were see in fourteen; metaphyseal bands in ten; periosteal reactions in four; osteosclerosis in two; mixed osteoscle-rosis and osteolysis in two; permetive pattern in eight; vertebral collapse in three children. During the course of the disease two patients developed avascular necrosis of the femoral head; one reported a pathologic femoral neck fracture; three presented collapse of one or more vertebral bodies. All these findings are not pathognomonic but the clinician should always include acute leukemia in the differential diagnosis of any child with unexplained radio-grafic changes and/or persistent skeletal pain

Introduction: The incidence of aseptic osteonecrosis is 1.09% to 10.1% following the combination chemotherapy and high dose corticosteroid therapy of acute lymphoblastic leukaemic patients. The treatment of younger patients with advanced avascular necrosis remains controversial. No definite evidence is available yet on the effect of disseminated metal ions on the body. The clinical consequence of systemic absorption of metal degradation products in the causation of leukaemia remains contentious. We describe a 21 year old case with avascular necrosis of the hip joint due to T-Cell Acute Lymphoblastic Leukaemia treated with Metal-on-Metal surface hip arthroplasty with an excellent outcome at 5 year follow-up. Case report: A 21 year old man presented with painful right hip for a period of four years. The past medical history was significant for T-Cell Acute Lymphoblastic Leukaemia which was treated with high dose corticosteroids and combination chemotherapy. He was diagnosed with avascular necrosis of the right hip and was offered hip replacement. He underwent a metal-on-metal surface hip replacement. The uncemented dual coated 54mm cup and cemented 48mm femoral head (Cormet 2000, Corin Medical) were implanted. Now at 5 years follow up since the surface hip replacement he has an excellent result. His haematological indices remain normal and he remains in remission. Conclusion: Avascular necrosis of the femoral head is a well-known but rare complication of chemotherapy for leukaemia with a reported incidence ranging from 1 to 10 per cent. Metal-on-metal hip resurfacing arthroplasty is a potentially viable option for younger patients with aseptic osteonecrosis secondary to combination chemotherapy and high dose corticosteroid therapy used in the management of acute lymphoblastic leukaemias. Contrary to the general belief, we found no relapse in the leukaemia with use of metal-on-metal surface hip prosthesis till five years of follow-up

Purpose of study: ALL is the commonest childhood malignancy and current survival rates reach 80%. Consequently adverse effects of therapy may have significant long-term implications. Treatment is risk stratified with the higher intensity regimens B and C receiving more Dexamethasone and Methotrexate, both of which are known to have significant bony effects. The skeletal morbidity associated with ALL and its treatment, particularly AVN, is being increasingly identified. AVN is rare in paediatric practice. Its pathophysiology is largely unknown, although it is probably related to corticosteroid use.

Method: The records of a series of 7 out of 53 children treated with chemotherapy for ALL as per MRC ALL 99/01 and ALL 2003 protocols in a single tertiary paediatric oncology centre were reviewed. All 7 cases (3 male) had MRI confirmation of AVN (2 normal x-rays). All cases had been treated on higher intensity chemotherapy regimens and were at least 6 months from commencement of anti-leukaemic therapy. All presented with transient limb pain.

Results: The AVN was multi-focal (median 4 sites) and was associated with significant other bony abnormalities, including joint collapse, fracture, osteomyelitis and septic arthritis. In this series the dose of steroids did not correlate with the severity of the AVN. Treatment options were limited with all cases receiving conservative treatment

Conclusions: Careful consideration must precede a recommendation to stop steroids as this may compromise leukaemic cure. Although the long-term consequences of AVN on bone health are unknown, we recommend a high index of suspicion in professionals who are treating these children to ensure prompt diagnosis.

Aims. The aim of this study was to determine whether there is an increased prevalence of scoliosis in patients who have suffered from a haematopoietic malignancy in childhood. Methods. Patients with a history of lymphoma or leukaemia with a current age between 12 and 25 years were identified from the regional paediatric oncology database. The medical records and radiological findings were reviewed, and any spinal deformity identified. The treatment of the malignancy and the spinal deformity, if any, was noted. Results. From a cohort of 346 patients, 19 (5.5%) had radiological evidence of scoliosis, defined as a Cobb angle of > 10°. A total of five patients (1.4% of the total cohort) had a Cobb angle of > 40°, all of whom had corrective surgery. No patient with scoliosis had other pathology as a possible cause of the scoliosis and all had been treated with high doses of steroids for leukaemia, either acute or chronic myeloid, or acute lymphoblastic. Conclusion. There is an increased prevalence of idiopathic-like scoliosis and larger curves (Cobb angle of > 40°) associated with childhood leukaemia, which has not been previously reported in the literature. Causative factors may relate to the underlying disease process and/or its treatment. Cite this article: Bone Joint J 2021;103-B(8):1400–1404

Aims. Currently, the effect of drug treatment for osteoporosis is relatively poor, and the side effects are numerous and serious. Melatonin is a potential drug to improve bone mass in postmenopausal women. Unfortunately, the mechanism by which melatonin improves bone metabolism remains unclear. The aim of this study was to further investigate the potential mechanism of melatonin in the treatment of osteoporosis. Methods. The effects of melatonin on mitochondrial apoptosis protein, bmal1 gene, and related pathway proteins of RAW264.7 (mouse mononuclear macrophage leukaemia cells) were analyzed by western blot. Cell Counting Kit-8 was used to evaluate the effect of melatonin on cell viability. Flow cytometry was used to evaluate the effect of melatonin on the apoptosis of RAW264.7 cells and mitochondrial membrane potential. A reactive oxygen species (ROS) detection kit was used to evaluate the level of ROS in osteoclast precursors. We used bmal1-small interfering RNAs (siRNAs) to downregulate the Bmal1 gene. We established a postmenopausal mouse model and verified the effect of melatonin on the bone mass of postmenopausal osteoporosis in mice via micro-CT. Bmal1 lentiviral activation particles were used to establish an in vitro model of overexpression of the bmal1 gene. Results. Melatonin promoted apoptosis of RAW264.7 cells and increased the expression of BMAL1 to inhibit the activation of ROS and phosphorylation of mitogen-activated protein kinase (MAPK)-p38. Silencing the bmal1 gene weakened the above effects of melatonin. After that, we used dehydrocorydaline (DHC) to enhance the activation of MAPK-p38, and the effects of melatonin on reducing ROS levels and promoting apoptosis of RAW264.7 cells were also blocked. Then, we constructed a mouse model of postmenopausal osteoporosis and administered melatonin. The results showed that melatonin improves bone loss in ovariectomized mice. Finally, we established a model of overexpression of the bmal1 gene, and these results suggest that the bmal1 gene can regulate ROS activity and change the level of the MAPK-p38 signalling pathway. Conclusion. Our study confirmed that melatonin promotes the apoptosis of RAW264.7 cells through BMAL1/ROS/MAPK-p38, and revealed the therapeutic effect and mechanism of melatonin in postmenopausal osteoporosis. This finding enriches BMAL1 as a potential target for the treatment of osteoporosis and the pathogenesis of postmenopausal osteoporosis. Cite this article: Bone Joint Res 2023;12(11):677–690

Aim. Tedizolid is an oxazolidinone antibiotic that: (i) is recommended at the dose of 200 once daily in patients with skin and soft tissue infection; (ii) seems to have a better long-term hematological and neurological safety profile in comparison with linezolid; (iii) remains active on multidrug-resistant (MDR) Gram-positive pathogens. Consequently, it might represent an option as suppressive antimicrobial treatment (SAT) in patients with complex implant-associated bone and joint infection (BJI) due to MDR Gram-positive pathogens. Method. We performed a cohort study (2017–2020) to evaluate the long-term safety of tedizolid (200mg qd) as SAT in patients with implant-associated BJI. In all cases, the use of tedizolid was validated as the last oral treatment option during multidisciplinar meetings in a reference center for the management of BJI. Serious adverse events, any reason for discontinuation, and standard biological data, were prospectively collected. Results. Seventeen patients (13 males; median age 73 years) received tedizolid as SAT for late complex prosthetic-joint infections (n=16) or osteosynthesis (n=1). Pathogens were MDR coagulase negative staphylococci (16 patients), Corynebacterium striatrum (2 patients), Enterococcus faecium (1 patient) and/or S. aureus (1 patient). Tedizolid was always started after a primary treatment (median duration of intravenous 47 days; followed by linezolid in 12 patients including 9 who experienced linezolid-induced serious adverse event) that followed a surgery, mainly debridement and implant retention (13 patients). Median duration of tedizolid was 6 months (min, 1 month; max, 31 months). The only reason for discontinuation was a failure of the conservative strategy that occurred in four patients (17%) during the follow-up. No patients developed a serious adverse event, or a discontinuation of tedizolid due to an adverse event. Anemia was observed in two patients, who had already other known cause of anemia (chronic leukemia and oesophageal varices); stable thrombopenia was observed in a cirrhotic patient (80 G/L, stable during the treatment course of 12 months); and a transient mild neutropenia (1.4 G/L) was observed in another patient (Figure). No neurological adverse event was observed. Conclusions. Tedizolid seems to be a safe option as SAT in patients with complex implantassociated BJI due MDR Gram-positive pathogens. For any tables or figures, please contact the authors directly

Mesenchymal stem cells (MSC) have a well recognised potential for tissue repair. This potential is two pronged: they can differentiate into the functional cell types of the damaged tissues and they can support tissue recovery by secreting trophic factors, depositing an extracellular matrix (ECM) and dampening inflammation. Three-dimensional microscopy recently shown that MSCs in the bone marrow create an intricate proteo-cellular scaffold with the ECM forming an interconnected cellular continuum whose structure is guided by the deposited ECM. This proteo-cellular scaffold controls bone marrow functions from hematopoiesis to osteogenesis. In the current study we aimed to optimise ECM production under in vitro conditions by immortalised MSCs with the view that the generated ECM can be utilised for tissue repair. With immunocytochemistry we determined the deposition of bone marrow-characteristic ECM proteins: collagen I, III, IV, V, VI, laminin and fibronectin. While primary MSCs produced slightly higher amount ECM proteins than immortalised MSCs, the relative abundancy of the ECM proteins was very similar. In order to isolate the ECM, we optimised a decellularisation method based on gentle lysis with sodium-deoxycholate and DNase digestion. Immunostaining for collagen I, III, VI and fibronectin and labelling the nuclei with Hoechst-33342 confirmed removal of all cells while retaining the ECM in its original architecture. Ideally, the decellularised ECM retains associated cytokines and chemokines, such as CXCL12, important for attracting MSCs. To test this, we seeded Molm-13 leukemia cells on decellularised ECM as MSC-produced CXCL12- and other cytokines protect leukemia cells against chemotherapeutics. We found that the decellularisation process however removed these factors and thus for therapeutic purposes, the decellularised ECM would need to be re-loaded with the essential chemo/cytokines. Overall, we developed a system for decellularised ECM production by immortalised MSCs and the results warrant further exploration of this avenue

Objectives. This study aimed to explore the role of miR-320a in the pathogenesis of osteoarthritis (OA). Methods. Human cartilage cells (C28/I2) were transfected with miR-320a or antisense oligonucleotides (ASO)-miR-320a, and treated with IL-1β. Subsequently the expression of collagen type II alpha 1 (Col2α1) and aggrecan (ACAN), and the concentrations of sulfated glycosaminoglycans (sGAG) and matrix metallopeptidase 13 (MMP-13), were assessed. Luciferase reporter assay, qRT-PCR, and Western blot were performed to explore whether pre-B-cell leukemia Homeobox 3 (PBX3) was a target of miR-320a. Furthermore, cells were co-transfected with miR-320a and PBX3 expressing vector, or cells were transfected with miR-320a and treated with a nuclear factor kappa B (NF-κB) antagonist MG132. The changes in Col2α1 and ACAN expression, and in sGAG and MMP-13 concentrations, were measured again. Statistical comparisons were made between two groups by using the two-tailed paired t-test. Results. Expression of miR-320a was elevated in OA cartilage tissues and chondrocytes, and in IL-1β-stimulated C28/I2 cells (p < 0.05 or p < 0.01). MiR-320a overexpression enhanced IL-1β-induced down-regulation of Col2α1 and ACAN and sGAG, and increased the IL-1β-induced overexpression of MMP-13 (p < 0.01). PBX3 was a direct target of miR-320a. PBX3 and MG132 co-transfection attenuated the effects of miR-320a on the expression of Col2α1, ACAN, sGAG and MMP-13(p < 0.01). Conclusion. Overexpression of miR-320a might enhance IL-1β-induced cartilage degradation factors. These effects might be via targeting PBX3 and regulating NF-κB. Cite this article: Y. Jin, X. Chen, Z. Y. Gao, K. Liu, Y. Hou, J. Zheng. The role of miR-320a and IL-1β in human chondrocyte degradation. Bone Joint Res 2017;6:–203. DOI: 10.1302/2046-3758.64.BJR-2016-0224.R1

Avascular necrosis (AVN) is a serious complication of high-dose chemotherapy for haematological malignancy in childhood. In order to describe its incidence and main risk factors and to evaluate the current treatment options, we reviewed 105 children with a mean age of 8.25 years (1 to 17.8) who had acute lymphoblastic or acute myeloid leukaemia, or a non-Hodgkin’s lymphoma. Overall, eight children (7.6%) developed AVN after a mean of 16.8 months (8 to 49). There were four boys and four girls with a mean age of 14.4 years (9.8 to 16.8) and a total of 18 involved sites, 12 of which were in the femoral head. All these children were aged > nine years (p < 0.001). All had received steroid treatment with a mean cumulative dose of prednisone of 5967 mg (4425 to 9599) compared with a mean of 3943 mg (0 to 18 585) for patients without AVN (p = 0.005). No difference existed between genders and no thrombophilic disorders were identified. Their initial treatment included 11 core decompressions and two bipolar hip replacements. Later, two salvage osteotomies were done and three patients (four hips) eventually needed a total joint replacement. We conclude that AVN mostly affects the weight-bearing epiphyses. Its risk increases with age and higher steroid doses. These high-risk patients may benefit from early screening for AVN. Cite this article: Bone Joint J 2013;95-B:1708–13

Abnormal wear of cobalt-containing metal-on-metal joints is associated with inflammatory pseudotumours. Cobalt ions activate human toll-like receptor 4 (TLR4), which normally responds to bacterial lipopolysaccharide (LPS) in sepsis. Activation of TLR4 by LPS increases the expression of chemokines IL-8 and CXCL10, which recruit leukocytes and activated T-cells, respectively. This study was designed to determine whether cobalt induces a similar inflammatory response to LPS by promoting the expression of IL-8 and CXCL10. A human monocytic cell line, derived from acute monocytic leukaemia, was treated with cobalt ions and expression of IL-8 and CXCL10 measured at mRNA and protein levels. Cobalt-treated macrophages showed a 60-fold increase in IL-8 mRNA, and an eightfold increase in production of the mature chemokine (both p < 0.001); expression of the CXCL10 gene and protein was also significantly increased by cobalt (both p < 0.001). Experiments were also performed in the presence of CLI-095, a TLR4-specific antagonist which abrogated the cobalt-mediated increase in IL-8 and CXCL10 expression. . These findings suggest that cobalt ions induce inflammation similar to that observed during sepsis by the simultaneous activation of two TLR4-mediated signalling pathways. These pathways result in increased production of IL-8 and CXCL10, and may be implicated in pseudotumour formation following metal-on-metal replacement. Cite this article: Bone Joint J 2014; 96-B:1172–7

Advances in orthopaedic surgery have led to minimally invasive techniques to decrease patient morbidity by minimizing surgical exposure, but also limits direct visualization. This has led to the increased use of intraoperative fluoroscopy for fracture management. Unfortunately, these procedures require the operating surgeon to stay in close proximity to the patient, thus being exposed to radiation scatter. The current National Council on Radiation Protection recommends no more than 50 mSv of radiation exposure to avoid ill-effects. Risks associated with radiation exposure include cataracts, skin, breast and thyroid cancer, and leukemia. Despite radiation protection measures, there is overwhelming evidence of radiation-related diseases in orthopaedic surgeons. The risk of developing cancer (e.g. thyroid carcinoma and breast cancer) is approximately eight times higher than in unexposed workers. Despite this knowledge, there is a paucity of evidence on radiation exposure in orthopaedic surgery residents, therefore the goal of this study is to quantify radiation exposure in orthopaedic surgery residents. We hypothesize that orthopaedic surgery residents are exposed to a significant amount of radiation throughout their training. We specifically aim to: 1) quantify the amount of radiation exposure throughout a Canadian orthopaedic residency training program and 2) determine the variability in resident radiation exposure by rotation assignment and year of training. This ongoing prospective cohort study includes all local orthopaedic surgery residents who meet eligibility criteria. Inclusion criteria: 1) adult residents in an orthopaedic surgery residency program. Exclusion criteria: 1) female residents who are pregnant, and 2) residents in a non-surgical year (i.e. leave of absence, research, Masters/PhD). After completion of informed consent, each eligible resident will wear a dosimeter to measure radiation exposure in a standardized fashion. Dosimeters will be worn on standardized lanyards underneath lead protection in their left chest pocket during all surgeries that require radiation protection. Control dosimeters will be worn on the outside of each resident's scrub cap for comparison. Dosimeter readings will then be reported on a monthly and rotational basis. All data will be collected on a pre-developed case report form. All data will be de-identified and stored on a secure electronic database (REDCap). In addition to monthly and rotational dosimeter readings, residents will also report sex, height, level of training, parental status, and age for secondary subgroup analyses. Residents will also report if they have personalized lead or other protective equipment, including lead glasses. Resident compliance with dosimeter use will be measured by self report of >80% use on operative days. Interim analysis will be performed at the 6-month time point and data collection will conclude at the 1 year time point. Data collection began in July 2018 and interim 6-month results will be available for presentation at the CORA annual meeting in June 2019. This is the first prospective study quantifying radiation exposure in Canadian orthopaedic residents and the results will provide valuable information for all Canadian orthopaedic training programs

The incidence of cancer after hip replacement was studied in the 1.6 million inhabitants of Stockholm County, Sweden. A cohort of 10,785 individuals who had had hip replacement between 1974 and 1988 was followed from the date of operation to the first malignant tumour, to death, or to the end of 1989. The follow-up was based on 58,437 person-years at risk as calculated from information obtained by record-linkage with the National Cancer Registry and the National Cause-of-Death Register. The Standardised Morbidity Ratio (SMR) for all cancer sites, disregarding the length of follow-up, was 0.96 (95% CI 0.90 to 1.03). For lymphoma and leukaemia the corresponding SMR was 0.89 (0.68 to 1.14). Our results do not support previous suggestions of an increased incidence of leukaemia and lymphoma after total hip replacement

Background. Revision hip arthroplasty for excessive bone loss because of osteolysis or infection is difficult theme. Bone grafting is essential technique for bone loss and need of allograft is increasing. Recently, many hospital bone banks are established in Japan. The aim of this study is investigate efficacy and safety of allograft in our hospital bone bank. Material and method. We evaluated management, result and complication of allografts retrieved from living donors in our institute. Result. All donors meet the criteria of Japanese Orthopaedic Association (JOA) guideline and gave fully informed written consent. We obtained 75 femoral head grafts that were retrieved during primary total hip arthroplasty under sterile operating theatre conditions. No donor had hepatitis B and C, human immunodeficiency (HIV), Human T-cell leukemia (HTLV-1) and Syphilis. After heat treatment, allograft was swabbed for cultures and stored in freezer at −80□. All cultures ware negative and proved before implantation. We used allograft in 27 revision hip arthroplasty. Six cases were femoral side and 21cases were acetabular side. At the minimum of 3 months follow-up, 1 fracture of acetablar and 1 superficial infection occurred. No allergic reaction happened. Conclusion. Our bone bank thoroughly managed based on JOA guideline was effective and safe. Careful follow-up is needed for long-term implant fixation and osteoinduction

We describe a patient who developed avascular necrosis of both humeral trochleae after combination chemotherapy for acute lymphoblastic leukaemia. This presented as progressive stiffness of both elbows with little pain. Radiography and MRI confirmed the presence of avascular necrosis at both sites. This region corresponds to a watershed between the medial and lateral vascular arcades which supply the distal humerus and may explain the susceptibility of this bony region to avascular necrosis. Treatment involved capsulectomy of the elbow and removal of osteophytes giving a good functional outcome on both sides

It is reported that more than 10 million Japanese suffer from arthrosis. To cure these cartilage defects, total joint replacements, which are the most popular treatment methods for severe disease situation, have been operated as about two hundred thousand cases a year in Japan. Although the implants made of either ceramics, metals or plastics have high wear resistance quality, it becomes apparent that the endurance life of the artificial joints in considerable cases is limited by aseptic loosening to between 10–15 years. Here we focused on a poly(vinyl alcohol) (PVA) hydrogel as an artificial cartilage tissue to make an improvement of friction surface of the artificial joints. In this paper, we observed morphology of wear particles and assessed immune responses of wear particles from the hydrogel for confirming the validity of the gel as a biotribological material. We prepared 20 w/w% of PVA hydrogel by repeated freezing-thawing method. The number of the freezing-thawing cycles was five times. Polymerization degree and saponification degree of PVA (Kishida Chemical Co. Ltd., Japan) were 2000 and 98.4–99.8 mol%, respectively. To collect the wear particles of PVA hydrogel, we processed wear testing by using a purpose-build wear test machine of reciprocating pin-on-plate tribometer as shown in figure 1. We installed a Co-Cr-Mo ball of 26 mm in diameter as a stationary upper specimen and a PVA hydrogel plate of 2 mm in thickness as reciprocating lower specimen in a water bath. The lubricant was a distilled water containing eluted PVA which PVA-FT gel had been soaked in, filtered by 0.22 μm and autoclaved, subsequently. Siding speed was 50 mm/s and the total sliding distance was 3 km. We observed the wear particles which had been dried in a desiccator, by scanning electron microscope (SEM; SU8000, Hitachi High-Technologies). Additionally, to investigate the effect of the wear particles on response of phagocytosis of macrophages, here we used THP-1 cell line from Human acute monocytic leukemia as a macrophage, which was purchased from JCRB Cell Bank, and attached the macrophages on a dish after stimulating THP-1 by phorbol 12-myristate 13-acetate (PMA; Wako). After the wear test, we harvested the lubricant in aseptic clean hood and applied the particles to the macrophages to clarify the effect of wear particles of PVA hydrogel on immune response of the cell. To assess cytokine biosynthesis as immune responses, we assayed IL-1β and TNF-α biosynthesis in culture medium by ELISA (Thermo scientific), respectively. Figure 2 shows an SEM image of PVA hydrogel after wear test under 4.9 N loading. We observed the wear particles of varied sizes. When applying the wear particles to the macrophages in RPMI-1640 supplement with 10 v/v% fetal bovine serum, it seemed that there were not enough change on cytokine synthesis in culture medium between with/without the particles

Of 290 Ugandan children and adolescents with proven Burkitt's lymphoma 11 had lesions in the long bones or the pelvis. These started in the medulla as small osteolytic foci which coalesced and penetrated the cortex causing subperiosteal new bone formation in layers or spicules, and giving rise to large soft-tissue masses. Common sites were the femoral and tibial diaphyses and the metaphyses around the knee. Five were in the epiphyses. Other sites were the pelvis, humerus and ulna. One patient had a lymphomatous synovial effusion of the knee. In the lower limbs the lesions were often bilateral and symmetrical. Five patients had pathological fractures. Radiologically the lesions mimicked Ewing's sarcoma, osteosarcoma, osteomyelitis, acute leukaemia, syphilis and yaws, but clinically they were relatively painless, an important differential diagnostic feature. In the five patients with sustained remissions after chemotherapy the lesions and fractures healed well and the growth plates were undamaged

Purpose: The osteogenic effects of BMPs on mesenchymal stem cells (MSCs) are less profound in human as compared to rodent. The mechanism for this phenomenon is unclear. This study evaluated the effects of macrophages on proliferation and BMP-2 induced osteogenic differentiation of human MSCs. Method: MSCs were isolated from human bone marrow. Human monocytes THP-1 (human acute monocytic leukemia cell line) were induced into macrophages by phorbol myristate acetate. The conditioned media (CM) from monocytes and macrophages were collected separately. After treated with CM from monocytes or macrophages for 5 and 7 days, the proliferation rate of human MSCs was determined by WST-8 assay. A group without CM served as control. Pretreated human MSCs were then induced towards osteogenic differentiation by osteoinductive medium supplemented with 0.1ug/ml BMP-2. Expression levels of osteogenic markers were determined by real-time quantitative PCR. Alkaline phosphatase (ALP) activity and mineral deposition were assessed by p-NPP colorimetric kinetic assay and calcium assay, respectively. Results: The number of MSCs was significantly decreased in the group with macrophage CM at both 5 and 7 days (both p< 0.001) as compared with control group, but not in the group with monocytes CM. Expression levels of ALP and bone sialoprotein 2 in the macrophage CM group were significantly lower than those in the control group (p=0.003 and p< 0.001, respectively). ALP activity was also significantly lower in the group with macrophage CM than control group (p< 0.001). Although the expression levels of osteocalcin and RUNX2 as well as calcium deposition in the macrophage CM group were reduced, they did not reach statistical significance. Conclusion: Macrophages suppressed the proliferation of MSCs and inhibited BMP-2 induced osteogenic differentiation of human MSCs. In addition to known BMP antagonists, macrophages might be another important factor in suppressing the osteogenic effect of BMP-2 on human MSCs

INTRODUCTION. Total hip arthroplasty (THA) is not commonly performed in young patients. However, markedly advanced hip disease can cause disabling end-stage arthritis, and THA may be the only available option for pain relief and restoration of function. We report our experience with modern alternative bearing THA in patients younger than 21 years. METHODS. Twenty-one consecutive primary THAs were performed in 18 patients. Pre- and post-operative Harris Hip Scores (HHS) and any postoperative complications were recorded. Radiographs were reviewed for evidence of premature component loosening. Mean patient age at operation was 18 years (range, 13-20). There were 14 females (78%) and 4 males (22%). Nine patients (50%) were Caucasian, 8 (44%) were African-American, and 1 (6%) was Asian. Average follow-up was 45 months (range, 16-85). All patients failed conservative treatment; 15 patients had prior core decompression and bone grafting. Underlying etiology was chemotherapy induced osteonecrosis (7, 33%), steroid induced osteonecrosis (6, 29%), sickle cell disease (5, 24%), and chronic dislocation (3, 14%); 1 patient underwent THA for fracture of a previous ceramic bearing, 1 patient had a slipped capital femoral epiphysis, and 1 patient had idiopathic joint destruction. Components implanted were ceramic/ceramic (14, 67%), metal/highly cross-linked polyethylene (6, 29%), and metal/metal surface replacement (1, 5%). RESULTS. HHS scores improved from 43.6 pre-operatively to 83.6 post-operatively (p<0.001). There were no infections or dislocations, and one patient with acute lymphocytic leukemia experienced post-operative hypotension following bilateral THA which resolved. At time of final follow-up, there was no radiographic evidence of component loosening; one THA was revised for a cracked ceramic liner. CONCLUSION. At intermediate-term follow-up, clinical and radiographic results are favorable following alternative bearing THA in patients under age 21. Long-term follow-up is necessary to assess implant longevity in this patient population

Summary. Starting from human musculoskeletal sarcomas, we isolated a subset of cells that display cancer stem cell properties. The control of culture conditions is crucial to enhance the isolation of this cell population. Introduction. Cancer stem cells (CSCs) have emerged as the real responsible for the development, chemoresistance, and metastatic spread of different human cancers, including musculoskeletal sarcomas. However, unlike most leukemias and solid tumors, so far, data on musculoskeletal sarcomas refer to CSCs obtained from established cell lines, and only a few authors have reported on the isolation of CSCs from tissue samples [1-7]. Reasonably due to some peculiar features of mesenchymal tumors, including the lack of unique surface markers that identify tumor progenitors, there are still partial clues on the existence of a CSC population in these cancers. Here, we report the identification of putative CSCs in musculoskeletal sarcomas using the most general accepted isolation method, the sphere culture system. Accordingly to recent reports, we also analyzed the effects of reduced oxygen availability on the behavior of sarcoma CSCs. Patients & Methods. Between 2009 and 2012, we collected fresh tissue samples from 49 patients (25 males and 24 females, age 6–85 yr) with musculoskeletal sarcomas. Cells obtained from samples were cultured in anchorage-independent serum-starved conditions, in the presence of adequate growth factors, until the formation of floating spheres, here called ‘sarcospheres’. To obtain parental tumor cell cultures, single cells obtained from biopsies were in parallel seeded in anchorage-dependent conditions, in the presence of fetal bovine serum until the formation of cell monolayers. The obtained sarcospheres were characterised in terms of gene expression and in vivo tumorigenic potential. We then exposed sarcospheres obtained from a rhabdomyosarcoma model (RD cells) to a hypoxic environment (1% O. 2. ), and analyzed their growth and gene expression to that of sarcospheres grown at standard 21% O. 2. . Results. Using a sphere-forming assay, we established sphere cultures in 5 out of 49 cases (10.2 %). All sarcosphere cultures expressed consistent mRNA levels for OCT3/4, Nanog, and SOX2. CSCs from a chondrosarcoma and from a rhabdomyosarcoma also showed the ability to recapitulate the original tumor morphology in a mouse model. Finally, we observed that hypoxia induced a significant increase of the number and size of CSCs from RD. Discussion/Conclusion. Starting from human sarcoma biopsies and established cell lines, we were able to characterise the CSC subset of musculoskeletal sarcomas, that were isolated through the sphere system assay. These cells had stem-like properties, and showed in vivo tumorigenic ability. We also observed that exposure of CSCs to low oxygen conditions increased the number and size of spheres and the expression of stem cell-related markers, suggesting that the culture in hypoxic conditions could improve the yield of the isolation method here used, and that the oxygen availability is a crucial element in the physiological maintenance of CSCs of musculoskeletal sarcomas