Bone regeneration and repair are crucial to ambulation and quality of life. Factors such as poor general health, serious medical comorbidities, chronic inflammation, and ageing can lead to delayed healing and nonunion of fractures, and persistent bone defects. Bioengineering strategies to heal bone often involve grafting of autologous bone marrow aspirate concentrate (BMAC) or mesenchymal stem cells (MSCs) with biocompatible scaffolds. While BMAC shows promise, variability in its efficacy exists due to discrepancies in MSC concentration and robustness, and immune cell composition. Understanding the mechanisms by which macrophages and lymphocytes – the main cellular components in BMAC – interact with MSCs could suggest novel strategies to enhance bone healing. Macrophages are polarized into pro-inflammatory (M1) or anti-inflammatory (M2) phenotypes, and influence cell metabolism and tissue regeneration via the secretion of cytokines and other factors. T cells, especially helper T1 (Th1) and Th17, promote inflammation and osteoclastogenesis, whereas Th2 and regulatory T (Treg) cells have anti-inflammatory pro-reconstructive effects, thereby supporting osteogenesis. Crosstalk among macrophages, T cells, and MSCs affects the bone microenvironment and regulates the local immune response. Manipulating the proportion and interactions of these cells presents an opportunity to alter the local regenerative capacity of bone, which potentially could enhance clinical outcomes. Cite this article: Bone Joint Res 2024;13(9):462–473

Introduction: Metal-on-metal (MoM) articulations for THA are used successfully from CoCr-alloys. Low or high carbon hydride metals contain less or more than 0.2% carbon in the alloy. The systems show encouraging clinical results and lower rates of aseptic loosening in midterm results. Hypersensitivity reactions to high carbide MoM articulations were reported. The immune response is characterized by a perivascular T-/B-lymphocyte infiltration of the capsular tissue around the hip replacement. The present study examines if lymphocytic reactions are present in low carbide MoM THA and if distinct cytokines are released to joint fluids. Retrieval tissues from 28 patients were used. Joint fluids were aspirated at the time of surgery. Materials and Methods: Tissues were collected from 25 patients undergoing 26 aseptic revisions of MoM THA (CoCrMo, Sikomet. ®. , Plus Orthopaedics). The patients had following symptoms: Hip and femoral pain; recurrent dislocation and clicking noises. 8 patients had osteolysis, 12 patients showed a metallosis. The peripros-thetic tissues were examined by standard histology and immunohistochemistry. Joint fluids were frozen at the time of surgery. The control groups were patients with osteoarthritis of the hip (n=10), revisions from Al2O3-UHMWPE articulations (n=6), revisions of MoM with hypersensitivity reaction (n=18), and MoM without hypersensitivity reactions (n=8). The fluids were analyzed for various Interleukins, Il-1 receptor antagonist, G-CSF, GM-CSF, IFN gamma, MIP-1ß, and TNF-α. Results: 18 out of 26 cases showed diffuse and follicular lymphocyte infiltrations in the revision tissues. Perivas-cular T- and B-lymphocytes and few macrophages were also seen. In low and excessive metallosis no lymphocytes were observed. The tissue response in low carbide MoM is similar to high carbide MoM. Analysis of the cytokine profile in the joint fluids showed markers of osteoclast activation (Il-6 and −10) in all MoM articulations. TNF-α increase was increased in all loosening groups but was further increased in MoM. Il-5, IFN gamma, MIP-1ß, and GM-CSF were increased in all fluids from loosening cases but were further increased in MoM with lymphocyte activation. Discussion: Activation of lymphocytes in failed MoM THA’s is not necessarily related to high carbide MoM. Hypersensitivity also occurred in low carbide MoM THA. The cytokine profiles in the joint fluids showed distinct characteristics. Il-6 and Il-10, markers of osteo-clast activation, were elevated in all cases of bone loss and osteolysis. The increase in TNF-α may account for a regulation of the OPG/RANKL system TNF-a which can induce osteolysis. The elevated levels of Il-5, IFN gamma, MIP-1ß, and GM-CSF in MoM failures with hypersensitivity represent markers of chemotaxis and lymphocyte activation may account for index markers of hypersensitivity reaction

Introduction: Symptomatic abnormal soft-tissue masses relating to the hip joint, such as those described as pseudotumours, are being increasingly reported following metal-on-metal hip resurfacing arthroplasty (MoMHRA). These were found to be locally destructive, requiring revision surgery in a high proportion (75%) of patients. Lymphocyte infiltrations seen in pseudotumours were similar to aseptic lymphocyte vascular associated lesion (ALVAL), which is thought to represent a T-lymphocyte-mediated delayed type hypersensitivity. Therefore, a delayed hypersensitivity reaction to nickel (Ni), chromium (Cr) or cobalt (Co) has been suggested to play a role in pseudotumour aetiology. In patients with bilateral MoMHRA who presented with symptoms on one side, subsequent scans have demonstrated pseudotumours both on the symptomatic and asymptomatic side. Thus, there are concerns that there may be an appreciable number of asymptomatic pseudotumours that surgeons are unaware of and these may eventually become symptomatic. Aim: The aims of this study were:. to determine the prevalence of asymptomatic pseudotumours after MoMHRA; and. to measure Co and Cr ion levels as well as lymphocyte proliferation responses to Ni, Co and Cr (the principal elements in the CoCr alloy used in MoMHRA) in MoMHRA patients with and without asymptomatic pseudotumours. Methods: A total of 201 MoMHRA implanted hips in 158 patients (97 male, 61 female) with a mean age of 56 years (range 33–73 years) were evaluated. The mean follow-up was 61 months (range 13–88 months). Resurfacing devices implanted included 128 Birmingham Hip Resurfacing, 66 Conserve Plus and seven ReCap. The control groups included additional 20 patients, 10 male and 10 female (a mean age 68 years, range 57–80 years) with metal-on-polyethylene total hip arthroplasty and a further 22 age-matched patients (a mean age 55 years) without any metal implants. Ultrasound was used as the initial imaging modality and MRI was used to assess the extent of the identified masses. Patients with a soft-tissue mass had ultrasound-guided aspiration or core biopsy performed. Venous blood samples were collected in all patients for serum cobalt and chromium ion levels analysis using Inductively-Coupled Plasma Mass Spectrometer and lymphocyte transformation tests (LTT). The Oxford Hip Score (OHS) was used to measure the functional outcomes of patients. Acetabular component abduction angle was measured from standardised anteroposterior pelvis radiographs. Results: Prevalence – Pseudotumours were found in 7 patients (6 female and 1 male). The overall prevalence of asymptomatic pseudotumours was 4%, with a relatively very high (30%) prevalence in females with bilateral implants. Histological examinations showed extensive necrosis of connective tissue, in which there were scattered aggregates of metal particles and a diffuse lymphocyte infiltrate. Metal Ion Levels – The presence of pseudotumour was associated with significantly higher median serum cobalt levels (9.2mg/L vs. 1.9mg/L, p< 0.001), chromium levels (12.0mg/L vs. 2.1mg/L, p< 0.001), hip aspirate cobalt levels (1182 mg/L vs. 86.2mg/L, p=0.003), and aspirate chromium levels (883mg/L vs. 114.8mg/ L, p=0.006), as well as with inferior functional scores (OHS 41 vs. 47 p< 0.001). There was no significant difference in acetabular cup inclination angle (p=0.51). Lymphocyte Reactivity: A higher incidence and level of enhanced lymphocyte reactivity to Ni (p=0.001), but not to Co or Cr (the principal elements in the CoCr alloy used in metal-on-metal hip resurfacing implants), was found in patients with MoMHRA compared to the patients without MoM implants. However, lymphocyte reactivity to Co, Cr and Ni did not significantly differ in patients with pseudotumours compared to those patients without pseudotumours. Conclusion: The prevalence of asymptomatic pseudotumours in females was high, especially in females with bilateral MoMHRA implants (30%). The patients with ‘asymptomatic’ pseudotumours were in fact mildly symptomatic. Lymphocyte reactivity to Co, Cr and Ni did not differ in patients with pseudotumour compared to those patients without pseudotumours, suggesting that systemic hypersensitivity type IV reactions, mediated by lymphocyte reactivity to these metals, is not the dominant mechanism in pathogenesis of the soft tissue pseudotumours. Furthermore, pseudotumours were not detected in those patients who had normal levels of cobalt and chromium ions. This suggests that pseudotumours do not occur if MoM articulations are well functioning. Therefore, pseudotumours are likely to be a biological consequence of the large amount of metal debris generated in vivo due to excessive wear

We investigated the lymphocyte-mediated immune response to polymethylmethacrylate bone cement in 26 patients who had revision surgery for aseptic loosening of cemented total hip arthroplasties, at a mean time of seven years after the first replacement. We studied eight patients with cemented total hip arthroplasties which were not loose as controls. Patch tests to polymethylmethacrylate bone cement were positive in 13 patients with loosening, and these patients had higher lymphoblast transformation values against polymethylmethacrylate bone cement patients with a negative skin reaction (p < 0.01) or those in the control group (p < 0.001). Specific monoclonal antibodies were used to assess the percentage of certain cells of the immune system according to their cluster of differentiation (CD). There was a higher number of total T and B lymphocytes (CD2 and CD22) and interleukin-2 receptor-positive lymphocytes (activated cells, CD25) in patients with loose prostheses. More CD25 lymphocytes were found in patients with positive patch tests. The activation of the lymphocyte-mediated immune response was not related to the presence or absence of aggressive granulomatous lesions at the cement-bone interface

Recently, a series of locally destructive soft tissue pseudotumour has been reported in patients following metal-on-metal hip resurfacing arthroplasty (MoMHRA), requiring revision surgery in a high percentage of patients. Based on the histological evidence of lymphocytic infiltration, a delayed hypersensitivity reaction to nickel (Ni), chromium (Cr) or cobalt (Co) has been suggested to play a role in its aetiology. The aim of this study was to investigate the incidence and level of hypersensitivity reaction to metals in patients with pseudotumour. Materials and Methods: 25 patients were investigated in this Ethics approved study:. Group 1: MoMHRA patients with pseudotumours, detected on the ultrasound and confirmed with MRI (n=6, 5 F:1 M, mean age 53 years);. Group 2: MoMHRA patients without pseudotumours (n=13, 7 F:6 M, mean age 55 years); and. Group 3: age-matched control subjects without metal implants (n=6, 4 F:2 M, mean age 54 years). Lymphocyte transformation tests (LTT) were used to measure lymphocyte proliferation responses to metals. Peripheral blood mononuclear cells were isolated from heparinized blood samples using standard Ficoll–Hypaque® (Pharmacia). The PBMC were cultured at a cell density of 106 cells/mL. Culture was set up in the presence of either:. medium alone;. nickel chloride (Sigma; 10-4M-10-6M);. cobalt chloride (10-4M-10-6M); and. chromium chloride (10-4M-10-6M). After 5 days of culture, cells were pulsed with [3H]-thymidine and proliferation was assessed by scintillation counting. The stimulation index (SI) was calculated by the ratio of mean counts per minute of stimulated to unstimulated cultures. A SI value of greater than 2.0 was interpreted as a positive result. Results: A clinical history of metal allergy was reported in 2/6 in Group 1, 2/13 in Group 2, and none in Group 3. In pseudotumour group, the incidence of reactivity to Ni, Co and Cr was 60%, 17% and 0%, respectively. Within Group 2, the reactivity to Ni, Co and Cr was 69%, 8% and 15%, respectively. One control subject had reactivity to Ni. Inter-group comparisons of mean SI values (Kruskal-Wallis non-parametric analysis of variance) showed no significant differences (p> 0.05). Discussion: The incidence of enhanced lymphocyte response to metals in patients with MoMHRA was more common than the control group. However, in comparison with non-pseudotumour patients, there was no significant difference in the incidence or the level of lymphocyte reactivity in patients with pseudotumour. We conclude that patients with MoMHRA have an enhanced lymphocyte response to metal ions, reflecting exposure and immune reactivity. However, patients with pseudotumours have a similar proliferative response to those without pseudotumours, which suggests that type IV hypersensitivity may not be the cause of the pseudotumours

Introduction. Metal on metal articulations produce chromium (Cr) and cobalt (Co) debris, particularly when the articulations are worn in. High levels in the peripheral blood are indicative of excess wear and may cause adverse effects. The present RCT investigates metal ion levels and the relationship of Co, Cr ions and lymphocyte counts during the running-in period. Materials and Methods. Following randomization to RHA (ASRTM, DePuy) or THA we obtained whole blood (wb), and serum (s) samples at baseline, 8 w, 6 m and 1 y. We measured the Co and Cr concentrations, the total lymphocyte count as well as the CD3+, CD4+, CD8+, CD19+ and CD16+/CD56+ sub populations. Cup inclination and anteversion angles came from conventional radiographs. Activity was measured as steps by pedometer and UCLA activity. Data are presented as median (range). Results. We had 19 patients in each group. Age 57 (46–64) y (RHA) and 55 (44–64) y (THA). RHA only: head size: 51 (47 to 57)mm, cup inclination: 45.0 (40- 56)° and anteversion: 23 (7–38)°. The ion concentrations stayed below 0.2 ppb for THAs. For RHAs the Co and Cr concentrations generally rose markedly in the initial 8 weeks, followed by a slower ascent up to 1 year to wb Co: 1.0 (0.6–5.2), s Co: 1.3 (0.7–6.5), wb Cr: 1.3 (0.4–8.0) and s Cr: 1.7 (0.6–15) ppb. A high ion level was correlated to a small head size (p<0.03) and a cup inclination around 45° (p<0.04). We could not correlate the ion concentrations to the anteversion or the activity levels. The absolute lymphocyte counts were not always identical in the groups (eg. lower CD8+ for RHA) but there was no group difference when we analysed the change from baseline. We did not demonstrate any correlation between metal ion levels and lymphocyte subpopulations. Discussion. The findings of this study does not support the theory that metal ions suppress the lymphocytes or the CD8+ in particular (Hart et al., 2009). Our conclusions are limited by low numbers, but we suspect the theory could be biased by missing baseline values. Our study did not demonstrate the same 6–9 months ion peak found in other running-in studies (Back et al., 2005, Heisel et al., 2008), but rather a slow continuous rise with lower median ion concentrations. It could indicate lower wear or perhaps a longer running in period in our slightly older population. Contrary to our expectations we found that cups placed in optimal inclination displayed a higher ion level. Most of the smallest cups were found in this group, and the majority of the steep cups had very large heads. For this implant head size may be more important than cup position

Introduction. Modern processing techniques in bone banking are thought to decrease the presence of allogenic material in bone. This project was performed to observe any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement. Methods. 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Samples were collected pre-operatively and at set time intervals up to one year post-operatively. Using flow cytometry, analysis of venous blood allowed counts of the following cells: Helper T-lymphocytes, cytotoxic T-lymphocytes, memory T-lymphocytes, naïve T-lymphocytes, Natural Killer cells and B-lymphocytes. Results. All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive an allograft. Pre-operatively, a significant difference (p=0.03) was found between the groups of patients with respect to Natural Killer cells but other subsets showed no significant difference. Post-operatively, the significant difference between Natural Killer cells resolved. T-helper lymphocytes, cytotoxic lymphocytes, memory T-lymphocytes and naïve T-lymphocytes in both groups showed decreases in values immediately post-surgery, recovering to normal values within 6 weeks post-surgery. The allograft group showed significant increases from baseline in cytotoxic T-lymphocytes at 6 months (p<0.01) and memory T-lymphocytes one year post-operatively (p=0.04). B-lymphocyte numbers did not alter significantly from baseline. Discussion. Cytotoxic T-lymphocytes recognise HLA-class I molecules which are present on all nucleated cells and have been implicated in having a role in osteoclast regulation. Memory T-lymphocytes are produced after a naïve T-lymphocyte is exposed to an antigen. The observed increases of these subsets were not observed in the non-grafting group suggesting the allografted bone had elicited an immunological response. At 12 months all grafts appeared radiologically stable and the immunological response may have been beneficial to the outcome

We compared the peripheral blood and periprosthetic tissues of 53 patients at revision arthroplasty with those of 30 patients at primary arthroplasty to determine whether there is a systemic difference in lymphocytes in patients with worn hip implants. The absolute number and relative proportion of lymphocytes bearing CD2, CD3, CD4, CD8, CD16, CD19, HLA-DR, kappa and lambda antigens were compared with the levels of IL-1β, IL-6 and PGE. 2. in the pseudosynovial membrane as well as with a semiquantitative estimate of metal and polyethylene particles, necrosis and chronic inflammation and the total concentration of metals within the periprosthetic tissues. There was a significant increase in the relative proportion of CD2-positive T-cells and CD16-positive natural killer cells in the peripheral blood at revision arthroplasty compared with primary arthroplasty and an increased proportion of CD8-positive T-cells and a decreased ratio of CD4 to CD8 (helper inducer/suppressor cytotoxic cells). Three control patients, who went on to have revision surgery, had values at primary arthroplasty which were similar to those of patients at the time of revision surgery. These differences did not correlate with the local concentration of metal, plastic or cement or inflammatory response or the type of prosthesis. An inverse correlation was noted between the necrosis in the periprosthetic tissue and both the local production of IL-6 and the absolute numbers of T-cells in peripheral blood. We conclude that there may be several cell-mediated systemic immune responses to aseptic loosening, at least one of which may be directly related to events in the periprosthetic tissues. We cannot exclude the possibility that the changes in the proportion of CD8-positive cells reflected a predisposition, rather than a reaction, to loosening of the implant

A major concern in metal on metal bearings has been the elevated serum concentrations of cobalt and chromium. Recent papers have suggested that metal hypersensivity in a few cases could cause periprostetic lymphocyte accumulation leading prosthetic loosening. To measure the lymphocyte activation and proliferation in vitro by re-exposure of the cells to cobalt, chromium, nickel and titanium. To correlate the lymphocyte assay data to the serum concentration of metals and plasma cytokines. A prospective clinical study with the ASR (DePuy) and ReCap (Biomet) resurfacing hip implants. Blood samples were collected one and two years postoperatively, lymphocytes were isolated by density gradient centrifugation, cultured in a medium containing the patient’s serum and exposed to metal salts. Cells were analyzed by flow cytometry, evaluating number, viability, size and CD69 activation. A negative control and a positive control (phytohaemagglutinine) were included in the assay, and the responses to the metals were calculated in proportion to controls. 11 patients were assessed at one and two years follow up, 16 patients were assessed only at two years. Serum chromium and cobalt were measured preoperatively, six months, one year and two years postoperatively by graphite furnace absorptiometry. Plasma cytokines were measured by multiplexed immunoassay. In the assay the negative and positive controls gave the expected responses. When exposed to metals no response was found in the lymphocytes in any patients. There were no difference in response between one and two years. The results seems to indicate that the metal hypersensitivity is a rare condition in metal on metal arthroplasty. The results indicate that the method can be used to monitor hypersensitivity to implant metals

Introduction. The utilization of lymphocyte transformation testing (LTT) has increased for diagnosing metal sensitivity associated with TKA, but its validity for the diagnosis of TKA failure due to an immune reaction has not been established. Methods. We performed a retrospective study of 27 well-fixed, aseptic primary TKAs with persistent pain and/or stiffness, revised by a single, experienced surgeon for suspected metal allergy to nickel based on a positive LTT. Periprosthetic tissue samples obtained at the time of revision surgery were scored using the aseptic lymphocytic vasculitis-associated lesion (ALVAL) scoring system. Results. Eight patients were categorized as mildly reactive, 8 reactive, and 11 highly reactive to nickel by LTT. The predominant findings on routine histology were fibrosis and varying degrees of lymphocytic infiltration in 17/27 (63%) of the cases. The average ALVAL score of the cohort was 3.1 ± 1.9, out of a maximum score of 10. Average Knee Society Scores (KSS) improved post-revision, as did range of motion (all p<0.01). Neither LTT stimulation index as a continuous variable nor as a categorical variable (mild, moderate, high) was correlated with ALVAL score, pre-operative function, or change in function at last follow-up (0.015 < r < 0.30, 0.13 < p < 0.95) as measured by KSS. In addition, the ALVAL score did not correlate significantly with either pre-operative or post-operative KSS or range of motion (0.061 < r < 0.365, 0.09 < p < 0.88). Conclusions. Based on this analysis including histopathology, LTT results alone are insufficient for the diagnosis of TKA failure due to an immune reaction. A positive LTT may not indicate that an immune reaction is the cause of pain and stiffness post-TKA. The role of LTT in assessing immune failure of TKA needs further investigation. Diagnostic criteria for immune failure of a TKA need to be established

Total joint arthroplasty has proven to be efficient to relieve pain and regain mobility. In fact, most patients undergoing a total knee arthroplasty (TKA) are satisfied with their surgery (80 to 90%), yet 4 to 7% still complain of unexplainable pain and stiffness. Several authors have proposed that reactivity to the implant could explain this phenomenon. Still, no strong evidence supports this theory as of today. We aimed to determine the prevalence of metal and cement hypersensitivity in a cohort of patients with unexplained pain and stiffness after TKA. We retrieved data for a group of patients presenting unexplained pain and stiffness. We excluded all other potential known causes of pain. All patients were tested with a Lymphocyte Transformation Test from whole blood taps. We analysed data of hypersensitivity to metals (alloy particles of titanium and cobalt, aluminum, cobalt, nickel, zirconium, vanadium, molybdenum, cobalt, chromium and iron) and PMMA cement (bone cement monomer and particles). Fifty-three patients underwent a LTT for unexplained pain and stiffness after total knee arthroplasty between May 2012 and May 2015. The cohort consisted of 26 men and 27 women with a mean age of 66.3(±8.0) years. Six patients had no hypersensitivity (11.3%), leaving 88.7% of the cohort with hypersensitivity to metal and/or cement. Almost half the cohort of patients tested for PMMA was hypersensitive to cement (44.0%). The most common metal hypersensitivity was nickel (69.8%). Twelve patients presented sensitivity to only one metal (22.6%), whereas 35 patients were hypersensitive to more than one metal (66.0%). Eleven patients had revision surgery with a hypoallergenic prosthesis. Patients reported a significant diminution of pain as well as better knee function compared to preoperative status as early as 6 weeks postop, although some reported residual stiffness. The results of this study suggest that metal and/or cement hypersensitivity could play a role in cases of total knee arthroplasty with unexplained pain and stiffness. Randomised controlled clinical trials on the subject will be initiated by our team to further investigate this phenomenon

The long-term biological effects of wear debris are unknown. We have investigated whether there is any evidence of cumulative mutagenic damage in peripheral blood lymphocytes of patients undergoing revision arthroplasty of predominantly metal-on-plastic total hip replacements compared with those at primary arthroplasty. There was a threefold increase in aneuploidy and a twofold increase in chromosomal translocations which could not be explained by the confounding variables of smoking, gender, age and diagnostic radiographs. In the patients with TiVaAl prostheses there was a fivefold increase in aneuploidy but no increase in chromosomal translocations. By contrast, in patients with cobalt-chrome prostheses there was a 2.5-fold increase in aneuploidy and a 3.5-fold increase in chromosomal translocations. In six patients with stainless-steel prostheses there was no increase in either aneuploidy or chromosomal translocations. Our results suggest that future epidemiological studies of the putative long-term risks of joint replacement should take into account the type of alloy used in the prosthesis

Hip fractures are a significant cause of mortality and morbidity in the elderly. Malnutrition is a major element of this but no consensus exists as to the detection or management of this condition. Reported incidence in elderly hip fracture patients varies widely between 9.0% and 88.6%. The aim of this study was to evaluate the nutritional status of 415 patients with operatively managed hip fractures and determine the prognostic relevance of admission serum albumin and total lymphocyte count (TLC) assays. Protein-energy malnutrition (PEM) was defined as serum albumin < 3.5g/dl and a TLC < 1,500 cells/mm3. Delay to operation, duration of in-patient stay, re-admission (< 3 months) and in-patient, 3- and 12-month mortality were assessed as outcome variables. Survival data was available for 377 patients at 12 months. Of 377 patients, 53% (n=200) had both a serum albumin and TLC levels taken at admission, while 47% (n=177) had not. The incidence of PEM was 51%. Inhospital mortality for PEM patients was 9.8%, compared with 0% for patients with normal values of both laboratory parameters. Older patients were more likely to have lower albumin (p=0.017) and TLC (p=0.023). Nursing home patients were also more likely to have lower albumin (p=0.033). Multivariate analysis revealed a significant difference in 12-month mortality, with patients who had both a low albumin and a low TLC 4.6 times (95% CI: 1.0–21.3) more likely to die within 12 months postoperatively than patients who had normal values of both laboratory parameters. This was significant after adjusting for age, gender and domicile (p=0.049). Serum albumin and TLC in combination are accurate predictors of 12-month mortality in hip fracture patients. These results highlight the relevance of assessing the nutritional status of patients with hip fractures at the time of admission and emphasises the relationship between nutrition and outcome

Background: Protein energy malnutrition (PEM) is an accepted predictor of poor outcome in hip fracture patients. There is no universally accepted definition of PEM. Admission screening for PEM is not routinely performed for hip fracture patients. The reported incidence in elderly hip fracture patients varies widely between 9.0% and 88.6%. Aims: To determine the prognostic relevance of admission serum albumin and total lymphocyte count (TLC), as clinical markers of PEM and predictors of outcome for hip fracture patients. Methods: Retrospective review of 415 patients with operatively managed hip fracture. Protein-energy malnutrition was defined as albumin < 3.5g/dl and TLC < 1,500cells/mm3. Delay to operation, duration of in-patient stay, readmission (< 3 months) and in-patient, 3- and 12-month mortality were assessed as outcome variables. Results: Survival data was available for 377 patients at 12 months. Of 377 patients, 53% (n=200) had both a serum albumin and TLC levels taken at admission (study), while 47% (n=177) had not (control). Incidence of PEM was 51%. Older patients were more likely to have lower albumin (p=0.03) and TLC (p=0.012). Nursing home patients were also more likely to have lower albumin (p=0.049). In-hospital mortality for PEM patients was 9.8%, compared with 0% for patients with normal values of both laboratory parameters. Patients with PEM had a higher 12-month mortality compared to patients who had normal values of both laboratory parameters (Odds Ratio=4.52; p=0.049). Conclusion: Serum albumin and TLC in combination are accurate predictors of 12-month mortality in hip fracture patients. These results underscore the clinical relevance of assessing the nutritional status of patients with hip fractures at the time of admission and emphasises the relationship between nutrition and outcome in these patients

Background: Protein energy malnutrition (PEM) is an accepted predictor of poor outcome in hip fracture patients. There is no universally accepted definition of PEM. Admission screening for PEM is not routinely performed for hip fracture patients. The reported incidence in elderly hip fracture patients varies widely between 9.0% and 88.6%. Aims: To determine the prognostic relevance of admission serum albumin and total lymphocyte count (TLC), as clinical markers of PEM and predictors of outcome for hip fracture patients. Methods: Retrospective review of 415 patients with operatively managed hip fracture. Protein-energy malnutrition was defined as albumin < 3.5g/dl and TLC < 1,500 cells/ mm3. Delay to operation, duration of in-patient stay, readmission (< 3 months) and in-patient, 3- and 12-month mortality were assessed as outcome variables. Results: Survival data was available for 377 patients at 12 months. Of 377 patients, 53% (n=200) had both a serum albumin and TLC levels taken at admission (study), while 47% (n=177) had not (control). Incidence of PEM was 51%. Older patients were more likely to have lower albumin (p=0.03) and TLC (p=0.012). Nursing home patients were also more likely to have lower albumin (p=0.049). In-hospital mortality for PEM patients was 9.8%, compared with 0% for patients with normal values of both laboratory parameters. Patients with PEM had a higher 12-month mortality compared to patients who had normal values of both laboratory parameters (Odds Ratio=4.52; p=0.049). Conclusion: Serum albumin and TLC in combination are accurate predictors of 12-month mortality in hip fracture patients. These results underscore the clinical relevance of assessing the nutritional status of patients with hip fractures at the time of admission and emphasises the relationship between nutrition and outcome in these patients

Achilles tendinopathy is classically defined as a tendinosis devoid of an inflammatory cell population. However, recent literature suggests inflammation as a mediator in the pathogenesis. These finding were mainly based on semi-quantative immunohistochemistry. We therefore used flow cytometry to obatain a more accurate identification and quantification of the different cell types involved. Thirty-two samples were obtained from twelve patients with chronic tendinopathic lesions undergoing Achilles tendon surgery. Samples obtained from three patients with hemiplegia requiring surgical release due to spastic Achilles tendons served as control. We used two panels to identify the myeloid and lymphoid population targeting the following markers: CD45, CD3, CD8, CD4, CD19, CD11b, CD56, CD14, CD16, Vα7.2, 6b11, CD161, TCRγδ. To assess the presence of fibroblasts CD90 was targeted. The mean count of CD45+ hematopoietic cells in the tendinopathic samples was significantly higher than in the control samples, respectively 13.27% and 3.24% of the total cell count (P<0.001). The mean fraction of CD3+ cells present in the complete cell population was significantly higher in pathological samples than in control samples, respectively 1.70% and 0.37% (P<0.05). Presence of CD19+ B cells was not reported. The mean fraction of γδ T cells was significantly higher in tendinopathic samples compared to blood samples of the same patient and consisted of 12.9% and 5.8% γδ T cells respectively (P<0.05). These findings support an inflammatory cell infiltration in midportion Achilles tendinopathy that show similarities to enthesitis in SpA. This implies a potential target to investigate in novel treatment modalities.

Aims

Hip resurfacing remains a potentially valuable surgical procedure for appropriately-selected patients with optimised implant choices. However, concern regarding high early failure rates continues to undermine confidence in use. A large contributor to failure is adverse local tissue reactions around metal-on-metal (MoM) bearing surfaces. Such phenomena have been well-explored around MoM total hip arthroplasties, but comparable data in equivalent hip resurfacing procedures is lacking. In order to define genetic predisposition, we performed a case-control study investigating the role of human leucocyte antigen (HLA) genotype in the development of pseudotumours around MoM hip resurfacings.

Aims

Metal particles detached from metal-on-metal hip prostheses (MoM-THA) have been shown to cause inflammation and destruction of tissues. To further explore this, we investigated the histopathology (aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) score) and metal concentrations of the periprosthetic tissues obtained from patients who underwent revision knee arthroplasty. We also aimed to investigate whether accumulated metal debris was associated with ALVAL-type reactions in the synovium.

Objectives

Rotator cuff tears are among the most common and debilitating upper extremity injuries. Chronic cuff tears result in atrophy and an infiltration of fat into the muscle, a condition commonly referred to as ‘fatty degeneration’. While stem cell therapies hold promise for the treatment of cuff tears, a suitable immunodeficient animal model that could be used to study human or other xenograft-based therapies for the treatment of rotator cuff injuries had not previously been identified.

Aims. The modified Glasgow Prognostic Score (mGPS) uses preoperative CRP and albumin to calculate a score from 0 to 2 (2 being associated with poor outcomes). mGPS is validated in multiple carcinomas. To date, its use in soft-tissue sarcoma (STS) is limited, with only small cohorts reporting that increased mGPS scores correlates with decreased survival in STS patients. Methods. This retrospective multicentre cohort study identified 493 STS patients using clinical databases from six collaborating hospitals in three countries. Centres performed a retrospective data collection for patient demographics, preoperative blood results (CRP and albumin levels and neutrophil, leucocyte, and platelets counts), and oncological outcomes (disease-free survival, local, or metastatic recurrence) with a minimum of two years' follow-up. Results. We found that increased mGPS, tumour size, grade, neutrophil/lymphocyte ratio, and disease recurrence were associated with reduced survival. Importantly, mGPS was the best at stratifying prognosis and could be used in conjunction with tumour grade to sub-stratify patient survival. Conclusion. This study demonstrated that prognosis of localized STS strongly correlates with mGPS, as an increasing score is associated with a poorer outcome. We note that 203 patients (41%) with an STS have evidence of systemic inflammation. We recommend the mGPS and other biochemical blood indicators be introduced into the routine diagnostic assessment in STS patients to stratify patient prognosis. Its use will support clinical decision-making, especially when morbid treatment options such as amputation are being considered. Cite this article: Bone Joint J 2022;104-B(1):168–176

Aims. Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA). Methods. Studies were identified by searching electronic databases: Cochrane Central Register of Controlled Trials, Ovid MEDLINE, and Embase, from their inception to November 2020, for studies evaluating TKA patients with metal hypersensitivity/allergy. All studies reporting on diagnosing or managing metal hypersensitivity in TKA were included. Data were extracted and summarized based on study design, study population, interventions and outcomes. A practical guide is then formulated based on the available evidence. Results. We included 38 heterogeneous studies (two randomized controlled trials, six comparative studies, 19 case series, and 11 case reports). The evidence indicates that metal hypersensitivity is a rare complication with some histopathological features leading to pain and dissatisfaction with no reliable screening tests preoperatively. Hypoallergenic implants are viable alternatives for patients with self-reported/confirmed metal hypersensitivity if declared preoperatively; however, concerns remain over their long-term outcomes with ceramic implants outperforming titanium nitride-coated implants and informed consent is paramount. For patients presenting with painful TKA, metal hypersensitivity is a diagnosis of exclusion where patch skin testing, lymphocyte transformation test, and synovial biopsies are useful adjuncts before revision surgery is undertaken to hypoallergenic implants with shared decision-making and informed consent. Conclusion. Using the limited available evidence in the literature, we provide a practical approach to metal hypersensitivity in TKA patients. Future national/registry-based studies are needed to identify the scale of metal hypersensitivity, agreed diagnostic criteria, and management strategies. Cite this article: Bone Jt Open 2021;2(10):785–795

Objectives. Cortical and cancellous bone healing processes appear to be histologically different. They also respond differently to anti-inflammatory agents. We investigated whether the leucocyte composition on days 3 and 5 after cortical and cancellous injuries to bone was different, and compared changes over time using day 3 as the baseline. Methods. Ten-week-old male C56/Bl6J mice were randomized to either cancellous injury in the proximal tibia or cortical injury in the femoral diaphysis. Regenerating tissues were analyzed with flow cytometry at days 3 and 5, using panels with 15 antibodies for common macrophage and lymphocyte markers. The cellular response from day 3 to 5 was compared in order to identify differences in how cancellous and cortical bone healing develop. Results. Between day 3 and 5, the granulocytes increased in the cancellous model, whereas the lymphocytes (T cells, B cells, NK cells) and monocytes (CD11b+, F4/80+, CD206+, CD14+) increased in the cortical model. Conclusion. These results suggest an acute type of inflammation in cancellous bone healing, and a more chronic inflammation in cortical healing. This might explain, in part, why cancellous healing is faster and more resistant to anti-inflammatory drugs than are diaphyseal fractures. Cite this article: L. Tätting, O. Sandberg, M. Bernhardsson, J. Ernerudh, P. Aspenberg. Different composition of leucocytes in cortical and cancellous bone healing in a mouse model. Bone Joint Res 2018;7:620–628. DOI: 10.1302/2046-3758.712.BJR-2017-0366.R2

Introduction and Objective. Osteochondral allograft (OCA) transplants have been used clinically for more than 40 years as a surgical option for joint restoration, particularly for young and active patients. While immediate graft rejection responses have not been documented, it is believed that the host's immunological responses may directly impact OCA viability, incorporation, integrity, and survival, and therefore, it is of the utmost importance to further optimize OCA transplantation outcomes. The influences of sub-rejection immune responses on OCA transplantation failures have not been fully elucidated therefore aimed to further characterize cellular features of OCA failures using immunohistochemistry (IHC) in our continued hopes for the successful optimization of this valuable surgical procedure. Materials and Methods. With IRB approval, osteochondral tissues that were resected from the knee, hip, and ankle of patients undergoing standard-of-care revision surgeries (N=23) to treat OCA failures and tissues from unused portions of OCAs (N=7) that would otherwise be discarded were recovered. Subjective histologic assessments were performed on hematoxylin and eosin-stained and toluidine blue-stained sections by a pathologist who was blinded to patient demographics, outcomes data, and tissue source. IHC for CD3, CD8, and CD20 were performed to further characterize the and allow for subjective assessment of relevant immune responses. Results. Eleven (48%) of the failed OCAs had aggregates of CD3+, CD8+, and CD20+ lymphocytes around small blood vessels in the bone marrow spaces and adipose/collagenous tissue of the allograft, while the non-implanted healthy control OCA tissues did not show any evidence of inflammation. The remaining failed OCAs (52%) did not show a similar pattern of T- and B-cell infiltrates around blood vessels. Other histologic abnormalities associated with failed OCAs included avascular necrosis, subchondral micro and macro fractures, subchondral collapse, bacterial infection, and/or articular cartilage erosion or delamination. Conclusions. The results from the present study support this possibility in that mixed aggregates of CD3+, CD8+, and CD20+ lymphocytes were observed around small blood vessels in approximately half of the failed OCAs. This potentially cytotoxic immune response may have contributed to the lack of functional survival of the OCA noted in these cases, and warrants further investigation as a possible failure mechanism that may be mitigated using post-transplantation management strategies

We carried out a cross-sectional study with analysis of the demographic, clinical and laboratory characteristics of patients with metal-on-metal hip resurfacing, ceramic-on-ceramic and metal-on-polyethylene hip replacements. Our aim was to evaluate the relationship between metal-on-metal replacements, the levels of cobalt and chromium ions in whole blood and the absolute numbers of circulating lymphocytes. We recruited 164 patients (101 men and 63 women) with hip replacements, 106 with metal-on-metal hips and 58 with non-metal-on-metal hips, aged < 65 years, with a pre-operative diagnosis of osteoarthritis and no pre-existing immunological disorders. Laboratory-defined T-cell lymphopenia was present in13 patients (15%) (CD8. +. lymphopenia) and 11 patients (13%) (CD3. +. lymphopenia) with unilateral metal-on-metal hips. There were significant differences in the absolute CD8. +. lymphocyte subset counts for the metal-on-metal groups compared with each control group (p-values ranging between 0.024 and 0.046). Statistical modelling with analysis of covariance using age, gender, type of hip replacement, smoking and circulating metal ion levels, showed that circulating levels of metal ions, especially cobalt, explained the variation in absolute lymphocyte counts for almost all lymphocyte subsets

Introduction and Objective. The use of microfragmented adipose tissue (mFAT) for the treatment of musculoskeletal disorders, especially osteoarthritis, is gaining popularity following the positive results reported in recent case series and clinical trials. The purpose of this study is to characterize mFAT in terms of structure, cell content and secretome (i.e. protein and microvescicles released as paracrine mediators), and to compare it with unprocessed lipoaspirate tissue, in order to understand the possible mechanisms of action and the benefit derived from tissue processing. Materials and Methods. Unprocessed lipoaspirate (LA) and mFAT were obtained from 7 donors. Each tissue sample was divided in four aliquots: A) fixed in formalin for histological evaluation; B) enzymatically digested to harvest cells with the exclusion of adipocytes; C) cultured for 24 hours in serum-free DMEM to harvest secretome; D) freshly frozen for proteomic evaluation. Hematoxylin and eosin staning, as well as immunohistochemistry for CD31, CD90, CD146 were performed on aliquot A. Cell count, viability, senescence and immunophenotype were assessed on aliquot B. Culture medium from aliquot C was collected and used for proteomic analysis and micro-RNA extraction and quantitation from extracellular vesicles. Aliquot D was lysed, protein were extracted and analyzed using a high-throughput proteomic approach. Results. Histological investigations showed a lower red blood cell content in mFAT with respect to LA, while the presence of blood vessels (CD31+), stromal cells (CD90) and pericytes (CD146) was similar in all samples. These results were confirmed by flow cytometry, with reduction of erythrocytes (CD235a+) by 76% and reduction of lymphocytes (CD45+) by 79% in mFAT compared to LA. Otherwise, the proportions of stromal cells, pericytes and endothelial cells in LA and mFAT remained comparable. The percentage of senescent cells resulted similar before and after tissue processing, with very low values (< 5%). The analysis of the miRNAs contained in the extracellular vesicles in culture media identified 376 miRNAs in LA secretome and 381 in mFAT secretome. A high correlation in the expression of these miRNAs within subjects (LA and mFAT of each donor) was observed (R2> 0.8), indicating that processing in mFAT does not significantly alter the portfolio of miRNAs associated with extracellular vesicles. Proteomic analysis of secretome revealed that 217 proteins significantly differ between LA and mFAT. In particular, protein associated with acute phase were less represented in mFAT secretome, while intracellular proteins were more frequent. Proteomic analysis of tissues demonstrated a reduction of protein related to extracellular matrix and of proteins closely related to peripheral blood contamination in mFAT with respect to LA. Conclusions. Taken together, these results suggest that processing of LA into mFAT allow for removal of blood elements, in terms of red blood cells, lymphocytes, acute phase and complement system proteins, and for the reduction of extracellular matrix components. Otherwise, tissue structure, cell populations, cell viability and senescence are not influenced by tissue processing. Then, microfragmentation process represents a safe and efficient method for the application of adipose tissue properties to musculoskeletal disorders, allowing for the maintenance of all the effector elements for tissue regeneration while removing possible detrimental agents such as inflammatory mediators

Soft tissue sarcomas (STS) are rare, aggressive malignancies derived from connective tissues such as muscle and fat. Undifferentiated pleomorphic sarcoma (UPS) is one of the most common STS in adults. UPS is an aggressive, highly metastatic sarcoma, and is resistant to chemotherapy. New therapies for UPS are desperately needed. STS have an immune desert tumour immune microenvironment (TIME), characterized by a paucity of tumour infiltrating lymphocytes and subsequent resistance to immunotherapies such as immune checkpoint inhibitors. Strategies capable of creating an immune-rich, inflamed TIME may improve immunotherapy efficacies for sarcoma. Activation of the STING (stimulator of interferon genes) receptor can induce potent innate and adaptive immune responses within immunogenic solid tumours. However, this approach has never been attempted in immune-inert sarcomas. Purpose: To determine the therapeutic anti-tumour effects of STING activation in UPS tumours. We have developed an inducible, immune-competent mouse model of UPS. We evaluated intra-tumoural injection of the murine STING receptor agonist, DMXAA, into UPS-bearing immune-competent mice. DMXAA was injected into palpable UPS tumours of the hindlimb. Tumour volume and bioluminescence imaging was recorded bi-weekly. DMXAA treated UPS tumours were also evaluated for necrosis and immune infiltration at defined time points. UPS tumours developed necrosis and lymphocytic infiltration 72 hours after DMXAA treatment. A single intra-tumoural dose of DMXAA into UPS tumours resulted in durable cure in 50% of mice. All survivors rejected a re-challenge of the UPS tumours in both the contralateral hindlimb and lung, suggesting adaptive immunity. The therapeutic effects of DMXAA were mitigated in lymphocyte deficient Rag2 knockout mice. STING therapy is a promising immunotherapeutic opportunity for immune-inert sarcomas. Our data warrants further preclinical investigations in other sarcoma models and in combination with other immune-based therapies

The interleukin-6/gp130-associated Janus Kinases/STAT3 axis is known to play an important role in mediating inflammatory signals, resulting in production of matrix metalloproteinase-3 (MMP-3). The hip joints with rapidly destructive coxopathy (RDC) demonstrate rapid chondrolysis, probably by increased production of MMP-3 observed in the early stage of RDC. In the recent study, no apparent activation of STAT3 has been shown in the synovial tissues obtained from the osteoarthritic joint at operation. However, no data are currently available on STAT3 activation in the synovial tissues in the early stage of RDC. This study aimed to elucidate STAT3 activation in the synovial tissues in the early stage of RDC. Synovial tissues within 7 months from the disease onset were obtained from four RDC patients with femoral head destruction and high serum levels of MMP-3. RDC synovial tissues showed the synovial lining hyperplasia with an increase of CD68-positive macrophages and CD3-positive T lymphocytes. STAT3 phosphorylation was found in the synovial tissues by immunohistochemistry using anti-phospho-STAT3 antibody. The majority of phospho-STAT3-positive cells were the synovial lining cells and exhibited negative expression of macrophage or T cell marker. Treatment with tofacitinib, a Janus Kinase inhibitor, resulted in a decrease in phospho-STAT3-positive cells, especially with high intensity, indicating effective suppression of STAT3 activation in RDC synovial tissues. Inhibitory effect of tofacitinib could act through the Janus Kinase/STAT3 axis in the synovial tissues in the early stage of RDC. Therefore, STAT3 may be a potential therapeutic target for prevention of joint structural damage in RDC. Acknowledgements: This study was supported by Katakami Foundation for Clinical Research

Soft tissue sarcomas (STS) have not demonstrated favourable clinical responses to emerging immunotherapies such as checkpoint inhibitors. Studies in carcinomas and melanoma have demonstrated that tumours lacking T-cell infiltrates are associated with poor responses to immunotherapies. It is postulated that STS lack tumour asscoiated lymphocytes which renders these tumours insensitive to checkpoint inhibitors. Our objective was to develop a novel syngeneic mouse model of STS and characterize the immune phenotype of these tumours. Additionally, we sought to evaluate the therapeutic responses of these sarcomas to checkpoint inhibitors and a Type I interferon agonist. K-ras mutagenesis and p53 deletion was induced using a Lenti-Cre-recombinase injection into the hindlimb of 3 week old C57BL/6 mice. Tumours were harvested and characterized using standard histopathology techniques and whole trascriptome sequencing (RNAseq). Full body necrospy and histopathology was performed to identify metastases. Flow cytometry and immunohistochemistry was used to evaluate tumour immune phenotypes. Tumours were implanted into syngeneic C57BL/6 mice and the therapeutic responses to anti-CTLA4, anti-PD1 and DMXAA (Type I interferon agonist) were performed. Tumour responses were evaluated using bioluminescent imaging and caliper measurements. Soft tissue sarcomas developed in mice within 2–3 months of Lenti-Cre injection with 90% penetrance. Histologic analyses of tumours was consistent with a high-grade myogenic sarcoma characterized by smooth muscle actin, Desmin and Myogenin D positive immunostaining. Using crossplatform normalization protocols, geneexpression signatures of the mouse tumours most closely correlated with human undifferentiated pleomorphic sarcoma (UPS). Collectively, gene expression signatures of this murine sarcoma correlated with all muscle-derived human sarcomas (ERMS, ARMS, Synovial sarcoma, UPS). No lung or other visceral metastases were observed in all mice who developed spontaneous tumours. Immune phenotyping demonstrated a paucity of tumour-infiltrating lymphocytes (TILs, (TAMs). 50% of identified TILs in these murine sarcomas expressed PD-1, yet tumours were not responsive to anti-PD1 therapy or anti-CTLA4 therapy. A single intra tumoural (i.t.) injection of the Type I interferon agonist, DMXAA resulted in 80–90% tumour necrosis 72 hrs post-injection, decreased tumour viability up to 2 weeks post-injection and a marked infiltration of CD8+ T-cells and anitgen presenting dendritic cells and macrophages. Additional longitudinal experiments demonstrate a sustained and progressive anti-tumour effect in 83% (5/6) mice up to 6weeks following a single i.t. injection of DMXAA. All control treated mice (6/6) reached humane endpoint within 14 days. At 3 months post-DMXAA treatment, 4/6 mice were free of disease. We re-injected UPS tumours into these mice and tumours did not grow, suggesting abscopal effects after DMXAA treatment of primary tumours. We have characterized a new orthotopic and syngeneic mouse model of a myogenic soft tissue sarcoma. Like most human STS sub-types, these tumours have an immune inert tumour microenvironment and are not sensitive to checkpoint inhibitors. This model, syngeneic to C56BL/6 mice will enable future opportunities to investigate how various branches of the immune system can be targetted or manipulated to unearth new immunotherapeutic strategies for sarcoma. Using this model we have demonstrated that a single, intra-tumoural injection of a Type I interferon agonist can result in anti-tumour effects, recruit cytotoxic lymphocytes and antigen presenting cells with into the the tumour microenvironment. Abscopal tumour rejection after DMXAA treatement suggest adaptive T-cell responses against UPS are active in this model. Future work is needed to determine if upregulation of Type I inferferon pathways can be used as a therapeutic strategy for sarcoma or as a sensitization strategy for checkpoint inhibitors

Malnutrition is considered a risk factor for postoperative complications in total hip and knee arthroplasty, though prospective studies investigating this assumption are lacking. The aim of this study was to prospectively analyse the 90-day postoperative complications, postoperative length of stay (LOS) and readmission rates of patients undergoing primary total hip and total kneearthroplasty using albumin, total lymphocyte count (TLC) and transferrin as serum markers of potential malnutrition. 603 primary hip and 823 primary knee arthroplasties over a 3-year period from a single centre wereprospectively analysed. BMI, demographic and comorbidity data were recorded. Complications werecategorised as surgical site infection, venous thromboembolism (deep vein thrombosis andpulmonary embolus), implant related (such as dislocation), and non-implant related (such aspneumonia). Outcomes were compared between groups, with malnutrition defined as serumalbumin <3.5g/dL, transferrin <200 mg/dL, or TLC <1,500 cells/mm³. Potential malnutrition was present in 9.3% of the study population. This group experienced a longeraverage LOS at 6.5 days compared to the normal albumin group at 5.0 days (p=0.003). Surgical siteinfection rate was higher in the malnourished group (12.5 vs 7.8%, p=0.02). There was no differencebetween the two groups in implant related complications (0.8 vs 1.0%, p=0.95) medicalcomplications (7.8 vs 13.3%, p=0.17), rate of venous thromboembolism (2.3 vs 2.7%) or 90-dayreadmission rate (14.1 vs 17.0%, p=0.56). TLC and transferrin were not predictive of any of theprimary outcomes measured (p<0.05). Pacific Island (p<0.001), Indian (p=0.02) and Asian (p=0.02) patients had lower albumin than NZ European. This study demonstrates an association between low albumin levels and increased postoperativeLOS and surgical site infection in total joint arthroplasty, providing rationale for consideration ofpreoperative nutritional screening and optimisation

Tendinopathy can commonly occur around the foot and ankle resulting in isolated rupture, debilitating pain and degenerative foot deformity. The pathophysiology and key cells involved are not fully understood. This is partly because the dense collagen matrix that surrounds relatively few resident cells limits the ability of previous techniques to identify and target those cells of interest. In this study, we apply novel single cell RNA sequencing (CITE-Seq) techniques to healthy and tendinopathic foot/ankle tendons. For the first time we have identified multiple sub-populations of cells in human tendons. These findings challenge the view that there is a single principal tendon cell type and open new avenues for further study. Healthy tendon samples were obtained from patients undergoing tendon transfer procedures; including tibialis posterior and FHL. Diseased tendon samples were obtained during debridement of intractable Achilles and peroneal tendinopathy, and during fusion of degenerative joints. Single cell RNA sequencing with surface proteomic analysis identified 10 sub-populations of human tendon derived cells. These included groups expressing genes associated with fibro-adipogenic progenitors (FAPs) as well as ITGA7+VCAM1- recently described in mouse muscle but, as yet, not human tendon. In addition we have identified previously unrecognised sub-classes of collagen type 1 associated tendon cells. Each sub-class expresses a different set of extra-cellular matrix genes suggesting they each play a unique role in maintaining the structural integrity of normal tendon. Diseased tendon harboured a greater proportion of macrophages and cytotoxic lymphocytes than healthy tendon. This inflammatory response is potentially driven by resident tendon fibroblasts which show increased expression of pro-inflammatory cytokines. Finally, identification of a previously unknown sub-population of cells found predominantly in tendinopathic tissue offers new insight into the underlying pathophysiology. Further work aims to identify novel proteins targets for possible therapeutic pathways

Aims. As the population ages and the surgical complexity of lumbar spinal surgery increases, the preoperative stratification of risk becomes increasingly important. Understanding the risks is an important factor in decision-making and optimizing the preoperative condition of the patient. Our aim was to determine whether the modified five-item frailty index (mFI-5) and nutritional parameters could be used to predict postoperative complications in patients undergoing simple or complex lumbar spinal fusion. Methods. We retrospectively reviewed 584 patients who had undergone lumbar spinal fusion for degenerative lumbar spinal disease. The 'simple' group (SG) consisted of patients who had undergone one- or two-level posterior lumbar fusion. The 'complex' group (CG) consisted of patients who had undergone fusion over three or more levels, or combined anterior and posterior surgery. On admission, the mFI-5 was calculated and nutritional parameters collected. Results. Complications occurred in 9.3% (37/396) of patients in the SG, and 10.1% (19/167) of patients in the CG. In the SG, the important predictors of complications were age (odds ratio (OR) 1.036; p = 0.002); mFI-5 (OR 1.026 to 2.411, as score increased to 1 ≥ 2 respectively. ;. p = 0.023); albumin (OR 11.348; p < 0.001); vitamin D (OR 2.185; p = 0.032); and total lymphocyte count (OR 1.433; p = 0.011) . In the CG, the predictors of complications were albumin (OR 9.532; p = 0.002) and vitamin D (OR 3.815; p = 0.022). Conclusion. The mFI-5 and nutritional status were effective predictors of postoperative complications in the SG, but only nutritional status was successful in predicting postoperative complications in the CG. The complexity of the surgery, as well as the preoperative frailty and nutritional status of patients, should be considered when determining if it is safe to proceed with lumbar spinal fusion. Cite this article: Bone Joint J 2020;102-B(12):1717–1722

Abstract. Introduction. It is increasingly evident that synovium may play a larger role in the aetiology of osteoarthritis. We compared gene expression in whole tissue synovial biopsies from end-stage knee osteoarthritis and knee trauma patients with that of their paired explant cultures to determine how accurately cultured cells represent holistic synovial function. Methodology. Synovial tissue biopsies were taken from 16 arthroplasty patients and 8 tibial plateau fracture patients with no osteoarthritis. Pairs of whole tissue fragments were either immediately immersed in RNAlater Stabilisation Solution at 4o C before transfer to -80o C storage until RNA extraction; or weighed, minced and cultured at 500mg tissues/5ml media in a humidified incubator at 37oC, 5% CO2. After sub-culturing total RNA was extracted using RNAeasy Plus Mini Kit with gDNA removal. Following RT-PCR and quality assessment, cDNA was applied to Affymetrix Clariom D microarray gene chips. Bioinformatics analyses were performed. Results. PCA analysis illustrates the clear separation of expression array data from cultured cells compared with their parental whole tissues and no segregation between cells derived from osteoarthritic or trauma tissues. A differentially expressed gene heat map demonstrated the hierarchical independence of cultured cells from their paired sample parental tissues. The biological pathways enriched by these gene expression differences emphasise the activities of macrophages and lymphocytes lost from culture. Conclusion. Adherent synovial cells grown from different knee pathologies lose the expression patterns characteristic of their originating pathology. Interpretation of data needs caution as the cells are not representative of whole synovium

Wear and corrosion debris generated from total hip replacements (THR) can cause adverse local tissue reactions (ALTR) or osteolysis, often leading to premature implant failure. The tissue response can be best characterized by histopathological analysis, which accurately determines the presence of cell types, but is limited in the characterization of biochemical changes (e.g. protein conformation alteration). Fourier transform infrared micro-spectroscopy imaging (FTIRI) enables rapid analysis of the chemical structure of biological tissue with a high spatial resolution, and minimal additional sample preparation. The data provides the most information through multivariate method carried out by hierarchical clustering analysis (HCA). It is the goal of this study to demonstrate the beneficial use of this multivariate approach in providing pathologist with biochemical information from cellular and subcellular organization within joint capsule tissue retrieved from THR patients. Joint capsule tissue from 2 retrieved THRs was studied. Case 1: a metal-on-polyethylene THR, and Case 2: a dual modular metal-on-metal THR. Prior to FTIRI analysis, tissue samples were formalin-fixed paraffin-embedded and 5μm thick microtome sectioned samples were prepared and mounted on BaF. 2. discs and deparaffinized. FTIRI data were collected using high-definition transmission mode (pixel size: ∼1.1 μm. 2. ). Hyperspectral images were exported to CytoSpec V2.0.06 for processing and reconstruction into pseudo-color maps based on cluster assignments. Case 1 exhibited a strong presence of lymphocytes and macrophages (Fig. 1a). Since the process of taking second derivatives reduces the half width of the spectral peaks, it increases the sensitivity toward detecting shoulders or second peaks that may not be apparent in the raw spectra (Fig. 1b). Thus, areas occupied by lymphocytes and macrophages can be easily distinguished providing a fast tissue screening method. Here, HCA was able to distinguish macrophages and lymphocytes based on the infrared response, even in areas where both occurred intermixed. (Fig. 1c) The tissue in direct proximity to cells had a slightly altered collagenous structure. Case 1 also exhibited multiple glassy, green particles which can typically observed around THRs that underwent taper corrosion (Fig. 2a). HCA image was able to visualize and distinguish large CrPO. 4. particles, embedded within fibrin exudate rich areas, collagenous tissue without inflammatory cells, and a nearby area with a strong macrophage presence and some finer CrPO. 4. particles (Fig. 2d). Moreover, this method can not only locate macrophages, but distinguish particle-laden macrophages depending the type of particles within the cells. In Case 2 (Fig. 3a), clustering results (Fig. 3 b&c) are consistent with the fact that different particle types are associated with MoM bearing surface wear (Co rich particles), corrosion of the CoCrMo taper junctions (Cr-oxides and –phosphate), fretting of Ti-alloy dual modular tapers (Ti-oxides, Ti alloy particles), and even suture debris, which all occurred in this case. Although details of debris types are not available, specifications are possible by coupling other techniques. The results demonstrate that multivariate FTIRI based spectral histopathology is a powerful tool to characterize the chemical structure and foreign body response within periprosthetic tissue, thus providing insights into the biological impact of different types of implant debris. For any figures or tables, please contact the authors directly

Aims. This study aimed to examine the effects of tumour necrosis factor-alpha (TNF-α) on osteoblasts in metal wear-induced bone loss. Methods. TNF-α immunoexpression was examined in periprosthetic tissues of patients with failed metal-on-metal hip arthroplasties and also in myeloid MM6 cells after treatment with cobalt ions. Viability and function of human osteoblast-like SaOs-2 cells treated with recombinant TNF-α were studied by immunofluorescence, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) assay, western blotting, and enzyme-linked immunosorbent assay (ELISA). Results. Macrophages, lymphocytes, and endothelial cells displayed strong TNF-α immunoexpression in periprosthetic tissues containing metal wear debris. Colocalization of TNF-α with the macrophage marker CD68 and the pan-T cell marker CD3 confirmed TNF-α expression in these cells. Cobalt-treated MM6 cells secreted more TNF-α than control cells, reflecting the role of metal wear products in activating the TNF-α pathway in the myeloid cells. While TNF-α did not alter the immunoexpression of the TNF-receptor 1 (TNF-R1) in SaOs-2 cells, it increased the release of the soluble TNF-receptor 1 (sTNF-R1). There was also evidence for TNF-α-induced apoptosis. TNF-α further elicited the expression of the endoplasmic reticulum stress markers inositol-requiring enzyme (IRE)-1α, binding-immunoglobulin protein (BiP), and endoplasmic oxidoreductin1 (Ero1)-Lα. In addition, TNF-α decreased pro-collagen I α 1 secretion without diminishing its synthesis. TNF-α also induced an inflammatory response in SaOs-2 cells, as evidenced by the release of reactive oxygen and nitrogen species and the proinflammatory cytokine vascular endothelial growth factor. Conclusion. The results suggest a novel osteoblastic mechanism, which could be mediated by TNF-α and may be involved in metal wear debris-induced periprosthetic bone loss. Cite this article: Bone Joint Res 2020;9(11):827–839

Undifferentiated pleomorphic sarcoma (UPS) is one of the most common and aggressive adult soft tissue sarcomas (STS). Once metastatic, UPS is rapidly fatal. Most STS, including UPS, are resistant to conventional immunotherapies as these tumours have low numbers of spontaneous tumour infiltrating lymphocytes (TILs) and are densely populated with immune suppressive macrophages. Intra-tumoural activation of the STimulator of INterferon Genes (STING) pathway is a novel immunotherapeutic strategy to recruit anti-tumour TILs into the tumour microenvironment. In a murine model of UPS, we have demonstrated that intra-tumoural injection of a murine-specific STING agonist, DMXAA, results in profound immune mediated tumour clearance. Recently, molecules capable of activating both human and mouse STING pathways have been developed. In pursuit of clinically relevant therapeutic opportunities, the purpose of this study is to evaluate the anti-tumour potential of two agonists of the human and murine STING receptors: ADU-S100 and MSA-2 as monotherapies and in combination with the immune checkpoint inhibitor, anti-PD1 in a murine model of UPS. Immune competent mice were engrafted with murine UPS cells in the hindlimb muscle. Once palpable, mice in the monotherapy group were treated with a single intra-tumoural dose of 1) ADU-S100 or 2) MSA-2 or 3) DMXAA. In additional experimental groups, mice were treated with the different STING agonists and monoclonal anti-PD1. Tumour volume measurements and tumour bioluminescence were measured over time. To quantify dynamic changes in immune populations and in the tumour immune microenvironment, STING treated UPS tumours were evaluated using flow cytometry and mRNA quantification at various timepoints after therapy. DMXAA monotherapy produced complete tumour eradication in 50% of mice, whereas both ADU-S100 or MSA-2 monotherapy only extended survival but did not result in complete tumour clearance. Flow cytometry and transcriptional profiling of tumours at multiple timepoints post-treatment showed similar inflammatory changes and increased TILs numbers across all STING agonists. The addition of anti-PD1 treatment to STING therapy significantly extended survival times with both ADU-S100 and MSA-2, and resulted in 14% complete tumour clearance with ADU-S100. No complete survivors were observed with MSA-2-anti-PD1 combinations therapy. STING activation is a promising immunotherapeutic strategy for UPS. Recently developed human STING agonists are not as effective as DMXAA despite similar immunologic responses to treatment. STING and anti-PD-1 treatment were therapeutically synergistic for both human STING agonists. These results justify further research around STING activation as a therapeutic modality for STS. DMXAA may possess additional off-target therapeutic properties beyond STING activation which warrants further investigation. Elucidating these differences may be critical to further optimize STING therapy for human STS

Cobalt chrome alloy is commonly used in joint replacement surgery. However, it is recognised that some patients develop lymphocyte mediated delayed type hypersensitivity (DTH) responses to this material, which may result in extensive bone and soft tissue destruction. Phase 1. United Kingdom: From an existing database, we identified extreme phenotype patient groups following metal on metal (MoM) hip resurfacing or THR: ALVAL with low wearing prostheses; ALVAL with high wear; no ALVAL with high wear; and asymptomatic patients with implants in situ for longer than ten years. Class I and II HLA genotype frequency distributions were compared between these patients’ groups, and in silico peptide binding studies were carried out using validated methodology. Phase 2. United Kingdom: We expanded the study to include more patients, including those with intermediary phenotypes to test whether an algorithm could be developed incorporating “risk genotypes”, patient age, sex and metal exposure. This model was trained in phase 3. Phase 3. United Kingdom, Australia, United States. Patients from other centres were invited to give DNA samples. The data set was split in two. 70% was used to develop machine learning models to predict failure secondary to DTH. The predictions were tested using the remaining blinded 30% of data, using time-dependent AUROCs, and integrated calibration index performance statistics. A total of 606 DNA samples, from 397 males and 209 female patients, were typed. This included 176 from patients with failed prostheses, and 430 from asymptomatic patients at a mean of >10 years follow up. C-index and ROC(t) scores suggested a high degree of discrimination, whilst the IBS indicated good calibration and further backed up the indication of high discriminatory ability. At ten years, the weighted mean survival probability error was < 4%. At present, there are no tests in widespread clinical use which use a patient's genetic profile to guide implant selection or inform post-operative management. The algorithm described herein may address this issue and we suggest that the application may not be restricted to the field of MoM hip arthroplasty

Aims. The aim of this study was to evaluate the diagnostic value of preoperative serum CRP, white blood cell count (WBC), percentage of neutrophils (%N), and neutrophil to lymphocyte ratio (NLR) when using the fracture-related infection (FRI) consensus definition. Methods. A cohort of 106 patients having surgery for suspected septic nonunion after failed fracture fixation were studied. Blood samples were collected preoperatively, and the concentration of serum CRP, WBC, and differential cell count were analyzed. The areas under the curve (AUCs) of diagnostic tests were compared using the z-test. Regression trees were constructed and internally cross-validated to derive a simple diagnostic decision tree. Results. Using the FRI consensus definition, 46 patients (43%) were identified as infected. Sensitivity, specificity, and AUC of CRP were 67% (95% confidence interval (CI) 52% to 80%), 61% (95% CI 47% to 74%), and 0.64 (95% CI 0.54 to 0.74); of WBC count were 17% (95% CI 9% to 31%), 95% (95% CI 86% to 99%), and 0.57 (95% CI 0.50 to 0.62); of %N 13% (95% CI 6% to 26%), 87% (95% CI 76% to 93%), and 0.50 (95% CI 0.43 to 0.56); and of NLR 28% (95% CI 17% to 43%), 80% (95% CI 68% to 88%), and 0.54 (95% CI 0.46 to 0.63), respectively. A better performance of serum CRP was shown in comparison to the leucocyte count (p = 0.006), %N (p < 0.001), and NLR (p = 0.001). A statistically lower serum CRP level was shown in patients with an infection caused by a low virulence microorganism in comparison to high virulence bacteria (p = 0.008). We found that a simple decision tree approach using only low serum neutrophils (< 3.615 × 10. 9. /l) and low CRP (< 2.45 mg/l) may allow better identification of aseptic cases. Conclusion. The evaluated serum inflammatory markers showed limited diagnostic value in the preoperative diagnosis of FRI when using the uniform FRI Consensus Definition. Therefore, they should remain as suggestive criteria in diagnosing FRI. Although CRP showed a higher performance in comparison to the other serum markers, it is insufficiently accurate to diagnose a septic nonunion, especially when caused by low virulence microorganisms. Cite this article: Bone Joint J 2020;102-B(7):904–911

Introduction. In 2010, a widely used metal-on-metal hip implant was voluntarily recalled from the market by the manufacturer. Our lab performed detailed retrieval analysis of 548 of the explanted devices and 165 periprosthetic tissue specimens. We reported a high degree of variability in the multiple measurements that we performed on the components, including volumetric wear. Other studies using semi-quantitative tissue grading methods to describe the histology of the periprosthetic tissues from metal-on-metal hips have looked for relationships between component wear and histological features. Grammatopoulos et al found higher ALVAL scores in 45 hip resurfacing patients with pseudotumors compared to 11 without pseudotumors and a moderately positive correlation between wear and the histological rankings for tissue necrosis and lymphocytic response. We examined correlations between the component wear measurements from retrieval analysis and the tissue features in this large group of one metal-on-metal hip design. Materials and Methods. Tissues were processed routinely into paraffin sections, stained with H&E and characterized with light microscopic semi-quantitative scores for ALVAL features and for the number of macrophages and lymphocytes, extent of metal debris and the estimated percentage of necrosis per slide. Spearman correlation analysis was conducted to evaluate any correlations between retrieval wear measurements and histological findings. Results. The median combined cup and ball wear volume was 17.5mm3 in these 165 cases. The median tissue ALVAL score was 5.5 out of 10. Component total wear volume was not predictive of the ALVAL score (P = 0.09, R = −0.007) or the number of lymphocytes (P= 0.170, R= −0.077) but there was a positive correlation between wear volume and the ranking for macrophages in the tissues (P< 0.001, R=0.215). No other correlations were found for component wear. The median time to revision was 4.84 years. There was a negative correlation between tissue inflammation ranking (P=0.002, R=−0.183) and for lymphocyte ranking and time to revision (P=0.003, R=−0.173). There was a positive correlation between time to revision and the macrophage ranking (P=0.005, R=0.166). Conclusion. From this large-scale retrieval analysis of one design of metal-on-metal total hip, a high degree of variability was observed over the multiple analyses performed, including volumetric wear and tissue features. This likely reflects our previous observation that no single particular failure mechanism was predominant in this large cohort. Funded by DePuy Synthes Companies of Johnson & Johnson

Aim. The demonstration of the in vivo bactericidal efficacy of a new bone cement with rifampicin contained in microcapsules and its intra-articular release profile. Method. Fifteen New Zealand White rabbits were employed to reproduce periprosthetic infection by intra-articular inoculation of 10. 5. CFU/mL of Staphylococcus aureus ATCC® 29213 using as a target implant a 3D printed stainless steel tibial insert. 7 days after inoculation, the first stage of the two stage exchange was carried out and at this time the animals were divided into two study groups: group C (7 rabbits) that received a spacer with gentamicin and group R (8 rabbits) that received a spacer with gentamicin and rifampicin microcapsules. Response to infection was monitored by clinical (weight and temperature), hematological (leukocyte, lymphocyte and platelet counts) and biochemical (erythrocyte sedimentation rate) analyses at the time of inoculation, at the first stage of exchange, 4 days after first stage and weekly until the fourth week when animals were euthanized. Microbiological counts were performed at the first stage of exchange and at the end of the study. Results. 14/15 animals (93.3%) developed a PJI 1 week after the inoculation. A statistically significant elevation of the leukocyte and platelet count and a decrease in the percentage of lymphocytes (p=0.0001) was found and positive microbiological cultures. Four weeks after the placement of the spacer, no bacterial growth was found in the soft tissue or bone samples of the group with rifampicin microcapsules (group R), being these differences statistically significant with p=0.01 and 0.03 respectively. The rifampicin intra-articular release kinetics showed concentrations above the staphylococcal MIC at all time points. Conclusions. The bone cement with microencapsulated rifampicin is effective in the in vivo treatment of prosthetic joint infection due to biofilm-forming S. aureus

Little is known about the relationship between head-neck corrosion and its effect on the periprosthetic tissues and distant organs of patients hosting well-functioning devices. The purpose of this study was to investigate in postmortem retrieved specimens the degree and type of taper damage, and the corresponding histologic responses in periprosthetic tissues and distant organs. Fifty postmortem THRs (34 primaries, 16 revisions) retrieved after 0.5 to 26 years were analyzed. Forty-three implants had a CoCrMo stem and seven had a Ti6Al4V stem. All heads were CoCrMo and articulated against polyethylene cups (19 XLPE, 31 UHMWPE). H&E sections of joint pseudocapsules, liver, spleen, kidneys and lymph nodes were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue characteristics. Corrosion damage of the taper surfaces was assessed using visual scoring and quantitated with an optical coordinate measuring machine. SEM analysis was used to determine the acting corrosion mode. Polyethylene wear was assessed optically. The majority of tapers had minimal to mild damage characterized by local plastic deformation of machining line peaks. Imprinting of the stem topography onto the head taper surface was observed in 18 cases. Column damage on the head taper surface occurred in three cases. All taper surfaces scored moderate or severe exhibited local damage features of fretting and/or pitting corrosion. Moderate or severe corrosion of the head and/or trunnion was present in nine hips. In one asymptomatic patient with bilateral hips, lymphocyte-dominated tissue reactions involving perivascular infiltrates of lymphocytes and plasmacytes were observed. In this patient, mild, focal lymphocytic infiltrates were also present in the liver and kidneys, and there was focal histiocytosis and necrosis of the para-aortic lymph nodes. These two implants, which had been in place for 58.6 and 60.1 months, had severe intergranular corrosion of the CoCrMo trunnion, and column damage and imprinting on the head taper. In the other 41 hips, macrophage responses in the joint pseudocapsule to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal necrosis in the pseudocapsules of 12 arthroplasties was related to high concentrations of CoCrMo, TiAl4V, TiO, BaSO4 and polyethylene wear particles. High concentrations of these particles were also detected in para-aortic lymph nodes. Rare to mild macrophages were observed in liver and spleen. This is a comprehensive study of wear and corrosion within well-functioning postmortem retrieved THRs, and the resulting local and distant tissue reactions. One of eight patients with moderate or severe corrosion did have a subclinical inflammatory response dominated by lymphocytes after five years. To what extent such an inflammatory process might progress to become symptomatic is not known. Ionic and particulate products generated by corrosion disseminated systemically. The minor lymphocytic infiltrate in the liver and kidneys of one subject with bilateral severely corroded head-neck junctions might suggest possible metal toxicity. The diagnosis of adverse tissue reactions to corrosion of modular junctions can be challenging. Postmortem retrieval studies add to our understanding of the nature and progression of lymphocyte-dominated adverse local and potentially systemic tissue reactions to corrosion of modular junctions

Introduction and Objective. The early pro-inflammatory hematoma phase of bone healing is characterized by platelet activation followed by growth factor release. Bone marrow mesenchymal stromal cells (MSC) play a critical role in bone regeneration. However, the impact of the pro-inflammatory hematoma environment on the function of MSC is not fully understood. We here applied platelet-rich plasma (PRP) hydrogels to study how platelet-derived factors modulate functional properties of MSC in comparison to a non-inflammatory control environment simulated by fibrin (FBR) hydrogels. Materials and Methods. MSC were isolated from acetabular bone marrow of patients undergoing hip arthroplasty. PRP was collected from pooled apheresis thrombocyte concentrates. The phenotype of MSC was analyzed after encapsulation in hydrogels or exposure with platelet-derived factors with regards to gene expression changes, cell viability, extracellular vesicle (EV) release and immunomodulatory effects utilizing cellular and molecular, flow cytometry, RT-PCR, western blot and immunofluorescence stainings. Results. Our results showed that encapsulation of MSC in PRP induced changes in cell metabolism increasing lactate production and reducing mitochondria membrane potential. This was followed by significantly decreased mTOR phosphorylation and differential gene regulation. While PRP-released factors could support EV-biogenesis and immunoregulation-related gene expression, FBR hydrogel reduced CD63+ and CD81+ EV release by MSC. In co-cultures with mitogen stimulated PBMC, pre-exposure of MSC with PRP reduced the proliferation rate and frequency of peripheral blood CD4. +. and favored the persistence of FOXP3. +. regulatory T lymphocytes (32±4.7% compared to 9±2.3% in control co-cultures where MSC were exposed to FBR). Conclusions. Our data indicate that exposure of MSC with a hematoma environment causes metabolic adaptation of MSC followed by increased immune regulatory functions, which in turn might contribute to resolution of inflammation required for successful bone healing

Cytological analysis of material aspirated from the effusion which occasionally develops around a polyglycolic acid (PGA) osteosynthesis implant showed a predominance of inflammatory monocytes and in particular lymphocytes. In order to discover whether PGA implants are immunologically inert, density gradient-isolated peripheral blood mononuclear cells were cultured in 0.2 ml of 10% delta FCS-RPMI 1640 culture medium supplemented with 10 mg PGA. Phytohaemagglutinin (PHA) lectin, a purified protein derivate of tuberculin (PPD) antigen and culture medium alone were used as positive and negative controls. We studied lymphocyte activation kinetics on days 0, 1, 3 and 5. Major histocompatibility complex locus II antigen (MHC locus II antigen) and interleukin-2 receptor (IL-2R) expression were analysed using the avidin-biotin-peroxidase complex (ABC) method and lymphocyte DNA synthesis by using 3H-thymidine incorporation and beta-scintillation counting. Especially on culture days 0 and 1, lymphocytes and monocytes were seen by light microscopy to be attached to PGA particles. However, our results show no PGA-induced lymphocyte DNA synthesis, but PGA-induced MHC locus II antigen and IL-2R activation marker expression was seen, greater than in negative controls, but less than that seen in PPD antigen driven lymphocyte response. This suggests that PGA is an immunologically inert implant material, but it does seem to induce inflammatory mononuclear cell migration and adhesion, leading to a slight non-specific lymphocyte activation. This activation is lower than that seen in mitogen and antigen-driven lymphocyte responses

We have studied the relationship between metal ion levels and lymphocyte counts in patients with metal-on-metal hip resurfacings. Peripheral blood samples were analysed for lymphocyte subtypes and whole blood cobalt and chromium ion levels in 68 patients (34 with metal-on-metal hip resurfacings and 34 with standard metal-on-polyethylene total hip replacements). All hip components were radiologically well-fixed and the patients were asymptomatic. Cobalt and chromium levels were significantly elevated in the patients with metal-on-metal hip resurfacings, compared with the patients with standard metal-on-polyethylene designs (p < 0.0001). There was a statistically significant decrease in the level of CD8. +. cells (T-cytotoxic/suppressor) (p = 0.005) in the metal-on-metal hip resurfacing group. A threshold level of blood cobalt and chromium ions was associated with reduced CD8. +. T-cell counts. We have no evidence that our patients suffered as a result of this reduced level of CD8. +. T-cells

Aim. The diagnosis of septic arthritis mostly relies on clinical examination, several blood parameters including white blood cell count, C-reactive protein, sedimentation, and the analysis of the joint aspiration. However, the diagnosis can be difficult when the symptoms are vague and the information obtained from laboratory might be insufficient for definitive diagnosis. This study aimed to evaluate several ratios obtained from routine blood tests for a possible use in the diagnosis of septic arthritis. Method. The adult patients who were operated in our clinic due to septic arthritis between 2014–2020 were identified and retrospectively evaluated. The patients with any blood disorders or missing file information were excluded. A total of 36 patients were found to be eligible for inclusion. The control group included 40 patients without any sign of infection who underwent total knee arthroplasty due to knee osteoarthritis. Preoperative blood tests of each patients were examined. In addition to CRP and sedimentation values, neutrophil-lymphocyte, monocyte-lymphocyte, platelet-lymphocyte, and platelet count-mean platelet volume were calculated and receiving operating characteristics (ROC) curve analysis was made to determine the sensitivity, specificity and area under curve (AUC) values of these parameters. Results. The distribution of affected joint in septic arthritis group was as follow; 22 knees, 6 hips, 4 shoulders, 2 elbows, 1 wrist and 1 ankle. The cultures of joint aspiration yielded positive result in 19 patients while the cultures were negative in 17 patients. All of the analyzed parameters were significantly different between the groups (p<0.001). ROC curve analysis results are given in detail, in Table 1 and Figure 1. The AUC value was 97.3 when only CRP and sedimentation values were used but increased to 98.6 when neutrophile/ lymphocyte ratio was added and increased to 100 when all analyzed parameters were included. Conclusions. The analyzed parameters were found to increase the overall sensitivity and specificity when used together with acute phase reactants. However, when evaluated separately, CRP and sedimentation were still found as the most valuable parameters in the diagnosis of septic arthritis. In the diagnosis of septic arthritis, 35 mm/hr cut-off value for sedimentation and 10 mg/L cut-off value for CRP were found more sensitive and specific compared to standard laboratory cut-off values of 20 mm/hr and 5 mg/L. For any tables or figures, please contact the authors directly

Introduction. The combined incidence of anatomic (aTSA) and reverse total shoulder arthroplasties (rTSA) in the US is 90,000 per annum and rising. There has been little attention given to potential long-term complications due to periprosthetic tissue reactions to implant debris. The shoulder has been felt to be relatively immune to these complications due to lower acting loads compared to other joint arthroplasties. In this study, retrieved aTSAs and rTSAs were examined to determine the extent of implant damage and to characterize the nature of the corresponding periprosthetic tissue responses. Methods. TSA components and periprosthetic tissues were retrieved from 23 (eleven aTSA, twelve rTSA). Damage to the implants was characterized using light microscopy. Head/stem taper junction damage was graded 1–4 as minimal, mild, moderate or marked. Damage on polyethylene (PE) and metal bearing surfaces was graded 1–3 (mild, moderate, marked). H&E stained sections of periprosthetic soft tissues were evaluated for the extent and type of cellular response. A semi-quantitative system was used to score (1=rare to 4=marked) the overall number of particle-laden macrophages, foreign body giant cells, lymphocytes, plasma cells, eosinophils, and neutrophils. Implant damage and histopathological patterns were compared between the two TSA groups using the Mann-Whitney and Spearman tests. Results. The PE bearing surfaces of aTSAs were dominated by three-body wear and plastic deformation, whereas the rTSA PE components exhibited mainly polishing and scratching. Metal surface damage occurred in a few cases of both groups. Only one aTSA case exhibited marked taper corrosion. In both groups the primary nature of the inflammatory response was a moderate to marked macrophage response to wear particles (78% of cases). The particle-laden macrophages tended to occur in broad sheets and contained metal, PE, bone cement and suture debris. The extent of macrophage and foreign body giant cell responses was greater in the aTSA group (p≤0.001). Metal particles were seen in 63% of aTSAs and 83% of rTSAs. In the aTSA group, bone cement was seen in all cases and suture was observed in 9 cases, and their presence was larger compared to the rTSA group (p≤0.022). There was no difference in the number of other cell types between the groups. A mild lymphocyte response and chromium-phosphate debris was present within the tissue of the aTSA case with marked corrosion, which may be indicative of an early stage adverse local tissue reaction (ALTR) analog to total hip replacements with taper corrosion. Conclusion. Both groups exhibited a strong macrophage response to a combination of different types of implant debris—PE, metal, bone cement and suture. The prevalence of a marked macrophage response was larger in the aTSA group which may be explained by the larger overall presence of cement and suture within this group. PE particles may differ in size between groups due to different acting wear mechanisms which may also affect the extent of the macrophage response. Although corrosion within modular junctions was overall rare, the presence of one case with marked corrosion shows that taper corrosion and subsequent ALTRs are possible in TSAs. For any figures or tables, please contact authors directly

Currently, there is considerable interest in the role that metal allergy may play in the clinical performance of orthopaedic devices. The extant literature suggests that metal allergy is a real clinical phenomenon, albeit the prevalence and clinical impact are not defined. Degradation products in the form of ionic or particulate debris can complex with local proteins and alter their conformation so that they may not be recognised as self-proteins. This can result in an adaptive immune response. The typical paradigm proposed for such an allergy is that of a delayed type hypersensitivity response (Type 4) whereby the antigenic stimulus interacts with antigen presenting cells and T lymphocytes to elicit a cell mediated immune response. There is some evidence that patients with metal-on-metal bearings and/or high serum metal levels elicit more response to metal antigen challenge measured as either patch test sensitivity or lymphocyte proliferation. Thus, while there is an idiosyncratic aspect of the allergic response, there is also a dose response component. The diagnosis of metal allergy remains a challenge as patch testing has not been shown to correlate well with clinical symptoms. In-vitro assays, such as lymphocyte transformation testing, have promise but await robust clinical validation before they can be considered reliable diagnostic testing modalities. Allergy to implanted metal orthopaedic devices is a rare clinical event, and is a diagnosis of exclusion. Revision surgery should be considered a last resort with the understanding that the outcomes are unpredictable. Given the limitations of current diagnostic modalities, widespread screening of patients for metal allergies prior to TKA is not recommended

Early failure associated with adverse reactions to metal debris is an emerging problem after hip resurfacing but the exact mechanism is unclear. We analysed our entire series of 660 metal-on-metal resurfacings (Articular Surface Replacement (ASR) and Birmingham Hip Resurfacing (BHR)) and large-bearing ASR total hip replacements, to establish associations with metal debris-related failures. Clinical and radiological outcomes, metal ion levels, explant studies and lymphocyte transformation tests were performed. A total of 17 patients (3.4%) were identified (all ASR bearings) with adverse reactions to metal debris, for which revision was required. This group had significantly smaller components, significantly higher acetabular component anteversion, and significantly higher whole concentrations of blood and joint chromium and cobalt ions than asymptomatic patients did (all p < 0.001). Post-revision lymphocyte transformation tests on this group showed no reactivity to chromium or cobalt ions. Explants from these revisions had greater surface wear than retrievals for uncomplicated fractures. The absence of adverse reactions to metal debris in patients with well-positioned implants usually implies high component wear. Surgeons must consider implant design, expected component size and acetabular component positioning in order to reduce early failures when performing large-bearing metal-on-metal hip resurfacing and replacement

The dynamic association between the immune system and the skeletal system has recently been appreciated. It has been suggested that cells involved in the inflammatory cascade might modulate the bone fracture repair process. Interestingly a number of studies have demonstrated that ability of the T lymphocyte to affect bone remodelling and health profoundly. For example the presence of T lymphocytes has been shown to increase bone resorption during experimental induced arthritis. We wanted to investigate the role of specific T lymphocytes in fracture repair and required an in vivo model to deplete CD4 and CD8 T lymphocytes selectively. Method The cell lines of Anti-L3T4 (CD4), Anti-Lyt-2 (CD8) and Anti-phytochrome were obtained from ECACC and produced by Edinburgh University group, Immunosolv. Anti-phytochrome (AFRC MAC 51) antibody was used as the control. To each group of 5 murine models 50ìL of CD4 or CD8 or control antibody was injected ip on days 0, 1, 2, 7, 8, and 9. The body weight and behaviour were measured. On day 20 the spleens were sampled and a single cell suspension was created for each murine model. PE CD8 antibody and FITC CD4 antibody were then added to each sample. Each spleen sample was then cell sorted using the FACS machine. Results Compared to the control group the murine model injected with CD4 antibody had only 1.14 % of CD4 T cells remaining (mean 2.462 % +/− 0.270). Similarly, the murine models injected with CD8 antibody had only 1.8% of CD8 T cells remaining (mean 1.723 % +/− 1.036). Conclusion Our results suggest that to investigate the role of T lymphocytes in fracture repair, specific T lymphocytes can be successfully depleted with the repeated use of antibodies

Aim. Although established serum inflammatory biomarkers, such as serum C-reactive protein (CRP) and serum white blood cell count (WBC), showed low accuracies in the literature, they are still commonly used in diagnosing periprosthetic joint infections (PJI). For a sufficient preoperative diagnosis novel more accurate serum parameters are needed. The aim of our study was to evaluate the performances of the established and novel routinely available serum parameters in diagnosing periprosthetic joint infections when using the proposed European Bone and Joint Infection Society (pEBJIS) criteria. Method. In this retrospective study, 177 patients with an indicated revision surgery after a total joint replacement were included from 2015 to 2019. The easily accessible and routinely available serum parameters CRP, WBC, the percentage of neutrophils (%N), the neutrophils to lymphocytes ratio (NLR), fibrinogen and the platelet count to mean platelet volume ratio (PC/mPV) were evaluated preoperatively. The performances were examined via receiver operating characteristic (ROC) curve analysis (AUC). The curves were compared using the z-test. Seventy-five cases (42%) showed a PJI based on the pEBJIS-criteria. Results. The sensitivities of serum CRP (cut-off: ≥10mg/L), WBC (≥10×10^9 cells/L), %N (≥69.3%), NLR(≥ 3.82), fibrinogen (≥ 457 mg/dL), and PC/mPV (≥ 29.4) were calculated with 68% (95% CI: 57–78), 36% (26 – 47), 66% (54 – 76), 63% (51 – 73), 69% (57 – 78), and 43% (32 – 54), respectively. Specificities were 87% (79 – 93), 89% (81 – 94), 67% (57 76), 73% (63 – 81), 89% (80 – 93), and 81% (72 – 88), respectively. Serum CRP and fibrinogen showed better performances than the other evaluated serum parameters (p<0.0001). The median serum CRP (17.6 mg/L) in patients with PJI caused by a low virulence microorganism was lower compared with infections caused by high virulence organisms (49.2 mg/L; p=0.044). Synovial fluid leucocyte count and histology showed better accuracies than serum CRP, serum WBC, %N, NLR, serum fibrinogen, and PC/mPV (p<0.0001). Conclusions. Although serum CRP and fibrinogen showed the best performances among the evaluated serum inflammatory markers, their results should be interpreted with caution in clinical practice. Serum parameters may remain normal in chronic infections or may be elevated in patients with other inflammatory conditions. In addition, they also correlated poorly with synovial fluid leukocyte count and histology. Therefore, serum parameters are still insufficient to confirm or exclude a periprosthetic joint infection. Hence, they can only be recommended as suggestive criteria in diagnosing PJI

Mesenchymal stem cells (MSC) are multipotent cells that possess regenerative functions that are of interest for in osteoarticular diseases such as osteoarthritis (OA). These functions are thought to be primarily mediated by mediators released within extracellular vesicles (EV). The aim of this study was to compare the immunomodulatory effects of two major types of EV, exosomes and microparticles, secreted by MSCs. EV subsets were isolated from murine primary MSCs by ultracentrifugation. Size and structure were evaluated by Dynamic Light Scattering and electron microscopy. Expression of membrane and endosomal markers was tested by flow cytometry. Proliferation of murine splenocytes was quantified after 72h of incubation with EVs after CFSE-labelling. Phenotypic analysis of T lymphocyte subpopulations was also performed by flow cytometry. In vivo, EVs were injected in the knee joint in the collagenase-induced osteoarthritis (CIOA) model and histological score was performed. In vitro functional analysis indicated that addition of microparticles or exosomes in proliferative assays inhibited the proliferation of total splenocytes in a dose-dependent manner. Analysis of T cell subpopulations revealed a decrease in CD8. +. IFNγ. +. lymphocytes and an increase in both CD4. +. IL10. +. Tr1 and CD4. +. CD25. +. FOXP3. +. Treg cells. This immunomodulatory function of EVs was also observed in vivo in the CIOA model. In summary, our data indicated that the immunosuppressive effect of MSCs is in part mediated by exosomes and microparticles that play in vivo a major role in MSC-mediated therapeutic effect by reducing osteoarthritic symptoms

Osteoarthritis (OA) is a degenerative disease with a strong inflammatory component. Intra-articular (IA) injections of mesenchymal stem cells (MSCs) modulate local inflammation, although the lack of engraftment suggests that they undergo apoptosis. The aim of this study is to investigate the fate of IA-delivered MSCs in an animal model of OA and to assess the role of apoptosis in vitro. Collagenase-induced OA (CIOA) was performed on C57BL/6 mice and 2×10∧5 GFP+ MSCs were IA-injected in the animals. 3 days later, knee joints were digested into a single-cell suspension and MSCs retrieved by cell sorting. Conditioned medium (CM) of retrieved cells was tested on murine macrophages and cytokine secretion was measured. Apoptosis of MSCs was induced in vitro with staurosporine (STS) and evaluated by Annexin V/Sytox Blue staining; activation of caspases was measured by FLICA assays. Murine lymphocytes were cocultured with apoptotic MSCs and their proliferation measured by quantification of Cell Trace Violet. 1.63% of injected cells were retrieved and proliferated in culture. Their CM significantly modulated activation of macrophages, with greater effects from OA-induced MSCs. STS induced apoptosis with activation of Caspase 3/7. Apoptotic MSCs significantly prevented the proliferation of murine lymphocytes. MSCs can be administered and retrieved from murine knees. Retrieval yield is low, consistent with previous studies. MSCs were licensed from the OA joint to produce an immunosuppressive milieu that modulated macrophages ex vivo. In vitro, apoptosis increased the immunomodulatory potential of MSCs. This suggests that apoptosis may contribute to the therapeutic effects of MSCs in OA

Introduction. Neck of femur (NOF) fractures are one of the predominant reasons for hospital admissions in patients >65 year. These fractures are associated with a poor outcome; end to independent living in 60% of patients and a 6 month mortality of 30%. Previous studies have shown show elements of under/mal-nutrition on admission. In addition, their nutritional status shows some deterioration thereafter. The aim of this present study is to examine if the nutritional status of patients with NOF fracture admitted at our institution is associated with a larger post-operative haemoglobin drop. This is compared to an independent living age matched control group from the same geographical area. Methods. A retrospective audit of pathology results for three hundred fracture patients (n = 300) and one hundred age matched home living group pre-assessed of total hip replacement (n = 100). Total serum protein, albumin, total lymphocyte count levels were determined at the time of admission to assess nutritional status. Pre/post-operative haemoglobin, resultant haemoglobin drop, and 6 month mortality was assessed in NOF fracture patients. The nutritional parameters were correlated with the haemoglobin levels and mortality. Results. Fracture patients were found to be malnourished on hospital admission. 10% showed a total serum protein level of <60g/L, 21% showed an albumin level of <35 g/L and 66% had on a total lymphocyte count of <1,200 cells/ml. When compared to an age matched home living group, fracture patients had a significantly (p = <0.0001) lower protein (67.4 vs 74.5), albumin (38.8 vs 43.9) and total lymphocyte counts (1173.3 vs 1840.8). Pre/post-operative haemoglobin showed a positive correlation with albumin and protein levels (p = <0.01). Haemoglobin drop post-operatively showed a negative correlation with albumin and protein levels (p = <0.01). 6 month mortality was correlated with albumin, protein, and total lymphocyte count levels. Discussion. This study confirms that patients admitted with NOF fractures are malnourished on admission. In addition, we report that not only pre-operative haemoglobin is correlated to the malnourishment but also the post-operative haemoglobin drop is correlated to albumin/protein levels on admission. This leads us to hypothesise that these malnourished patients have a higher bleeding tendency. Thus, we propose that malnourishment can be identified by the orthopaedic team using relatively inexpensive laboratory tests such as albumin, protein and total lymphocyte count. Thereafter, appropriate measures should be instituted to prepare for intra/post-operative bleeding and higher need for blood transfusion

Aim. Cutibacterium acnes is involved in chronic/low-grade pathologies such as prosthetic joint infection (PJI) or sarcoidosis. During these diseases, granulomatous structures are frequently observed. In this study, we induced a physiological granulomatous reaction in response to different well-characterized clinical C. acnes isolates in order to investigate the cellular process during the granulomatous formation. Method. An acne C. acnes ATCC6919 isolate (clonal complex (CC) 18, phylotype IA1), a PJI C. acnes BL clinical isolate (CC36, phylotype IB) and a sarcoidosis C. acnes S8 strain (CC28, phylotype IA. 2. ) were included and co-culture with PBMC. Cellular aggregation was followed daily using light microscopy. At various time points of incubation (day 3 and day 7), granuloma structures were processed for microscopic observation, colony forming unit enumeration after Triton ×100 lysis to release the internalized bacteria (bacterial load within the granulomas), as well as for flow cytometric analysis (detection of CD4, CD8 and NK lymphocytes). Results. All C. acnes isolates generated granulomatous structures in our experimental conditions. The bacterial burden was better controlled by granulomas induced by sarcoidosis C. acnes isolate. PJI C. acnes isolate, belonging to CC36, promoted the recruitment of CD8. +. lymphocytes inside the granuloma. At the opposite, acne and sarcoidosis C. acnes isolates, belonging, respectively, to phylotype IA. 1. /CC18 and phylotype IA. 2. /CC28 generated a higher number of granuloma and promoted the recruitment of CD4. +. lymphocytes inside the granuloma. Conclusions. Our results provide new arguments supporting the role of C. acnes in the development of infections and new explanations concerning the mechanisms underlying PJI due to C. acnes. This model appears to be a possible alternative assay to animal models for studying the immune response to C. acnes infection

Purpose. Various approaches have been reported for the total hip replacement (THR). In recent years, a muscle sparing approach with low postoperative muscle weakness and low dislocation risk has been frequently selected. However, such surgery has a learning curve. Thus, at the time of switching from the conventional approach to such approaches, invasion or infection risk may increase with the operation time extension. The purpose of this study is to clarify the change of invasiveness or latent infection rate with the change in approach in order to select the cases safely at the beginning of introducing a new approach in THR. Methods. In facility A, THR was performed with Dall's approach (Dall), but 1 surgeon changed Dall to anterolateral modified Watson-Jones approach (OCM) and another surgeon changed Dall to direct anterior approach (DAA). In facility B, all 3 surgeons changed posterolateral (PL) approach to OCM. The subjects are 150 cases in total, including the each last 25 cases operated with the conventional approach and the each first 25 cases operated with a new approach (Dall to OCM: 25 + 25, Dall to DAA: 25 + 25, PL to OCM: 25 +25 cases). And, differences in operative time, intraoperative bleeding volume, postoperative hospital stay, and postoperative hemoglobin, white blood cell count, lymphocyte count, creatine kinase (CK), C-reactive protein (CRP) were investigated. Results. The average age of subjects was 64 years (31–87 years old), and there were 27 male subjects and 123 female subjects. In the change from Dall to OCM, only the postoperative hospital stay decreased significantly. In the change from Dall to DAA, the length of hospital stay and postoperative CRP significantly decreased, but the intraoperative bleeding volume increased. In the change from PL to OCM, the operation time, postoperative CRP and CK decreased, but postoperative Hb decreased. Cases with lymphocytes less than 1000/µL or less than 10% after surgery on day 4 are latent infection cases, and in such cases the operation time was significantly longer, the postoperative Hb was significantly lower, and the postoperative CK was significantly higher. However, such cases were not significantly increased by the change of operation approach. Conclusion. Introduction of the muscle sparing approach improved many items on surgical invasion, but some items deteriorated especially at the beginning of a new approach. In the early stages of introduction of the new approach, choosing cases without obesity and without lots of muscle volume may reduce latent infection

Aims: To assess the value of measuring the subpopulations of T and B lymphocytes in patients with musculoskeletal tumours as an immunodiagnostic procedure in primary diagnosis of tumours. Methods: In this prospective study blood samples were obtained from 145 patients aged 04–98 presenting with musculoskeletal tumours. Measurements of subpopulations of T and B lymphocytes (CD3, CD4, CD8, Helper/Suppressor ratio and CD19) were based upon the principle of Ortho Cytoron Absolute Flow Cytometry. The histological diagnosis of tumours was obtained by the histopathological investigation of the biopsy samples and the ßow cytometry results allocated accordingly. Results: Of the 145 patients, osteomyelitis was diagnosed in 15 (10.34%) patients. Median values of subpopulations of T and B lymphocytes were signiþcantly raised in patients with osteomyelitis, as follows: CD3 2456, CD4 1479, CD8 929, Help/Sup ratio 1.8 and CD19 560. Results were also calculated for osteosarcomas, Ewing sarcomas, giant cell tumours, chondrosarcomas, metastatic carcinomas, synovial cell sarcomas, chondroblastomas and others, with their median values within normal reference levels. To conþdently out rule or conþrm the diagnosis of osteomyelitis the cut off point values of lymphocytes (the highest value in other patients groups) were measured. The cut off point values were found to be: CD3 2420, CD4 1400, CD8 873 and CD19 550. Conclusions: The subpopulattions of T and B lymphocytes were signiþcantly raised in patients with osteomyelitis in contrast to other causes. In this study it is clearly shown that the levels of CD3, CD4, CD8 and CD19 above the presented cut off values are an important and accurate conþrming factor for the diagnosis of suspected osteomyelitis

Introduction. Little is known about the relationship between head-neck corrosion and its effect on periprosthetic tissues and distant organs in the majority of patients hosting apparently well-functioning devices. We studied the degree and type of taper damage and the histopathologic response in periprosthetic tissue and distant organs. Methods. A total of 50 contemporary THRs (34 primary, 16 revision) retrieved postmortem from 40 patients after 0.4–26 years were studied. Forty-three femoral stems were CoCrMo and 7 were Ti6Al4V. In every case, a CoCrMo-alloy head articulated against a cementless polyethylene cup (19 XLPE and 31 UHMWPE). H&E and IHC sections of the joint pseudocapsules and liver were graded 1–4 for the intensity of various inflammatory cell infiltrates and tissue necrosis. The nature of the tissue response in the joint capsule, liver, spleen, kidneys and lymph nodes was assessed. Wear and corrosion products in the tissues were identified using SEM and EDS. Taper surfaces were graded for corrosion damage using modified Goldberg scoring and examined by SEM to determine the acting corrosion mode. Correlations between damage scores and the histologic variables were generated using the Spearman test. Results. No correlation was seen between taper damage scores and the macrophage response in the joint pseudocapsule. The distribution of corrosion scores for heads and femoral trunnions is shown in Figure 1. Moderate or severe corrosion of the head and/or trunnion was present in 9 hips (8 CoCr/CoCr and 1 CoCr/TiAlV). One patient with bilateral hips had local ALVAL-like lymphocyte-dominated tissue reactions (Figure 2) and mild focal lymphocytic infiltrates in the liver and kidneys (Figure 3). This was associated with severe intergranular corrosion of the CoCrMo trunnion and column damage on the head taper. Particle-laden macrophages in pseudocapsules were significantly correlated with liver macrophages (r=.382, p=0.012) and liver lymphocytes (r=.367, p=0.013). Pseudocapsule macrophage responses to metallic and/or polyethylene wear particles ranged widely from minimal to marked. Focal tissue necrosis was related to high concentrations of particulate wear debris. A minimal number of metallic particle-laden macrophages were also detected in the liver and spleen; and macrophage granulomas were present in para-aortic lymph nodes, especially in revision cases. DISCUSSION. The generation of metal ions and particulates at corroded CoCrMo heads and CoCrMo or Ti6Al4V trunnions was a significant contributor to the presence of perivascular lymphocytes within the joint pseudocapsule, with 1 patient showing a histologic pattern consistent with ALVAL. Patient factors and the rate of corrosion are among variables influencing whether an ALVAL-type reaction will develop and whether or not it will become symptomatic. Macrophages in the joint pseudocapsules were positively correlated with inflammatory cells in the liver. In this study, the intensity of inflammatory infiltrates in distant organs was mild. However, several cases of organ dysfunction have been reported in association with catastrophic wear of CoCrMo components. It continues to be essential to minimize the generation of metal ions and particulates and to improve strategies for identifying and managing patients exposed to high levels of degradation products. For any figures or tables, please contact the authors directly

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

1. A comparative study has been made of the major transplantation antigens present on the chondrocyte isolated from articular cartilage of the sheep and lymphocytes from the cartilage donors. 2. It has been shown that the chondrocyte possesses antigens of the major histocompatibility system in common with the lymphocyte. 3. In order to demonstrate the similarity between the antigen structure of the chondrocyte and the lymphocyte it was necessary to treat cartilage cells with papain after isolation in order to remove the matrix more completely. Failure to do this led to an apparent deficit of antigens on the chondrocyte. 4. It was found that lysis of cells by antibodies was slower when chondrocytes were the target cells than when lymphocytes were used. It is concluded that this is due to a protective role of remaining cartilage matrix

Aim. To validate the implementation of relatively inexpensive and reliable laboratory tests in everyday clinical practice for the early recognition of malnutrition in patients with a hip fracture. Correlation of malnutrition with clinical parameters. Method. Retrospective study including all elderly patients operated for a hip fracture during a five year period. Patients were evaluated according to two laboratory parameters: serum albumin and total lymphocyte count. Both parameters are established and widely used nutritional indexes. Based on the results, patients were divided into four groups: Patients in group A had both parameters within normal limits. Group B had a low total lymphocyte count and a normal albumin level. Reversibly, patients in group C had a low albumin level and a normal total lymphocyte count. In group D both values were abnormal. The groups were compared according to three clinical parameters: waiting time to operation, duration of hospital stay and one year postoperative mortality. Results. Three hundred and twenty nine patients were included in the study. Statistically important differences were found for all three clinical parameters between malnourished patients (group D) and those with normal values (group A). Conclusion. Serum albumin levels and a total lymphocyte count are reliable nutritional indexes in patients with a hip fracture. Their implementation in clinical practice can contribute to the early recognition and appropriate treatment of patients with a worse prognosis

Bacteriophage state currently an attractive alternative for antibiotics, especially due to the strong in vitro activity and lack of side effects. Eight patients with chronic infection in musculoskeletal system.are presented. This group includes: 3 cases of deep periprosthetic infection, posttraumatic osteomyelitis of tibia in 2 cases, infected pseudoarthrosis of femur in 1 case, chronic hematogenous osteomyelitis of tibia in 1 case, chronic infection in diabetic foot in 1 case. Adequate tissue specimen for bacteriology was taken during operation and selection of bacteria strains was subsequently done and appropriate phage were cultured. Phage were taken orally by patients 4–6 weeks after operation. Despite of paralel phage and systemic antibiotic administration all patients underwent operative debridement of infected bone. Simultaneously, every 7 days parameters of immunological response was measured in peripheral blood. They were: lymphocyte B activity (PFC and SAC test), lymphocyte T (NK) activity and phagocytose stimulation (PMA 30 test). There was a two-fold increase of lymphocyte B activity in PFC test with peak on day 7 after phage administration. Additionally slightly increase of NK cells and phagocytic activity and both increase and decrease of lymphocyte B and T activity in SAC test was observed. Eventually remission of infection was achieved in 6 from 8 patients. It is difficult to state a correlation between in vitro bactericidal effect of bacteriophage, immunological stimulation in peripheral blood and clinical results achieved after both operative and antimicrobial therapy

Mesenchymal stem cells (MSCs) are immunosuppressive and have been used to facilitate tissue repair in the context of allogeneic implantation. However, xenogeneic cell transplantation has not been fully explored. The present study investigated the feasibility of xenogeneic MSCs implantation in mice. MSCs were harvested from the bone marrow of GFP rats (Green Fluorescent Protein transgenic rats), and cultured as previously described. 1 million GFP MSCs were loaded onto the synthetic HA/TCP porous Skelite blocks and implanted intramuscularly into the quadriceps of the MF1 and SCID mice. After 11 weeks, the implants were harvested and processed for histology examination. Upon termination, the mononuclear cells from the peripheral blood of each animal were also collected for mixed lymphocyte culture to examine lymphocyte proliferation potential and T-cell mediated cell lysis (cytotoxic) assays. In the SCID mice, there was sparse osteoid tissue formation in the implants, whereas only dense connective tissues were seen in the implants of the MF1 mice. Osteocalcin mRNA expression was confirmed in the osteoid tissues in the implants from the SCID mice, but it was not detected in the MF1 mice by RT in situ PCR examination. Cells of GFP-rat origin were observed in both the MF1 and SCID mice (more so in the SCID mice) after 11 weeks implantation, which were confirmed by positive immunostaining of anti-GFP antibody. In the MF1 mice after 11 weeks xenogeneic MSCs implantation, the rate of lymphocyte proliferation was significantly increased when mixed with the GFP-MSCs compared to that of mixed lymphocyte culture assays in the SCID or MF1 mice without xenogeneic MSCs implantation, suggesting that implantation of xenoge-neic MSCs has promoted host anti-graft immunogenic responses towards to otherwise immunosuppressive MSCs. In conclusion, xenogeneic rat MSCs transplanted in immunocompetent mice has survived for prolonged period, but their function was comprised to certain extent and this may be due to the increased host anti-graft immune sensitization after exposed to the xenogeneic MSCs

Introduction. Mechanical or corrosive failure of total knee arthroplasties (TKAs) is difficult to diagnose with current laboratory and radiographic analyses. As such, the goal of this study was to determine the mean blood concentration of cobalt, chromium, and titanium in a series of revision TKAs with mechanical implant failure and evaluate whether they facilitated identification of the underlying TKA failure mechanism. Methods. Serum cobalt, chromium, and titanium levels and synovial fluid characteristics were evaluated in 12 patients (13 aseptic revision TKAs) who underwent revision TKA between 2000 and 2020 at a single academic institution for mechanical implant failure or corrosion. Seventy-five percent were re-revisions of previously revised TKAs. Mean time to revision was 6 years. Modular metallic junctions were present in 100%. Twenty-five percent did not have another in situ total joint arthroplasty, and the remaining patients did not have a metal-on-metal articulation that could lead to elevation in serum metal ion levels. Mean follow-up after the revision TKA was 8 months. Results. Mean serum cobalt, chromium, and titanium concentrations were 11 ng/mL, 6 ng/mL, and 3 ng/mL, respectively. Serum metal ion levels facilitated failure mechanism identification in 75%, which included modular junction failure (6 cases), constraint locking mechanism failure (3 cases), corrosion of modular metallic interfaces (2 cases), and implant fracture (1 case). Arthrocentesis was performed in 75%. Mean synovial fluid cell count was 950 cells/mcL. Monocytes were the predominant mean cell type (41%), followed by neutrophils (35%), and lymphocytes (22%). Conclusion. Serum metal ion assessment should be considered when the etiology of painful primary or revision TKAs, particularly those with modular metallic junctions, remains elusive after routine evaluation

The December 2015 Oncology Roundup. 360 . looks at: Amputation may not be the best option; Growing golf balls bad news!; How close is safe? Radiotherapy and surgery; Lymphocyte: monocyte ratio in osteosarcoma; Are borderline cartilage tumours really borderline?; Boosting algorithms improves survival estimates; CT better than Mirels?

Aims. Tissue responses to debris formed by abrasion of polymethylmethacrylate (PMMA) spacers at two-stage revision arthroplasty for prosthetic joint infection are not well described. We hypothesised that PMMA debris induces immunomodulation in periprosthetic tissues. Patients and Methods. Samples of tissue were taken during 35 two-stage revision arthroplasties (nine total hip and 26 total knee arthroplasties) in patients whose mean age was 67 years (44 to 85). Fourier transform infrared microscopy was used to confirm the presence of PMMA particles. Histomorphometry was performed using Sudan Red and Haematoxylin-Eosin staining. CD-68, CD-20, CD-11(c), CD-3 and IL-17 antibodies were used to immunophenotype the inflammatory cells. All slides were scored semi-quantitatively using the modified Willert scoring system. Results. The mean CD-68 scores did not show any significant change during the six weeks between the stages. Perivascular and diffuse scores showed significant difference in CD-3, CD-20, CD-11(c) and IL-17. At the time of re-implantation, a shift in the pattern of the expression of dendritic cells towards a perivascular arrangement and towards the periphery of PMMA particles was observed. Positive microbiological cultures were found at the time of re-implantation in three patients. Five further revisions were required for other reasons. Conclusion. Our results represent a biological reaction of the synovial tissues to spacers with a less diffuse expression of dendritic cells and an increased expression of perivascular lymphocytes. The use of spacers in two-stage revision for infection probably induces an immunomodulation of synovial tissues. Cite this article: Bone Joint J 2016;98-B:1062–8

Aims: To assess the value of measuring subpopulations of T and B lymphocytes in children with bone tumours as an immunodiagnostic procedure in primary diagnosis of tumours. Methods: In this prospective study blood samples were obtained from 36 patients aged 04–16 presenting with bone tumours in Cappagh Orthopaedic Hospital. Measurements in Immunology laboratory were based upon the principle of Ortho Cytoron Absolute flowcytometry. Levels of CD3 (Total T cells), CD4 (Helper cells), CD8 (Suppressor cells), Helper/Suppressor ratio and CD19 (B cells) were measured. Histological diagnosis of tumours was obtained by histopathological investigation of biobsy samples and flow cytometry results allocated accordingly. Results: Of 36 patients, 12 (33.12%) had osteosarcoma, 10 (27.7%) Ewing’s sarcoma, 4 (11.1%) giant cell tumour and 10 (27.7%) osteomyelitis. Median values of lymphocytes were within normal values in patients with tumours other than oseomyelitis. In children with osteomyelitis median values were: CD3 2456, CD4 1479, CD8 929, Help/Sup ratio 1.8 and CD19 560 and all significantly raised. Confidence intervals were: CD3 467, CD4 292, CD8 470, and CD19 148. IN order to confidently outrule or confirm the diagnosis of osteomyelitis we measured the cut off point values of lymphocytes (the highest value in other patients groups). The cut off point values were found to be: CD3 2420, CD4 1400, CD8 873 and CD19 550. Conclusions: The main use of measuring T and B lymphocytes response is in establishing the correct diagnosis between suspected osteomyelitis and other bone tumours. The CD3, CD4, CD8 and CD19 were significantly raised in children with osteomyelitis in contrast to other causes. Levels of CD3, CD4, CD8 and CD19 above the presented cut off values are an important and accurate confirming factor for the diagnosis of suspected osteomyelitis

Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset, and implant stability. This option is widely used in Region Emilia Romagna, Italy, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy. The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening. Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board. It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /litre). It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase. Level of Evidence. III retrospective, comparative study. Acknowledgments. The research was funded by Ministry of Health, grant ‘Early diagnosis of pending failure…’RF 20091472961

It is thought that metal ions from metal on metal bearing hip replacements cause DNA damage and immune dysfunction in the form of T cell mediated hypersensitivity. To explore the hypothesis that there is a relationship between metal ion levels and DNA damage and immune dysfunction in matched patient groups of hip resurfacings and standard hip replacements reflected in the levels of lymphocyte subtypes (CD3+ T cells, CD4+ T helper cells, CD8 +T cytotoxic/suppressor cells, CD16 +Natural Killer and CD19+ B cells) in peripheral blood samples, we analysed peripheral blood samples from 68 patients: 34 in the hip resurfacing group and 34 in the standard hip arthroplasty group. Samples were analysed for counts of each sub-group of lymphocyte and cytokine production. Whole blood cobalt and chromium ion levels were measured using inductively-coupled mass spectrometry. All hip components were well fixed. Cobalt and chromium levels were significantly elevated in the resurfacing group compared to the hybrid group (p<0.001). There was a statistically significant decrease in the resurfacing group's level of CD8+ cells (T cytotoxic/suppressor) (p=0.010). No other subgroup of lymphocytes was significantly affected. Gamma interferon levels post antigen challenge were severely depressed in the hip resurfacing group. A threshold level of blood cobalt and chromium ions for depression of CD8+ T cells was observed. Hip resurfacing patients have levels above this threshold whilst standard hip replacements fall below it. The patients all had normal levels of CD16 +Natural Killer and CD19+ B cells suggesting that this is not a bone marrow toxic effect. Cytokine analysis confirmed that some aspects of T cell function in hip resurfacing patients are severely depressed

Objectives. T-cells are considered to play an important role in the inflammatory response causing arthroplasty failure. The study objectives were to investigate the composition and distribution of CD4+ T-cell phenotypes in the peripheral blood (PB) and synovial fluid (SF) of patients undergoing revision surgery for failed metal-on-metal (MoM) and metal-on-polyethylene (MoP) hip arthroplasties, and in patients awaiting total hip arthroplasty. Methods. In this prospective case-control study, PB and SF were obtained from 22 patients (23 hips) undergoing revision of MoM (n = 14) and MoP (n = 9) hip arthroplasties, with eight controls provided from primary hip osteoarthritis cases awaiting arthroplasty. Lymphocyte subtypes in samples were analysed using flow cytometry. Results. The percentages of CD4+ T-cell subtypes in PB were not different between groups. The CD4+ T-cells in the SF of MoM hips showed a completely different distribution of phenotypes compared with that found in the PB in the same patients, including significantly decreased CD4+ T-central memory cells (p < 0.05) and increased T-effector memory cells (p < 0.0001) in the SF. Inducible co-stimulator (ICOS) was the only co-stimulatory molecule with different expression on CD4+ CD28+ cells between groups. In PB, ICOS expression was increased in MoM (p < 0.001) and MoP (p < 0.05) cases compared with the controls. In SF, ICOS expression was increased in MoM hips compared with MoP hips (p < 0.05). Conclusions. Increased expression of ICOS on CD4+ T-cells in PB and SF of patients with failed arthroplasties suggests that these cells are activated and involved in generating immune responses. Variations in ICOS expression between MoM and MoP hips may indicate different modes of arthroplasty failure. Cite this article: Professor P. A. Revell. Increased expression of inducible co-stimulator on CD4+ T-cells in the peripheral blood and synovial fluid of patients with failed hip arthroplasties. Bone Joint Res 2016;5:52–60. doi: 10.1302/2046-3758.52.2000574

Summary Statement. Cross-talk between cells from immune and bone system might play a role in molecular regulation of subchondral bone sclerosis in osteoarthritis. Macrophages, B-lymphocytes and tartrate-resistant acid phosphatase activity are specifically increased in sclerotic subchondral bone of patients with knee osteoarthritis. Background. Recent investigations have provided substantial evidence that distinct molecular and morphological changes in subchondral bone tissue, most notably sclerosis, play an active and important role in the pathogenesis of OA. The cellular and molecular regulation of this pathological process remains poorly understood. Here, we investigated whether osteoimmunology, the reciprocal signaling between cells from the immune and bone system, is involved in OA subchondral bone sclerosis. Patients & Methods. Tibial plateaus and informed consent were obtained from patients undergoing total knee arthroplasty due to end-stage OA. Subchondral bone mineralization distribution was analyzed using computed tomography osteoabsoptiometry (CT-OAM) and standardised cryosections of low (non-sclerotic) and high (sclerotic) bone mineralization were prepared (n=18 each). Cartilage degeneration was graded in Safranin-O-stained sections using the Mankin scoring system. The presence of T-lymphocytes, B-cells and macrophages was assessed using immunohistochemical staining of their respective surface markers CD3, CD20 and CD68. Osteoclast activity was visualised by staining of the enzyme marker tartrate-resistant acid phosphatase (TRAP). Cellular characterization of ex vivo subchondral bone outgrowth cultures was performed using alkaline phosphatase (ALP), TRAP staining. Correlation between histological parameters was assessed using Spearman's rank correlation. Statistical differences were calculated using Wilcoxon signed rank test or paired t-test, where appropriate. Results. CT-OAM revealed a heterogeneous distribution of subchondral bone mineralization in OA tibial plateaus, displaying focal areas of sclerosis that overlapped macroscopically with areas of cartilage damage. These data were confirmed at the histological level by a strong correlation between Mankin score and grade of sclerosis (r=0.7, p<0.001). Immunohistochemistry showed that CD20. +. , but not CD3. +. , lymphocytes and CD68. +. mononuclear (macrophage) and multinucleated (osteoclast) cells were present in subchondral marrow spaces. Notably, the number of CD20. +. lymphocytes and CD68. +. cells was significantly (p<0.05) increased in sclerotic subchondral bone. Enhanced osteoclast activity was confirmed by a significantly increased (p<0.05) number of multinucleated and mononuclear TRAP. +. cells in sclerotic bone. Finally, the number of CD68. +. cells was strongly correlated (p<0.001) with Mankin score (r=0.7), grade of sclerosis (r=0.8), CD20. +. lymphocytes (r=0.8), and TRAP-positive cells (r=0.9). Outgrowth cultures of subchondral bone showed cells of different morphologies including fibroblast-shaped osteoblasts and macrophage-like cells. Expression of ALP was detected in the prior, while TRAP expression was evident in the latter. Corresponding with histological analyses, the number of TRAP. +. cells was increased in ex vivo outgrowth cultures of sclerotic compared to non-sclerotic subchondral bone. Conclusions. Together, our data suggest that osteoimmunological mechanisms, specifically the interaction of CD68. +. macrophages with bone-resident cells, play a - previously unknown - role in regulating subchondral bone sclerosis in progressive OA. Targeting osteoimmunology might hold potential as a disease-modifying treatment for OA

Metal-on-metal (MOM) hip resurfacings release chromium and cobalt wear debris into the surrounding joint. The hip tissue taken from failed MOM hips shows specific histological features including a subsurface band-like infiltrate of macrophages with particulate inclusions, perivascular lymphocytic infiltrate and fibrin exudation. This tissue response has been called Aseptic Lymphocytic Vasculitis Associated Lesion (ALVAL). There is a recognised carcinogenic potential associated with hexavalent chromium and epidemiological data from first generation MOM arthroplasties may suggest an increased incidence of haematological malignancy. The ALVAL type reaction includes a marked proliferation of lymphocytes in the perivascular space and thorough investigation of this lymphocytic response is warranted. This study aims to further characterise the lymphocytic infiltrate using immunohistochemistry and to test clonality using polymerase chain reaction (PCR). Tissues from revised all cause failed MOM hip arthroplasties (n=77) were collected and analysed initially using routine H&E staining. Those that met the diagnostic criteria of ALVAL described above (n=34) were further stained with a panel of immunohistochemical markers (CD3, CD4, CD8 (T-cell markers) and CD20 (B-cell marker)). 10 representative ALVAL cases were selected and sent for gene rearrangement studies using PCR to determine whether the lymphocytes were polyclonal or monoclonal in nature. The analysis of the lymphocytic aggregates in ALVAL, showed a mixed population of B and T cells. Within the aggregates, there was a predominance of B cells (CD20) over T cells (CD3). Of the 10 cases which were analysed by PCR, 7 were suitable for interpretation. None of these cases showed evidence of monoclonal lymphocyte proliferation. The carcinogenic potential of wear debris from MOM hips, particularly affecting the haematopoietic system should be investigated. This study has shown a predominantly B-lymphocyte response in tissues surrounding MOM hips which is polyclonal. Although the numbers are small, the study suggests an immune mediated response in MOM hip tissue and excludes a neoplastic proliferation. However, long term follow up of patients with MOM hips may be prudent

Modular femoral stems for total hip arthroplasty (THA) were introduced to allow additional options for surgeons in controlling leg lengths, offset and implant stability. This option is widely used in our Region, where the study was conducted, having a modular neck stem nearly 35% of primary THA in 2013. Great majority of modular neck is made of Titanium alloy. The study was designed as a retrospective descriptive case series of 67 hips in patients who underwent revision of a THA. All had a Titanium modular neck. In 44 cases revision was due to breakage of the neck, in the remaining 23 it was due to different reasons unrelated to modular neck such as bone fracture, breakage of a ceramic component, cup loosening. Mean follow up was 3.5 yrs. For all patients excised capsule and surrounding tissue were graded for presence of necrosis, inflammatory exudate, lymphocytes, and wear particles using light microscopy of routine paraffin sections stained with hematoxylin and eosin. The retrieved modular neck-body and head-neck junctions were examined for evidence of fretting and corrosion. For some patient dosage of circulating Titanium was obtained. Approval was obtained from institutional review board. It resulted that a variable amount of wear was observed in the first group of patients, with no evidence of lymphocytic reaction, but with variable notes of necrosis. Broken necks showed different patterns of damage, with different degree of corrosion, beside the fatigue fracture. In the second group wear was less evident or absent and negativity of lymphocyte reaction was substantially confirmed. Circulating Titanium ions were one order of magnitude higher in first group (mean 35 micrograms /liter). It can be concluded that fracture of Titanium modular necks occurs progressively, wear does not induce lymphocytic reaction and circulating ions increase

In vitro studies on isolated bone cells were undertaken to investigate the presence of transplantation (histocompatibility) antigens. Bone cells were cultured with allogeneic lymphocytes and exposed to cytotoxic sera containing antibodies against transplantation antigens, to determine their antigenic profile. Preliminary results suggest that bone cells may not express lymphocyte stimulating antigens in an active form, at least after the isolation procedure performed. On the other hand, bone cells were killed by cytotoxic antibodies in a specific way, providing evidence for the presence of serologically defined (SD) transplantation antigens on the cell surface. Additional studies with absorbed sera suggest "sharing" of histocompatibility antigens between bone cells and lymphocytes. The relevance of the surface antigens of bone cells to clinical fields such as bone allotransplantation, susceptibility to various orthopaedic diseases and skeletal sarcomata is discussed

We aimed to assess whether the immunological abnormalities which have been observed in patients with loose total hip replacements (THRs) are present in patients with a well-fixed prosthesis. We examined blood samples from 39 healthy donors, 22 patients before THR and 41 with well-fixed THRs of different types (15 metal-on-metal, 13 metal-on-polyethylene, 13 ceramic-on-ceramic). Before THR, the patients showed a decrease in leukocytes and myeloid cells in comparison with healthy donors, and a prevalence of type-1 T lymphocytes, which was confirmed by the increase in ratio of interferon-γ to interleukin 4. Moreover, patients with metal-on-metal or metal-on-polyethylene implants showed a significant decrease in the number of T lymphocytes and a significant increase in the serum level of chromium and cobalt, although no significant correlation was observed with the immunological changes. In the ceramic-on-ceramic group, leukocytes and lymphocyte subsets were not significantly changed, but a significant increase in type-2 cytokines restored the ratio of interferon-γ to interleukin 4 to normal values. We conclude that abnormalities of the cell-mediated immune response may be present in patients with a well-fixed THR, and that the immunological changes are more evident in those who have at least one metal component in the articular coupling

Introduction: Approximately 0.5 % of patients with metal on metal hip replacements develop post operative pain which is thought to be due to an immune reaction to metal wear particles, known as Aseptic Lymphocyte Dominated Vasculitis Associated Lesion (ALVAL). Treatment usually requires revision to a non metal on metal hip.. Is the development of ALVAL more likely in those patients with high wear rates?. Methods: Retrieved Metal on Metal (MOM) hip implants; periprosthetic tissue and blood samples were obtained from patients (n = 18) undergoing revision for unexplained pain at a mean of 2 years post operatively. The following variables were measured:. linear wear rate (depth of the femoral head and acetabular socket wear patch/time from operation);. the diagnosis and severity of ALVAL from histological sections of periprosthetic tissue (Wilhert grading system);. pre-revision whole blood cobalt, and chromium levels using Inductively Coupled Plasma Mass Spectrometry. All implants and tissue samples were analysed against control samples from patients undergoing revision of MOM hips for fractured femoral neck or impingement. Results: Linear wear rates of retrieved implants, and blood levels of cobalt and chromium from patients with unexplained plain were greater than from control patients. Histolopathological analysis of tissue showed dense inflammatory infiltrates with healthy looking endothelial cells in all vessels from both patient groups. Discussion and Conclusion: A painful MOM hip was associated with high wear rates and blood metal levels. The local inflammatory response was similar to “ALVAL”, ie lymphocyte dominated, but not exclusive to those patients with unexplained pain. We question whether ALVAL represents a vasculitis, or merely a classical lymphocyte driven inflammatory tissue response to metal debris particles

Introduction: Freezing and storage of fresh frozen femoral heads destined for use in revision hip arthroplasty is thought to result in graft cell death. Washing of the graft following the morsellisation process also removes a large proportion of the marrow content of the allograft. However, the immunological load of the impaction allografting process remains unknown. The aim of this study was to investigate the immune response by observing any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement. Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Venous blood samples were collected pre-operatively and at set time intervals up to one year post-operatively. Using flow cytometry, analysis of venous blood allowed counts of the following cells: Helper T-lymphocytes, cytotoxic T-lymphocytes, memory T-lymphocytes, naïve T-lymphocytes, Natural Killer cells and B-lymphocytes. Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Pre-operatively, a significant difference (p=0.03) was found between the groups of patients with respect to Natural Killer cells but other subsets showed no significant difference. Post-operatively the significant difference between Natural Killer cells resolved. T-helper lymphocytes, cytotoxic lymphocytes, memory T-lymphocytes and naïve T-lymphocytes in both groups showed decreases in values immediately post surgery, recovering to normal values within 6 weeks post-surgery. The allograft group showed significant increases from baseline in cytotoxic T-lymphocytes at 6 months (p< 0.01) and memory T-lymphocytes one year postoperatively (p=0.04). B-lymphocyte numbers did not alter significantly from baseline. Conclusion: Cytotoxic T-lymphocytes recognise HLA-class I molecules which are present on all nucleated cells and have been implicated in having a role in osteoclast regulation. Memory T-lymphocytes are produced after a naïve T-lymphocyte is exposed to an antigen. The observed increases of these subsets were not observed in the non-grafting group suggesting the allografted bone had elicited an immunological response. At 12 months all grafts appeared radiologically stable and the immunological response may have been beneficial to the outcome

The long term biological effects of wear products following total hip arthroplasty (THA) are unclear. However, the indications for THA are expanding, with increasingly younger patients undergoing the procedure. This prospective, randomised study compared two groups of patients undergoing THA after being randomised to receive one of two different bearing surfaces: metal-on-polyethylene (MoP) n = 22 and metal-on-metal (MoM) n = 23. We investigated the relationship between three variables: bearing surface (MoP vs MoM), whole blood levels of chromium (Cr) and cobalt (Co) and chromosomal aberrations in peripheral lymphocyte pre-operatively and at one, two and five years post-surgery. Our results demonstrated significantly higher mean cobalt and chromium (Co and Cr) blood levels in the MoM group at all follow-up points following surgery (p < 0.01), but there were no significant differences in the chromosomal aberration indices between MoM and MoP at two or five years (two years: p = 0.56, p = 0.08, p = 0.91, p = 0.51 and five years: p = 0.086, p = 0.73, p = 0.06, p = 0.34) for translocations, breaks, loss and gain of chromosomes respectively. Regression analysis showed a strong linear relationship between Cr levels and the total chromosomal aberration indices in the MoM group (R. 2.  = 0.90016), but this was not as strong for Co (R. 2. = 0.68991). In the MoP group, the analysis revealed a poor relationship between Cr levels and the total chromosomal aberration indices (R. 2. = 0.23908) but a slightly stronger relationship for Co (R. 2. = 0.64292). Across both groups, Spearman’s correlation detected no overall association between Co and Cr levels and each of the studied chromosomal aberrations. There remains no clear indication which THA bearing couple is the most biocompatible, especially in young active patients. While THA continues to be very successful at alleviating pain and restoring function, the long-term biological implications of the procedure still require further scrutiny. Cite this article: Bone Joint J 2015;97-B:1183–91

Unlike metal-on-Polyethylene, metal-on-metal (MoM) implants seem to affect the adaptive immune response as evident from the associated perivascular infiltrate containing lymphocytes and plasma cells. This is more pronounced in implant failure secondary to aseptic loosening, and may represent the failure mode. A reduction in CD8+ T lymphocyte counts has also been described with Hip Resurfacing. MoM articulations produce a much smaller order of size of wear particles (nanoparticles) than metal-on- Polyethylene, which may be responsible for the observed adaptive immune system effects. We therefore analyzed the effects of CoCr nanoparticles (CoCrNP) on Dendritic Cells, T cells & B cells. We produced CoCrNP using repetitive short spark discharges between electrodes of prosthetic CoCr alloy. Electron micrography and Brunauer-Emmet-Teller method both confirmed nanoparticle size. The following experiments were then undertaken. Dendritic Cells were cultured from mouse bone marrow and incubated with CoCrNP of varying concentrations for 24hrs, or lipopolysaccharide as a positive control. Activation status was then characterized by CD40 expression on fluorescence activated cell sorting (FACS) analysis. T Cell Viability; Cells from mouse lymph nodes were incubated with CoCrNP in varying concentrations. At 48hrs, Propidium Iodide (PI) was added and proportion of CD4+ lymphocytes that were PI+ve determined by FACS analysis. T Cell proliferation; Cells from mouse lymph nodes were cultured in medium without phenol red and incubated with μCD3 (anti CD3), μCD3 + CoCrNP, μCD3 + μCD28 or μCD3 + μCD28 + CoCrNP. At 48hrs, Almar Blue was added & difference in light absorbance at 570nm & 600nm was then used to determine T cell proliferation at 72hrs. Cells from lymph nodes of an MD4 (Hen Egg Lysozyme (HEL) specific B cell receptor transgenic) mouse were incubated with CoCrNP, HEL (positive control) or CoCrNP + HEL. B cell activation at 48hrs was characterised by CD40 and CD86 expression on FACS analysis. We found CoCrNP did not significantly increase CD40 expression on DCs, neither did it alter CD40 or CD86 expression on B cells. Using a sublethal concentration of CoCrNP as determined from the viability tests, CoCrNP inhibited CD3 & CD3/CD28 dependent T-cell proliferation. This would indicate CoCrNP reduces T cell proliferation and/or survival, which may explain the observed reduction in CD8+ count with hip resurfacing. Understanding the development of the Peri-vascular infiltrate associated with MoM implants will however, probably require more complex (most likely in vivo) models

The peri-prosthetic tissue response to wear debris is complex and influenced by various factors including the size, area and number of particles. We hypothesised that the ‘biologically active area’ of all metal wear particles may predict the type of peri-prosthetic tissue response. . Peri-prosthetic tissue was sampled from 21 patients undergoing revision of a small diameter metal-on-metal (MoM) total hip arthroplasty (THA) for aseptic loosening. An enzymatic protocol was used for tissue digestion and scanning electron microscope was used to characterise particles. Equivalent circle diameters and particle areas were calculated. Histomorphometric analyses were performed on all tissue specimens. Aspirates of synovial fluid were collected for analysis of the cytokine profile analysis, and compared with a control group of patients undergoing primary THA (n = 11) and revision of a failed ceramic-on-polyethylene arthroplasty (n = 6). . The overall distribution of the size and area of the particles in both lymphocyte and non-lymphocyte-dominated responses were similar; however, the subgroup with lymphocyte-dominated peri-prosthetic tissue responses had a significantly larger total number of particles. . 14 cytokines (interleukin (IL)-1ß, IL-2, IL-4, IL-5, IL-6, IL-10, IL-13, IL-17, interferon (IFN)-γ, and IFN-gamma-inducible protein 10), chemokines (macrophage inflammatory protein (MIP)-1α and MIP-1ß), and growth factors (granulocyte macrophage colony stimulating factor (GM-CSF) and platelet derived growth factor) were detected at significantly higher levels in patients with metal wear debris compared with the control group. . Significantly higher levels for IL-1ß, IL-5, IL-10 and GM-CSF were found in the subgroup of tissues from failed MoM THAs with a lymphocyte-dominated peri-prosthetic response compared with those without this response. . These results suggest that the ‘biologically active area’ predicts the type of peri-prosthetic tissue response. The cytokines IL-1ß, IL-5, IL-10, and GM-CSF are associated with lymphocyte-dominated tissue responses from failed small-diameter MoM THA. Cite this article: Bone Joint J 2015;97-B:917–23

Aims

The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI.

Aim. Traditionally, serum white blood count (WBC), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) have been utilized as markers to evaluate septic arthritis (SA). Recently, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) have been identified as prognostic factors for treatment failure, mortality and morbidity in various clinical settings. To date, these markers have not been utilized for evaluating outcomes after hip and knee SA. Thus, the purpose of this study was to determine the ability of admission NLR and PLR to predict treatment failure and postoperative 90-day mortality in hip and knee SA. Method. A retrospective study was performed using our institutional research patient database to identify 235 patients with native hip and knee septic arthritis from 2000–2018. Patient demographics, comorbidities and social factors (alcohol intake, smoking and intravenous drug use) were obtained, and NLR and PLR were calculated based on complete blood count values (absolute neutrophil, lymphocyte and platelet count) on admission. Treatment failure was defined as any reoperation or readmission within 90 days after surgery. Receiver operating curves were analyzed, and optimal thresholds for NLR and PLR were determined using Youden's test. Univariate and multivariate analyses were performed to determine if these ratios were independent predictors of treatment failure and 90-day mortality after surgery. These ratios were compared to serum WBC, CRP, and ESR. Results. Optimal thresholds for NLR was 9.49 (sensitivity=60%, specificity=84%) and PLR was 303 (sensitivity=54%, specificity=77%). With univariate analysis, NLR>9.49 was associated with failure (odds ratio [OR]=7.64, 95%. Confidence Interval [CI]=4.10–14.21) and 90-day mortality (OR=9.83, 95% CI=2.74–35.25). PLR>303 was associated with increased failure (OR=3.85, 95% CI=2.12–7.00). In multivariate analysis controlling for patient demographics, comorbidities and social factors, elevated NLR remained an independent predictor of failure (OR=7.04, 95% CI=3.78–13.14) and 90-day mortality (OR=5.98, 95% CI=1.60–22.32), whereas PLR remained a predictor of failure (OR=3.58, 95% CI=1.95–6.58). NLR was a better predictor of failure and 90- day mortality compared to serum WBC, CRP, and ESR. Conclusions. This study demonstrates that NLR is a good estimate of SA and performs better than serum WBC, CRP and. ESR to predict treatment failure and 90-day mortality. Elevated NLR is a reliable novel biomarker that may be utilized when evaluating SA patients, and this accessible test could be utilized in the musculoskeletal infection field

Introduction. There has been much controversy around metal on metal hip replacements of late due to adverse metal reactions. There is evidence implicating lymphocyte mediated response (type IV delayed-hypersensitivity) to metal debris generated by the implants as one of the main factors responsible for the reactions. Our understanding of these adverse reactions continues to improve but we also recognize that the majority of patients with MOM implants are asymptomatic with well functioning implants. Studies have shown up to 16% allergy to metal ions on pre-operative allergy patch testing. We set out to determine the incidence of hypersensitivity to Cobalt, Chromium and Molybdenum in a arthroplasty population. Method. We assayed whole blood using a validated optimized lymphocyte transformation test, MELISA as part of a prospective randomized study on large diameter bearing surfaces. We recruited 47 subjects, 19 males, 28 females (35–75 yrs). Specific exclusions included presence of metal implants in the body and industrial exposure to metals. Results. Results were available for 46 patients. Four patients (9%) demonstrated hypersensitivity to Cobalt and none to Chromium or Molybdenum. Two were female and two male. The result was weakly positive in three patients and strongly positive in one female. Conclusion. Hypersensitivity in patients without prior exposure to Cobalt, Chromium and Molybdenum is low. The relevance of a positive hypersensitivity test and implications on the choice of bearings is a subject that requires further research. NO DISCLOSURES

Introduction. The resurgence of TB worldwide has several underlying causes, but HIV infection has undoubtedly been a key factor in the current TB epidemic. Since TB is endemic in the developing world the influence of HIV is of concern, particularly with the emergence of multi-drug-resistant strains. The remarkable susceptibility of patients with AIDS to develop TB has shown the critical role of CD4 lymphocytes in protective immunity. In the absence of immunological surveillance by CD4 cells, 5-10% of persons with latent foci of TB reactivate each year. Aim. This paper highlights the presentation and outcome following treatment in HIV patients with spinal TB. Methods. 81 HIV+ve patients with spinal tuberculosis were prospectively evaluated between 2006 and 2007. The mean age was 31 years and 63% were females. The thoracic spine was affected in 45, lumbar (33) and cervical (3). Non-contiguous lesions were noted in six patients. Sixty-six (81%) patients had neurological deficit. The mean Hb was (10.1gm/dl), mean WCC 4.9, mean lymphocyte count was 1.8, mean ESR 79mm/h and the mean CD4 count was 268 cell/cumm. Co-morbidities were seen in 68% of patients. All patients were optimised prior to treatment. Posterolateral decompression was performed in 29 cases, anterior decompression (25), needle biopsy (13), incision and drainage 5 and 9 were treated non-operatively. Medication included ARV (72 patients) and anti-TB in all patients. Results. The mean follow-up was 21 months. Eleven (13.5%) patients developed wound infection and one child died. Complete recovery occurred in 23 patients (35%). The mean CD4 count was 341 cell/cumm. Conclusion. The short term results are encouraging. These patients are best managed by a multidisciplinary team to monitor potential complications from dual therapy, to ensure compliance and adequate nutrition

Purpose. Metal-on-Metal (MoM) hip bearings are being implanted in ever-increasing numbers and into ever-younger patients. The consequence of chronic exposure to metal ions is a cause for concern. Therefore, using cytogenetic biomarkers, we investigated a group of patients who have had MoM bearings in situ for in excess of 30 years. Method. Whole blood specimens were obtained from an historical group of patients who have had MoM bearings in situ for in excess of 30 years. Blood was also obtained from an age and sex matched control group and from patients with Metal-on-Polyethylene (MoP) components of the same era. The whole blood was cultured with Pb-Max karyotyping medium and harvested for cytogenetics after 72 hrs. The 24 colour FISH (Fluorescent In Situ Hybridisation) chromosome painting technique was performed on the freshly prepared slides, allowing chromosomal mapping. Each slide was evaluated for chromosomal aberrations (deletions, fragments and translocations) against the normal 46 (22 pairs and two sex) chromosomes. At least 20 metaphases per sample were scored and the number of aberrations per cell calculated. Results. Chromosomal aberrations, including deletions, fragments and translocations were only detected in the peripheral blood lymphocytes isolated from the group that had MoM bearings. These changes were not present in the age and sex matched control group. The chromosomal aberrations were also detected in the patients previously exposed to MoM bearings who have been revised to a MoP articulation. Conclusion. We have detected dramatic chromosomal aberrations in peripheral blood lymphocytes in a group of patients chronically exposed (over 30 years) to elevated metal ions. It is not known whether these aberrations have clinical consequences or whether they are reproduced in other cells in the body. The results emphasise the need for further investigations into the effect of chronic exposure to elevated metal ions produced by orthopaedic implants

The nervous system is known to be involved in inflammation and repair. We aimed to determine the effect of physical activity on the healing of a muscle injury and to examine the pattern of innervation. Using a drop-ball technique, a contusion was produced in the gastrocnemius in 20 rats. In ten the limb was immobilised in a plaster cast and the remaining ten had mobilisation on a running wheel. The muscle and the corresponding dorsal-root ganglia were studied by histological and immunohistochemical methods. In the mobilisation group, there was a significant reduction in lymphocytes (p = 0.016), macrophages (p = 0.008) and myotubules (p = 0.008) between three and 21 days. The formation of myotubules and the density of nerve fibres was significantly higher (both p = 0.016) compared with those in the immobilisation group at three days, while the density of CGRP-positive fibres was significantly lower (p = 0.016) after 21 days. Mobilisation after contusional injury to the muscle resulted in early and increased formation of myotubules, early nerve regeneration and progressive reduction in inflammation, suggesting that it promoted a better healing response

Introduction. It is well-known that wear debris generated by metal-on-metal hip replacements leads to aseptic loosening. This process starts in the local tissue where an inflammatory reaction is induced, followed by an periprosthetic osteolysis. MOM bearings generate particles as well as ions. The influence of both in human bodies is still the subject of debate. For instance hypersensitivity and high blood metal ion levels are under discussion for systemic reactions or pseudotumors around the hip replacement as a local reaction. The exact biopathologic mechanism is still unknown. The aim of this study was to investigate the impact of local injected metal ions and metal particles. Material and Methods. We used an established murine inflammation model with Balb/c mice and generated three groups. Group PBS (control group, n=10) got an injection of 50µl 0.1 vol% PBS-suspension, Group MI (Metal-ion, n=10) got an injection of 50µl metal ion suspension at a concentration of 200µg/l and Group MP (Metal-particles, n=10) got an injection of 50µl 0.1 vol% metal particle suspension each in the left knee. After incubation for 7 days the mice were euthanized and the extraction of the left knee ensued. Followed by immunhistochemical treatment with markers of inflammation that implied TNFα, IL-6, IL-1β, CD 45, CD 68, CD 3, we counted the positive cells in the synovial layer in the left knees by light microscopy, subdivided into visual fields 200× magnified. The statistical analysis was done with Kruskal-Wallis test and a post hoc Bonferroni correction. Results. The Group with metal particles showed significantly elevated inflammatory markers (TNFα, IL-6, IL-1β, CD 68, CD 45) compared to all other groups. Interestingly, CD 3 as a marker for T-lymphocytes showed no increased levels in all groups. The metal ion group showed significant elevated CD 45 expressions compared to the control group. Conclusion. The results clearly demonstrate that especially metal wear particles lead to an intensive inflammatory reaction. The tissue formations in the metal particle group show an osseous destructive behavior in previously demonstrated results, comparable to pseudotumors. But, in this study, the expression of the immunohistological markers CD 3, CD 45 and CD 68 indicate that the tissue consists of leucocytes and macrophages, whereas lymphocytes could not be detected. This might be due to an acute inflammatory reaction, whereas the adaptive immune response by T-lymphocytes seems not (yet) to be activated. Overall it must be stated that solid metal wear particles are responsible for local inflammatory reactions, whereas it is still unknown whether wear particles corrode in vivo and release a potentially high level of locally toxic metal ions

Inflammatory changes in synovial tissues occur commonly in knee osteoarthritis (OA) and are termed “inflammatory OA”. The pathogenic significance of this inflammatory OA is uncertain. It is also not known whether inflammatory changes in the synovial membrane are reflected in the synovial fluid (SF) and whether the SF contains a similar inflammatory cell infiltrate. This study examined 34 cases of knee joint OA and cytologically and immunohistochemically characterised inflammatory cells in the synovial membrane and SF. Specimens of SF and synovial membrane were taken at the time of knee arthroplasty. All cases of inflammatory OA synovium contained (CD68+) macrophages; several cases also contained a scattered, focally heavy (CD3+) lymphocytic infiltrate and occasional lymphoid aggregates. Inflammatory changes in OA SF reflected this cell composition with numerous CD68+ macrophages and CD3+ lymphocytes being noted in inflammatory OA cases. The SF volume was greater (> 5ml) in cases of inflammatory OA. Non-inflammatory OA knee joints contained very few inflammatory cells, which were mainly macrophages, in both the synovial membrane and SF. Our findings indicate that inflammatory changes in the synovial membrane of OA knee joints are reflected in the SF and that the volume of SF is commonly increased in cases of inflammatory OA. Both macrophages and lymphocytes in the inflammatory infiltrate of knee joint SF may contribute to joint destruction in OA by providing mononuclear phagocyte osteoclast precursors and the production of inflammatory cytokines and growth factors that promote osteoclastogenesis. In conclusion, the cytology of SF and synovitic membrane are similar in inflammatory OA. With knee effusions of greater than 5mls and inflammatory synovitic membrane consideration of total knee arthoplasty in the presence of single compartment disease should be considered because of the risk of further joint destruction

Aims

To investigate the correlations among cytokines and regulatory T cells (T-regs) in ankylosing spondylitis (AS) patients, and their changes after anti-tumour necrosis factor-α (TNF-α) treatment.

In the past, the clinical outcome of earlier types of resurfacing hip arthroplasty was often characterised by a high percentage of failures and early mobilisations. An implant retrieval of a Co-Cr head and UHMWPE cup cemented resurfacing hip prosthesis was analysed. The implant was in place 11 years, without any clinical problem for nearly 10 years. The cup was highly worn. There was a complete fracture of the interface between cement and bone at the base of the femural neck. A significant hyperplastic reaction was present at the level of the synovial membrane, with fibrin deposits, hyperplasia of lining cells and a cellular infiltrate formed mostly by macrophages, with occasional giant cells and localised groups of perivascular lymphocytes. Immunohistochemical analysis showed that all lymphocytes were of the T type and that the largest part of macrophages containing debris were not activated. Inside the prosthetic head there were only traces of ossified tissue. This picture indicated that for a long time no viable bone tissue had been in contact with the cement and bone rarefaction was massive. The study shows an important cause of the failure of earlier types of hip resurfacing arthroplasty, namely the abnormal stress distribution that caused the complete bone rarefaction

We analysed the cellular immune response in ten transplantations of different massive bone allografts, of which five had a poor clinical outcome. Cytotoxic T lymphocytes (CTL) and T helper lymphocytes (TH) against mismatched donor antigens were found in all patients. More importantly, CTL with a high affinity for donor antigens were found in five cases. High-affinity CTL need no CD8 molecule to stabilise the antigen binding and are strongly associated with rejection of heart and corneal transplants. Even after removal of most of the bone-marrow cells, we found high-affinity CTL and high TH frequencies. This T-cell response could be detected over a period of years. We conclude that frozen bone allografts can induce high-affinity donor-specific CTL. The present assay allows qualification and quantification of the levels of CTL and TH in the blood. This approach may be helpful in studying the effect of the immune response on the outcome of the graft

Introduction: We have previously shown an association between whole blood metal particles from unilateral metal on metal (MOM) hip resurfacing and reduced CD8+ T cells (JBJS Br April 2006). There are no reported clinical effects of these findings. Certain patients maybe at high risk of developing clinical effects; one such group is patients with bilateral hip resurfacings. There are no published studies of bilateral hip resurfacings. Our aim was to investigate the association between whole blood metal ions and reduced CD8+ T cells in a follow up cohort of bilateral MOM hip resurfacings. Method : Peripheral blood samples were analysed from patients with bilateral MOM hip resurfacings (n=25), unilateral hip resurfacings (n=34) and metal on polyethylene (MOP) hip arthroplasty (n=34). Samples were analysed for: lymphocyte subsets (FACS analysis); whole blood cobalt and chromium ion levels (using inductively-coupled mass spectrometry). Xrays revealed all hip components were well fixed. Results : When compared to patients with standard MOP hip replacements there was a 30% reduction in both the bilateral and unilateral resurfacing groups’ level of CD8+ cells (T cytotoxic) (p=0.010). All other lymphocyte subgroups were not significantly different. There was evidence of a threshold effect of raised metal ions and reduced CD8+ T cells but no evidence of a dose-response relationship. Conclusions : Bilateral MOM hip resurfacing is associated with a reduced CD8+ T cell count when compared to MOP hip arthroplasty. This association is not significantly different from the levels seen after unilateral MOM hip resurfacing

1. On the basis of, first, a mathematical analysis of the age-specific and sex-specific prevalence of Dupuytren's contracture; second, the genetical aspects; and last, the pathology, it is concluded that Dupuytren's contracture is probably a spontaneous disturbed-tolerance auto-immune disease. 2. The proportion of predisposed individuals at birth is about 20 per cent of males and females in the population studied by Early (1962), although it differs between populations and races. 3. The disease is probably initiated by four random, dependent-type, autosomal somatic gene mutations in a stem cell of the lymphoid system. With the accumulation of the fourth and final somatic mutation, a "forbidden-clone" of lymphocytes is probably generated. There is a latent period between the occurrence of the last initiating event and diagnosis. 4. In men the average latent period is about fifteen years, in women it is about thirty years. 5. The target tissue primarily attacked by forbidden lymphocytes is unknown, although proliferating fibroblasts are evidently a consequence of the auto-immune attack

Introduction: Although the influence of preoperative nutritional status on short term outcome in arthroplasty is well known, its relationship with early prosthetic joint infection (EPJI) in total knee replacement remains unclear. Aim: Our aim was to assess the effect of preoperative nutritional status on patients who went on to present with EPJI following total knee replacement surgery. This assessment was based on preoperative blood tests and anthropometric measurements. Methods: A total of 213 patients undergoing total knee replacement between December 2007 and May 2008 were included in the study. Patients with rheumatoid arthritis were excluded. For each patient we pre-operatively checked haemoglobin level, CRP, ESR, total lymphocyte and protein count, albumin and pre-albumin concentration and triglicerids, cholesterol and creatinine levels. Triceps skindfold and arm/muscle circumference were measured the day before surgery. The body mass index was calculated based on the information contained in the anaesthetic chart. We also collected information about co-morbidities such as Diabetes, High blood pressure, ASA grading, age and gender. Information about early infections, both superficial and deep, was collected. A descriptive statistical analysis and logistic regression models approach for independent risk factors were performed. Results: The mean age was 71.5 years. There were 162 female and 51 male. Eleven patients (5.16%) had early wound infection: 5 deep EPJI and 6 superficial. Neither co-morbidities nor preoperatively laboratory test except CRP (OR 1.44, p=0.03) were associated with a high early infection risk. However, there was an inversely proportional relationship between EPJI and anthropometric measurements: triceps skindfold (OR 0.9 p=0.011) and fat area (FA) (OR 0.94, p=0.01). Conclusion: A low triceps skindfold and FA were associated with an increment of risk of EPJI after a knee replacement. Although the relationship between some laboratory test as pre-albumin and lymphocyte account and wound healing and postoperatively complications is well known, we didn’t find it with EPJI in our group except for CRP levels

Aims

This study aimed to compare the performance of survival prediction models for bone metastases of the extremities (BM-E) with pathological fractures in an Asian cohort, and investigate patient characteristics associated with survival.

Introduction and aim: We have previously shown suppressed levels of CD8+ T lymphocytes in patients with metal-on-metal (MOM) hip resurfacing compared to patients with metal on polyethylene hip replacements. Functional assessment of T lymphocytes may help to determine the importance of this CD8+ reduction following hip resurfacing. Method: We isolated peripheral blood mononuclear cells (PBMC) from patients with unilateral MOM hip resurfacing (n=7) and healthy controls without hip replacement (n=8). Patients with hip resurfacing had excellent Harris Hip scores (mean 90) and well fixed components on radiographs. Whole blood and serum levels of Cobalt (Co) and Chromium (Cr) ions were measured with Inductively-Coupled Mass Spectrometry. T cell function was assessed by. cell proliferation assays (3H-thymidine incorporation) and. cytokines secretion (ELISA) following exposure to antigen challenge using Tetanus Toxoid and polyclonal mitogen phytohaemoagglutinin (PHA). Results: Co and Cr ion levels were significantly elevated in the MOM hip resurfacing group compared to the control group (p< 0.001). Proliferation rates of T cells were comparable between the two groups over one week, but interferon-gamma (IFN-γ) production in the MOM hip resurfacing group was significantly decreased (p < 0.05), when compared to the control group. Conclusion: IFN-γ is normally produced by CD8+ (T cytotoxic cells) and CD4+ (T helper 1 cells) in response to viral infection and high levels of IFN-γ is associated with autoimmune disease. Raised levels of metal ions from hip resurfacing reduces the production of IFN-γ following stimulation with PHA. This finding has been patented for potential therapeutic use through MRC technology

Metal meshes are used in revision surgery of the hip to contain impacted bone grafts in cases with cortical or calcar defects in order to provide rotational stability to the stem. However, the viability of bone allografts under these metal meshes has been uncertain. We describe the histological appearances of biopsies obtained from impacted bone allografts to the calcar contained by a metal mesh in two femoral reconstructions which needed further surgery at 24 and 33 months after the revision procedure. A line of osteoid and viable new bone was observed on the surface of necrotic trabeculae. Active bone marrow between these trabeculae showed necrotic areas in some medullary spaces with reparative fibrous tissue and isolated reactive lymphocytes. This is interpreted as reparative changes after revascularisation of the cancellous allografts. These pathological findings are similar to those reported in allografts contained by cortical host bone and support the hypothesis that incorporation of morcellised bone under metal meshes is not affected by these devices

Background: Metal-on-Metal (MoM) hip bearings are being implanted in ever increasing numbers and into ever-younger patients. The consequence of chronic exposure to metal ions is a cause for concern. Therefore, by using cytogenetic biomarkers, we investigated a group of patients who have had MoM bearings in-situ for in excess of 30 years. Method: Whole blood specimens were obtained from an historical group of patients who have had MoM bearings in-situ for in excess of 30 years. Blood was also obtained from an age and sex matched control group and from patients with Metal-on-Polyethylene (MoP) components of the same era. The whole blood was cultured with Pb-Max karyotyping medium and harvested for cytogenetics after 72 h. The 24 colour FISH (Fluorescent In Situ Hybridisation) chromosome painting technique was performed on the freshly prepared slides allowing chromosomal mapping. Each slide was evaluated for chromosomal aberrations (deletions, fragments and translocations) against the normal 46 (22 pairs and two sex) chromosomes. At least 20 metaphases per sample were scored and the number of Aberrations per cell calculated. Results: Chromosomal aberrations, including deletions, fragments and translocations were only detected in the peripheral blood lymphocytes isolated from the group that had MoM bearings. These changes were not present in the age and sex matched control group. The chromosomal aberrations were also detected in the patients previously exposed to MoM bearings who have been revised to a MoP articulation. Conclusion: We have detected dramatic chromosomal aberrations in peripheral blood lymphocytes in a group of patients chronically exposed (over 30 years) to elevated metal ions. It is not known whether these aberrations have clinical consequences or whether they are reproduced in other cells in the body. The results emphasise the need for further investigations into the effect of chronic exposure to elevated metal ions produced by Orthopaedic implants

The pathogenesis of osteolysis in failed total hip arthroplasty is not fully understood. The purpose of this study is to identify CD4+CD25+ Regulatory T cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis. Intra-operative tissue samples and peripheral blood were collected from patients undergoing revision total hip arthroplasty surgery. Regulatory T cells were present in the tissues, and significantly increased in the peripheral blood in patients with failed total hips compared to normal controls. Further characterization of these regulatory T cells are warranted as they may play a role in osteolysis in loose total hip replacements. Osteolysis remains the most common complication following total joint arthroplasty. To date, no authors have investigated the role of CD4+CD25+ regulatory T cells (T. REG. ) participating in the osteolytic pathogenesis. The purpose of this study is to quantitate the presence of T. REG. cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis. Fifteen consecutive patients booked for revision total hip arthroplasty secondary to osteolysis were included. Tissue samples were collected: peripheral blood (PB), synovial fluid (SF), synovial tissue (ST), and interface tissue (IT) between the failed component and the bone defect. Total lymphocytes were isolated and analyzed using fluorescent-tagged antibody cell sorting (FACS) for the presence of T. REG. cells. Frozen sections of ST and IT were analyzed with immunohistochemistry for T. REG. cells. T. REG. cells were significantly upregulated (p< 0.01) in the PB (68%) of revision hip patients compared to normal controls PB (44%). In the synovial tissue (ST) and interface tissue (IT), 57% of the lymphocytes isolated were TREG cells. The presence of T. REG. cells in the ST and IT were confirmed with immunohistochemistry. T. REG. cells are upregulated in the peripheral blood of patients with failed total hips secondary to osteolysis. The TREG cells are also present in the synovial tissue and interface tissue. Evidence for involvement of regulatory T cells contribute to our understanding of this complex biologic response to artificial wear particles. Functional studies of these T. REG. cells are warranted as they are upregulated in patients with loose total hip replacements

Malnutrition has been identified as an independent risk factor for surgical site infection (SSI). Guidelines advise that malnourished patients should be counselled and strategies implemented to improve nutritional intake prior to surgery. However, the current total hip replacement (THR) literature lacks of prospective clinical trials. The aim of this study was to investigate if the probability of acute SSI following THR is related to whether or not the patient had pre-operative low transferrin levels, low albumin levels and/or low total lymphocyte cell count (TLC). All patients receiving THR in a single Institution during a 2-year period were assessed prospectively for presence of malnutrition and SSI within 3 months after unilateral THR. Malnutrition was defined as albumin <35 g/L, transferrin <2g/L or TLC < 1.5 E. 9. /L. Patients with previous infection(s) were excluded. Multivariate analysis included gender, age, BMI, diabetes, and immunocompromised status. 478 patients with a complete dataset were included in the study; 137 (27.6%) had at least one low value of transferrin, TLC or albumin. SSI was recorded in 22 hips (4.6%) including 6 deep infections. Hypoalbuminaemia (RR, 1.28, p=0.5), low transferrin (RR, 1.39, p=0.4) or low TLC (RR, 1, p=0.1) were not associated with SSI. Multivariate analysis showed no association between abnormal blood tests suggesting malnutrition, BMI and SSI. Only BMI had a low p value for association with SSI (p=0.006). This study shows that abnormal blood tests associated with malnutrition are not an independent risk factor for SSI in THR

Rheumatoid arthritis (RA) is an autoimmune disease that involves T and B cells and their reciprocal immune interactions with proinflammatory cytokines. T cells, an essential part of the immune system, play an important role in RA. T helper 1 (Th1) cells induce interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), and interleukin (IL)-2, which are proinflammatory cytokines, leading to cartilage destruction and bone erosion. Th2 cells primarily secrete IL-4, IL-5, and IL-13, which exert anti-inflammatory and anti-osteoclastogenic effects in inflammatory arthritis models. IL-22 secreted by Th17 cells promotes the proliferation of synovial fibroblasts through induction of the chemokine C-C chemokine ligand 2 (CCL2). T follicular helper (Tfh) cells produce IL-21, which is key for B cell stimulation by the C-X-C chemokine receptor 5 (CXCR5) and coexpression with programmed cell death-1 (PD-1) and/or inducible T cell costimulator (ICOS). PD-1 inhibits T cell proliferation and cytokine production. In addition, there are many immunomodulatory agents that promote or inhibit the immunomodulatory role of T helper cells in RA to alleviate disease progression. These findings help to elucidate the aetiology and treatment of RA and point us toward the next steps.

Cite this article: Bone Joint Res 2022;11(7):426–438.

Coxarthrosis is a common problem. Changes in all articular structures during coxarthrosis were described extensively, besides labrum. This study was designed to:. describe histological changes in the labrum during coxarthrosis, and correlate them with radiographic changes. compare changes in various portions of the labrum. assess labrum status in main etiological types of coxarthrosis. Methods: Consecutive patients scheduled for THR were analyzed. Cases of systemic disorders, septic arthritis of the hip, previous hip surgeries were excluded. All hips were assessed radiographically, and staged according to Hip Osteoarthrosis Radiographic Grading System (HORGS) and for etiology to: dysplastic, idiopathic and avascular necrosis (AVN) groups. From the group of 90 patients in 77 hips we were able to harvest hip labrum during THR. All labra were examined by histological techniques for the presence of: labral matrix degeneration of, granular matrix breakdown, pseudocysts formation, matrix calcifications, chondrocyte apoptosis, macrophage and lymphocyte infiltration, vascular ephiteliar cell and blood vessel formation. After analysis labral histological degeneration score (LHDS) (0–11 points) was designed and computed. Results: Degeneration of the labral matrix was found in all specimens, granular matrix breakdown in 98%, pseudocysts in 91%, calcifications in 22 %, apoptosis in 19%, macrophage infiltration in 30%, lymphocyte infiltration in 19 %, vascular ephiteliar cell in 39 % and blood vessel formation in 35 % of specimens. Average LHDS for all cases was 5.4, and was the highest (6.1) in dysplastic coxarthrosis, followed by idiopathic changes (LHDS 5.7). Significantly lower (p=0.02) values were found in AVN group (LDHS 3.7). In 35 randomly selected patients anterior, middle and posterior portion of labrum was evaluated separately. The highest LDHS was found in middle portion 5.9, comparing to anterior (LDHS 3.5) and posterior (LDHS 4.25) portion, and this difference was significant (p=0.002). Radiographic assessment showed that 10 % of patients had grade 1 changes according to HORGS, 28 % grade 2, and 62% grade 3 changes. Strong correlation (p=0.0002) was found between LDHS and radiographic HORGS scores. Labra of the patients with severe coxathrosis showed more degeneration changes. Conclusions: Hip labrum shows various degenerative changes in the course of coxarthrosis like other structures in the joint. Degree of histological degeneration correlates well with radiographic changes. Small labral changes were found in AVN group with no destruction of acetabulum, the highest labral degeneration was found in cases of dysplastic coxarthrosis. The biggest changes were noted in the middle portion of the labrum. The results of this study proved that degeneration of the labrum is simultaneous with other articular structures and labral degeneration itself promotes coxarthrosis