Introduction. The intra-operative diagnosis of Prosthetic Joint Infection (PJI) is a dilemma requiring intra-operative sampling of suspicious tissues for frozen section, deep tissue culture and histopathology to secure a diagnosis. Alfa defensin-1 testing has been introduced as a quick and reliable test for confirming or ruling out PJI. This study aims to assess its intra-operative reliability compared to the standard tests. Methods. Twenty patients who underwent revision hip and knee arthroplasty surgery were included. Patients joint aspirate was tested intra-operatively with the Synovasure kit, which takes approximately ten minutes for a result. Our standard protocol of collecting 5 deep tissue samples for culture and one sample for histopathology was followed. Results for Alfa defensin-1 test were then compared with final culture and histopathology results in all these patients. Results. Our results show an excellent correlation with the final deep tissue cultures and histopathology outcomes. Literature reports frozen section to have low (58–73%) sensitivity but high (96%) specificity. Conclusions. Alfa defensin-1 test is easy, quick and efficient; results were available immediately intra-operatively. Cryosection is time consuming with samples shipped to the reference laboratory at times resulting in intra-operative delays. In our practice Alfa defensin-1 test certainly will replace frozen section for intra-operative testing

Aim. The localization of sequestrum in chronic osteomyelitis (COM) is crucial in preoperative planning. The identification of sequestrum on plain X-ray could be difficult. CT and MRI were reported to show the sequestrum. We aimed to analyze the sequestrum characteristics on 18F-FDG-PET-CT images. Methods. A prospective study included all patients diagnosed with long-bone chronic osteomyelitis. All patients had preoperative 18F-FDG-PET-CT. Images were analyzed using RadiAnt DICOM Viewer. Axial cuts were used to measure the Standard Uptake Ratio (SUV)max in the Region of Interest (ROI) in the sequestrum, the surrounding area, and the normal bone in the same cut. Surgical debridement was done as standard; samples were taken for microbiology and histopathology, and the intraoperative finding was documented. Results. Nineteen patients (17 males/2 females) were operated on in one center between October/2021 and Jan/2023 at a mean age of 32±18. There were 10 tibias, 7 femurs, one ulna, and one fibula. Ten had postoperative COM, six open fractures, and three hematogenous OM. They all showed sequestrum on PET-CT; the dead bone appeared void, surrounded by a halo of increased uptake. There was a trend of lower uptake in the sequestrum compared to the halo around. The mean SUVmax at the sequestrum was 4.18±3.16, compared to the surrounding halo, 7.08±5.81. The normal bone has a mean SUVmax of 1.61±1.42. Sequestrum was removed successfully in all cases. Conclusion. 18F-FDG-PET-CT can precisely localize the sequestrum preoperatively, it has a lower uptake than tissues around it. This would facilitate planning and improve the quality of debridement

INTRODUCTION. Tuberculosis (TB) is a public health challenge. However, musculoskeletal involvement represents 10–15% of all extrapulmonary cases. Upper extremity involvement is extremely rare. The slow progressive course of clinical symptoms and lack of radiological signs lead to difficulties in establishing early diagnosis. Hence, the patients who have tuberculosis of the wrist are usually misdiagnosed. We report 5 cases of tuberculosis of the wrist seen in our unit from the year 2012 to 2021. METHODS. Cases were retrospectively evaluated on demographics, nature of history, clinical presentation, culture finding, and histopathological findings from 2012 to 2021 at our unit. RESULTS. A total of 5 cases were evaluated retrospectively. Three patients were more than 60 years old and two were less than 30 years old. Four of the patients presented with wrist swelling 2 of them had wrist pain and only 1 patient had discharge from the wound. The duration of the symptoms ranges from 2 months to 3 years. Only one of the patients had a history of pulmonary TB contact whereas the others didn't. All patients underwent surgery. All of the patients had positive cultures for Mycobacterium tuberculosis complex and histopathological examination showed necrotizing granulomatous inflammation from specimens taken intraoperatively, which confirmed the diagnosis of tuberculosis of the wrist. DISCUSSIONS. Our cases show that the common presentation of tuberculosis of the wrist was comparable to other literature. Most of the patients presented with chronic wrist swelling with or without wrist pain. The diagnosis of the disease was delayed an average of 10 - 12 months from symptoms onset to diagnosis. S. Bayram et al reported a case where the diagnosis was made 45 months later. Due to its rarity, it often is misdiagnosed, resulting in delays in the proper treatment. CONCLUSION. The diagnosis of the TB wrist remains difficult because of insidious and non-specific. presentation. However, early diagnosis is essential to avoid delays in treatment and complications. Hence, chronic wrist pain, and swelling with or without unexplained bone erosion around the wrist area must be highly suspected of being osteoarticular tuberculosis

Background and aim. In 2019, specific diagnostic and antibiotic treatment recommendations for diabetic foot infection (DFI) and osteomyelitis (DFO) were introduced in our institution. They include principles on numbers of biopsies to obtain for microbiological/histopathological examinations, labeling anatomic localization, and antibiotic treatment (ABT) duration based on the aforementioned findings. ABT should be stopped after complete resection of infected bone. In case of incomplete resection, treatment is continued for 4–6 weeks. Two years after the introduction of these recommendations, we investigated the degree of implementation for hospitalized patients. Method. Adult patients with DFI/DFO undergoing surgical intervention from 01/2019–12/2021 were reviewed retrospectively. Diagnostic procedures were assigned to each episode when performed ≤30 days before surgical invention. Chi-square and Mann-Whitney-U tests were performed where appropriate. Results. We included 80 patients with 117 hospital episodes and 163 surgical interventions (mean 1.5 episodes and 2 interventions per patient). The mean age was 69.6 (SD 11.5) years, 75% were male. Vascular examination and MRI were performed in 70.9% and 74.4% of episodes, respectively. Impaired perfusion and DFO were confirmed in 34.9% and 56.3%, respectively. Blood cultures were sampled in 34.2%, bacteremia detected in 7.7% with S. aureus being the most common microorganism. Biopsies were obtained in 71.8% of operations, in 90.5% of those 3–5 samples. These were sent for histological examination in 63.2% of the interventions. In 43.6% the anatomic location was labeled ‘proximal to the resection margin’. Preoperative antibiotics were administered in 41.9% of the episodes because of concomitant soft-tissue infections. The most commonly used compound was amoxicillin/clavulanate (74.4%). ABT duration varied significantly when there were signs of DFO in preoperative MRI (p=0.015). The mean duration of antibiotic therapy was 9 (IQR 5–15) days in surgically cured episodes and 40.5 (IQR 15–42) days in cases with resection margins in non-healthy bone (p<0.0001). The results were similar when analyzing treatment duration with respect to osteomyelitis in histology: 13 (IQR 8–42) versus 29 (IQR 13–42) days, respectively (p=0.026). Conclusions. The adherence to recommendations in terms of biopsy sampling was excellent, moderate for sending samples to histology and poor for labeling the anatomic location. The adherence to ABT duration was good but can be improved by shortening treatment duration for surgically cured cases. Results of preoperative MRI appear to be influential on the decision-making for treatment duration

Aim. Treatment algorithms for fracture-related nonunion depend on the presence or absence of bacterial infection. However, the manifestation of septic nonunion varies. Low-grade infections, unlike manifest infections, lack clinical signs of infection and present similarly to aseptic nonunion. The clinical importance of low-grade infection in nonunion is not entirely clear. Therefore, the aim of this study was to evaluate the clinical relevance of low-grade infection in the development and management of femoral or tibial nonunion. Method. A prospective, multicenter clinical study enrolled patients with nonunion and regular healed fractures. Preoperatively, complete blood count without differential, C-reactive protein (CRP), and procalcitonin were obtained, clinical signs of infection were recorded, and a suspected septic or aseptic diagnosis was made based on history and clinical examination. During surgical nonunion revision or routine implant removal, tissue samples were collected for microbiology and histopathology, and osteosynthesis material for sonication. Nonunion patients were followed for 12 months. Definitive diagnosis of “septic” or “aseptic” nonunion was made according to diagnostic criteria for fracture-related infection, considering the results of any further revision surgery during follow-up. Results. 34 patients with regular healed fractures were included. 62 nonunion patients were diagnosed as aseptic, 22 with manifest, and 23 with low-grade infection. The positive predictive value was 88% and the negative predictive value 72% for the suspected diagnosis. The nonunion groups had significantly higher CRP levels than the regular healer group. Differentiation between septic and aseptic nonunion based on blood values was not possible. Low-grade infection demonstrated less frequently histopathologic signs of infection than manifest infection (22% vs. 50%, p=0.048), with 15% of regular healers having histopathologic signs of infection. Cutibacterium acnes was less present in manifest compared to low-grade infection (p=0.042). Healing rates for septic nonunion involving C. acnes were significantly lower for manifest infection (20%) than for low-grade infection (100%, p=0.002). Patients with low-grade infection were treated with systemic antibiotics less frequently than patients with manifest infection (p=0.026), with no significant difference in healing rate (83% vs. 64%), which was slightly lower for low-grade infection than for aseptic nonunion (90%). Conclusions. Low-grade infections play a significant role in nonunion development and are difficult to diagnose preoperatively due to the lack of clinical signs of infection and unremarkable blood counts. However, our results imply that for low-grade infections, antibiotic therapy may not always be mandatory to heal the nonunion. This study was supported by the German Social Accident Insurance (FF-FR0276)

Aim. To make an inoculum for induction of Implant-Associated Osteomyelitis (IAO) in pigs based on bacterial aggregates resembling those found on the human skin, i.e. aggregates of 5–15 µm with low metabolic activity. The aggregates were evaluated and compared to a standard planktonic bacterial inoculum. Method. The porcine Staphylococcus aureus strain S54F9 was cultured in Tryptone Soya Broth for seven days. Subsequently, the culture was filtered through cell strainers with pore sizes of 15 µm and 5 µm, respectively. The fraction of 5–15 µm aggregates in the top of the 5 µm filter was collected as the aggregate-inoculum. The separation of aggregates into different size fractions was evaluated by light microscopy. The metabolism of the aggregate-inoculum and a standard overnight planktonic inoculum was evaluated with isothermal microcalorimetry. In total, six female minipigs were allocated into three groups (n=2), receiving different inoculums. Group A: overnight planktonic inoculum; 10. 4. CFU S. aureus (S54F9), Group B: seven days old 5–15 µm aggregate-inoculum; 10. 4. CFU S. aureus (S54F9), Group C: saline. All inoculums were placed in a pre-drilled implant cavity in the right tibia of the pig and a sterile stainless-steel implant was inserted. The pigs were euthanized seven days after surgery. Postmortem macroscopic pathology, microbiology, computed tomography and histopathology were performed. Results. The separation of aggregates into different size fractions was done successfully by the filtering method. Isothermal microcalorimetry showed, a delayed Time-to-peak metabolic activity of the aggregate-inoculum compared to the planktonic inoculum. S. aureus was isolated from subcutis, bone and implants from all animals in groups A and B. Both group A animals showed osteomyelitis at gross inspection with suppuration and sequestration, while groups B and C animals had no macroscopic lesions. From CT scans, both group A animals also showed positive signs of osteomyelitis, i.e., osteolysis, while only one animal in group B did, and none in group C. Histopathological examination of the bones showed more extensive inflammation in group A animals compared to those in group B, which showed more osteoid formation. Conclusions. Formation and separation of low metabolism bacterial aggregates into different size fractions was possible. The aggregates can be used as inoculum in the porcine IAO model, with microbiological re-isolation from both implants and tissue. Furthermore, the aggregates caused a less aggressive IAO, than the planktonic counterparts. Using aggregated bacteria as inoculum appears to be more relevant to the clinical situation of infecting bacteria

Aim. Differentiation of infected (INF) nonunion from aseptic (AS) nonunion is crucial for the choice of intra- and postoperative treatment. Preoperative diagnosis of infected nonunion is challenging, especially in case of low-grade infection lacking clinical signs of infection. Standard blood markers such as C-reactive protein or leucocyte count do not aid in preoperative diagnosis. Proteomic profiling has shown promising results for differentiation of numerous chronic disease states, and in this study was applied to preoperative blood samples of patients with nonunion in an attempt to identify potential biomarkers. Method. This prospective multicenter study enrolled patients undergoing revision surgery of femur or tibia nonunion. Patients with implant removal after regular fracture healing (HEAL) were included as a control-group. Preoperative blood samples, intraoperative tissue samples, sonication of osteosynthesis material and 1-year-follow-up questionnaire were taken. Nonunion patients were grouped into INF or AS after assessing bacterial culture and histopathology of retrieved samples. Diagnosis of infection followed the fracture related infection consensus group criteria, with additional consideration of healing one year after revision surgery. Targeted proteomics was used to investigate a predefined panel of 45 cytokines in preoperative blood samples. Statistical differences were calculated with Kruskal Wallis and Dunn's post hoc test. Cytokines with less than 80% of samples being above the lower limit of detection range (LLDR) were excluded for this study. Results. We recruited 62 AS, 43 INF and 32 HEAL patients. Patients in the two nonunion groups (INF and AS) did not differ concerning smoking, diabetes or initial open or closed fracture. Thirty-two cytokines were above LLDR in >80% of patients. INF patients showed a significant difference in expression of 8 cytokines compared to AS, with greatest differences observed for Macrophage Colony Stimulating Factor 1 (MCSF-1) and Hepatocyte Growth Factor (HGF) (p<0.01). In comparing AS with HEAL patients, 9 cytokines displayed significant differences, including interleukin (IL)-6, Vascular Endothelial Growth Factor A (VEGFA), Matrix Metalloproteinase 1 (MMP-1). Comparison of INF with HEAL patients revealed significantly different expression of 20 cytokines, including. IL-6, IL-18, VEGFA or MMP-1. Conclusions. Our study revealed differences in plasma cytokine profile of blood samples from INF and AS patients. Although no single biomarker is sufficient to differentiate these patients preoperatively in isolation, future multivariant analysis of this cytokine data in combination with clinical characteristics may provide valuable diagnostic insights. Funded by German Social Accident Insurance (FF-FR 0276) and AO Trauma (AR2021_04)

Diffuse-type Tenosynovial Giant-Cell Tumour (d-TGCT) of large joints is a rare, locally aggressive, soft tissue tumour affecting predominantly the knee. Previously classified as Pigmented Villonodular Synovitis (PVNS), this monoarticular disease arises from the synovial lining and is more common in younger adults. Given the diffuse and aggressive nature of this tumour, local control is often difficult and recurrence rates are high. Current literature is comprised primarily of small, and a few larger but heterogeneous, observational studies. Both arthroscopic and open synovectomy techniques, or combinations thereof, have been described for the treatment of d-TGCT of the knee. There is, however, no consensus on the best approach to minimize recurrence of d-TGCT of the knee. Some limited evidence would suggest that a staged, open anterior and posterior synovectomy might be of benefit in reducing recurrence. To our knowledge, no case series has specifically looked at the recurrence rate of d-TGCT of the knee following a staged, open, posterior and anterior approach. We hypothesized that this approach may provide better recurrence rates as suggested by larger more heterogeneous series. A retrospective review of the local pathology database was performed to identify all cases of d-TGCT or PVNS of the knee treated surgically at our institution over the past 15 years. All cases were treated by a single fellowship-trained orthopaedic oncology surgeon, using a consistent, staged, open, posterior and anterior approach for synovectomy. All cases were confirmed by histopathology and followed-up with regular repeat MRI to monitor for recurrence. Medical records of these patients were reviewed to extract demographic information, as well as outcomes data, specifically recurrence rate and complications. Any adjuvant treatments or subsequent surgical interventions were noted. Twenty-three patients with a minimum follow-up of two years were identified. Mean age was 36.3 at the time of treatment. There were 10 females and 13 males. Mean follow-up was seven and a half years. Fourteen of 23 (60.9%) had no previous treatment. Five of 23 had a previous arthroscopic synovectomy, one of 23 had a previous combined anterior arthroscopic and posterior open synovectomy, and three of 23 had a previous open synovectomy. Mean time between stages was 87 days (2.9 months). Seven of 23 (30.4%) patients had a recurrence. Of these, three of seven (42.9%) were treated with Imatinib, and four of seven (57.1%) were treated with repeat surgery (three of four arthroscopic and one of four open). Recurrence rates of d-TGCT in the literature vary widely but tend to be high. In our retrospective study, a staged, open, anterior and posterior synovectomy provides recurrence rates that are lower than rates previously reported in the literature. These findings support prior data suggesting this approach may result in better rates of recurrence for this highly recurrent difficult to treat tumour

Diffuse-type Tenosynovial Giant-Cell Tumour (d-TGCT) of large joints is a rare, locally aggressive, soft tissue tumour affecting predominantly the knee. Previously classified as Pigmented Villonodular Synovitis (PVNS), this monoarticular disease arises from the synovial lining and is more common in younger adults. Given the diffuse and aggressive nature of this tumour, local control is often difficult and recurrence rates are high. Current literature is comprised primarily of small, and a few larger but heterogeneous, observational studies. Both arthroscopic and open synovectomy techniques, or combinations thereof, have been described for the treatment of d-TGCT of the knee. There is, however, no consensus on the best approach to minimize recurrence of d-TGCT of the knee. Some limited evidence would suggest that a staged, open anterior and posterior synovectomy might be of benefit in reducing recurrence. To our knowledge, no case series has specifically looked at the recurrence rate of d-TGCT of the knee following a staged, open, posterior and anterior approach. We hypothesized that this approach may provide better recurrence rates as suggested by larger more heterogeneous series. A retrospective review of the local pathology database was performed to identify all cases of d-TGCT or PVNS of the knee treated surgically at our institution over the past 15 years. All cases were treated by a single fellowship-trained orthopaedic oncology surgeon, using a consistent, staged, open, posterior and anterior approach for synovectomy. All cases were confirmed by histopathology and followed-up with regular repeat MRI to monitor for recurrence. Medical records of these patients were reviewed to extract demographic information, as well as outcomes data, specifically recurrence rate and complications. Any adjuvant treatments or subsequent surgical interventions were noted. Twenty-three patients with a minimum follow-up of two years were identified. Mean age was 36.3 at the time of treatment. There were 10 females and 13 males. Mean follow-up was seven and a half years. Fourteen of 23 (60.9%) had no previous treatment. Five of 23 had a previous arthroscopic synovectomy, one of 23 had a previous combined anterior arthroscopic and posterior open synovectomy, and three of 23 had a previous open synovectomy. Mean time between stages was 87 days (2.9 months). Seven of 23 (30.4%) patients had a recurrence. Of these, three of seven (42.9%) were treated with Imatinib, and four of seven (57.1%) were treated with repeat surgery (three of four arthroscopic and one of four open). Recurrence rates of d-TGCT in the literature vary widely but tend to be high. In our retrospective study, a staged, open, anterior and posterior synovectomy provides recurrence rates that are lower than rates previously reported in the literature. These findings support prior data suggesting this approach may result in better rates of recurrence for this highly recurrent difficult to treat tumour

Introduction. We demonstrate the preliminary results with a novel technique to solve large bone defects using two lengthening nails, working together and aligned in a custom made device. An illustrative case that successfully produced 17 cm bone in 3.5 months, is presented. Materials and Methods. A 28 year old healthy male presented with a slowly growing mass in the left femur. No general symptoms were reported, no weight loss, no previous illness. Histopathology, CT and MRI scans revealed a malignant diaphyseal bone tumor. A three-stage trifocal bone transport was projected and conducted based on a 3D model test. Results. Trifocal bone transport using two lengthening nails in a custom made device, reduced the 17 cm bone defect in 3.5 months. Follow up was 9 months. Conclusions. The presented technique successfully solved the clinical problem and is a showcase for further developments of internal devices for complex and large bone losses and lengthenings

Aim. To describe the histopathology of the first and last debrided bone tissue in chronic osteomyelitis and answer the following research question; is the last debrided bone tissue viable and without signs of inflammation?. Method. In total, 15 patients with chronic osteomyelitis were allocated to surgical treatment using a one stage protocol including extensive debridement. Suspected infected bone tissue eradicated early in the debridement procedure was collected as a clearly infected sample (S1). Likewise, the last eradicated bone tissue was collected as a suspected non-infected sample (S2), representing the status of the bone void. In all cases, the surgeon debrided the bone until visual confirmation of healthy bleeding bone. The samples were processed for histology, i.e. decalcification and paraffin embedding, followed by cutting and staining with Haematoxylin and Eosin. Immunohistochemistry with MAC-387 antibodies towards the calprotectin of neutrophil granulocytes (NGs) was also performed and used for estimation of a neutrophil granulocyte (NG) score (0, 1, 2 or 3), by the method described for fracture related infections (1). Results. For the S1 samples the median NG score was 3 which is considered confirmatory for infection. However, following debridement the median NG score was significantly (p = 0.032) reduced to 2. Often NGs were seen as single cells, but in seven S1 samples and in one S2 sample massive NG accumulations were observed. The S1 samples showed a mix of granulation tissue, fibrosis, viable bone, and bone necrosis. The S2 samples contained viable bone tissue and occasionally (10/15) small fragments of necrotic bone or bone debris were seen. Furthermore, a large number of erythrocytes were observed in most S2 samples. Conclusions. The present study shows that the inflammatory response still existents after debridement, although the response fades from the center of infection. Therefore, sampling of debrided bone tissue for histology must be performed initially during surgery, to avoid underestimation of the inflammatory response, i.e. the NG score. The last debrided bone tissue cannot by definition be considered completely viable and caution should be made to remove blood (rinse) before intraoperative evaluation of the viability of debrided cancellous bone. Remnant necrotic bone fragments or debris could represent low-vascular hiding places for leftover bacteria. Application of local antibiotics might have a central role in clearing of these small non-viable bone pieces at the bone void interface

Aim. When a prosthetic joint infection (PJI) is suspected, guidelines recommend performing periprosthetic samples, at least one for histopathological examination and 3 to 6 for microbiological culture. The diagnosis of infection is based on the presence of neutrophil granulocytes whose number and morphology can be variable, resulting in definition of “acute” inflammation. The acute inflammation of periprosthetic tissue is supportive of infection. Since 2007, in our hospital, for all patients with suspected PJI who underwent surgery, from each sample taken by the surgeon, one part has been sent to the pathologist and the other one to the microbiologist. Our aim was to compare histopathological to microbiological results from samples taken intraoperatively at the same site. Method. We conducted a retrospective study including all surgeries for which at least one couple “histopathology-culture” was found. Exclusion criterion was a history of antimicrobial treatment 2 weeks prior the surgery. Results. From July 2007 to April 2015, 309 surgeries for suspected PJI were performed in 181 patients. Median age of the study population was 70 years, 60% of patients were male, 45% had a history of joint infection. The location of arthroplasty was knee in 50% of cases and hip in 46%, ankle and shoulder in 4%. Surgery was performed within one month after the last prosthetic surgery in 15% of cases. According to the criteria from the Musculoskeletal Infection Society, 60% of cases should have been considered as having an infection. The median number of samples per surgery was 4 (IQR 3–5) for histopathological examination and 5 (IQR 4–6) for culture. Finally, 1247 couples “histopathology-culture” were available. Among them, histopathological examination showed acute inflammation in 292 cases (23%) and subacute inflammation in 327 cases (26%). Microorganisms considered to be pathogenic were found in 582 samples (47%). The presence of neutrophil granulocytes was well correlated with the presence of those microorganisms (OR=4.1; IC 95% 3.1–5.5). As expected, the highest correlation between acute inflammation and positive culture was observed for early infection (< 1 month) (OR = 9; 3.6–23.4) and Staphylococcus aureus infection (OR = 4.8; 3.3–7.0). There was no correlation between acute or low-grade inflammation and anaerobic or Candida infection. Conclusions. Our results confirmed histopathological examination is better correlated with culture in acute infection and/or infection due to highly virulent bacteria but must be interpreted with caution in case of chronic infection or infections due to microorganisms with low virulence

Aim. Adequate debridement of necrotic bone is of paramount importance for eradication of infection in chronic osteomyelitis. Currently, no tools are available to detect the exact amount of necrotic bone in order to optimize surgical resection. The aim of the present study was to evaluate the feasibility of an intraoperative illumination method (VELscope. ®. ) and the correlation between intraoperative and pathohistological findings in surgically treated chronic fracture related infection patients. Method. Ten consecutive patients with chronic fracture related infections of the lower extremity were included into this prospectively performed case series. All patients had to be treated surgically for fracture related infections requiring bony debridement. An intraoperative illumination method (VELscope®) was used to intraoperatively differentiate between viable and necrotic bone. Tissue samples from the identified viable and necrotic bone areas were histopathologically examined and compared to intraoperative findings. Results. In all included patients, the intraoperative illumination was deemed helpful to differentiate between necrotic and viable bone tissues during bony debridement. The histopathological examination of the samples showed good correlation of the intraoperative illumination findings with histopathological signs of necrosis for areas deemed dead and histopathological signs of intact bone for areas deemed vital during illumination. Conclusions. The fluorescence-assisted, intraoperative detection of necrotic and viable bone using the VELscope. ®. is an easy-to-use procedure that can help surgeons to optimize intraoperative bone resection in chronic fracture related infections by unmasking viable from necrotic bone tissue. This may help to improve resection techniques and eventually treatment outcome in patients in the future

Background. Ultrasound and MRI are recommended tools in evaluating postoperative pain in metal-on-metal hip (MoM) arthroplasty. Aim. To retrospectively compare MRI and ultrasound results of the hip with histopathology results in failed (MoM) hip arthroplasty. Methods. 25 hips (16 patients) who underwent revision hip surgery for painful (MoM) hip replacement/resurfacing were included in this study (March 2011 to May 2012). Average age 50.4 yrs (37–69y). Blood test for cobalt and chromium levels, ultrasound and MRI were done prior to revision surgery. 23 hips had ultrasound scan. 21 of these hips also had MRI scan prior to surgery. Scans were done at an average of 50 months from primary metal-on-metal surgery. All the ultrasound & MRI were done and reported by a single musculo-skeletal radiologist. During surgery multiple tissue samples were taken from acetabulum, capsule as well as tissue surrounding the femoral neck and sent for histopathology. 21 hip histopathology results were positive for metalosis. 2 hip histopathology results were negative for metalosis. Metalosis as defined by our histopathologist as that which is showing the presence of sheets of macrophages with dark brown pigmentation in their cytoplasm under polarized light. Results. Ultrasound examination was positive for fluid collection in 18 (78.2%). MRI was positive in 16 (76.1%). 4 patients (19%) had negative ultrasound and MRI results but were revised due to pain and were found to have histopathology positive metalosis. One patient had ultrasound positive for fluid collection with negative MRI. One patient was MRI positive for fluid but normal ultrasound findings. Conclusion. Although ultrasound and MRI are useful in screening of MoM patients still there are a significant percentage of hips, which failed with negative radiology findings

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

Introduction and aim. TKR remains one of the most successful surgeries in orthopedics. Still a sizeable number of patients remain dissatisfied reaching to a level of 30%. Our aim was to examine the excised synovium from the suprapatellar region in all osteoarthritic knees and evaluate the histopathological report to know if in a few cases the unrelenting pain and discomfort could be due to some undiagnosed pathology within the joint. Materials and Methods. We selected 40 consecutive knees at our institution operated from Oct 2014 to Jan 2015. Of the total knees 7 patients were operated as single stage bilateral TKR. Supra patellar synovium was thoroughly excised and sent for histopathology examination. Patients who were clinically, serologically and radiologically diagnosed as rheumatoid arthritis or sero negative arthritis were excluded. The implant used was Maxx Freedom knee (PS design). Results. We found abnormal reports in 8 of our 40 knees (20%). 6 of these were proven to be rheumatoid arthritis whilst 2 of the knees showed chronic villous synovitis. Conclusion. 20% of our patients exhibited result which were totally unexpected. This could be one of the many causes in persistently dissatisfied patient after a technically well done TKR. So as a routine we advocate all surgeons to send the excised synvoium for histopathology during a routine TKR. Also a large multi-centric study undertaken at various centers would definitely help to throw more light on this not so well understood topic and thus help reduce this lot of dissatisfied patients

Anterior lumbar inter-body fusion (ALIF) is a surgical procedure that is available to chronic lower back pain patients who fail to respond to conservative treatments. Failure to achieve fusion may result in persistence of pain. Fusion of the lumber vertebral segment is more accurately assessed using fine-cut helical Computed tomography (CT) scans (0.25 mm thickness slices). Unfortunately this technique exposes the body to high radiation dose with hazard of increase risk of late malignancy. An alternative imaging tool is radiostereometry (RSA) which developed as a means to determine the magnitude of relative motion between two rigid bodies. In this study we used RSA to detect movement at the fused lumbar segment (ALIF site) during flexion and extension and compare the results obtained with fine-cut helical CT scan using histopathology as final gold standard assessment tool. ALIF of three levels of lumbar spine (L1-L2, L3-L4, and L5-L6) was done in 9 sheep. The sheep divided into three groups (3sheep each). The first group had RSA assessment immediately, 3, and 6 months after surgery. The second group had RSA immediately, 3, 6, 9 months after surgery. The third group had an RSA immediately, 3, 6, 9, 12 months after surgery All the animals were humanly killed immediately after having the last scheduled RSA (group1, group2, and group 3 sheep were killed 6 month, 9month and 12 months after surgery respectively). This followed by in vitro fine cut CT and histopathology after the animals are scarified. Micro CT scan has been also used to identify the area where histopathology slide should be made to pick up fusion. Fine cut CT scan assessment for all sheep were done. The CT scan has been reported by two independent radiologists. Histopathology has been started and will finish in 2 weeks. RSA showed there was significant increasing stiffness of the spine though the fused segments as the time pass on compare to immediate postoperative assessment. CT scan were done and showed variable fusion though out the spinal segments. Histopathology of all sheep has been started and the results will be available in 2 weeks which will be followed by statistical assessment to decide how accurate RSA compare to CT scan in assessment of fusion

Aim. The liver is the major source of acute phase proteins (APPs) and serum concentrations of several APPs are widely used as markers of inflammation and infection. The aim of the present study was to explore if a local extra hepatic osseous acute phase response occurs during osteomyelitis. Method. The systemic (liver tissue and serum) and local (bone tissue) expression of several APPs during osteomyelitis was investigated with qPCR and ELISA in a porcine model of implant associated osteomyelitis (IAO) at 5, 10 and 15 days after inoculation with S. aureus or saline, respectively. Additionally, samples were also collected from normal heathy pigs and pigs with spontaneous, chronic, haematogenous osteomyelitis. Afterwards, immunohistochemistry towards different upregulated APPs was performed on the porcine osteomyelitis lesions and on bone biopsies from human patients with chronic osteomyelitis. Results. All infected porcine bone lesions (apart from Day 5 in the IAO model) were made up by necrosis, pus, and various degree of fibrotic encapsulation. A local, highly significant upregulation of Serum Amyloid A (SAA, up to 4000-fold upregulation), Complement component C3 (C3), and Inter-Alpha-Trypsin Inhibitor Heavy Chain 4 (ITIH4) were present in infected pigs compared to sterile controls. For the experimental IAO animals, the upregulation of C3 and ITIH4 increased over time, i.e., the highest expression was seen on day 15 after bacterial inoculation. In the liver, only C-reactive protein (CRP) and ITIH4 (not SAA or C3) were slightly upregulated in infected pigs. Serum concentrations of CRP, SAA and haptoglobin were only upregulated at day 5 in IAO infected animals. Immunohistochemically, comparable numbers of APP positive cells (leucocytes and bone cells) were found in human and porcine bone samples with chronic osteomyelitis. Conclusions. This is to our knowledge the first description of local APP up-regulation during chronic bone infection. Only small changes in the expression of APPs were found in the liver and serum samples. Thus, the presence of an osseous upregulation of APPs appears to be part of a predominantly local response that will be difficult to measure systemically. The importance of a local immune response in bone infections seems logical as the blood supply is severely impaired during osteomyelitis. There is a real need for supportive diagnostic bone infection criteria which should be based on a comprehensive understanding of the local inflammatory response. As seen from the present study, staining for SAA or C3 could potentially improve the diagnostic performance of histopathology

Aims. Tuberculosis (TB) infection of bones and joints accounts for 6.7% of TB cases in England, and is associated with significant morbidity and disability. Public Health England reports that patients with TB experience delays in diagnosis and treatment. Our aims were to determine the demographics, presentation and investigation of patients with a TB infection of bones and joints, to help doctors assessing potential cases and to identify avoidable delays. Patients and Methods. This was a retrospective observational study of all adults with positive TB cultures on specimens taken at a tertiary orthopaedic centre between June 2012 and May 2014. A laboratory information system search identified the patients. The demographics, clinical presentation, radiology, histopathology and key clinical dates were obtained from medical records. Results. A total of 31 adult patients were identified. Their median age was 37 years (interquartile range (IQR): 29 to 53); 21 (68%) were male; 89% were migrants. The main sites affected were joints (10, 32%), the spine (8, 26%) and long bones (6, 19%); 8 (26%) had multifocal disease. The most common presenting symptoms were pain (29/31, 94%) and swelling (26/28, 93%). ‘Typical’ symptoms of TB, such as fever, sweats and weight loss, were uncommon. Patients waited a median of seven months (IQR 3 to 13.5) between the onset of symptoms and referral to the tertiary centre and 2.3 months (IQR 1.6 to 3.4.)) between referral and starting treatment. Radiology suggested TB in 26 (84%), but in seven patients (23%) the initial biopsy specimens were not sent for mycobacterial culture, necessitating a second biopsy. Rapid Polymerase Chain Reaction-based testing for TB using Xpert MTB/RIF was performed in five patients; 4 (80%) tested positive for TB. These patients had a reduced time between the diagnostic biopsy and starting treatment than those whose samples were not tested (median eight days versus 36 days, p = 0.016). Conclusion. Patients with bone and joint TB experience delays in diagnosis and treatment, some of which are avoidable. Maintaining a high index of clinical suspicion and sending specimens for mycobacterial culture are crucial to avoid missing cases. Rapid diagnostic tests reduce delays and should be performed on patients with radiological features of TB. Cite this article: Bone Joint J 2018;100-B:119–24

A-70-year old woman underwent uncomplicated total hip arthroplasty using a titanium modular stem with a 46mm CoCr femoral head, a titanium shell, and a metal linear (Wright Medical Technology). Eight years after implantation, she presented with a painful left hip. A pelvic radiograph revealed adequate positioning of both hip implants without any signs of wear of loosening. CT scanning confirmed the presence of a 5 × 5 cm soft tissue mass in the ilium above the cup component accompanied by the iliac fracture. The patient was diagnosed as having an adverse reaction to metal debris (ARMD) after a metal-on-metal THA and revision was performed. Perioperatively?tissue necrosis and partial destruction of the abductor mechanism were found in the absence of any macroscopic infection. Both the neck trunnion and bore of the head showed slight signs of corrosion. The modular neck was revised with a ceramic 28mm head and a new dual-mobility liner(Zimmer Biomet). The iliac fracture was fixed with a porous trabecular metal augment(Zimmer Biomet). The histopathology of tissue sample revealed extensively necrotic material with focal cellular areas of inflammatory cells containing macrophages and neutrophilas. Metalic debris was also scattered in the necrotic materials. After the revision, the patient was recovered without pain or dislocation, and iliac fracture was well fixed. Instability is a substantial problem in the revision of ARMD. Extensive necrosis with gross deficiency of the abductor mechanism is associated with postoperative dislocation. Revision of failed MoM THA a dual-mobility device an effective strategy