First experiences of a hospital-based 3D printing facility - an analytical observational study.

PURPOSE: To identify the clinical impact and potential benefits of in-house 3D-printed objects through a questionnaire, focusing on three principal areas: patient education; interdisciplinary cooperation; preoperative planning and perioperative execution. MATERIALS AND METHODS: Questionnaires were sent from January 2021 to August 2022. Participants were directed to rate on a scale from 1 to 10. RESULTS: The response rate was 43%. The results of the rated questions are averages. 84% reported using 3D-printed objects in informing the patient about their condition/procedure. Clinician-reported improvement in patient understanding of their procedure/disease was 8.1. The importance of in-house placement was rated 9.2. 96% reported using the 3D model to confer with colleagues. Delay in treatment due to 3D printing lead-time was 1.8. The degree with which preoperative planning was altered was 6.9. The improvement in clinician perceived preoperative confidence was 8.3. The degree with which the scope of the procedure was affected, in regard to invasiveness, was 5.6, wherein a score of 5 is taken to mean unchanged. Reduction in surgical duration was rated 5.7. CONCLUSION: Clinicians report the utilization of 3D printing in surgical specialties improves procedures pre- and intraoperatively, has a potential for increasing patient engagement and insight, and in-house location of a 3D printing center results in improved interdisciplinary cooperation and allows broader access with only minimal delay in treatment due to lead-time.

The significance of surveillance imaging in children with Ewing sarcoma and osteosarcoma.

Primary bone tumors in children and adolescents, while rare, pose significant challenges in diagnosis and management. Children treated for Ewing sarcoma and osteosarcoma are offered a 5-year follow-up program after end of treatment, including radiological surveillance of primary location of tumor and the lungs. There is no consensus regarding how often and how the children should be followed with radiological imaging. This retrospective descriptive study of 69 patients (34 with Ewing sarcoma and 35 with osteosarcoma) investigated the consequences of abnormal findings in 1279 follow-up images. Nine relapses were detected, 4 in the Ewing group (3 local and 1 pulmonary) and 5 in the osteosarcoma group (1 local and 4 pulmonary). Of these, only two patients exhibited symptomatic relapses, with the remainder identified through imaging. The positive predictive value for relapse detection was 0.44 in the Ewing group, and 0.5 in the osteosarcoma group. In the Ewing sarcoma patient image follow-up program, the probability of anomaly detection was 12% (95% CI, 10-15). For osteosarcoma patients, the likelihood was 6% (95% CI, 4-8). Our data indicates that abnormal findings on follow-up images rarely represents relapse of tumor. As the surveillance protocol differs between the patient groups, wherein Ewing sarcoma patients primarily are monitored through MRI while osteosarcoma patients are predominantly tracked via X-rays, there is an increased occurrence of incidental findings in the first group. However, it is imperative to interpret imaging data in conjunction with clinical information, avoiding isolated reliance on imaging results when making treatment decisions.

Elevated cobalt levels in metal-on-polyethylene knee megaprostheses: a prospective 1-year cohort study of 56 patients with hip and knee megaprostheses.

BACKGROUND AND PURPOSE: Concerns have emerged regarding elevated levels of cobalt and chromium in patients with metal-on-metal megaprostheses. This prospective study aims to identify systemic cobalt and chromium levels in metal-on-polyethylene knee and hip megaprostheses and their associations with other factors. METHODS: 56 patients underwent knee or hip megaprosthesis surgery at 2 sarcoma centers. Serum cobalt and chromium levels were measured preoperatively and thrice within the first year using inductively coupled plasma mass spectrometry. RESULTS: A statistically significant difference in serum cobalt levels (1.4 ppb; 95% confidence interval [CI] 0.0-3.3) was observed 1 year after knee megaprosthesis surgery compared with preoperative levels. In contrast no difference in chromium levels was observed after 1 year compared with preoperative levels (0.05 ppb; CI 0.0-0.8). An association between younger age, higher eGFR, and increased cobalt levels was observed. No significant correlations were found between ion levels and resection length or the number of modular connections. CONCLUSION: We found elevated serum ion levels in metal-on-polyethylene knee megaprostheses in contrast to metal-on-polyethylene hip megaprostheses. Furthermore, a positive correlation between cobalt and chromium levels, and between cobalt and eGFR was identified, along with a negative correlation between cobalt and age. This study highlights the importance of monitoring systemic cobalt and chromium levels in patients with megaprostheses.

Validation of a novel risk score to predict early and late recurrence in solitary fibrous tumour.

BACKGROUND: Current risk models in solitary fibrous tumour (SFT) were developed using cohorts with short follow-up and cannot reliably identify low-risk patients. We recently developed a novel risk model (G-score) to account for both early and late recurrences. Here, we aimed to validate the G-score in a large international cohort with long-term follow-up. METHODS: Data were collected from nine sarcoma referral centres worldwide. Recurrence-free interval (RFi) was the primary endpoint. RESULTS: The cohort comprised 318 patients with localised extrameningeal SFTs. Disease recurrence occurred in 96 patients (33%). The estimated 5-year RFi rate was 72%, and the 10-year RFi rate was 52%. G-score precisely predicted recurrence risk with estimated 10-year RFi rate of 84% in low risk, 54% in intermediate risk and 36% in high risk (p < 0.001; C-index 0.691). The mDemicco (p < 0.001; C-index 0.749) and SalasOS (p < 0.001; C-index 0.674) models also predicted RFi but identified low-risk patients less accurate with 10-year RFi rates of 72% and 70%, respectively. CONCLUSIONS: G-score is a highly significant predictor of early and late recurrence in SFT and is superior to other models to predict patients at low risk of relapse. A less intensive follow-up schedule could be considered for patients at low recurrence risk according to G-score.

The association between socioeconomic position and tumour size, grade, stage, and mortality in Danish sarcoma patients - A national, observational study from 2000 to 2013.

Background: Survival in sarcoma patients depends on a range of prognostic factors. An association between cancer survival and socioeconomic position is known for several other cancers. We therefore examined the relations between three socioeconomic factors and risk of presenting with known tumour related prognostic factors, and the overall mortality of the different socioeconomic and prognostic factors in 1919 patients diagnosed with sarcoma in Denmark 2000-2013.Material and methods: Patients with sarcoma in extremities or trunk wall aged 30 years or more at diagnosis were identified in the Danish Sarcoma Registry and linked on an individual level to Danish national registries. We obtained data on educational level, disposable income and cohabitation status. Odds ratios (ORs) were estimated for the association between the socioeconomic factors and grade, stage and tumour size. Hazard ratios (HRs) were estimated using Cox proportional hazard models.Results: In adjusted analyses, educational level, income and cohabitation status were not associated with high grade or dissiminated stage at time of diagnosis. However, living alone was statistically significantly associated with having a large soft tissue sarcoma (≥5 cm) at time of diagnosis (OR 1.51; CI1.12-2.03). The overall mortality was statistically significantly increased in the group of patients with ≤10 years of education (HR 1.27; CI 1.02-1.57), in patients with the 20% lowest income (HR 1.30; CI 1.00-1.67) and nearly in patients living alone (HR 1.16; CI 0.99-1.36).Conclusion: In this nationwide, multicentre, population-based study, soft tissue sarcoma patients living alone had greater risk of having a large tumour at time of diagnosis. Soft tissue and bone sarcoma patients with a short education, low income, or living alone, had a higher mortality. This might indicate that the social differences in mortality might be related to treatment aspects and the biology of the disease rather that the diagnostic process.

Diagnostic accuracy of ultrasound-guided core biopsy of peripheral nerve sheath tumors.

PURPOSE: To retrospectively evaluate the diagnostic accuracy of and complications from ultrasound-guided core needle biopsy (UGCNB) of suspected peripheral nerve sheath tumors (PNSTs). METHODS: Patients undergoing UGCNB from January 2004 to December 2016, based on the suspicion of PNST, were included in the study. Age, gender, anatomical location, dates of relevant events, and histopathological reports of the UGCNB cores and the resected tumors were retrieved from the patients' medical records. RESULTS: A total of 154 UGCNBs were identified. One hundred and forty (90.9%) of these resulted in a conclusive histopathological report, while 14 were unsuited for histopathological analysis due to insufficient amount of tissue and/or nonrepresentative tissue. The overall diagnostic accuracy of UGCNB with respect to discriminate malignant from benign tumors was 99.3%, while correct specific UGCNB diagnoses were confirmed in 95.1% of the cases. Sensitivity and specificity were 90.9% (95% CI: 58.7-99.8%) and 100% (95% CI: 97.2-100%), respectively. The positive predictive value was 100%, and the negative predictive value was 99.2%. Except for one patient, who reported mild dysesthesia, which resolved 2 days after the UGCNB, no complications were reported. CONCLUSION: This study suggests that UGCNB is accurate and safe in patients suspected for PNST.

Long-term results of the Global Modular Replacement System tumor prosthesis for reconstruction after limb-sparing bone resections in orthopedic oncologic conditions: Results from a national cohort.

BACKGROUND AND OBJECTIVES: We investigated implant revision, implant failure, and amputation risk after limb-sparing bone tumor surgery using the Global Modular Replacement System (GMRS) tumor prosthesis in patients suffering from bone sarcomas (BS), giant cell tumors (GCT), or metastatic bone disease (MBD). MATERIAL AND METHODS: A retrospective study of a nationwide consecutive cohort (n = 119, 47 [12-81] years, M/F = 65/54) having limb-sparing surgery and reconstruction using the GMRS tumor prosthesis due to bone tumors (BS/GCT/MBD = 70/8/41) from 2005 to 2013. Anatomical locations were as followed: distal femur (n = 49), proximal femur (n = 41), proximal tibia (n = 26), or total femur (n = 3). Kaplan-Meier survival analysis and competing risk analysis with death as a competing risk were used for statistical analysis. RESULTS: For BS and GCT patients, 5-year patient survival was 72% (95% confidence interval [CI]: 59-85%) and for MBD 33% (95% CI: 19-48%). Thirty-two patients underwent revision surgery (5-year revision incidence 14%; 95% CI: 8-21%). Twelve patients had revision of bone-anchored parts (implant failure) with a 5-year revision incidence 6% (95% CI: 2-10%). Ten amputations were performed due to local relapse (n = 9) or recurrent infections (n = 1) with a 5-year incidence of amputation: 8% (95% CI: 3-13%). CONCLUSIONS: We identified a low risk of revision and amputation when using the GMRS tumor prosthesis for limb-sparing bone tumor.

Validity and Reliability Evaluation of Four Commercial Activity Trackers' Step Counting Performance.

INTRODUCTION: Activity trackers are useful tools for physical rehabilitation purposes. Most available activity trackers are designed for fitness and wellness use, lacking in both accuracy and precision at lower speeds. Validity and reliability at all clinically relevant speeds are crucial selection criteria for use in clinical practice. The aim of this study was to assess the validity and reliability of four consumer-based activity trackers at clinical relevant walking speeds for patient groups undergoing rehabilitation. METHODS: The four commercial activity trackers Fitbit Surge (FS), Fitbit Charge HR (FC), Microsoft Band 2 (MB), and A&D 101NFC Activity Monitor (A&D) were evaluated at 2, 4, 4.5, and 5.5 km/h. Twenty healthy participants aged 25.6 ± 2 years walked on a treadmill at the four velocities in two trials of 100 steps each. Mean average percentage error (MAPE), intraclass correlation coefficient (ICC), and Bland-Altman 95% limits of agreement were calculated to assess validity and reliability. RESULTS: MAPE levels were between -8% and -6% for FS, -15% and 0% for MB, 7% and 21% for FC, and -53% and 1% for AD. The biggest inaccuracies were seen at 2 km/h, where AD underestimated by 53%. The highest accuracy was predominantly found with MB and AD, which overestimated ≤2% at velocities ≥4 km/h. ICC was moderate (0.73) for FS, good (0.88) for MB, moderate (0.52) for FC, and excellent (0.98) for AD. CONCLUSIONS: MB, FS, and AD accurately counted steps, when participants walked with velocities corresponding to a brisk walk (≥4 km/h). Walking at lower speeds (≤2 km/h) was not counted accurately. Thus, the four evaluated activity trackers are not useful for patient groups walking at lower speeds during rehabilitation, nor for counting indoor walking.

Factors associated with reduced functional outcome and quality of life in patients having limb-sparing surgery for soft tissue sarcomas - a national multicenter study of 128 patients.

BACKGROUND: Limb-sparing surgery for sarcomas has become possible in most cases. However, the impact of the procedure on the functional outcome has only been investigated in a few studies. The aim of this study has been to identify tumor- and patient-related factors associated with reduced functional outcome and quality of life after limb-sparing surgery in soft tissue sarcoma patients. MATERIAL AND METHODS: In total, 128 patients (mean age = 58, female/male = 54/74) who were treated with limb-sparing surgery without bone resection for soft tissue sarcomas in Denmark during the period 1 January 2009 to 31 December 2011 were included. Patients were asked to participate at least one year after surgery, and patients who had experienced local recurrence or metastatic disease were excluded. The Toronto Extremity Salvage Score (TESS) measured functional disability, while the Musculoskeletal Tumor Society Score (MSTS) measured functional impairment. European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 measured quality of life. Tumor- and patient-related factors (age, gender, tumor depth, tumor size, malignancy, comorbidity, location, and radiotherapy) were extracted from the Danish National Sarcoma Database. Wilcoxon rank-sum test and Kruskal-Wallis were used for univariable analysis. Adjusted odds ratios were estimated by using multiple logistic regression models. RESULTS: In the multiple regression analysis, it was found that female gender (p = 0.03), lower extremity tumors (p < 0.01) and radiotherapy (p = 0.02) resulted in an increased risk of a lower TESS score. Initial reduced postoperative function was found to be associated with a lower functional outcome. Patients with reduced functional outcome have increased risk for reduced quality of life (p < 0.01). CONCLUSION: The results of this study show that patient- and tumor-related factors have an important role in the functional outcome.

Characteristics of 64 sarcoma patients referred to a sarcoma center after unplanned excision.

BACKGROUND AND METHODS: Unplanned excision of sarcoma before referral to specialist centers can affect prognosis and surgical outcome. The diagnostic pathway of these patients is uncertain and needs to be reviewed. We aimed to describe patient and tumor characteristics, initial symptoms, initial and final diagnosis, and explore reasons for unplanned excision in this patient group. From a previous study on 258 sarcoma patients, we identified 64 patients referred after surgery. Medical records were reviewed. RESULTS: The majority were soft tissue sarcomas, most often with thoracic location. Leiomyosarcoma was the most frequent final diagnosis, lipoma, and fibroma/dermatofibroma the most frequent initial diagnoses. Fifty percent were superficial small tumors, and 60.9% had not received diagnostic imaging before surgery. Fifty percent were referred from public surgical departments, and 1/3 from private specialists. Twenty-three patients had initial presence of alarm symptoms registered before surgery, the remaining 2/3 fell outside referral criteria or alarm symptoms were not discovered. CONCLUSIONS: Patients referred after unplanned excision often have small superficial tumors and the majority fall outside of defined referral criteria. Referral criteria are not a guarantee for detection of all sarcomas and surgeons should always be aware of the possibility of malignancy when removing a tumor.

Alarm symptoms of soft-tissue and bone sarcoma in patients referred to a specialist center.

BACKGROUND AND PURPOSE: The Danish Cancer Patient Pathway for sarcoma defines a set of alarm symptoms as criteria for referral to a sarcoma center. This may exclude cancer patients without alarm symptoms, so we investigated the presence of alarm symptoms (defined as being indicative of a sarcoma) in patients who had been referred to the Aarhus Sarcoma Center. PATIENTS AND METHODS: We reviewed the medical records of all 1,126 patients who had been referred, with suspected sarcoma, from other hospitals in the period 2007-2010 for information on symptoms, clinical findings, and diagnosis. Alarm symptoms were analyzed for predictive values in diagnosing sarcoma. RESULTS: 179 (69%) of 258 sarcoma patients were referred with alarm symptoms (soft-tissue tumor>5 cm or deep-seated, fast-growing soft-tissue tumor, palpable bone tumor, or deep persisting bone pain). The remaining 79 sarcomas were found accidentally. "Size over 5 cm" for soft-tissue tumors, and "deep persisting bone pain" for bone tumors had the highest sensitivity and positive predictive value. Of the 79 sarcoma patients who were referred without alarm symptoms, 7 were found accidentally on imaging, 5 were referred with suspected recurrence of a sarcoma, 64 were referred with a confirmed histological diagnosis, and 3 were referred for other reasons. INTERPRETATION: Defined alarm symptoms are predictive of sarcoma, but one-third of the patients were found accidentally. Further studies on presenting symptoms in primary care are needed to assess the true value of alarm symptoms.

Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis.

BACKGROUND: Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy. METHODS: 52 hips in 52 patients (median age 60 (51-64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity. RESULTS: A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups. INTERPRETATION: While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain.

Evaluation of Two Different Approaches for Selecting Patients for Postoperative Radiotherapy in Deep-Seated High-Grade Soft Tissue Sarcomas in the Extremities and Trunk Wall.

Two national sarcoma centers have had different approaches for selecting patients with grade 2-3 deep-seated soft tissue sarcomas (STS) for postoperative radiotherapy (RT). We evaluated potential differences in local recurrence in patients treated at the two centers. At Sarcoma Center 1 (SC1), RT was the standard treatment for all tumors except certain small tumors excised with a margin wider than 1 cm. Sarcoma Center 2 (SC2) avoided RT for tumors regardless of tumor size if removed with a margin wider than 1 cm and/or a solid barrier. We included 386 patients (SC1/SC2 = 196/190) over 18 years of age diagnosed with a non-metastatic grade 2-3, deep-seated STS of the extremities or trunk wall, who underwent primary surgical treatment (only tumors excised with a negative margin) from 1 January 2000, to 31 December 2016. Kaplan-Meier survival analysis, competing risk analysis, and cause-specific Cox regression were applied. A total of 284 patients received primary RT, 163 (83%) at SC1 and 121 (64%) at SC2 (p < 0.001). The cumulative incidence of local recurrence at five years was 15% (95% CI: 10-19%) at SC1 and 14% (95% CI: 9-19%) at SC2. Multivariate analysis showed no significant differences in local recurrence between the centers. We concluded that when entering all available patients into the analysis using an intention-to-treat principle, a more selective approach to postoperative RT in patients with grade 2-3 deep-seated STS did not lead to a higher local recurrence rate. However, with this study design, we cannot rule out if the local recurrence rate could have been lower if RT was administered to all tumors removed with a margin wider than 1 cm and/or a solid barrier.

Doxorubicin concentrations in bone tumour-relevant tissues after bolus and continuous infusion: a randomized porcine microdialysis study.

PURPOSE: Doxorubicin is a widely used chemotherapeutic drug that can be administered intravenously as both a bolus infusion and a continuous infusion. The latter is believed to lower the risk of cardiotoxicity, which is a critical long-term complication of doxorubicin treatment. The local tissue concentrations of doxorubicin will be reflected in both treatment efficacy and toxicity, but very limited information is available. The aim of this study was to measure the concentration of doxorubicin after continuous and bolus infusion in tissue compartments around a typical location of a bone tumour. METHODS: Sixteen pigs (female, Danish Landrace, mean weight 77 kg) were randomized into two groups of eight. Both groups received an intravenous infusion of 150 mg doxorubicin; Group 1 received a bolus infusion (10-15 min) and Group 2 received a continuous infusion (6 h). Before infusion, microdialysis catheters were placed intravenously and in four bone tumour-relevant tissue compartments (cancellous bone, subcutaneous tissue, synovial fluid of the knee joint and muscle tissue). Sampling was done (n = 15) over 24 h, and venous blood samples were collected as a reference. RESULTS: Area under the concentration-time curve (AUC0-24 h) for plasma (total concentration) was significantly different between the two groups, while peak drug concentration (Cmax) was significantly higher in two compartments (plasma and synovial fluid of the knee joint) in Group 1 compared to Group 2. Overall, the unbound tissue concentrations were extremely low with values below 0.20 µg/mL. CONCLUSION: The pharmacokinetic profile for doxorubicin in the investigated tissues is very similar when comparing bolus and 6 h continuous infusion.

A Population-Based Long-Term Follow-Up of Soft Tissue Angiosarcomas: Characteristics, Treatment Outcomes, and Prognostic Factors.

Angiosarcoma is a rare aggressive and understudied soft tissue sarcoma with pending evidence-based treatment guidelines due to varying study cohorts and inconsistent outcome measures. Surgery with wide resection is currently considered to be the cornerstone in management. In a population-based cohort identified from Danish National Health Registers between 2000 and 2017, this study aimed to define prognostic factors in patients with newly diagnosed soft tissue angiosarcoma. Kaplan-Meier survival analysis demonstrated 5-year overall survival of 28%. Competing risk analysis demonstrated cumulative incidence of local recurrence of 30% and metastasis of 43%. Multivariable Cox models among 154 included patients demonstrated age above 60 years and metastasis to be independently associated with worse overall survival. Cutaneous tumors, surgery, and negative resection margin were independently associated with improved overall survival. Adjuvant oncological treatment did not improve overall survival, risk of metastasis, or recurrence. Negative margin was not associated with lower risk of recurrence and metastasis. We conclude that, despite demonstrated improved survival after surgery with wide resection, overall survival remains poor.

Comparison of tendon attachment to 3D printed Ti6Al4V implant versus Trevira® implant: A paired experimental animal study.

BACKGROUND: Soft-tissue attachment is crucial for the success of megaprosthesis surgery and improvement in current treatment is needed. The aim of this study was to compare the biomechanical and histomorphometric properties of soft-tissue attachment between 3D printed Ti6Al4V implants featuring a 630 µm microporous structure and commercially available Trevira® implants with a 200 µm porous structure in a non-loadbearing ovine model. METHODS: Ten skeletally mature ewes underwent surgical implantation with both implants. After 4-weeks, mechanical pull-out testing assessed the attachment strength, while histomorphometric analysis evaluated fibroblast cell profile density, multinucleated giant cell profile density, microvessel length and volume density. RESULTS: 3D printed Ti6Al4V implants demonstrated a 129% greater attachment strength compared to Trevira® implants (p = 0.003). In the Trevira® group, a 35% increase in fibroblast profile density (p < 0.001) and a 98% increase in multinucleated giant cell profile density (p < 0.001) were observed, with no significant difference in microvessel length density between the groups. However, the Ti6Al4V group exhibited a 50% higher microvessel volume density (p < 0.001) compared to the Trevira® group. CONCLUSION: 3D printed Ti6Al4V implants with a 630 µm microporous structure demonstrated superior attachment strength, enhanced neovascularization, and reduced foreign body reaction compared to the Trevira® implants. These findings suggest that 3D printed Ti6Al4V implants may enhance soft-tissue attachment in megaprosthesis surgeries.

Controversies in orthopaedic oncology.

Chondrosarcoma is the second most common surgically treated primary bone sarcoma. Despite a large number of scientific papers in the literature, there is still significant controversy about diagnostics, treatment of the primary tumour, subtypes, and complications. Therefore, consensus on its day-to-day treatment decisions is needed. In January 2024, the Birmingham Orthopaedic Oncology Meeting (BOOM) attempted to gain global consensus from 300 delegates from over 50 countries. The meeting focused on these critical areas and aimed to generate consensus statements based on evidence amalgamation and expert opinion from diverse geographical regions. In parallel, periprosthetic joint infection (PJI) in oncological reconstructions poses unique challenges due to factors such as adjuvant treatments, large exposures, and the complexity of surgery. The meeting debated two-stage revisions, antibiotic prophylaxis, managing acute PJI in patients undergoing chemotherapy, and defining the best strategies for wound management and allograft reconstruction. The objectives of the meeting extended beyond resolving immediate controversies. It sought to foster global collaboration among specialists attending the meeting, and to encourage future research projects to address unsolved dilemmas. By highlighting areas of disagreement and promoting collaborative research endeavours, this initiative aims to enhance treatment standards and potentially improve outcomes for patients globally. This paper sets out some of the controversies and questions that were debated in the meeting.

Marker-based or model-based RSA for evaluation of hip resurfacing arthroplasty? A clinical validation and 5-year follow-up.

BACKGROUND: The stability of implants is vital to ensure a long-term survival. RSA determines micro-motions of implants as a predictor of early implant failure. RSA can be performed as a marker- or model-based analysis. So far, CAD and RE model-based RSA have not been validated for use in hip resurfacing arthroplasty (HRA). MATERIALS/METHODS: A phantom study determined the precision of marker-based and CAD and RE model-based RSA on a HRA implant. In a clinical study, 19 patients were followed with stereoradiographs until 5 years after surgery. Analysis of double-examination migration results determined the clinical precision of marker-based and CAD model-based RSA, and at the 5-year follow-up, results of the total translation (TT) and the total rotation (TR) for marker- and CAD model-based RSA were compared. RESULTS: The phantom study showed that comparison of the precision (SDdiff) in marker-based RSA analysis was more precise than model-based RSA analysis in TT (p CAD < 0.001; p RE = 0.04) and TR (p CAD = 0.01; p RE < 0.001). The clinical precision (double examination in 8 patients) comparing the precision SDdiff was better evaluating the TT using the marker-based RSA analysis (p = 0.002), but showed no difference between the marker- and CAD model-based RSA analysis regarding the TR (p = 0.91). Comparing the mean signed values regarding the TT and the TR at the 5-year follow-up in 13 patients, the TT was lower (p = 0.03) and the TR higher (p = 0.04) in the marker-based RSA compared to CAD model-based RSA. INTERPRETATION: The precision of marker-based RSA was significantly better than model-based RSA. However, problems with occluded markers lead to exclusion of many patients which was not a problem with model-based RSA. HRA were stable at the 5-year follow-up. The detection limit was 0.2 mm TT and 1° TR for marker-based and 0.5 mm TT and 1° TR for CAD model-based RSA for HRA.

Role of high­sensitivity C­reactive protein in patients with sarcoma.

Immunotherapy has shown promising results in lung cancer and melanomas; however, the responses have been poor in patients with sarcoma. Understanding the relationship between the immune system and sarcoma is essential to develop improved immunotherapy approaches. High-sensitivity C-reactive protein (hs-CRP) has been proposed as a prognostic marker in other cancer types; however, to the best of our knowledge, the association between hs-CRP levels and mortality in patients with sarcoma has not been investigated. The present prospective, non-randomised, non-interventional explorative study investigated the prognostic value of hs-CRP in patients with sarcoma. Patients referred to the sarcoma centre of Aarhus University Hospital (Aarhus, Denmark) were included between April 2014 and December 2020. Clinical data were obtained from the national quality sarcoma database and biomarkers other than hs-CRP were obtained from the clinical laboratory information system. The study cohort consisted primarily of patients with localised sarcoma. hs-CRP was significantly higher in patients with bone sarcoma (P=0.022) and soft tissue sarcoma (STS; P<0.001) compared with control patients. For STS, grade III tumours but not metastatic disease were associated with a higher hs-CRP level (P=0.0001). Elevated hs-CRP levels were associated with increased overall mortality [hazard ratio (HR), 1.91; 95% CI, 1.33-2.75; P=0.001]. Furthermore, elevated hs-CRP levels were also associated with decreased progression-free survival (HR, 1.64; 95% CI, 1.17-2.29; P=0.004). Furthermore, for patients with hs-CRP <8 mg/l, higher hs-CRP was associated with an increased risk of recurrent disease and reduced overall survival compared with those of patients with low hs-CRP. In conclusion, the present study demonstrated that hs-CRP was a prognostic factor for overall mortality and progression-free survival in patients with localised sarcoma at the time of diagnosis. Further studies are required to investigate the mechanism behind the association between hs-CRP and sarcoma prognosis and its potential use in clinical practice.

Macrophage Biomarkers sCD163 and sSIRPα in Serum Predict Mortality in Sarcoma Patients.

Most soft tissue sarcoma (STS) patients do not respond to traditional checkpoint inhibitor treatment, which may be due to infiltrating immunosuppressive tumour-associated macrophages. This study investigated the prognostic value of four serum macrophage biomarkers. Methods: Blood samples were taken from 152 patients with STS at the time of diagnosis; clinical data were prospectively collected. The concentrations of four macrophage biomarkers (sCD163, sCD206, sSIRPα, sLILRB1) were measured in serum, dichotomised based on median concentration, and evaluated either individually or when combined with established prognostic markers. Results: All macrophage biomarkers were prognostic of overall survival (OS). However, only sCD163 and sSIRPα were prognostic for recurrent disease (sCD163: hazard ratio (HR): 1.97 (95% CI: 1.10-3.51) and sSIRPα: HR: 2.09 (95% CI: 1.16-3.77)). A prognostic profile was made based on sCD163 and sSIRPα; it also included c-reactive protein and tumour grade. Patients with intermediate- or high-risk prognostic profiles (adjusted for age and tumour size) had a higher risk of recurrent disease compared to low-risk patients (HR: 2.64 (95% CI: 0.97-7.19)) and (HR 4.3 (95% CI: 1.62-11.47)), respectively. Conclusion: This study demonstrated that serum biomarkers of immunosuppressive macrophages were prognostic for OS; when combined with well-established markers of recurrence they allowed for a clinically relevant categorising of patients.