Advanced imaging shows extra-articular abscesses in two out of three adult patients with septic arthritis of the native hip joint.

Background: Septic arthritis (SA) of the native adult hip is a rare orthopaedic emergency requiring prompt diagnosis and treatment. As clinical presentation and laboratory findings are frequently atypical, advanced imaging is often requested. This retrospective study aimed to investigate the prevalence and pattern of extra-articular infectious manifestations and their implications for pre-operative advanced imaging in patients with proven SA of the native hip joint. Methods: Out of 41 patients treated surgically for SA of the native hip during a 16-year period at our tertiary referral hospital, 25 received advanced imaging (computed tomography (CT), magnetic resonance imaging (MRI), or fluorodeoxyglucose positron emission tomography (FDG PET-CT)) prior to initial intervention. For each investigation, a specific set of variables was systematically interpreted, and the most suitable surgical approach was determined. The prognostic value was evaluated by comparing specific outcome measures and the extent of extra-articular involvement. Results: It was found that 32 % of patients had an abscess in one anatomical region, 32 % of patients had abscesses in multiple anatomical regions, and only 36 % of patients had no substantial abscess. Gluteal abscesses were especially common in patients with SA due to contiguous spread. Abscesses in the iliopsoas region were more common in patients with SA due to hematogenous seeding. A combination of several different surgical approaches was deemed necessary to adequately deal with the various presentations. No significant prognostic factors could be identified. Conclusion: We recommend performing advanced imaging in patients with suspected or proven septic arthritis of the native hip joint, as extra-articular abscesses are present in 64 % and might require varying anatomical approaches.

Predictors of mortality one year after pelvic fractures in an older population: a retrospective cohort study.

The goal was to investigate if patient characteristics can be used to predict 1-year post-fracture mortality after pelvic fracture. Multivariate logistic regression identified male gender, comorbidities and presence of in-hospital complications as predictors of 1-year mortality. PURPOSE: Osteoporotic pelvic fractures have significant mortality and morbidity in the older population. The aim of this study was to investigate the factors predicting one-year mortality of patients sustaining a low-impact pelvic fracture (pelvic ring and acetabulum). METHODS: A total of 282 patients aged ≥ 65 years presenting with a low-energy pelvic ring (n =254) or acetabular (n =28) fracture to the emergency department at the University Hospitals Leuven were included. Demographic and clinical data were retrospectively collected and predictors for mortality one year after pelvic ring fractures were evaluated. RESULTS: The one-year mortality after osteoporotic pelvic ring fractures and acetabular fractures was respectively 20.4% (95% CI 15.7-26.0) and 14% (95% CI 4.0-32.7). Multivariate logistic regression adjusted for confounders identified male gender (OR 3.18; 95% CI (1.06-9.49), p =0.038), a higher number of comorbidities (OR 1.5; 95% CI (1.16-1.95), p =0.002) and in-hospital complications (OR 5.00; 95% CI (1.39-17.97), p =0.014) as independent predictors of one-year mortality after pelvic ring fractures. CONCLUSION: The one-year mortality after low-energy pelvic is high and can be predicted by different patient characteristics. These findings can guide pelvis fracture treatment decisions in the older population.

3D-validation of a simple tool to measure tibiofemoral axial rotation in tibial plateau fractures.

OBJECTIVES: Rotated tibial plateau fractures (TPF) frequently involve multiple planes of movement, yet current presurgical assessment methods do not account for tibiofemoral axial rotation. This study introduces and validates a simple tool to measure rotation-the Gerdy-Tibial-Tuberosity-Surgical-Epicondylar-Axis (GTT-SEA) angle. METHODS: Forty-seven preoperative 2D CT from a TPF database at a tertiary trauma center were retrieved, and 3D models reconstructed. Three observers made repeated 2D and 3D measurements of the GTT-SEA angle, spaced 4 weeks apart, for 20 patients. Inter- and intra-observer agreement and 2D-3D correlation were calculated. A reference angle was defined from non-operated patients, to classify 28 patients with MRI into neutral, external rotation, and internal rotation groups. The classification agreement and soft tissue involvement between groups were analyzed. RESULTS: Mean 2D GTT-SEA angle was 17.65 ± 2.36° in non-operated patients, and 13.86 ± 3.90° in operated patients. 3D GTT-SEA angle was 18.92 ± 4.53° in non-operated patients, and 14.76 ± 6.03° in operated patients. 2D-3D correlation was moderate to good (ICC 0.64 ~ 0.83). Two-dimensional (ICC 0.70) and 3D (ICC 0.55) inter-observer agreements were moderate; 2D (ICC 0.82 ~ 0.88) and 3D (ICC 0.76 ~ 0.95) intra-observer agreements were good to excellent. Rotation classification agreement was slight (kappa 0.17) for 2D and good (kappa 0.76) for 3D. More popliteofibular ligament injury was detected in rotated knees (p = 0.016). CONCLUSIONS: The GTT-SEA angle offers simple, accessible, yet reliable measurement of tibiofemoral axial rotation. Though a true reference range remains to be determined, this tool adds valuable information to existing TPF classifications, potentially allowing assessment of soft tissue involvement in TPF. CLINICAL RELEVANCE STATEMENT: The GTT-SEA angle will benefit patients who sustain tibial plateau fractures, by allowing physicians to more accurately measure and plan for the injury in 3D, and raising suspicion for otherwise undetected soft tissue injuries, which can impact operative outcomes. KEY POINTS: • Traumatic fractures of the tibial plateau may contain rotation-induced soft tissue injuries. • A new tool to measure axial rotation between the femur and tibia was found to have moderate to excellent inter- and intra-rater reliability. • The tool may have potential in predicting soft tissue injury and assisting with the decision to receive MRI.

Treatment and outcome of fracture-related infection of the clavicle.

INTRODUCTION: The number of operatively treated clavicle fractures has increased over the past decades. Consequently, this has led to an increase in secondary procedures required to treat complications such as fracture-related infection (FRI). The primary objective of this study was to assess the clinical and functional outcome of patients treated for FRI of the clavicle. The secondary objectives were to evaluate the healthcare costs and propose a standardized protocol for the surgical management of this complication. METHODS: All patients with a clavicle fracture who underwent open reduction and internal fixation (ORIF) between 1 January 2015 and 1 March 2022 were retrospectively evaluated. This study included patients with an FRI who were diagnosed and treated according to the recommendations of a multidisciplinary team at the University Hospitals Leuven, Belgium. RESULTS: We evaluated 626 patients with 630 clavicle fractures who underwent ORIF. In total, 28 patients were diagnosed with an FRI. Of these, eight (29%) underwent definitive implant removal, five (18%) underwent debridement, antimicrobial treatment and implant retention, and fourteen patients (50%) had their implant exchanged in either a single-stage procedure, a two-stage procedure or after multiple revisions. One patient (3.6%) underwent resection of the clavicle. Twelve patients (43%) underwent autologous bone grafting (tricortical iliac crest bone graft (n = 6), free vascularized fibular graft (n = 5), cancellous bone graft (n = 1)) to reconstruct the bone defect. The median follow-up was 32.3 (P25-P75: 23.9-51.1) months. Two patients (7.1%) experienced a recurrence of infection. The functional outcome was satisfactory, with 26 out of 28 patients (93%) having full range of motion. The median healthcare cost was € 11.506 (P25-P75: € 7.953-23.798) per patient. CONCLUSION: FRI is a serious complication that can occur after the surgical treatment of clavicle fractures. In our opinion, when treated adequately using a multidisciplinary patient-specific approach, the outcome of patients with an FRI of the clavicle is good. The median healthcare costs of these patients are up to 3.5 times higher compared to non-infected operatively treated clavicle fractures. Although not studied individually, we consider factors such as the size of the bone defect, condition of the soft tissue, and patient demand important when it comes to guiding our surgical decision making in cases of osseous defects.

Chronic nonbacterial osteomyelitis in children: a multicentre Belgian cohort of 30 children.

BACKGROUND: To evaluate clinical characteristics, imaging findings, therapeutic approach and outcome of paediatric patients with Chronic Non-Bacterial Osteomyelitis (CNO). METHODS: Retrospective review of 30 children diagnosed with CNO at two tertiary care centres in Belgium. Imaging data were evaluated by blinded paediatric radiologists. RESULTS: Mean age at onset was 10.3 years and mean age at diagnosis was 11.7 years. Bone pain was the leading symptom (29/30 patients). Out of 180 symptomatic lesions, 131 were confirmed on MRI as hyperintense geographic lesions on STIR images at the metaphysis and epiphysis adjacent to growth plates of tubular bones. The most common sites of involvement were the lower limbs, spine, sternoclavicular joint and humerus. For nearly half of the patients (14/30) monotherapy with NSAIDs was sufficient to obtain remission. The remaining 16 patients received second-line therapy: bisphosphonates (n = 15/30), disease-modifying antirheumatic drugs (n = 7/30), etanercept (n = 4/30) and tocilizumab (n = 1/30). Remission was reached after a mean time of 37.6 months in 26/30 patients. The prognosis was worse for patients with spinal involvement, resulting in more long-term sequelae. CONCLUSIONS: We present a multicentre paediatric cohort of 30 CNO patients. A typical pattern of bone involvement could be found on MRI. NSAIDs were administered as first-line treatment. Second-line strategies included bisphosphonates, corticosteroids, methotrexate, etanercept and tocilizumab. TRIAL REGISTRATION: Retrospectively registered. Registratienummer EC KUL: MP018023.

Unraveling the Molecular Basis of the Dystrophic Process in Limb-Girdle Muscular Dystrophy LGMD-R12 by Differential Gene Expression Profiles in Diseased and Healthy Muscles.

Limb-girdle muscular dystrophy R12 (LGMD-R12) is caused by two mutations in anoctamin-5 (ANO5). Our aim was to identify genes and pathways that underlie LGMD-R12 and explain differences in the molecular predisposition and susceptibility between three thigh muscles that are severely (semimembranosus), moderately (vastus lateralis) or mildly (rectus femoris) affected in this disease. We performed transcriptomics on these three muscles in 16 male LGMD-R12 patients and 15 age-matched male controls. Our results showed that LGMD-R12 dystrophic muscle is associated with the expression of genes indicative of fibroblast and adipocyte replacement, such as fibroadipogenic progenitors and immune cell infiltration, while muscle protein synthesis and metabolism were downregulated. Muscle degeneration was associated with an increase in genes involved in muscle injury and inflammation, and muscle repair/regeneration. Baseline differences between muscles in healthy individuals indicated that muscles that are the most affected by LGMD-R12 have the lowest expression of transcription factor networks involved in muscle (re)generation and satellite stem cell activation. Instead, they show relative high levels of fetal/embryonic myosins, all together indicating that muscles differ in their baseline regenerative potential. To conclude, we profiled the gene expression landscape in LGMD-R12, identified baseline differences in expression levels between differently affected muscles and characterized disease-associated changes.

Validation of the diagnostic criteria of the consensus definition of fracture-related infection.

BACKGROUND: The recently developed fracture-related infection (FRI) consensus definition, which is based on specific diagnostic criteria, has not been fully validated in clinical studies. We aimed to determine the diagnostic performance of the criteria of the FRI consensus definition and evaluated the effect of the combination of certain suggestive and confirmatory criteria on the diagnostic performance. METHODS: A multicenter, multi-national, retrospective cohort study was performed. Patients were subdivided into an FRI or a control group, according to the treatment they received and the recommendations from a multidisciplinary team ('intention to treat'). Exclusion criteria were patients with an FRI diagnosed outside the study period, patients younger than 18 years of age, patients with pathological fractures or patients with fractures of the skull, cervical, thoracic and lumbar spine. Minimum follow up for all patients was 18 months. RESULTS: Overall, 637 patients underwent revision surgery for suspicion of FRI. Of these, 480 patients were diagnosed with FRI, treated accordingly, and included in the FRI group. The other 157 patients were included in the control group. The presence of at least one confirmatory sign was associated with a sensitivity of 97.5%, a specificity of 100% and a high discriminatory value (AUROC 0.99, p < 0.001). The presence of a clinical confirmatory criterion or, if not present, at least one positive culture was associated with the highest diagnostic performance (sensitivity: 98.6%, specificity: 100%, AUROC: 0.99 (p < 0.001)). In the subgroup of patients without clinical confirmatory signs at presentation, specificities of at least 95% were found for the clinical suggestive signs of fever, wound drainage, local warmth and redness. CONCLUSIONS: The presence of at least one confirmatory criterion identifies the vast majority of patients with an FRI and was associated with an excellent diagnostic discriminatory value. Therefore, our study validates the confirmatory criteria of the FRI consensus definition. Infection is highly likely in case of the presence of a single positive culture with a virulent pathogen. When certain clinical suggestive signs (e.g., wound drainage) are observed (individually or in combination and even without a confirmatory criterion), it is more likely than not, that an infection is present.

Whole-body diffusion-weighted magnetic resonance imaging for the detection of bone metastases and their prognostic impact in metastatic renal cell carcinoma patients treated with angiogenesis inhibitors.

Background: Metastatic renal cell carcinoma (mRCC) patients with bone metastases (BM) are at high risk for skeletal related events and have a poorer outcome when treated with vascular endothelial growth factor receptor-tyrosine kinase inhibitors (VEGFR-TKIs). Computed tomography (CT) lacks sensitivity to detect BM in mRCC. We aimed to determine the added value of whole body diffusion-weighted magnetic resonance imaging (WB-DWI/MRI) to CT for the detection of BM in mRCC and to estimate the prognostic impact of the number of BM in mRCC patients treated with VEGFR-TKIs.Material and methods: We conducted a prospective study including consecutive mRCC patients treated with a first-line VEGFR-TKI in the metastatic setting. All patients underwent a pretreatment thoracic-abdominal-pelvic CT and WB-DWI/MRI. CT and WB-DWI/MRI were compared for the detection of BM. The number of detected BM was correlated with response rate (RR), progression-free survival (PFS) and overall survival (OS) after start of the VEGFR-TKI.Results: Ninety-two patients were included. BM were found in 55% of the patients by WB-DWI/MRI and in 43% of the patients by CT (p = .003). Mean number of BM discovered per patient was 6.8 by WB-DWI/MRI versus 1.9 by CT (p = .006). The cutoff of ≤5 versus >5 BM on WB-DWI/MRI had the highest discriminative power for all outcome measures. Patients with >5 BM had a lower RR (10% versus 42%), more frequently early progressive disease (43% versus 13%, p = .003), shorter PFS (4 versus 10 months, p = .006) and shorter OS (10 versus 35 months, p < .0001) compared to patients with ≤5 BM.Conclusion: WB-DWI/MRI detects significantly more BM in mRCC patients than CT, allowing better estimation of the prognostic impact of BM in mRCC patients treated with VEGFR-TKIs. The prognostic impact should now be validated in patients treated with immune checkpoint inhibitors.

Segmental Bone Loss of the Clavicle due to Fracture-Related Infection: A Multidisciplinary Challenge.

As the surgical treatment of clavicular fractures is increasingly utilized in orthopedics, the number of related complications rises as well. We present a case of segmental bone loss of the clavicle due to fracture-related infection. Treatment was based on a multidisciplinary team approach, which was important for a successful outcome.

Standardization of torsional CT measurements of the lower limbs with threshold values for corrective osteotomy.

INTRODUCTION: Re-establishing anatomic rotational alignment of shaft fractures of the lower extremities remains challenging. Clinical evaluation in combination with radiological measurements is important in pre- and post-surgical assessment. Based on computed tomography (CT), a range of reference values for femoral torsion (FT) and tibial torsion (TT) have historically been reported, which require standardization to optimize the significant intra- and inter-observer variability. The aims of this study were (re-)evaluation of the reference FT and TT angles, determination of the normal intra-individual side-to-side torsional differences to aid the surgical decision-making process for reoperation, and development of a novel 3D measurement method for FT. MATERIALS AND METHODS: In this retrospective study, we included 55 patients, without any known torsional deformities of the lower extremities. Two radiologists, independently, measured the rotational profile of the femora using the Hernandez and Weiner CT methods for FT, and the tibiae using the bimalleolar method for TT. The intra-individual side-to-side difference in paired femora and paired tibiae was determined. A 3D technique for FT assessment using InSpace® was designed. RESULTS: FT and TT demographic values were lower than previously reported, with mean FT values of 5.1°-8.8° and mean TT values of 25.5°-27.7°. Maximal side-to-side differences were 12°-13° for FT and 12° for TT. The Weiner method for FT was less variable than the Hernandez method. The new 3D method was equivocal to the conventional CT measurements. CONCLUSION: The results from this study showed that the maximal side-to-side tolerance in asymptomatic normal adult lower extremities is 12°-13° for FT and 12° for TT, which could be a useful threshold for surgeons as indication for revision surgery (e.g., derotational osteotomy). We developed a new 3D CT method for FT measurement which is similar to 2D and could be used in the future for virtual 3D planning.

Bone Scintigraphy in Poststreptococcal Periostitis With Dysproteinemia.

A 39-year-old man presented with severe bone pain in the tibiae and forearms in the wake of a poststreptococcal sepsis complicated with pneumonia and erysipelas 4 months earlier. Bone scintigraphy was indicative of periostitis of the tibia, ulna, and radius bilaterally, and in combination with the increased inflammatory parameters and dysproteinemia, the diagnosis of Goldbloom syndrome was made. Goldbloom syndrome is an idiopathic periosteal hyperostosis associated with dysproteinemia and elevated inflammatory parameters. Although it has only been described in children/adolescents, this case illustrates that, in the specific clinical and biochemical setting, it should also be considered in adults.

Weak associations between structural changes on MRI and symptoms, function and muscle strength in relation to knee osteoarthritis.

PURPOSE: To explore associations between MRI-defined structural abnormalities and clinical features related to knee osteoarthritis (OA). METHODS: Structural and clinical knee OA features were assessed in 87 women (45 with knee OA symptoms). Structural features were quantified by the Kellgren and Lawrence grade on radiography and by the Boston-Leeds Osteoarthritis Knee Score on MRI. Clinical features were assessed using the Knee Injury and Osteoarthritis Outcome Score, functional tests and muscle strength measurements. Associations were examined using regression analyses. RESULTS: Limited significant associations between structural and clinical features were found. An increased meniscal signal was associated with more pain/symptoms (P < 0.027). An anterior cruciate ligament tear was associated with poorer stair climbing test performance (P = 0.045). In a stepwise linear regression model, patellofemoral cartilage integrity and pain explained 28 % of the isometric quadriceps strength variability. The amount of cartilage lesions, loose bodies and pain explained 38 % of the isokinetic quadriceps strength variability. Synovitis/effusion and patellofemoral cartilage integrity combined with pain explained 34 % of the isometric hamstring strength variability. CONCLUSION: Although MRI-detected cartilage lesions, synovitis/effusion and loose bodies did explain part of the muscle strength variability, results suggest that MRI does not improve the link between joint degeneration and the clinical expression of knee OA. MRI contributes less than expected to the understanding of pain and function in knee OA and possibly offers little opportunity to develop structure-modifying treatments in knee OA that could influence the patient's pain and function. LEVEL OF EVIDENCE: Case series with no comparison groups, Level IV.