Rifampin-resistant periprosthetic joint infections are associated with worse functional outcome in both acute and chronic infection types.

Periprosthetic joint infections (PJI) pose a significant challenge in orthopaedic surgery, often requiring extensive surgical debridement and prolonged antibiotic treatment to eliminate the causative pathogens. Rifampin, known for its potent activity against biofilms, has been crucial in managing PJI by penetrating and disrupting these formations, thereby improving treatment efficacy. In this sense, antibiotic protocols lacking rifampin have shown increased failure rates. Consequently, the development of rifampin resistance could severely influence the prognosis of PJI. The aim of this clinical study was to assess how rifampin resistance affects the functional outcome in patients with PJI. In this single-centre comparative cohort study, we systematically documented all patients who presented with a PJI during the period spanning from 2018 to 2020. Two distinct groups were established for the study: Group 1 comprised 35 patients with a PJI caused by rifampin-susceptible pathogens and group 2 consisted of 28 patients with PJI caused by rifampin-resistant pathogens. A total of 63 patients (34 females) with a mean age of 68 years and a mean follow up of 37 months were included. The examination of patient-specific parameters did not reveal any identified risk factors as influential. Patients with a rifampin-resistant pathogen underwent a greater number of surgical revisions (6.9 ± 5.1 compared to 3.59 ± 3.39, p = 0.0011) and had extended durations of antibiotic treatment (p = 0.0052). The results of the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score revealed significant differences in clinical outcome between both groups in every domain, even when stratified by acute and chronic entities. In total the WOMAC increased significantly from 21.57 ± 14.9 points in group 1 to 71.47 ± 62.7 points in group 2 (p < 0.001). The higher failure rates observed in group 2 were not statistically significant (p = 0.44). The current study demonstrates that PJI caused by rifampin-resistant bacteria are associated with a significantly worse functional outcome in both acute and chronic infection types without significantly affecting total failure rates.

Higher Accuracy of Arthroscopy Compared to MRI in the Diagnosis of Chondral Lesions in Acute Ankle Fractures: A Prospective Study.

Even after successful surgery for acute ankle fractures, many patients continue having complaints. A possible explanation is the presence of concomitant chondral lesions. The aim of this study is to investigate the accuracy of MRI compared to that of arthroscopy in the assessment of chondral lesions in acute ankle fractures. In this prospective single-center study, patients presenting with acute ankle fractures over a period of three years were identified. A preoperative MRI was performed within a maximum of 10 days after trauma. During surgery, ankle arthroscopy was also performed. The International Cartilage Repair Society (ICRS) cartilage lesion classification was used to grade the detected chondral lesions. To localize the chondral lesions, the talar dome was divided into eight zones and the tibial/fibular articular surfaces into three zones. In total, 65 patients (28 females) with a mean age of 41.1 ± 15 years were included. In the MRI scans, 70 chondral lesions were detected (69.2% of patients) affecting mostly the tibial plafond (30%) and mostly graded as ICRS 3. The mean lesion area measured was 20.8 mm2. In the arthroscopy, 85 chondral lesions were detected (70.8% of patients) affecting mostly the medial surface of the talar dome (25.9%) and mostly graded ICRS 3. The mean lesion area measured was 43.4 mm2. The highest agreement between the two methods was observed in the size estimation of the chondral lesions. The present study shows the reduced accuracy of MRI when compared to arthroscopy in the assessment of traumatic chondral lesions in the setting of acute ankle fractures especially regarding lesion size. MRI remains an essential instrument in the evaluation of such lesions; however, surgeons should take this discrepancy into consideration, particularly the underestimation of chondral lesions' size in the preoperative planning of surgical treatment and operative technique.

Incidental findings are frequent in shoulder CT and MRI scans and increase with age.

Objectives: CT and MRI scans of the shoulder can lead to the identification of incidental findings (IF), which can have a major impact on the further treatment of the patient. The aim of this retrospective study was to record the prevalence of IF, incidentalomas (IT) and malignant IT for CT and MRI examinations of the shoulder and to investigate the effect of patient characteristics on the statistical occurrence of IF, IT and malignant IT. Materials and methods: A total of 903 shoulder examinations (415 CT, 488 MRI) were retrospectively analyzed for the presence of IF, subsequently categorized (harmless IF, IT requiring clarification, malignant IT) and analyzed regarding patient characteristics. The statistical analysis was carried out using independent t- and chi-square tests. A significance level of p < 0.05 was set. Results: Among the 903 patients evaluated (436 female, 467 male), 153 (16.9%) patients experienced IF (harmless IF: 101 (11.2%) patients, IT: 94 (10.4%), malignant IT: 4 (0.4%). The average age of the patients without IF and IT was significantly lower compared to the patients with IF and IT (p < 0.001). While IF occurred in 31.1% of the CT, IF was only detected in 4.9% of the MRI (p < 0.001). Conclusion: IF have a high prevalence (16.9%), especially in CT examinations of the shoulder, which increases with age. The exact detection and initiation of appropriate therapy is of great clinical importance, as early detection of life-threatening diseases enables more effective treatment and a potential gain in health and lifespan.

One- vs. Two-Stage Revision for Periprosthetic Shoulder Infections: A Systematic Review and Meta-Analysis.

Periprosthetic shoulder infection (PSI) remains a challenging complication after shoulder arthroplasty. Therapeutic options include one- or two-stage revision, irrigation and debridement, and resection arthroplasty. With our systematic review and meta-analysis, we aimed to compare one- and two-stage revisions for periprosthetic shoulder joint infections and determine the most appropriate therapeutic procedure. We performed an extensive literature search in PubMed, Ovid Medline, Cochrane Library, Web of Science, and CINAHL and filtered out all relevant studies. The meta-analysis was performed using the random-effects model, heterogeneity was analyzed using I2, and publication bias was assessed using the Egger's test. A total of 8 studies with one-stage revisions, 36 studies with two-stage revisions, and 12 studies with both one-stage and two-stage revisions were included. According to the random-effects model, the reinfection rate for the entirety of the studies was 12.3% (95% Cl: 9.6-15.3), with a low-to-moderate heterogeneity of I2 = 47.72%. The reinfection rate of the one-stage revisions was 10.9%, which was significantly lower than the reinfection rate of the two-stage revisions, which was 12.93% (p = 0.0062). The one-stage revision rate was significantly lower with 1.16 vs. 2.25 revisions in the two-stage revision group (p < 0.0001). The postoperative functional outcome in one-stage-revised patients was comparable but not statistically significant (p = 0.1523). In one- and two-stage revisions, most infections were caused by Cutibacterium acnes. In summary, our systematic review and meta-analysis show the superiority of single-stage revision regarding reinfection and revision rates in periprosthetic shoulder joint infection.

Cemented versus Cementless Stem Fixation in Revision Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

The number of revision knee arthroplasties (rTKA) is growing significantly as is the use of intramedullary stems for optimized stability. The choice of the most appropriate stem fixation method is still controversial. The purpose of this meta-analysis is to compare cemented versus cementless stem fixation in rTKA. Publications with patients undergoing rTKA with a follow-up > 24 months were systemically reviewed. Extracted parameters included total revision and failure rates for any reason, incidence of aseptic loosening, periprosthetic infection, and radiolucent lines, as well as the clinical outcome. A statistical regression analysis was then performed on all extracted clinical and radiological outcome data. A total of 35 publications met the inclusion criteria and were included and analyzed. Overall, 14/35 publications compared cementless versus cemented stem fixation, whereas 21/35 publications investigated only one stem fixation method. There were no significant differences in revision (p = 0.2613) or failure rates (p = 0.3559) and no differences in the incidence of aseptic loosening (p = 0.3999) or periprosthetic infection (p = 0.1010). The incidence of radiolucent lines was significantly higher in patients with cemented stems (26.2% versus 18.6%, p < 0.0001). However, no differences in clinical outcomes were observed. No superiority of a specific stem fixation method in rTKA was found. Rates of revision or failure for any reason as well as incidence of aseptic loosening and periprosthetic infection in cemented versus cementless stem fixation showed no significant difference. A higher incidence of radiolucent lines was observed in cemented stem fixation; however, no effect was observed on the clinical outcome.

In Vitro Biocompatibility of the Novel Ceramic Composite Baghdadite for Defect Augmentation in Revision Total Hip Arthroplasty.

Biological augmentation of bony defects in weight-bearing areas of both the acetabulum and the femur remains challenging. The calcium-silicate-based ceramic Baghdadite is a very interesting material to be used in the field of revision total hip arthroplasty for the treatment of bony defects in weight-bearing and non-weight-bearing areas alike. The aim of this study was to investigate the biocompatibility of Baghdadite utilizing an osteoblast-like, human osteosarcoma cell line (MG-63) and the human monocytic leukemia-derived cell line (THP-1). THP-1-derived macrophages and MG-63 were indirectly exposed to Baghdadite for 7 days using a transwell system. Viability was assessed with MTT assay and pH analysis. To investigate proliferation rate, both cell lines were labelled using CFSE and flow cytometrically analyzed. ELISA was used to measure the secretion of IL-1ß, IL-6 and TNFα. The investigation of viability, while showing a slight difference in optical density for the MTT assays in MG-63 cells, did not present a meaningful difference between groups for both cell lines. The comparison of pH and the proportion of living cells between groups did not present with a significant difference for both THP-1 and MG-63. Baghdadite did not have a relevant impact on the proliferation rate of the investigated cell lines. Mean fluorescence intensity was calculated between groups with no significant difference. Baghdadite exerted a proinflammatory effect, which could be seen in an upregulated production of TNFα in macrophages. Production of IL-1ß and IL-6 was not statistically significant, but the IL-6 ELISA showed a trend to an upregulated production as well. A similar effect on MG-63 was not observed. No relevant cytotoxicity of Baghdadite ceramics was encountered. Baghdadite ceramics exhibit a proinflammatory potential by significantly increasing the secretion of TNFα in THP-1-derived macrophages. Whether this proinflammatory potential results in a clinically relevant effect on osteointegration is unclear and requires further investigation. Baghdadite ceramics provide an interesting alternative to conventional bone substitutes and should be further investigated in a biomechanical and in vivo setting.

A Multi-Disciplinary MRI Assessment May Optimize the Evaluation of Chondral Lesions in Acute Ankle Fractures: A Prospective Study.

Chondral lesions (CL) in the ankle following acute fractures are frequently overlooked immediately after the injury or diagnosed at a later stage, leading to persistent symptoms despite successful surgery. The literature presents a wide range of discrepancies in the reported incidence of CLs in acute ankle fractures. The objective of this prospective study is to provide a precise assessment of the occurrence of chondral lesions (CLs) in acute ankle fractures through MRI scans conducted immediately after the trauma and prior to scheduled surgery. Furthermore, the study aims to highlight the disparities in the interpretation of these MRI scans, particularly concerning the size and extent of chondral damage, between radiologists and orthopedic surgeons. Over the period of three years, all patients presenting with an unstable ankle fracture that underwent operative treatment were consecutively included in this single-center prospective study. Preoperative MRIs were obtained for all included patients within 10 days of the trauma and were evaluated by a trauma surgeon and a radiologist specialized in musculoskeletal MRI blinded to each other's results. The location of the lesions was documented, as well as their size and ICRS classification. Correlations and kappa coefficients as well as the p-values were calculated. A total of 65 patients were included, with a mean age of 41 years. The evaluation of the orthopedic surgeon showed CLs in 52.3% of patients. CLs occurred mainly on the tibial articular surface (70.6%). Most talar lesions were located laterally (11.2%). The observed CLs were mainly ICRS grade 4. According to the radiologist, 69.2% of the patients presented with CLs. The most common location was the talar dome (48.9%), especially laterally. Most detected CLs were graded ICRS 3a. The correlation between the two observers was weak/fair regarding the detection and classification of CLs and moderate regarding the size of the detected CLs. To enhance the planning of surgical treatment for ankle chondral lesions (CLs), it may be beneficial to conduct an interdisciplinary preoperative assessment of the performed scans. This collaborative approach can optimize the evaluation of ankle CLs and improve overall treatment strategies.

Vitamin D level and low-energy fracture risk in children and adolescents: a population-based case-control study of 45 cases.

The objective is to document the rate of vitamin D deficiency and insufficiency among children with low-energy fractures and compare it to fracture-free control group. We included all children under 15 years presenting to the emergency department with low-energy fractures; controls were children without history of fractures from the outpatient department. Conventional X-ray and laboratory blood tests were performed. Vitamin D deficiency was defined as serum level ≤20 ng/ml, and the mean values were compared through two-sample t-tests. The influence of vitamin D on the fractures was defined using Chi-square test, significance with P-value < 0.05. The relationships between variables and odds of fracture occurrence were examined using logistic regression models. The final sample included 37 cases (30 males, 7 females, 7.4 ± 3.7 years) and 70 control individuals (42 males, 28 females, 7.8 ± 4.6 years) without significant differences regarding age, sex, and month of inclusion. Children with fractures had lower levels of vitamin D (21.87 ± 8.40 ng/ml vs. 25.89 ± 7.62 ng/ml) (P = 0.01). Vitamin D played a protective role against low-energy fractures (OR, 1.08; 95% CI, 1.01-1.14; P = 0.02), boys showed three times greater fracture risk than girls (OR, 3.00; 95% CI, 1.12-8.07; P = 0.03). Finally, vitamin D deficiency correlated with almost five times increased risk of pediatric low-energy fractures (OR, 4.63; 95% CI, 1.92-11.18; P = 0.001). This is the first MENA study establishing a relation between vitamin D deficiency and low-energy fractures among children and adolescents. The findings show the protective role of vitamin D on the pediatric bone and may help physicians preventing morbidity on children and costs on their families and the socioeconomic health system.

Cervical vertebral body replacement using a modern in situ expandable and angulable corpectomy cage system: early clinical and radiological outcome.

PURPOSE: Vertebral body replacement (VBR) cages are commonly implanted to reconstruct the cervical vertebrae in cases of tumour, trauma, spondylodiscitis, and degeneration. Expandable cages have been widely used for this purpose; however, the lacking congruence at the implant-bone interface and consequent implant displacement were considered as a serious drawback of such systems. Aim of this study is to evaluate the early clinical and radiological outcome of a modern in situ not only expandable but also angulable cervical corpectomy cage system. METHODS: A total of 42 patients who underwent a single or multilevel cervical VBR procedure were included and retrospectively evaluated in this single-centre case series. The neurological status was assessed using American Spinal Injury Association (ASIA) score. Complications were categorized into surgical (including implant-associated) and general medical. Radiographic parameters included regional angulation, segmental height, and coronal alignment. RESULTS: Mean age was 59.5 ± 20.6 years. The recorded ASIA score improved postoperatively by 10 points (p  0.0001). Surgical including implant-associated complication rates were 19.05%. Radiographic evaluation showed a height gain of 11.2 mm (p < 0.0001), lordotic correction of 7° (p < 0.0001), and coronal alignment of 3° (p < 0.0001). At the last follow-up, loss of angulation correction of 1.9° (p  0.0002), subsidence of 1.92 mm (p  0.0006), and fusion rates of 68.42% were observed. CONCLUSIONS: The use of an in situ angulable and expandable cage system in cervical VBR seems to offer better results compared to conventional static or expandable cages regarding segmental height gain, lordotic correction, and clinical improvement as well as low complication and revision rates. Significant height gain in multilevel surgeries is associated with higher rates of implant-associated complications.

Anthropometric measurements of the pediatric hip using CT-based simulated anteroposterior radiographs of the pelvis.

Normal anatomical variants and pathological deformities of the pediatric hip can only be differentiated after a prior definition of normal ranges for anthropometric parameters with increasing age. Aim of the present study was to provide reliable reference values of the pediatric hip morphometry, using computed tomography (CT)-based rotation-corrected summation images of the pelvis that simulate the widely available plain radiograph-based measurements, but offer the higher precision of the CT technique. This retrospective study included 85 patients (170 hips) under 15 years of age (0-15). The measured anthropometric parameters included femur head extrusion index, lateral center-edge angle, acetabular inclination, Tönnis angle, and femoral neck-shaft angle. Mean values, range, SD, P values, intra-rater, and inter-rater reliability were calculated. All measurements correlated with age. None of the measurements correlated with gender or side. Rapid growth phases were noted in all measurements at the age of 12 (14 in males and 11 in females). The inter-rater and intra-rater reliability was high (range inter/intraclass correlation coefficient 0.926-0.998 Cronbach's alpha 0.986-0.998). The present work provides age- and gender-related normative values of the classically used hip measurements as well as growth phases describing pediatric hip morphology in a broad age range. A discrepancy was noted between the values measured in the current study and the classical X-ray-based reference values in the literature especially for the Tönnis angle and LCEA values. This suggests that the rotation and inclination correction in the CT-based techniques might have the advantage of compensating for a possible overestimation in the conventional X-ray-based methods.

Anthropometric three-dimensional computed tomography reconstruction measurements of the acetabulum in children/adolescents.

The key element for differentiation between normal anatomical variants and pathological deformities is the prior definition of normal ranges for anthropometric parameters of acetabulum according to each age group. Aim of the present study is to analyze the development of the acetabulum in children/adolescents by accurate anthropometric measurements using 3D-CT scans and determine the variations occurring depending on age, gender and/or side. This retrospective observational study included 85 patients (170 hips) under 15 years of age (0-15) undergoing 1.5mm CT scanning for non-hip related reasons. The measurements were performed by 2 board-certified orthopaedic surgeons. Each year of life represented an age group forming a total of 16 groups. Median number of patients per age group was 12 (range 4-16). The anthropometric parameters included acetabular volume, inclination, version, depth (coronal and axial), width (coronal and axial), Tönnis angle as well as anterior and posterior acetabular sector angles. Mean values, range, standard deviation, p-values, intra- and interrater reliability were calculated. All measurement values correlated significantly with age. Statistically, there was no side or gender related difference. Rapid growth phases were observed at the age of 11-12. The inter- and intrarater reliability was high (range ICC 0.8-0.99, Cronbach alpha 0.86-0.99, Bland-Altman good agreement). The present data provides age- and gender-related normative values as well as growth phases describing acetabular morphology. It should help paediatricians as well as paediatric and orthopaedic surgeons as a tool for early diagnosis of deformity and guidance for possible procedures.

[Use of custom-made acetabular components (CMAC) as part of a two-stage procedure in patients with severe periacetabular bone loss]. / "Custom-made acetabular components" (CMAC) beim zweizeitigen Wechsel und bei höhergradigen periazetabulären Knochendefekten.

OBJECTIVE: Implantation of custom-made acetabular components (CMAC) with load transmission onto the remaining bone stock and reconstruction of the "center of rotation" (COR) in cases of severe periacetabular bone defects. INDICATIONS: Severe periacetabular bone loss (Paprosky type IIIA/B) with or without pelvic discontinuity after septic or aseptic loosening with inadequate load capacity of the dorsal pillar and/or large supraacetabular defects. CONTRAINDICATIONS: Acute or local infections, lack of compliance, taking into account the risks and complications: missing or limited expected postoperative functional gain, multimorbid patients with potential inoperability during the first and/or second intervention. SURGICAL TECHNIQUE: Lateral transgluteal or posterolateral approach while protecting neurovascular and muscular structures. Preparation of the implant site based on preoperative planning with augmentation of bone defects as far as possible. Primarily stable anchoring with 2 angle-stable pole screws in the ilium, an optional pole screw in the pubic bone for determination of COR, and stabilization screws in the iliac wing (optionally angle-stable). Use of dual mobility cup according to the soft tissue tension and intraoperative stability. POSTOPERATIVE MANAGEMENT: For the first 6 weeks postoperative partial weight-bearing (20 kg), followed by a gradual increase of the load (10 kg per week). RESULTS: Between 2008 and 2018, 47 patients with a Paprosky type III defect underwent implantation of a monoflanged CMAC. Main complication was a periprosthetic joint infection with subsequent need for implant removal in 9 of 10 cases. Harris Hip Score improved from 21.1 to 61.5 points. X­ray imaging displayed an angle of inclination of 42.3 ± 5.3°, an anteversion of 16.8 ± 6.2°, a ∆ H of 0.5 ± 0.2 mm and a ∆ V of 17.7 ± 1.1 mm according to Roessler et al.

5-Year Clinical and Radiographic Results of the Direct Anterior Approach for Total Hip Arthroplasty Using a Collared Cementless Femoral Short-Stem Prosthesis.

The aim of this study was to investigate the radiological and clinical outcome of the direct anterior approach (DAA) in total hip arthroplasty (THA) using a collared cementless femoral short-stem. This retrospective study included 124 patients with 135 THAs operated from 2014 to 2016 using a collared cementless triple tapered hydroxyapatite-coated femoral short-stem (AMIStem H Collared®, Medacta International, Castel San Pietro, Switzerland) implanted with a DAA. Follow-up was performed at three months, 12 months, and five years. Clinical outcome was assessed using the hip osteoarthritis outcome score (HOOS) and radiological analysis was done using conventional radiographs, which included evaluation of the femur morphology based on Dorr classification, of radiolucencies based on the Gruen zone classification and of stem subsidence. The mean age was 67.7 ± 11.3 years and the mean body mass index (BMI) was 27.4 ± 4.4 kg/m2. The stem survival rate at five years was 99.1% with one revision due to recurrent dislocations. Mean HOOS score improved from 40.9 ± 18.3 preoperatively to 81.5 ± 19.7 at three months, 89.3 ± 10.9 at 12 months, and 89.0 ± 14.0 at five years (all with p < 0.001). No significant correlations were found between age, femoral bone morphology, BMI and HOOS, and the appearance of relevant radiolucencies.

Risk factors for implant failure of custom-made acetabular implants in patients with Paprosky III acetabular bone loss and combined pelvic discontinuity.

BACKGROUND: Severe acetabular bone loss in revision total hip arthroplasty (RTHA), both with or without pelvic discontinuity, remains a great challenge in orthopaedic surgery. OBJECTIVE: The aim of this study was to evaluate risk factors for failure of custom-made acetabular implants in RTHA. METHODS: Seventy patients with severe acetabular bone loss (Paprosky Type III) and pelvic discontinuity, who required RTHA, were included in our study. All prostheses were constructed based on a thin-layer computed-tomography (CT) scan of the pelvis. The treatment was considered unsuccessful in the event of periprosthetic joint infection (PJI) or aseptic loosening (AL) with need for explantation of the custom-made acetabular implant. RESULTS: The average follow-up was 41.9 ± 34.8 months (range 1.5-120). Implant survival at last follow-up was 75.7% (53 of 70). Explantation was necessary in 17 cases (15 PJI; 2 AL). Previous PJI as reason for RTHA (p= 0.025; OR 3.56 (95% CI: 1.14; 11.21)), additional revision of femoral components (p= 0.003; OR 8.4 (95% CI: 1.75; 40.42)), rheumatoid disease (p= 0.039; OR 3.43 (95% CI: 1.01; 11.40)), elevated preoperative CRP > 15.2 mg/l (p= 0.015; AUC: 0.7) and preoperative haemoglobin < 10.05 (p= 0.022; AUC: 0.69) were statistically significant risk factors associated with treatment failure. Age and BMI were not statistically significant contributing to implant failure. CONCLUSION: Risk factors for treatment failure were a previous PJI, additional revision of femoral component, rheumatoid disease, elevated preoperative CRP and low preoperative haemoglobin. Awareness of these risk factors will help to improve future treatment standards.

Anthropometry of the proximal femur and femoral head in children/adolescents using three-dimensional computed tomography-based measurements.

PURPOSE: Defining normal anthropometric ranges of proximal femur and femoral head for each age group in children/adolescents is a necessity when differentiating normal anatomical variants from pathological deformities. Aim of this study is to define a set of normal anthropometric parameters based on 3D-CT measurements in normal asymptomatic children/adolescents and analyse the variations arising depending on age, side, and/or gender. METHODS: Morphology of the proximal femur was retrospectively assessed in 170 hips (85 children, < 15 years). Measurements included covered femoral head volume (CFHV), femoral head diameter (FHD), femoral head extrusion index (FHEI), coronal alpha angle (CAA), lateral centre-edge angle (LCEA), anterior (AOS) and posterior head-neck offset (POS) and femoral neck-shaft angle (FNSA). Correlation analyses as well as inter- and intra-rater reliability were performed. RESULTS: CFHV, LCEA, FHD and AOS/POS increased with age and FHEI, CAA, and FNSA decreased with age. None of the measurements correlated with the side. AOS showed a poor correlation with gender. Rapid growth phases were observed at the age of 1, 7 and 11. The inter- and intra-rater reliability was high (range ICC 0.8-0.99 Cronbach alpha 0.86-0.99). CONCLUSION: This data delivers a description of growth phases as well as gender and age-correlated reference values of the proximal femoral morphology that could be used by paediatricians and orthopaedic/paediatric surgeons to early diagnose proximal femur deformities and provide guidance in the planning of possible operations.

Superinfection with Difficult-to-Treat Pathogens Significantly Reduces the Outcome of Periprosthetic Joint Infections.

Periprosthetic joint infection (PJI) is a serious complication after total joint arthroplasty. In the course of a PJI, superinfections with pathogens that do not match the primary infecting micro-organism may occur. To our knowledge, there are no published data on the outcome of such infections in the literature. The aim of this study was to assess the outcome of PJI with superinfections with a difficult-to-treat (DTT) pathogen. Data of 169 consecutive patients with PJI were retrospectively analyzed in this single-center study. Cases were categorized into: Group 1 including non-DTT-PJI without superinfection, Group 2 DTT-PJI without superinfection, Group 3 non-DTT-PJI with DTT superinfection, and Group 4 non-DTT-PJI with non-DTT superinfection. Group 3 comprised 24 patients and showed, after a mean follow-up of 13.5 ± 10.8 months, the worst outcome with infection resolution in 17.4% of cases (p = 0.0001), PJI-related mortality of 8.7% (p = 0.0001), mean revision rate of 6 ± 3.6 (p < 0.0001), and duration of antibiotic treatment of 71.2 ± 45.2 days (p = 0.0023). PJI caused initially by a non-DTT pathogen with a superinfection with a DTT pathogen is significantly associated with the worst outcome in comparison to non-DTT-PJI, PJI caused initially by a DTT pathogen, and to non-DTT-PJI with a non-DTT superinfection.

Periprosthetic Infections of the Shoulder Joint: Characteristics and 5-Year Outcome of a Single-Center Series of 19 Cases.

Periprosthetic shoulder infection (PSI) remains a devastating complication after total shoulder arthroplasty (TSA). Furthermore, there is a paucity in the literature regarding its diagnostic and therapeutic management, especially the absence of therapy concepts devised exclusively for PSI. The aim of the presenting study is to examine the characteristics and outcome of patients with PSI who were treated according to well-established algorithms developed originally for periprosthetic joint infection (PJI) of the hip and knee and determine if these algorithms can be applied to PSI. This single-center case series included all patients with a PSI presenting between 2010 and 2020. Recorded parameters included age, sex, affected side, BMI, ASA score, Charlson comorbidity index, preoperative anticoagulation, indication for TSA (fracture, osteoarthritis or cuff-arthropathy), and type of infection (acute or chronic PSI). The outcome was divided into treatment failure or infect resolution. Staphylococcus epidermidis and aureus were the commonest infecting pathogens. Acute PSI was mainly treated with debridement, irrigation, and retention of the prosthesis (DAIR) and chronic cases with two/multiple-stage exchange. The treatment failure rate was 10.5%. C-reactive protein was preoperatively elevated in 68.4% of cases. The mean number of operative revisions was 3.6 ± 2.6, and the mean total duration of antibiotic treatment was 72.4 ± 41.4 days. The most administered antibiotic was a combination of clindamycin and fluoroquinolone. In summary, the data of the current study suggest that therapeutical algorithms and recommendations developed for the treatment of PJI of the hip and knee are also applicable to PSI.

Delayed Rifampin Administration in the Antibiotic Treatment of Periprosthetic Joint Infections Significantly Reduces the Emergence of Rifampin Resistance.

Rifampin is one of the most important biofilm-active antibiotics in the treatment of periprosthetic joint infection (PJI), and antibiotic regimens not involving rifampin were shown to have higher failure rates. Therefore, an emerging rifampin resistance can have a devastating effect on the outcome of PJI. The aim of this study was to compare the incidence of rifampin resistance between two groups of patients with a PJI treated with antibiotic regimens involving either immediate or delayed additional rifampin administration and to evaluate the effect of this resistance on the outcome. In this retrospective analysis of routinely collected data, all patients who presented with an acute/chronic PJI between 2018 and 2020 were recorded in the context of a single-center comparative cohort study. Two groups were formed: Group 1 included 25 patients with a PJI presenting in 2018-2019. These patients received additional rifampin only after pathogen detection in the intraoperative specimens. Group 2 included 37 patients presenting in 2019-2020. These patients were treated directly postoperatively with an empiric antibiotic therapy including rifampin. In all, 62 patients (32 females) with a mean age of 68 years and 322 operations were included. We found a rifampin-resistant organism in 16% of cases. Rifampin resistance increased significantly from 12% in Group 1 to 19% in Group 2 (p < 0.05). The treatment failure rate was 16% in Group 1 and 16.2% in Group 2 (p = 0.83). The most commonly isolated rifampin-resistant pathogen was Staphylococcus epidermidis (86%) (p < 0.05). The present study shows a significant association between the immediate start of rifampin after surgical revision in the treatment of PJI and the emergence of rifampin resistance, however with no significant effect on outcome.

Singleton-Merten syndrome: A rare cause of femoral head necrosis.

Singleton-Merten syndrome (SMS) is a type I interferonopathy. In this report, we disclose the first-to the best of our knowledge-direct association of SMS with femoral head necrosis (FHN). The following case report presents the condition of a 38-year-old male suffering from SMS with FHN, characterized by acute symptoms and rapid disease progression. As per the recommendations of the Association Research Circulation Osseous (ARCO) and the S3-guidelines, we successfully treated the FHN with core decompression. Our histological results correlate with the changes described in medical literature in patients with SMS and MDA5-knockout in vivo experiments such as osteopenia, widened medullary cavity, and thin cortical bone. Moreover, the conducted immunohistochemistry shows strong CD56 positivity of the osteoblasts and osteocytes, as well as significant CD68 and CD163 positivity of the middle-sized osteoclasts. Collectively, these findings suggest an underlying syndrome in the FHN. A six-month post-operative follow-up revealed complete recovery with the absence of the initial symptoms and ability to resume normal daily activities. Taken together, our findings suggest that SMS is an additional cause of FHN in young adults. Early detection and adequate treatment using well-established joint-preserving techniques demonstrate a favorable improvement of the patient's clinical condition.

Synovial Complement Factors in Patients with Periprosthetic Joint Infection after Undergoing Revision Arthroplasty of the Hip or Knee Joint.

The role and diagnostic value of the synovial complement system in patients with low-grade periprosthetic joint infection (PJI) are unclear. We sought to evaluate, for the first time, the usefulness of synovial complement factors in these patients by measuring the individual synovial fluid levels of complement factors (C1q, C3b/iC3b, C4b, C5, C5a, C9, factor B, factor D, factor H, factor I, properdin, and mannose-binding lectin [MBL]). The patients (n = 74) were classified into septic (n = 28) and aseptic (n = 46). Receiver-operator characteristic curves and a multiple regression model to determine the feasibility of a combination of the tested cytokines to determine the infection status were calculated. The synovial fluid levels of C1q, C3b/C3i, C4b, C5, C5a, MBL, and properdin were significantly elevated in the PJI group. The best sensitivity and specificity was found for C1q. The multiple regression models revealed that the combination of C1q, C3b/C3i, C4b, C5, C5a, and MBL was associated with the best sensitivity (83.3%) and specificity (79.2%) for a cutoff value of 0.62 (likelihood ratio: 4.0; area under the curve: 0.853). Nevertheless, only a combined model showed acceptable results. The expression patterns of the complement factors suggested that PJI activates all three pathways of the complement system.