Midterm results of modular hinge total knee arthroplasty using cementless osseointegrating stems: low fixation associated complications and good functional outcome in primary and revision knee arthroplasty.

PURPOSE: This study aimed to investigate functional outcome and complications after primary and revision modular H-TKA using hybrid fixation with cementless stems. METHODS: Between 2015 and 2018, 48 patients with 50 implants were included after hybrid implantation of a single design H-TKA system using cementless osseointegrating stems and modular components. Complications and clinical outcome were analysed using Knee Society Score (KSS), the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) and the Short-Form Health Survey 12 (SF-12) score. RESULTS: Indications for implantation were aseptic revision (n = 29, 58%), primary TKA (n = 19, 38%) and two-stage septic revisions (n = 2, 4%). Complications were reported in 26% (n = 12), whereas complications associated with hybrid fixation occurred in 5 (10%) cases, with 2 (4%) requiring revision surgery for aseptic loosening and 3 (6%) treated with an adapted postoperative protocol for perioperative fractures. Implant survivorship was 84% after a mean follow-up of 54 months. Postoperative KSS significantly improved from 51.50 (12-100) to 78.36 (41-99; p < 0.001). The mean WOMAC score was 19.26 (0-55), SF-12 PCS was 41.56 points (22.67-57.66) and SF-12 MCS was 49.21 points (23.87-63.21). CONCLUSION: Hybrid modular implantation in H-TKA provides satisfactory clinical and functional results in primary and revision TKA. Clinical outcomes significantly improve with reduced pain, increased mobility, and good-to-excellent functional scores after implantation. Whilst implant survival is comparable to previous studies and complications associated with hybrid fixation are low, general complication rates are comparably high.

The optimal diagnostic cut-off of WBC and PMN counts for joint aspiration in periprosthetic joint infection is 2479/µL and 67%, respectively: ICM criteria thresholds are too high.

BACKGROUND: Various organizations have published definitions for periprosthetic joint infection (PJI) with significant differences in the cut-offs of white blood cell (WBC) count and polymorphonuclear (PMN) leukocyte cells. Herein, we aim to analyze optimal cut-offs in patients which are planned to undergo a prosthesis revision and compare them with the actual published thresholds of the International Consensus Meeting (ICM) and European Bone and Joint Infection Society (EBJIS). METHODS: A test kit was compiled in a monocentric prospective study, according to the ICM criteria (2018) and 2021 EBJIS criteria. The kit was implemented using: blood samples (including leukocyte count and C-reactive protein); samples for examining the synovial fluid (WBC count, PMN cell differentiation, microbiological culture for incubation over 14 days, alpha-defensin ELISA laboratory test, and leukocyte-esterase test). The cut-offs for WBC and PMN counts were investigated using ROC analyses and Youden index. The ICM 2018 criteria were applied, using alpha-defensin in all cases. Patients which have to undergo a prosthesis revision were included, a pre-operative joint aspiration had been performed, and the patients had been followed up prospectively. RESULTS: 405 patients were examined with the compiled test kit; 100% had a complete dataset with respect to alpha-defensin; 383 patients, according to WBC count; and 256, according to PMN cell differentiation The cut-off of 2478.89 cells/µl in the WBC count (sensitivity: 87.70%; specificity: 88.10%) and the cut-off of 66.99% in PMN differentiation showed the best accuracy (sensitivity: 86.00%; specificity: 88.80%). Other published cut-offs for WBC were tested in this cohort and showed the following accuracy: 3000/µl (EBJIS/ICM; sensitivity: 82.10%; specificity: 91.00%), 2000/µl (sensitivity: 89.60%; specificity: 83.40%), and 1500/µl (sensitivity: 91.50%; specificity: 75.00%). The published cut-offs for PMN had the following accuracy in this cohort: 80% (ICM; sensitivity: 66.3%; specificity: 96.50%), 70% (sensitivity: 82.6%; specificity: 90%), and 65% (EBJIS, sensitivity: 86%; specificity: 88.8%). CONCLUSIONS: This study aims to improve current cut-offs for PMN- and WB-Count, even though PJI diagnosis is based on the combination of all defined tests. The optimal diagnostic cut-off of WBC and PMN counts was found to be 2479/µL and 67%, respectively, whereas ICM cut-offs in this cohort seem too high, as they provide high specificity but very low sensitivity. On the other hand, a cut-off for WBC count of 1500/µl alone would be very low, leading to low specificity and very high suspicion of PJI. The current consensus guidelines could be actualized considering these results to significantly improve the diagnostic quality. LEVEL OF EVIDENCE: II.

[Implementation of a standardized clinical test kit for diagnostics of periprosthetic infections in the clinical routine. German version]. / Implementierung eines standardisierten Test-Kits zur Diagnostik von periprothetischen Infektionen in der klinischen Routine.

BACKGROUND: The number of primary arthroplasties is increasing and the proportion of revision arthroplasties is becoming increasingly more important. The need for standardized and guideline-based diagnostics for the safe detection of a periprosthetic joint infection (PJI) is becoming apparent. In the past 10 years various organizations have published definitions and diagnostic guidelines. The implementation of an inhouse standard test kit could help to simplify the process and could improve the diagnostic quality. METHOD: In 2016 a test kit was compiled in a monocentric prospective study, taking the International Consensus Meeting (ICM) criteria 2014 and the Infectious Diseases Society of America (IDSA) criteria into account, which also fulfils the definitions of the ICM criteria 2018 and criteria of the European Bone and Joint Infection Society 2021. The test kit was implemented in the clinical setting of a special department for aseptic and septic revision arthroplasty. The usability and accuracy of the test kit were examined. RESULTS: The test kit was implemented using blood samples (leukocyte count; C­reactive protein, CRP), samples for examining the synovial fluid (white blood cell count, PMN cell differentiation, microbiological culture for incubation over 14 days, alpha-defensin enzyme-linked immunosorbent assay, ELISA, leukocyte esterase test strips) together with information and request forms. Between April 2016 and February 2020 a total of 405 patients were investigated. Within 3 calendar years, the use of the test kit increased from 59% initially to 86%, and finally to 96% of cases in the third calendar year. The leukocyte esterase test strip was reliable in only 72%, due to undifferentiated readability or blood contamination. The costs increased by the only commercially available alpha-defensin ELISA test by approx. 52€ per puncture. The best individual test showed a sensitivity/specificity of 92.8%/95.2% with alpha-defensin. It was calculated which combinations showed a similar test quality and different combinations, such as CRP+ cell count+ microbiology showed a sensitivity/specificity both of around 90%. Metallosis is a challenge for preoperative PJI diagnostics. DISCUSSION: In a prospective study it was shown, that the implementation of the standardized test kit lead to a guideline based PJI diagnostic in all cases and thus to a significantly increase of the diagnostic quality. There is currently no single test that reliably excludes or proves an infection. The alpha-defensin laboratory ELISA test showed the best test accuracy, whereby the consideration of test combinations is obligatory and at the same time safe.

Modular knee arthrodesis secures limb, mobility, improves quality of life, and leads to high infection control in periprosthetic knee infection, when revision knee arthroplasty is not an option.

INTRODUCTION: This study compared the outcome of knee arthrodesis versus hinged total knee arthroplasty (TKA) in patients suffering from periprosthetic joint infection (PJI). METHODS: 104 patients with PJI were treated using a two-stage exchange of failed TKA. In case of non reconstructable bone loss or loss of extension mechanism, a modular intramedullary arthrodesis nail was used for reimplantation [Knee Arthrodesis Module (KAM); n = 52]. The control group was retrospectively matched treated using a hinged revision TKA [Rotating Hinge Knee (RHK); n = 52]. PJI remission rates, functional outcome (WOMAC; KSS) and quality of life (SF-12), as well as comorbidities and pain were evaluated. RESULTS: Mean age was 72.5 years. Charlson Comorbidity Index was higher in the KAM group (3.3 vs. 2.8). PJI remission rate was 89.4% (88.5% vs. 90.4%, respectively). In case of reinfection, implant retention was mostly possible in the RHK group (7.7%), whereas amputations were mostly performed in the KAM group (9.6%). Significant pain reduction (VAS 7.9-2.8) was achieved in both groups. Walking distance was significantly reduced in the KAM groups versus the RHK group (504 vs. 1064 m). WOMAC and KSS function scores were significantly reduced in the KAM group (25 vs. 40 and 35 vs. 64). Only moderate reduction in quality of life in the KAM group was observed (SF-12 physical: 34 vs. 40; SF-12 mental: 51 vs. 56) respectively. CONCLUSIONS: Arthrodesis using a modular intramedullary nail is an alternative for limb salvage, pain reduction, and preservation of quality of life and everyday mobility, when revision TKA is not an option. This study presents the largest number of case, comparing the outcome after performing an arthrodesis versus hinged TKA after septic failed TKA.

Implementation of a standardized clinical test kit for diagnostics of periprosthetic infections in the clinical routine.

BACKGROUND: The number of primary arthroplasties is increasing and the proportion of revision arthroplasties is becoming increasingly more important. The need for standardized and guideline-based diagnostics for the safe detection of a periprosthetic joint infection (PJI) is becoming apparent. In the past 10 years various organizations have published definitions and diagnostic guidelines. The implementation of an inhouse standard test kit could help to simplify the process and could improve the diagnostic quality. METHOD: In 2016 a test kit was compiled in a monocentric prospective study, taking the International Consensus Meeting (ICM) criteria 2014 and the Infectious Diseases Society of America (IDSA) criteria into account, which also fulfils the definitions of the ICM criteria 2018 and criteria of the European Bone and Joint Infection Society 2021. The test kit was implemented in the clinical setting of a special department for aseptic and septic revision arthroplasty. The usability and accuracy of the test kit were examined. RESULTS: The test kit was implemented using blood samples (leukocyte count; C­reactive protein, CRP), samples for examining the synovial fluid (white blood cell count, PMN cell differentiation, microbiological culture for incubation over 14 days, alpha-defensin enzyme-linked immunosorbent assay, ELISA, leukocyte esterase test strips) together with information and request forms. Between April 2016 and February 2020 a total of 405 patients were investigated. Within 3 calendar years, the use of the test kit increased from 59% initially to 86%, and finally to 96% of cases in the third calendar year. The leukocyte esterase test strip was reliable in only 72%, due to undifferentiated readability or blood contamination. The costs increased by the only commercially available alpha-defensin ELISA test by approx. 52€ per puncture. The best individual test showed a sensitivity/specificity of 92.8%/95.2% with alpha-defensin. It was calculated which combinations showed a similar test quality and different combinations, such as CRP+ cell count+ microbiology showed a sensitivity/specificity both of around 90%. Metallosis is a challenge for preoperative PJI diagnostics. DISCUSSION: In a prospective study it was shown, that the implementation of the standardized test kit lead to a guideline based PJI diagnostic in all cases and thus to a significantly increase of the diagnostic quality. There is currently no single test that reliably excludes or proves an infection. The alpha-defensin laboratory ELISA test showed the best test accuracy, whereby the consideration of test combinations is obligatory and at the same time safe.

Salvage procedure for chronic periprosthetic knee infection: the application of DAIR results in better remission rates and infection-free survivorship when used with topical degradable calcium-based antibiotics.

PURPOSE: Debridement, systemic antibiotics and implant retention (DAIR) is very successful for early periprosthetic joint infection (PJI), but can fail in late-onset cases. We selected patients with PJI who were unsuitable for two-stage exchange total knee arthroplasty (TKA) and compared the outcomes of DAIR with or without degradable calcium-based antibiotics. METHODS: All patients fulfilled the criteria for late-onset PJI of TKA, as defined by an International Consensus Meeting in 2013, but were unsuitable for multistage procedures and TKA exchange due to operative risk. Fifty-six patients (mean age: 70.6 years, SD ± 10.8), in two historical collectives, were treated using a single-stage algorithm consisting of DAIR without antibiotics (control group, n = 33, 2012-2014), or by DAIR following the implantation of degradable antibiotics as indicated by an antibiogram (intervention group, n = 23, 2014-2017). OSTEOSET® (admixed vancomycin/tobramycin), and HERAFILL-gentamicin® were used as carrier systems. The primary endpoint was re-infection or surgical intervention after DAIR. RESULTS: There were no significant differences between the two groups in terms of mean age, Charlson comorbidity index or the rate of mixed infections. Overall, 65.2% of patients achieved remission in the intervention group compared with only 18.2% in the control group (p < 0.001); 50% of re-infections in the intervention group even occurred after 36 months. Kaplan-Meier analysis showed that, compared with controls, the intervention group experienced significantly longer 3-year infection-free survival. CONCLUSION: DAIR shows poor efficacy in difficult-to-treat cases, as demonstrated in our control group, which had a re-infection rate of 81.8%. In contrast, a DAIR group receiving topical calcium-based antibiotics showed significantly higher 3-year infection-free survival. Therefore, the combination of DAIR and degradable antibiogram-based local antibiotics is a reasonable salvage procedure for this body of patients. This is important as the number of severely sick patients who are too old for appropriate PJI treatment is estimated to increase significantly due to demographic change.

[Development and validation of a checklist for evaluating videos for learning resuscitation measures]. / Entwicklung und Validierung einer Checkliste zur Bewertung von Videos zum Erlernen von Reanimationsmaßnahmen.

BACKGROUND: Well-performed resuscitation measures can improve the outcome in the event of cardiovascular arrest. Medical students often use teaching videos to learn practical skills. Studies confirmed the often inadequate quality of the videos on resuscitation available on the Internet. An evaluation using a validated checklist based on the current guidelines has so far been lacking. OBJECTIVE: The development and validation of a checklist for evaluating instructional videos on resuscitation. MATERIAL AND METHODS: In an expert workshop, checklist items were formulated based on the current guidelines. The checklist was tested by emergency physicians in a 4-step review process. The evaluations were analyzed and the items adjusted and specified if necessary. After the review process was completed, the checklist was applied to 74 videos on the topic of resuscitation. RESULTS: The checklist consists of 25 items in 4 categories (initial measures, chest compression, AED use, breathing), which are rated on a 3-level Likert scale. A total of 16 emergency doctors participated in the study and rated an average of 9.3 ± 5.7 videos each. The reviewers agreed in 65.1 ± 12.6% of the cases. The highest agreement was achieved in the subtopic AED, with the item "do not touch patients in shock" having the highest agreement. The items in the thoracic compression category were most often rated differently. CONCLUSION: For the first time, a checklist for evaluating instructional videos for resuscitation was created and validated for German-speaking countries.

[Early Results of Adjuvant Topical Treatment of Recurrent Osteomyelitis with Absorbable Antibiotic Carriers]. / Erste Ergebnisse in der Anwendung resorbierbarer, lokaler Antibiotikaträger bei Rezidivosteomyelitiden.

Background Treatment of musculoskeletal infections principally consists of radical surgical debridement and systemic administration of antibiotics. Additional local antibiotic therapy is not yet generally established, and lacks evidence-based proof of efficacy. Nonetheless, there are a variety of practical approaches, as most specialised departments are unwilling to forego this option. The established polymethylmetacrylate (PMMA) carrier system has a number of practical disadvantages. This has led to the increased use of absorbable carrier systems, and those based on calcium sulphate have given particularly encouraging results. In this article, we present our experience with this procedure in the treatment of osteomyelitis. There is currently no standard procedure or algorithm for the use of local antibiotic carriers in the treatment of recurrent osteomyelitis. Material and Methods Between February 2014 and May 2015, a total of 93 patients were treated with an absorbable carrier of topical antibiotics based on calcium sulphate. These patients had suffered from a recurrence of osteomyelitis that had been unsuccessfully treated by the primary implantation of a PMMA chain and systemic antibiotics. The treatment algorithm consisted of radical debridement, followed by implantation of a commercial PMMA chain. If no remission of the infection was observed, the chains were surgically removed and replaced with an absorbable carrier system and antibiotics chosen in accordance with the resistogram. Pursuant to the classification of Cierny and Mader, 10 patients were classified as type I, 5 as type II, 55 as type III and 23 as type IV. The mean follow-up period was 11 months. Two carrier systems, Osteoset® and Herafill®, were purchased from Wright Medical Technology Inc., Arlington, TN, USA and Heraeus Medical GmbH, Wehrheim, Germany, respectively. These were used as supplied for tobramycin and gentamycin. In the case of Osteoset, it was also possible to add an additional arbitrary, water-soluble antibiotic. Systemic administration of antibiotics was carried out in parallel in accordance with the resistogram. Results The most common clinical entities were femoral (36 %) and tibial (29 %) osteitis. Vancomycin (38 %) and tobramycin (38 %) were the most frequently used topical antibiotics, followed by gentamycin (17 %), ceftriaxone (4 %), fosfomycin (2 %) and colistin (1 %). Systemic administration of antibiotics was carried out in parallel, in accordance with the resistogram. In 85 % of all patients, remission was achieved. Infections with methicillin-resistant Staphylococcus aureus (MRSA; 62 %) and Pseudomonas aeruginosa (43 %) showed significantly poorer remission rates. The bacterial spectrum was primarily composed of Staphylococcus aureus (28 %), Staphylococcus epidermidis (22 %), Pseudomonas aeruginosa (7 %) and Enterococcus faecalis (5 %), as well as Escherichia coli and Klebsiella oxytoca (4 %). Conclusion Topical adjuvant antibiotic therapy based on an absorbable carrier system offers an expedient extension of the treatment of osteomyelitis. The remission rate of 85 % for recurrent infections encouraged the use of a therapeutic alternative for many patients. We developed an algorithm for the treatment of osteomyelitis, which includes the application of local antibiotics with different compositions and absorbable carriers. We present early results of successful treatment of patients with recurrent osteomyelitis, after futile topical therapy with non-absorbable antibiotic chains.