Analysis of risk factors leading to failure in septic two-stage exchange arthroplasty

The aim of this habilitation script was to arm the treating physicians with an armamentarium of knowledge to achieve better success in eradicating PJI. Therefore, the published data concentrated on identification of the factors leading to failure in two-stage exchange arthroplasty in patients with PJI and on optimization of infection-free survival. Microbial biofilm makes the diagnosis and the treatment of PJI more challenging and therefore biofilm-active antibiotics are crucial to enhance treatment success. Microorganisms, for which no biofilm active antibiotic exits, presents a major difficulty in achieving high infect eradication rates in these patients. According to the results of this habilitation script however, an individualization of antimicrobial and surgical therapy regimes with a longer prothesis-free interval and longer antibiotic administration may enable achieving similar success rates in patients irrespective of causative microorganism after two-stage exchange arthroplasty. Furthermore, the data presented in this habilitation script emphasizes the implementation of a treatment supported by a multidisciplinary team approach as a crucial step to optimize outcome in patients with PJI. It could have been shown, that high infection eradication rates can be achieved by using a standardized two-stage exchange arthroplasty supported by a multidisciplinary team even in a challenging patient cohort. Given the fact, that there is a wide variety in the definition of PJI and its treatment success, which causes a heterogeneity of existing studies, further research is highly needed on more precisely defining PJI and success. Thus, consistency in definition between studies will enhance the overall quality of existing literature. Especially, when defining treatment success, it is important to distinguish between a new infection and an ongoing infection, as this prevent patients from unnecessary surgical interventions and antimicrobial treatment

Enterococcal periprosthetic joint infection: clinical and microbiological findings from an 8-year retrospective cohort study

BACKGROUND: Treatment of enterococcal periprosthetic joint infections (PJI) is challenging due to non-standardized management strategies and lack of biofilm-active antibiotics. The optimal surgical and antimicrobial therapy are unknown. Therefore, we evaluated characteristics and outcome of enterococcal PJI. METHODS: Consecutive patients with enterococcal PJI from two specialized orthopedic institutions were retrospectively analyzed. Both institutions are following the same diagnostic and treatment concepts. The probability of relapse-free survival was estimated using Kaplan-Meier survival curves and compared by log-rank test. Treatment success was defined by absence of relapse or persistence of PJI due to enterococci or death related to enterococcal PJI. Clinical success was defined by the infection-free status, no subsequent surgical intervention for persistent or perioperative infection after re-implantation and no PJI-related death within 3 months. RESULTS: Included were 75 enterococcal PJI episodes, involving 41 hip, 30 knee, 2 elbow and 2 shoulder prostheses. PJI occurred postoperatively in 61 episodes (81%), hematogenously in 13 (17%) and by contiguous spread in one. E. faecalis grew in 64 episodes, E. faecium in 10 and E. casseliflavus in one episode(s). Additional microorganism(s) were isolated in 38 patients (51%). Enterococci were susceptible to vancomycin in 73 of 75 isolates (97%), to daptomycin in all 75 isolates, and to fosfomycin in 21 of 22 isolates (96%). The outcome data was available for 66 patients (88%). The treatment success after 3 years was 83.7% (95% confidence interval [CI]; 76.1-96.7%) and the clinical success was 67.5% (95% CI; 57.3-80.8%). In 11 patients (17%), a new PJI episode caused by a different pathogen occurred. All failures occurred within 3 years after surgery. CONCLUSION: About half of enterococcal PJI were polymicrobial infections. The treatment success was high (84%). All treatment failures occurred within the first 3 years after revision surgery. Interestingly, 17% of patients experienced a new PJI caused by another pathogen at a later stage

No clinical consequence of liner malseating in dual-mobility THAs at short term: a systematic review

BACKGROUND: Liner malseating is well described in ceramic-on-ceramic total hip arthroplasties (THAs). However, limited information is known on this complication among dual-mobility articulations. As such, this systematic review analyzed liner malseating in dual-mobility THAs concerning prevalence, clinical implications, and associated risk factors. METHODS: A PRISMA criteria-based systematic review was performed, and PubMed, Web of Science, MEDLINE, and Cochrane used as data bases. All original studies from 1980 to 2022 were considered eligible for inclusion, and Methodological Index for Nonrandomized Studies (MINORS) used for quality assessment. RESULTS: In total, five retrospective cohort studies with 2330 patients (2673 dual-mobility THAs) were included. Mean age was 66.9 years, mean BMI was 29.8 kg/m2, and 35% of patients were female. Rates of malseating ranged from 0.15% to 5.8%, with a total of 53 malseated liners identified throughout all studies (1.98%). Based on THA manufacturer, malseating occurred in 48 Stryker (1.96%) and 5 Biomet Zimmer (2.14%) THAs. Mean clinical follow-up was 2.2 years (mean range, 1.3 to 6.4 years). Except one patient reporting of pain at 2 years, no revision or negative clinical implication was noted in any of the malseated liners, including normal ranged metal ions measured in four cases. A smaller acetabular component size was identified as a statistically significant risk factor for malseating in one study. Mean MINORS score was 9.8. CONCLUSIONS: Liner malseating is a rare finding in patients undergoing THAs with dual-mobility articulations. While prelim results demonstrate no negative clinical consequences to date, existing studies are limited, refer to short-term outcomes only, and do not prospectively follow-up affected patients. LEVEL OF EVIDENCE: IV

High rate of unexpected positive cultures in presumed aseptic revision of stiff shoulders after proximal humerus osteosynthesis

Background: The aim of this study was to investigate the prevalence of positive microbiology samples after osteosynthesis of proximal humerus fractures at the time of revision surgery and evaluate clinical characteristics of patients with positive culture results. Methods: All patients, who underwent revision surgery after locked platting, medullary nailing or screw osteosynthesis of proximal humeral fractures between April 2013 and July 2018 were retrospectively evaluated. Patients with acute postoperative infections, those with apparent clinical signs of infection and those with ≤1 tissue or only sonication sample obtained at the time of implant removal were excluded. Positive culture results of revision surgery and its correlation with postoperative shoulder stiffness was analyzed in patients with an interval of ≥6 months between the index osteosynthesis and revision surgery. Results: Intraoperatively obtained cultures were positive in 31 patients (50%). Cutibacterium acnes was the most commonly isolated microorganism, observed in 21 patients (67.7%), followed by coagulase negative staphylococci in 12 patients (38.7%). There were significantly more stiff patients in the culture positive group compared to the culture-negative group (19/21, 91% vs. 15/26, 58%, p = 0.02). Furthermore, 11 of 12 (91.7%) patients with growth of the same microorganism in at least two samples had a stiff shoulder compared to 23 of 35 (65.7%) patients with only one positive culture or negative culture results (p = 0.14). Conclusion: Infection must always be considered as a possibility in the setting of revision surgery after proximal humerus osteosynthesis, especially in patients with postoperative stiffness

Candida periprosthetic joint infections — risk factors and outcome between albicans and non-albicans strains

Background: Despite its scarcity, fungal periprosthetic joint infection (PJI) is of great clinical relevance as diagnosis and treatment are highly challenging. Previous analyses focused on the treatment rather than the role of the causative fungal agent on clinical outcome. This is the largest study of its kind to evaluate Candida strain-dependent differences in patients with fungal PJI. Methods: We retrospectively analyzed 29 patients who underwent surgical intervention due to Candida hip or knee PJI in our department from 2010 to 2018. PJI was defined according to IDSA, recurrent PJI according to modified Delphi consensus criteria. Statistical analysis was performed using t-test, chi-square test with Yates correction, and log rank test. Results: Besides age and affected joint, no significant differences were found between Candida albicans and non-albicans PJI patients (75.83 versus 64.11 years, p = 0.012; 12 hip versus two knee cases, p = 0.013). Most patients received two- (27.59%) or three-stage exchange surgery (41.38%). There was a statistical trend towards an increase in surgery needed in non-albicans Candida PJI (2.92 versus 2.12; p = 0.103). After initial Candida PJI treatment, functional prosthesis implantation was achieved in 72.41% of all patients. At last follow-up, infection-free survival was at 26.79% in Candida albicans versus 72.00% in non-albicans PJI (p = 0.046). Conclusions: In this study, we found infection-free survival rates to be significantly decreased in patients with albicans compared to non-albicans Candida PJI. While age and affected joint might play a confounding role, we speculate the causative pathogen to play a decisive role in disease progression

Is a preoperative pathogen detection a prerequisite before undergoing one-stage exchange for prosthetic joint infection of the hip?

BACKGROUND A preoperative pathogen detection is considered a prerequisite before undergoing one-stage exchange for prosthetic joint infection (PJI) according to most guidelines. This study compares patients with and without preoperative pathogen detection undergoing one-stage exchange for PJI of the hip. The authors put up the hypothesis that a preoperative pathogen detection is no prerequisite in selected cases undergoing one-stage exchange. METHODS 30 consecutive patients with PJI of the hip, treated with one-stage exchange, between 2011 and 2021, were retrospectively included. Mean age was 70 years and mean follow-up 2.1 ± 1.8 years. PJI was defined according to the European Bone and Joint Infection Society. One-stage exchange was performed in (1) chronic PJI longer than 4 weeks, (2) well-retained bone condition, (3) absence of multiple prior revisions for PJI (≤ 2) with absence of difficult-to-treat pathogens in the past, and (4) necessity/preference for early mobility due to comorbidities/age. RESULTS One-stage exchange was performed in 20 patients with and in 10 without a preoperative pathogen detection. Age (71 years, 68 years, p = 0.519), sex (50% and 30% males, p = 0.440), American Society of Anesthesiologists Score (2.2, 2.4, p = 0.502), and Charlson Comorbidity Index (3, 4, p = 0.530) did not differ among the two groups. No significant differences were noted concerning preoperative CRP (15 mg/l, 43 mg/l, p = 0.228), synovial cell count (15.990/nl, 5.308/nl, p = 0.887), radiological signs of loosening (55%, 50%, p = 0.999), and intraoperative histopathology. Except a higher rate of coagulase-negative staphylococci (70%, 20%, p = 0.019) in patients with a preoperative pathogen detection, no significant differences in pathogen spectrum were identified among groups. Revision for PJI recurrence was performed in one patient with an initial preoperative pathogen detection (3.3%). Additional revisions were performed for dislocation in two and postoperative hematoma in one patient. Revision rate for both septic and aseptic causes (p = 0.999), stay in hospital (16 and 15 days, p = 0.373) and modified Harris Hip Score (60, 71, p = 0.350) did not differ between groups. CONCLUSION Patients with and without a preoperative pathogen detection did not show significant differences concerning baseline characteristics, clinical and functional outcomes at 2 years. An absent preoperative pathogen detection is no absolute contraindication for one-stage exchange in chronic PJI, if involving good bone quality and absence of multiple prior revisions

The role of serum C-reactive protein in the diagnosis of periprosthetic shoulder infection

Introduction: There is a paucity of literature regarding serum C-reactive protein (CRP) in the evaluation of a shoulder periprosthetic joint infection (PJI). The purpose of the current study was to establish cutoff values for diagnosing shoulder PJI and evaluate the influence of the type of infecting microorganism and the classification subgroups according to last proposed International Consensus Meeting (ICM) criteria on the CRP level. Materials and methods: A retrospective analysis of all 136 patients, who underwent septic or aseptic revision shoulder arthroplasty in our institution between January 2010 and December 2019, was performed. Shoulder PJI was defined according to the last proposed definition criteria of the ICM. Serum CRP levels were compared between infected and non-infected cases, between infection subgroups, as well as between different species of infecting microorganisms. A receiver-operating characteristic (ROC) analysis was performed to display sensitivity and specificity of serum CRP level for shoulder PJI. Results: A total of 52 patients (38%) were classified as infected, 18 meeting the criteria for definitive infection, 26 for probable infection and 8 for possible infection. According to the ROC curve, an optimized serum CRP threshold of 7.2 mg/l had a sensitivity of 69% and specificity of 74% (area under curve = 0.72). Patients with definitive infection group demonstrated significantly higher median serum CRP levels (24.3 mg/l), when compared to probable, possible infection groups and PJI unlikely group (8 mg/l, 8.3 mg/l, 3.6 mg/l, respectively, p < 0.05). The most common isolated microorganism was Cutibacterium acnes in 25 patients (48%) followed by coagulase-negative staphylococci (CNS) in 20 patients (39%). Patients with a PJI caused by high-virulent microorganisms had a significantly higher median serum CRP level compared to patients with PJI caused by low-virulent microorganisms (48 mg/l vs. 11.3 mg/l, p = 0.04). Conclusions: Serum CRP showed a low sensitivity and specificity for the diagnosis of shoulder PJI, even applying cutoffs optimized by receiver-operating curve analysis. Low-virulent microorganisms and patients with probable and possible infections are associated with lower CRP levels compared to patients with definitive infection and infections caused by high-virulent microorganisms

Comparison of Structural Subscapularis Integrity After Latarjet Procedure Versus Iliac Crest Bone Graft Transfer

Background: Although clinical outcome scores are comparable after coracoid transfer procedure (Latarjet) and iliac crest bone graft transfer (ICBGT) for anterior shoulder instability with glenoid bone loss, a significant decrease in internal rotation capacity has been reported for the Latarjet procedure. Hypothesis: The subscapularis (SSC) musculotendinous integrity will be less compromised by ICBGT than by the Latarjet procedure. Study Design: Cohort study; Level of evidence, 3. Methods: We retrospectively analyzed pre- and postoperative computed tomography (CT) scans at short-term follow-up of 52 patients (26 Latarjet, 26 ICBGT) previously assessed in a prospective randomized controlled trial. Measurements included the preoperative glenoid defect area and graft area protruding the glenoid rim at follow-up and tendon thickness assessed through SSC and infraspinatus (ISP) ratios. Fatty muscle infiltration was graded according to Goutallier, quantified with muscle attenuation in Hounsfield units, and additionally calculated as percentages. We measured 3 angles to describe rerouting of the SSC musculotendinous unit around the bone grafts. Results: SSC fatty muscle infiltration was 2.0% ± 2.2% in the Latarjet group versus 2.4% ± 2.2% in ICBGT (P = .546) preoperatively and showed significantly higher values in the Latarjet group at follow-up (5.3% ± 4.5% vs 2.3% ± 1.7%; P = .001). In total, 4 patients (15.4%) in the Latarjet group showed a progression from grade 0 to grade 1 at follow-up, whereas no changes in the ICBGT group were noted. The measured rerouting angle of the SSC muscle was significantly increased in the Latarjet group (11.8° ± 2.1°) compared with ICBGT (7.5° ± 1.3°; P < .001) at follow-up, with a significant positive correlation between this angle and fatty muscle infiltration (R = 0.447; P = .008). Ratios of SSC/ISP tendon thickness were 1.03 ± 0.3 in the Latarjet group versus 0.97 ± 0.3 (P = .383) in ICBGT preoperatively and showed significantly lower ratios in the Latarjet group (0.7 ± 0.3 vs 1.0 ± 0.2; P < .001) at follow-up. Conclusion: Although clinical outcome scores after anterior shoulder stabilization with a Latarjet procedure and ICBGT are comparable, this study shows that the described decline in internal rotation capacity after Latarjet procedure has a radiographic structural correlate in terms of marked thinning and rerouting of the SSC tendon as well as slight fatty degeneration of the muscle

Computed tomography analysis of native hips shows no correlation between hip anatomy and the distribution of hip musculature in horizontal plane

Einleitung: Dislokationen des künstlichen Hüftgelenkersatzes (H-TEP) sind multifaktoriell bedingt. Zuletzt konnte gezeigt werden, dass sowohl die Positionierung der Implantate wie auch die Wahl des Zuganges und damit der periartikulären Muskelschädigung entscheidend sind. Die gewählten Implantate und deren Positionierung bedingen und bestimmen den Bewegungsumfang und die Stabilität des Hüftgelenkes über diesen Bewegungsumfang. Zielwerte hierfür sind jedoch nicht klar zu definieren, denn weder durch die safe zone nach Lewinnek noch durch die weitgehende Rekonstruktion der nativen Hüftgelenkgeometrie konnten Dislokationen sicher vermieden werden. Ziel dieser Arbeit ist es, die Gelenkgeometrie und die Größe und Ausrichtung der hüftgelenkumgreifenden Muskulatur hinsichtlich eines Zusammenhanges zu analysieren. Methodik: Die knöcherne Anatomie (femorale Antetorsion (AT), azetabuläre Anteversion (AV) und kombinierte Anteversion) und die Muskelvolumina der Musculi glutei und des Musculus tensor fasciae latae wurden aus Computertomographie-Daten von 49 Patienten (23 Frauen und 26 Männern) bilateral erfasst. Nachfolgend wurden die Zusammenhänge zwischen der Muskelkraftzugrichtung und Verteilung der pelvitrochantären Muskulatur und der AV, AT und kombinierten Anteversion analysiert. Ergebnisse: Die Messungen zeigten eine azetabuläre Anteversion von 21,9° ± 5,9°, eine femorale Antetorsion von 7,22° ± 7,4° und eine kombinierte Anteversion von 29,2° ± 9°. Das Muskelvolumen für jeden Muskel betrug: gluteus maximus: 780 ± 227ccm, gluteus medius: 322 ± 82ccm, gluteus minimus: 85 ± 20ccm, tensor fasciae latae: 68 ± 22ccm. Die daraus berechnete Muskelkraftzugrichtung betrug 18,92° ± 1,29°. Die analysierten Parameter ließen keinen Zusammenhang zwischen der Orientierung der Gelenkpartner (AV, AT und kombinierte Anteversion) und der Verteilung der gelenkumgreifenden Muskulatur erkennen. Diskussion: Es hat sich in horizontaler Ebene keine Korrelation zwischen der Muskelverteilung und knöchernen Gelenkorientierung gezeigt. Das ist der theoretische Hintergrund dafür, dass es bei der H-TEP-Implantation in erster Linie der iatrogen gesetzte Schaden ist, der zu einer Neuausrichtung des muskulären Gleichgewichtes führt. Deshalb ist davon auszugehen, dass die postoperative Muskelinsuffizienz nach H-TEP Implantation eher der Grund der Hüftgelenkinstabilität in eine Richtung ist, als eine patienten-spezifische Muskelverteilung. Wichtiger jedoch noch, dass der durch den gewählten chirurgischen Zugang entstehende Muskelschaden diese Gleichverteilung ändert und somit zur Gewährleistung idealer Stabilität nach H-TEP safe zone zugangsspezifisch zu definieren ist. Deshalb müssen zukünftige Normwerte für eine Rekonstruktion des Hüftgelenks iatrogene muskuläre Einflüsse mehr berücksichtigen und zugangsspezifischer sein.Introduction: Dislocation after hip joint arthroplasty (THA) occurs approach oriented, in spite of an implantation of the joint components in accepted safe zones defined by Lewinnek. Every operative approach leads to a concrete muscle damage, which can lead to dislocation. As a result, the assumption is deduced, that an ideal positioning of joint components should be defined approach specific to minimize the rate of dislocation. Requirement for this assumption is an equally distributed periarticular musculature around the hip joint without any demography or joint associated differences in THR-population. The aim of this study was to analyze the relationship between joint geometry and orientation of the hip musculature. Methods: The bony anatomy of the hip (femoral antetorsion (AT), acetabular anteversion (AV) and combined anteversion) and the muscle volumes of the gluteal muscle group and the tensor fasciae latae were retrospectively analyzed bilaterally based on computer tomography data of 49 patients. Muscle force directions (MFD) were determined for each muscle using the measured volumes and were then summed as the MFD of the hip muscle group, which was then correlated with the bony anatomy. Results: The measurements yielded a mean AV of 21.9° ± 5.9°, AT of 7.22° ± 7.4°, and combined anteversion of 29.2° ± 9°. The mean muscle volume for each muscle was: gluteus maximus: 780 ± 227 ccm, medius: 322 ± 82 ccm, minimus: 85 ± 20 ccm, tensor fasciae latae: 68 ± 22ccm. The mean MFD was 18.92° ± 1.29°. The analysis showed a uniform distribution of the musculature without correlation with the bony anatomy. Conclusion: The uniform distribution of the hip musculature can serve as an explanatory model for the observation that hip joint instability after THA due to muscular insufficiency has to be attributed most likely to the muscle damage during the surgical approach rather than to a patient-specific muscle distribution. Muscle damage arising from the chosen surgical approach alters this uniform distribution, and thus the safe zone providing ideal stability after THA should be defined specifically for each approac

Aspergillus PJI - A systematic analysis of all known cases and report of a new one

Fungi resemble less than one percent of all periprosthetic joint infections (PJI). While Candida PJI is well described, Aspergillus PJI has only been reported in a few cases without any systematic analysis present at this point. This review aims to systematically summarize and describe all cases of Aspergillus PJI. The systematic review used PubMed and Cochrane Library to identify case reports and studies eligible for inclusion. One additional case was reported by the authors. T-, Mann-Whitney U- and Fisher-exact tests were used for calculations. Overall, 11 cases of Aspergillus PJI were identified, and ten could be included for a detailed analysis (four hip, four knee, one elbow, one PIP-arthroplasty infection). A. fumigatus was identified in four, A. terreus in three, and A. niger in two cases. The average patient age at time of Aspergillus spp. diagnosis was 64.1 years (32-83) and the mean time from primary implantation to Aspergillus PJI 5.2 years (1-16). The calculated CCI was 2.7 (0-6). Surgery included one-, two-, three-stage-, and spacer-exchange, debridement and resection arthroplasty. Four patients were treated with a triazole for an average of three months, three with amphotericin (mean eight weeks), one with both amphotericin (six weeks) and triazole (seven months). In one patient, reinfection with Coagulase Negative Staphylococci following Aspergillus PJI treatment was noted after four years. A. terreus (p = .048) was associated with failed prosthesis reimplantation (n = 4). To give a resume, Aspergillus PJI is a rare, yet severe complication, with heterogeneous clinical presentation. Complete prosthesis removal is the treatment of choice