The influence of biological DMARDs on aseptic arthroplasty loosening: a retrospective cohort study.

OBJECTIVE: To investigate whether biological DMARDs affect the risk of aseptic loosening after total hip/knee arthroplasty (THA/TKA) in patients with RA. METHODS: We retrospectively identified all patients suffering from RA who underwent THA/TKA at our academic centre between 2002 and 2015 and linked them with an existing prospective observational RA database at our institution. The risk of aseptic loosening was estimated using radiological signs of component loosening (RCL). A time-dependent Cox regression analysis was used to compare the risk of implant loosening between patients treated with traditional DMARDS and biological DMARDs, or alternately both over time. RESULTS: A total of 155 consecutive total joint arthroplasties (TJAs) (103 TKA vs 52 THA) was retrospectively included in the study. Mean age at implantation was 59 ± 13 years. Mean follow-up time was 69 ± 43 months. Overall, 48 (31%) TJAs showed signs of RCL, with 28 (27.2%) RCLs occurring after TKA compared with 20 after THA (38.5%). A significant difference regarding the incidence of RCL between the traditional DMARDs group (39 cases of RCL, 35%) and the biological DMARDs group (nine cases of RCL, 21%) (P = 0.026) was observed using the log-rank test. This was also true when using a time-dependent Cox regression with therapy as well as arthroplasty location (hip vs knee) as variables (P = 0.0447). CONCLUSION: Biological DMARDs may reduce the incidence of aseptic loosening after TJA in patients with RA compared with traditional DMARDs. This effect seems to be more pronounced after TKA than THA.

Thirty-Year Minimum Follow-Up Outcome of a Straight Cementless Rectangular Stem.

BACKGROUND: Meta-diaphyseal fixation of straight, tapered, uncemented stems has been proven to be very reliable for total hip arthroplasty in 10 to 20 years of follow-up studies. The aim of the study was to evaluate whether the implant survival as well as radiological and functional outcome have changed in patients with a minimum follow-up of 30 years. METHODS: From a total of 210 patients, who received a straight, rectangular, tapered cementless stem and a threaded cup, there were 37 total hip arthroplasties (33 patients) still available for follow-up after a minimum of 30 years. Patients were examined clinically and radiographically, and revision surgeries were recorded. RESULTS: There was a low rate of revisions of the femoral stem with a survival probability of 0.92 (confidence interval 0.85 to 0.96) at 30 years. Survival probability of the acetabular component decreased drastically with 0.45 (confidence interval 0.30 to 0.59). Radiographic analysis of the stem revealed radiolucencies in 73% (n = 16), but only in the proximal/metaphyseal part and none of the stems were radiographically loose. CONCLUSION: In this minimum 30-year follow-up study, a straight rectangular cementless implant continues to provide excellent implant survival and high patient satisfaction. However, survival rates of the whole total hip replacement system were reduced by a high revision rate due to wear-related problems.

25-Year experience with adult polytraumatized patients in a European level 1 trauma center: polytrauma between 1995 and 2019. What has changed? A retrospective cohort study.

PURPOSE: To analyze the changes of the clinical characteristics, injury patterns, and mortality rates of polytraumatized patients within the past 25 years in a European Level I trauma center. METHODS: 953 consecutive polytraumatized patients treated at a single-level 1 trauma center between January 1995 and December 2019 were enrolled retrospectively. Polytrauma was defined as AIS ≥ 3 points in at least two different body regions. Retrospective data analysis on changes of clinical characteristics and mortality rates over time. RESULTS: A significant increase of the average age by 2 years per year of the study could be seen with a significant increase of geriatric patients over time. No changes of the median Injury Severity Score (ISS) could be seen over time, whereas the ISS significantly decreased by patient's year. The rates of concomitant severe traumatic brain injury (TBI) remained constant over time, and did not increase with rising age of the patients. Although, the mortality rate remained constant over time the relative risk of overall in-hospital mortality increased by 1.7% and the relative risk of late-phase mortality increased by 2.2% per patient's year. CONCLUSION: The number of polytraumatized patients remained constant over the 25-year study period. Also, the mortality rates remained stable over time, although a significant increase of the average age of polytraumatized patients could be seen with stable injury severity scores. Severe TBI and age beyond 65 years remained independent prognostic factors on the late-phase survival of polytraumatized patients. TRIAL REGISTRATION: NCT04723992. LEVEL OF EVIDENCE: Prognostic study, level III.

Proximal femoral reconstruction with modular megaprostheses in non-oncological patients.

INTRODUCTION: Multiple revision hip arthroplasties and critical trauma might cause severe bone loss that requires proximal femoral replacement (PFR). The aim of this retrospective study was to analyse complication- and revision-free survivals of patients who received modular megaprostheses in an attempt to reconstruct massive non-neoplastic bone defects of the proximal femur. Questions/purposes (1) What were general complication rates and revision-free survivals following PFR? (2) What is the incidence of complication specific survivals? (3) What were risk factors leading to a diminished PFR survival? MATERIALS AND METHODS: Twenty-eight patients with sufficient follow-up after receiving a modular proximal femoral megaprosthesis were identified. The indications for PFR included prosthetic joint infection (PJI), periprosthetic fracture, aseptic loosening, non-union and critical femoral fracture. Complications were grouped according to the ISOLS-classification of segmental endoprosthetic failure by Henderson et al. RESULTS: Overall, the complication-free survival was 64.3% at one year, 43.2% at five years and 38.4% at ten years, with 16 patients (57%) suffering at least one complication. Complications were dislocation in eight patients (29%), PJI in 6 patients (21%), periprosthetic fracture in five patients (18%), and aseptic loosening in six patients (21%). Prosthesis stem cementation showed a lower risk for revision in a cox proportional hazard model (95% CI 0.04-0.93, HR 0.2, p = 0.04). CONCLUSION: PFR with modular megaprostheses represents a viable last resort treatment with high complication rates for patients with severe proximal femoral bone loss due to failed arthroplasty or critical fractures. In revision arthroplasty settings, PFR cementation should be advocated in cases of impaired bone quality.

Inferior performance of established and novel serum inflammatory markers in diagnosing periprosthetic joint infections.

PURPOSE: Besides other diagnostic test methods, established serum inflammatory markers such as serum C-reactive protein or leukocyte count are widely used preoperatively to aid in diagnosing periprosthetic joint infections (PJI). Although low accuracies were reported, these parameters are easily accessible and routinely available. Novel biomarkers with promising results in diagnosing PJI (platelet count to mean platelet volume ratio) or other infectious conditions (percentage of neutrophils, neutrophils to lymphocytes ratio) were described. The purpose of this study was to investigate the diagnostic value of established and novel serum inflammatory biomarkers for the diagnosis of PJI so as to compare the results to find the serum inflammatory marker with the best performance. METHODS: In 177 patients with a previous total hip (n = 91) or knee (n = 86) arthroplasty and indicated revision surgery, the diagnostic value of the routinely available serum inflammatory markers C-reactive protein (CRP), white blood cell count (WBC), percentage of neutrophils (%N), neutrophils to lymphocytes ratio (NLR), fibrinogen and platelet count to mean platelet volume ratio (PC/mPV) were examined retrospectively via receiver operating characteristic curve analysis (AUC). The curves were compared using the z-test. RESULTS: Sensitivities of serum CRP, WBC, %N, NLR, fibrinogen and PC/mPV were calculated with 68%, 36%, 66%, 63%, 69% and 43%, respectively. Specificities were 87%, 89%, 67%, 73%, 89% and 81%, respectively. Serum CRP (0.78) and fibrinogen (0.79) showed significantly better AUCs compared with serum WBC (0.63), %N (0.67), NLR (0.68) and PC/mPV (0.62) (p < 0.0001). Patients with PJI caused by a low-virulent microorganism (median CRP: 17.6 mg/L) obtained lower CRP levels compared with infections caused by high-virulent microorganisms (median CRP: 49.2 mg/L; p = 0.044). The combination of CRP and fibrinogen showed a better sensitivity (77%) with similar specificity (83%) than one method alone but not at a significant level (CRP (p = 0.200); fibrinogen (p = 0.437)). CONCLUSION: Serum CRP and fibrinogen showed the best accuracies among these widely available serum inflammatory parameters. However, due to the insufficient performance, these biomarkers can only be recommended as suggestive criteria in diagnosing PJI. The preoperative workup should always be complemented by more specific tests such as synovial fluid analysis.

Does a Competing Risk Analysis Show Differences in the Cumulative Incidence of Revision Surgery Between Patients with Oncologic and Non-oncologic Conditions After Distal Femur Replacement?

BACKGROUND: Distal femur replacement is frequently used for limb salvage after bone tumor resections. It is also used in patients with severe bone loss because of traumatic conditions or revision TKA. Some studies on distal femur replacement reported on revision-free survival without distinguishing between patients with oncologic diagnoses and those without, although these patients might be incomparable because of their differences in important patient- and disease-specific characteristics. This may lead to an inaccurate and undifferentiated interpretation of the results of survival analyses. QUESTIONS/PURPOSES: (1) What is the overall cumulative incidence of revision surgery after cemented and cementless distal femoral replacement, as determined with a competing risk analysis? (2) Does the cumulative incidence of revision surgery change over time? (3) Are there differences in the cumulative incidence of revision surgery between patients with oncologic conditions and those without who are treated with cemented or cementless distal femoral replacement? METHODS: A total of 403 patients were possible candidates for distal femoral replacement. Of these, 56 patients elected to undergo different procedures, 83 were excluded because an expendable growing prosthesis was implanted, and 28 were lost to follow-up. Therefore, 229 patients who underwent distal femoral replacement for oncologic or non-oncologic reasons between 1983 and 2016 were retrospectively included in this study. The type of fixation method (cemented or cementless) was obtained from the patients' medical records, operation reports, and radiographic analyses from plain radiographs. All radiographs were standardized and obtained at standard time intervals in our institution. No algorithm regarding the fixation approach was followed. According to our data, patients receiving cementless fixation were younger and therefore likely to be more active than those receiving cemented fixation. The median follow-up duration of the overall cohort was 85 months (range 0.1-391 months). Patients who died or had revision surgery before the 2-year minimum follow-up interval were adequately considered using competing risk calculation. The reasons for revision surgery were classified using the classification system proposed by the International Society for Limb Salvage. A competing risk analysis was performed to estimate the cumulative incidence function of revision, accounting for death as a competing event. To evaluate the influence of potential prognostic factors, including diagnosis (oncologic versus non-oncologic), fixation (cemented versus cementless), year of distal femoral replacement, age, and sex on the occurrence of revision surgery, univariate and multivariable Fine and Gray models were applied. RESULTS: The competing risks analysis revealed cumulative incidences of revision surgery for any cause (Types 1 to 5) of 26% (95% CI, 20.3%-31.9%) at 12 months, 37.9% (95% CI, 31.3%-44.4%) at 24 months, 52.6% (95% CI, 45.1%-59.5%) at 5 years, and 58.2% (95% CI, 50.1%-65.4%) at 10 years for all patients. Rotating hinge-type prostheses showed a lower cumulative incidence of revision surgery (41.6%; 95% CI, 31.8%-51%) than fixed-hinge prostheses did (64%; 95% CI, 50.5%-74.5% ) at 5 years (Gray's test: p = 0.01). According to the multivariate Fine and Gray model, the year of surgery did not have any effect on the risk of revision surgery (1994 to 2003: hazard ratio 0.70; 95% CI, 0.46-1.07); 2004 to 2016: HR 0.83; 95% CI, 0.52-1.34; p = 0.26). The multivariate analysis, adjusted for disease, sex, age, cementation, and year of surgery, revealed a difference in the risk of revision surgery between patients with oncologic disease and those with non-oncologic disease (HR 0.44 for oncologic versus non-oncologic; 95% CI, 0.22-0.87; p = 0.02) and a reduction in the risk of overall revision with cemented fixation in patients with oncologic disease (HR 0.53; 95% CI, 0.29-0.98; p = 0.03). CONCLUSION: This study indicates that even with newer implants, there was a high incidence of revision surgery after distal femoral replacement. According to our analysis, patients with oncologic diagnoses have a lower likelihood of revision when the stem is cemented whereas the type of fixation did not impact patients with non-oncologic diagnoses. Because of differences in patient demographics (age, etiology of disease, and use of chemotherapy) and outcomes of fixation, oncologic and non-oncologic patients should be analyzed separately in survival studies about distal femoral replacement. LEVEL OF EVIDENCE: Level III, therapeutic study.

Zirconium Nitride Coating Reduced Staphylococcus epidermidis Biofilm Formation on Orthopaedic Implant Surfaces: An In Vitro Study.

BACKGROUND: One of the most commonly identified pathogens responsible for orthopaedic implant infection is Staphylococcus epidermidis, which can form biofilms on surfaces. Currently, orthopaedic implants made of various surface materials are available, each with features influencing osseointegration, biocompatibility, and adherence of bacteria to the surface, which is the first step in biofilm formation. The aim of this experimental study was to investigate the effect of a high tribologic-resistant 2.5-µm zirconium nitride top coat on an antiallergic multilayer ceramic-covered cobalt-chromium-molybdenum surface on the formation of S. epidermidis biofilm compared with other commonly used smooth and rough orthopaedic implant surface materials. QUESTIONS/PURPOSES: (1) When evaluating the surfaces of a cobalt-chromium-molybdenum (CoCrMo) alloy with a zirconium (Zr) nitride coating, a CoCrMo alloy without a coating, titanium alloy, a titanium alloy with a corundum-blasted rough surface, and stainless steel with a corundum-blasted rough surface, does a Zr coating reduce the number of colony-forming units of S. epidermidis in an in vitro setting? (2) Is there quantitatively less biofilm surface area on Zr-coated surfaces than on the other surfaces tested in this in vitro model? METHODS: To determine bacterial adhesion, five different experimental implant surface discs were incubated separately with one of 31 different S. epidermidis strains each and subsequently sonicated. Twenty test strains were obtained from orthopaedic patients undergoing emergency hip prosthesis surgeries or revision of implant infection and 10 further strains were obtained from the skin of healthy individuals. Additionally, one reference strain, S. epidermidis DSM 3269, was tested. After serial dilutions, the number of bacteria was counted and expressed as colony-forming units (CFUs)/mL. For biofilm detection, discs were stained with 0.1% Safranin-O for 15 minutes, photographed, and analyzed with computer imaging software. RESULTS: The lowest bacterial count was found in the CoCrMo + Zr surface disc (6.6 x 10 CFU/mL ± 4.6 x 10 SD) followed by the CoCrMo surface (1.1 x 10 CFU/mL ± 1.9 x 10 SD), the titanium surface (1.36 x 10 CFU/mL ± 1.8 x 10 SD), the rough stainless steel surface (2.65 x 10 CFU/mL ± 3.8 x 10 SD), and the rough titanium surface (2.1 x 10 CFU/mL ± 3.0 x 10 SD). The mean CFU count was lower for CoCrMo + Zr discs compared with the rough stainless steel surface (mean difference: 2.0 x 10, p = 0.021), the rough titanium alloy surface (mean difference: 1.4 x 10, p = 0.002), and the smooth titanium surface (mean difference: 7.0 x 10, p = 0.016). The results of biofilm formation quantification show that the mean covered area of the surface of the CoCrMo + Zr discs was 19% (± 16 SD), which was lower than CoCrMo surfaces (35% ± 23 SD), titanium alloy surface (46% ± 20 SD), rough titanium alloy surface (66% ± 23 SD), and rough stainless steel surface (58% ± 18 SD). CONCLUSIONS: These results demonstrate that a multilayer, ceramic-covered, CoCrMo surface with a 2.5-µm zirconium nitride top coat showed less S. epidermidis biofilm formation compared with other surface materials used for orthopaedic implants. CLINICAL RELEVANCE: CoCrMo with a 2.5-µm zirconium nitride top coat seems to be a promising surface modification technology able to reduce bacterial attachment on the surface of an implant and, hence, may further prevent implant infection with S. epidermidis biofilm formation.

Distal femoral reconstruction following failed total knee arthroplasty is accompanied with risk for complication and reduced joint function.

BACKGROUND: Substantial bone loss following failed total knee arthroplasty (TKA) represents a major challenge in revision arthroplasty, that can require distal femoral reconstruction (DFR). In this study, we aimed to assess the clinical outcome and the complication frequencies of individuals who underwent DFR with modular megaprostheses. Additionally, we aimed to compare functional outcome measures after DFR in these sophisticated cases to an age-matched control group of total knee prostheses to quantify the potential loss of function. METHODS: A retrospective chart review of 30 consecutive patients after DFR from 1997 to 2017 with a mean age of 74.38 years (± 10.1) was performed. Complications were classified according to the Henderson classification. Knee Society Score (KSS) was calculated and range of motion (ROM) was assessed. RESULTS: Thirteen (43.3%) patients had at least one complication requiring revision surgery. Revision-free survival was 74.8% at one year, 62.5% at three and 40.9% at 10 years post-op. Soft-tissue failure complications were found in three (10.0%) patients, aseptic loosening in four (13.3%) patients, structural failure in one (3.3%) patient and infection in eight (26.6%) patients. Of those with infection, five (16.6%) experienced ongoing prosthetic joint infection and three (10.0%) developed new infection after distal femur reconstruction. Patients with DFR achieved 69.3% of KSS pain score, 23.1% KSS function score and 76.2% of ROM compared to patients with primary TKA. CONCLUSIONS: DFR after failed TKA represents a treatment procedure with high risk for complication in this particular group. Despite the prospect of rapid postoperative mobilization, reduced functionality, range of motion and mobilization have to be considered when choosing this treatment option.

Modern cemented total knee arthroplasty design shows a higher incidence of radiolucent lines compared to its predecessor.

PURPOSE: To prevent early failure it is necessary to evaluate modern TKA system for possible shortcomings during implantation. The aim of this study was to evaluate the radiographic outcome and short-term survival of a modern cemented primary TKA system compared to its predecessor. METHODS: The authors reviewed 529 primary cemented TKAs [276 Attune (ATT) and 253 PFC Sigma (PFC)], which were implanted between 2014 and 2017 concerning the radiographic outcome and short-term survival. Radiographs were taken before discharge, 6 weeks, 6 months and 12 months postoperatively. Radiographic analysis was performed by two independent assessors using the Modern Knee Society Radiographic Evaluation System. RESULTS: The incidence of radiolucent lines was significantly higher in the ATT group compared with the PFC group 12 months postoperatively (35.1%; n = 97 TKAs vs. 7.5%; n = 19 TKAs; p < 0.001). Survival analysis could not show any differences in revision-free survival or revision rate. CONCLUSION: The modern primary TKA system shows an increased number of radiolucent lines, especially on the tibial component in this short-term analysis and may mostly be due to technique-related issues. Patients with those radiolucent lines even though they show no clinical evidence for loosening should be closely monitored at regular intervals. These findings are of vital clinical importance because surgeons should be aware of particular challenges in preparation and cementing technique once they are using this TKA-system. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.

Multiplex PCR Unyvero i60 ITI application improves detection of low-virulent microorganisms in periprosthetic joint infections.

PURPOSE: The aim of this study was to evaluate the pre-operative performance of an automated multiplex PCR (mPCR) system in patients with suspected periprosthetic joint infection (PJI). METHODS: Under sterile conditions, synovial fluid samples from patients with a suspected PJI were collected pre-operatively. One hundred eighty microliter of the aspirate was used for analysis in the mPCR. The remaining joint fluid was sent for microbiological analysis. PJI was diagnosed by using the Musculoskeletal Infection Society (MSIS) criteria. Total percentage agreement and Cohen's kappa coefficient were calculated to measure overall agreement. RESULTS: Overall, 90 patients with a suspected PJI were included. Using MSIS criteria, 38 (42%) patients were classified as septic. Total percent agreement between mPCR and synovial fluid culture was 86% with a Cohen's kappa of 0.68. The mPCR and synovial fluid culture showed sensitivities of 71% and 84%, respectively. Combined evaluation provided an even higher sensitivity of 92%. While Cutibacterium spp. were detected five times by mPCR, it could only be cultured once. A higher detection rate of CoNS by mPCR (n = 7) compared to conventional culture (n = 5) was also demonstrated. In comparison to synovial fluid culture, the mPCR missed Staphylococcus aureus five times. CONCLUSION: With a moderate agreement between synovial fluid mPCR and culture, the mPCR system could be a useful adjunct in diagnosing a PJI pre-operatively. Due to faster availability of results and a higher detection rate of low-virulent microorganisms, it can complement conventional culture.

A comparative study of intraoperative frozen section and alpha defensin lateral flow test in the diagnosis of periprosthetic joint infection.

Background and purpose - For decision-making (aseptic vs. septic), surgeons rely on intraoperatively available tests when a periprosthetic joint infection (PJI) cannot be confirmed or excluded preoperatively. We compared and evaluated the intraoperative performances of the frozen section and the alpha defensin lateral flow test in the diagnosis of PJI. Patients and methods - In this prospective study, consecutive patients with indicated revision surgery after arthroplasty were included. Patients were classified as having PJI using the MusculoSkeletal Infection criteria. The presence of alpha defensin was determined using the lateral flow test intraoperatively. During revision surgery, tissue samples were harvested for frozen and permanent section. Analysis of diagnostic accuracy was based on receiver-operating characteristics. Results - 101 patients (53 hips, 48 knees) were eligible for inclusion. Postoperatively, 29/101 patients were diagnosed with PJI, of which 8/29 cases were definitely classified as septic preoperatively. Of the remainder 21 septic cases, the intraoperative alpha defensin test and frozen section were positive in 13 and 17 patients, respectively. Sensitivities of the alpha defensin test and frozen section were 69% and 86%, respectively. The area under the curves of both tests showed a statistically significant difference (p = 0.006). Interpretation - The frozen section showed a significantly higher performance compared with the alpha defensin test and a near perfect concordance with the definitive histology, and therefore remains an appropriate intraoperative screening test in diagnosing PJI. Although the sensitivity of the alpha defensin test was lower compared with that of frozen section, this test is highly specific for confirming the diagnosis of PJI.

Preoperative MRI is helpful but not sufficient to detect associated lesions in patients with chronic ankle instability.

PURPOSE: The aim of this study was to determine the reliability and validity of preoperative magnetic resonance imaging (MRI) scans for the detection of additional pathologies in patients with chronic ankle instability (CAI) compared to arthroscopic findings. METHODS: Preoperative MRI images of 30 patients were evaluated regarding articular and periarticular comorbidities and compared to intraoperative findings. The reliability of MRI was determined by calculating specificity, sensitivity, as well as positive and negative predictive values. The accuracy of the classification of cartilage lesions by Outerbridge and Berndt and Harty rating scales was determined by calculating the area under the receiver operating curve (AUC). RESULTS: In total, 72 additional pathologies were found arthroscopically compared to 73 lesions gathered from MRI images. Sensitivity ranged from 89% for peroneal tendinopathy to 28% for additional ligamentous lesions. Specificity ranged from 100% for anterolateral impingement, loose bodies and peroneal tendinopathy to 38% for additional ligamentous lesions. For cartilage lesions, sensitivity was at 91% and specificity was at 55% for the Outerbridge grading scale. For the Berndt and Harty classification system, sensitivity was at 91% and specificity was at 28%. Correlation of additional pathologies ranged from weak (r s = 0.48; p = 0.02) to moderate results (r s = 0.67; p < 0.001). CONCLUSION: CAI is associated with a high incidence of additional pathologies. In some cases, MRI delivers insufficient results, which may lead to misinterpretation of present comorbidities. MRI is a helpful tool for preoperative evaluation, but arthroscopy remains gold standard in the diagnosis of associated lesions in patients with CAI. LEVEL OF EVIDENCE: III.

Failed Two-Stage Exchange: Factors Leading to Unachievable Endoprosthetic Reconstruction After Multiple Revision Surgeries.

BACKGROUND: Information about the outcome after failed 2-stage exchange is scarce. The aim of this study is to determine possible influencing factors leading to multiple revisions, resulting in a failed endoprosthetic joint reconstruction. METHODS: Medical records of patients (15 hip and 29 knee joints) who had undergone additional revision surgeries due to a failed 2-stage exchange were reviewed concerning infection parameters, number and type of procedure(s), current state of the revised joint, and whether failure of endoprosthetic reconstruction had occurred. RESULTS: Endoprosthetic reconstruction was achieved in 52.3% (n = 23) of the patients. About 36.4% (n = 16) of patients successfully reached the second stage of the initial 2-stage exchange. Half of the patients (n = 22) had to undergo spacer exchange in the initial interstage period. Five or more revision surgeries significantly increased the odds of failure of endoprosthetic reconstruction compared to patients with <5 revision surgeries (odds ratio 4.98, 95% confidence interval 1.34-18.4, P = .016). Patients with initial culture-negative revision surgery showed no significant differences in the odds of failure of endoprosthetic reconstruction (odds ratio 0.69, 95% confidence interval 0.20-2.43, P = .567). CONCLUSION: Patients undergoing re-revision surgery due to a failed 2-stage exchange are very likely to ultimately experience a failed endoprosthetic reconstruction. The identification of the underlying pathogen does not influence the likelihood of a better outcome in terms of a successful endoprosthetic reconstruction.

The influence of antibiotic-loaded cement spacers on the risk of reinfection after septic two-stage hip revision surgery.

PURPOSE: The aim of this study was the evaluation of possible outcome differences of patients undergoing two-stage hip exchange with antibiotic-loaded spacers, compared to patients without an interim spacer implantation. METHODS: We evaluated 46 patients undergoing two-stage hip revision surgery. Twenty-five patients received an interim ALS. Additional to a Kaplan-Meier survival analysis, a competing risk analysis was performed to estimate the cumulative incidence function for re-revisions due to infection accounting for death as a competing event. RESULTS: Nine patients (seven non-ALS vs. two ALS) had to undergo re-revision surgery due to reinfection of the hip joint. The non-ALS group showed a risk of re-revision of 19% (95% CI 5-38%) at 12 and 24 months and 30% (95% CI 12-51%) at 36 months. The group with ALS implantation displayed a 0% risk of re-revision surgery in the first 36 months. The Gray test revealed a significant difference in the cumulative incidence between both observed groups (p = 0.026). CONCLUSION: Our findings suggest that ALS implantation significantly reduces the risk of reinfection after two-stage hip revision surgery.

Surgical treatment of shoulder infections: a comparison between arthroscopy and arthrotomy.

BACKGROUND: Management of bacterial shoulder infections includes antibiotic therapy and surgical joint decompression. Arthroscopy and open arthrotomy are recommended treatment options. Whether 1 of the 2 surgical options is superior remains unclear. The present study aimed (1) to compare the reinfection rates after arthroscopy and open arthrotomy and (2) to identify risk factors of reinfection after surgical intervention. MATERIALS AND METHODS: The data of 59 consecutive patients were available for final analysis. All patients received arthroscopy or open arthrotomy at our institution between 2001 and 2015. The reinfection rates between the 2 distinct interventions were compared. We also evaluated the influence of potential confounders, such as age, sex, comorbidities, microbiological findings, duration of symptoms, osteoarthritis, Gächter score, and preoperative inflammatory parameters, on the recurrence of infections and compared the functional outcome between the 2 surgery groups. RESULTS: From 59 included patients, 38 (64.4%) underwent open arthrotomy, and 21 (35.6%) were treated arthroscopically. Reinfection was documented in 18 patients (30.5%). The reinfection rate was significantly higher in arthroscopically treated patients (11 [52.4%]) than in patients who underwent open arthrotomy (7 [18.4%]; P = .007). An infection with Staphylococcus aureus negatively influenced the treatment success (P = .034). CONCLUSION: According to our data, open arthrotomy is the more effective treatment method in septic arthritis of the shoulder, with lower reinfection rates and a comparable functional outcome. Furthermore, we could identify Staphylococcus aureus as an independent risk factor for the recurrence of infections.

Outcome of Total Hip and Total Knee Revision Arthroplasty With Minor Infection Criteria: A Retrospective Matched-Pair Analysis.

BACKGROUND: Although diagnostic modalities for the detection of periprosthetic joint infection have improved, some infectious revision cases may still be diagnosed as aseptic complications. We raised the question whether patients with positive Musculoskeletal Infection Society minor infection criteria differ in their outcome parameters (revision-free survival, revision rate) when compared to patients with "true" aseptic complications. Additionally, we asked whether the indication for revision surgery (eg, loosening) might have an influence on possible outcome discrepancies. METHODS: A retrospective matched-pair analysis was performed with 98 patients who had undergone revision surgery after total joint arthroplasty. Forty-nine patients showed less than 3 positive minor criteria (PMC), whereas 49 patients without any PMC were compared regarding re-revision rate and revision-free survival. Reasons for revisions were categorized according to loosening, liner wear, implant failure, and soft-tissue complication. RESULTS: In the group of patients with PMC, 30.6% (n = 15) had to undergo re-revision compared to 6.12% (n = 3) in the true aseptic complication control group. The long-term implant survival in the PMC group was 69.4% (95% confidence interval [CI], 47-69 months) and in the aseptic control group was 93.9% (95% CI, 82-94 months; P = .001). In patients with PMC and loosening of the implant, the long-term survival was 55.2% (95% CI survival time, 28.9-53.2 months) whereas in patients without PMC and loosening, the overall survival was 96.2% (95% CI survival time, 83.5-96 months; P = .001). CONCLUSION: Our findings suggest that in the presence of prosthetic loosening, even a single positive minor criterion may have a negative impact on the outcome after total hip arthroplasty and total knee arthroplasty revision surgeries.

Computer navigation-assisted surgery for musculoskeletal tumors: a closer look into the learning curve.

BACKGROUND: Computer navigation-assisted surgery for musculoskeletal tumors has shown to reduce the risk of intra-lesional margins in resection. Experiences with this method are still limited to smaller case series. METHOD: We reviewed our first experiences in 24 patients in whom computer navigation-assisted surgery had been performed. In 7 of these patients (6 male and 1 female), this has influenced the surgical treatment plan and navigation was used for both tumor resection and reconstruction. Three of the patients suffered from a chondrosarcoma, 2 from an osteosarcoma, 1 from a fibrosarcoma and 1 from an Ewing's sarcoma. Tumors were localized in the femur (n = 2), the tibia (n = 1), the sacrum (n = 1), the humerus (n = 1), the ilium (n = 1) and in the gluteal region (n = 1). RESULTS: The mean registration error was 0.9 mm. No intra-operative complications occurred. Two postoperative complications were observed which required revision surgery. Except for one marginal resection, all tumors were excised with wide margins. One patient suffered from a local recurrence, and one patient died of disease after distant metastatic dissemination. CONCLUSION: Computer navigation-assisted surgery represents a safe and helpful tool for the resection of musculoskeletal tumors and may influence surgical treatment plans in selected cases to provide more limited resections. Surgeons should be aware of risks considering biomechanical and oncological consequences in doing so. Further investigations and the evaluation of newer techniques (e.g., computed tomography-guided navigation) are needed to assess long-term outcomes of computer navigation assistance in musculoskeletal tumor surgery.

Megaprostheses in the treatment of periprosthetic fractures of the knee joint: indication, technique, results and review of literature.

BACKGROUND: Periprosthetic fractures (PPFs) after total knee arthroplasty (TKA), especially in patients with multiple revisions, remain challenging mainly due to bone quality and loss of bone stock. Megaprostheses, although providing immediate stability and weight bearing, are rarely used in this indication. The aim of the study was to provide a description of the surgical technique and evaluate the outcome of this technique with respectable published data. MATERIALS AND METHODS: Systematic literature review revealed seven studies dealing with treating PPF after TKA using megaprostheses. Including the results of 11 cases treated in our institution between January 2008 and December 2014, 144 megaprostheses have been evaluated in the current literature with indication of PPF after TKA. Mean age at operation ranged from 68.4 to 81 years and mean follow-up from 6 to 58.6 months. RESULTS: Revision rates after implantation of megaprostheses in PPFs ranged from 0 % (two studies with a mean follow-up of 6 and 33 months, respectively) to 55 %, all primarily performed for mechanical and nonmechanical failures (20 and 25, respectively). However infection was the most predominant reason for nonmechanical failure. Mortality rates ranged from 6.6 % after 1 year to 45 % after a mean follow-up of 34 months. CONCLUSION: Megaprostheses represent a valuable option in distal femoral PPFs type 3 according to Su et al., as well as proximal tibia PPFs type 1B according to Felix et al., with loose tibial components. Infection remains the most frequent nonmechanical complication. Prospective clinical studies are required to exactly define the outcome of this technique in PPFs; use of the Henderson classification system would allow comparison between megaprostheses in oncological and nononcological indications.

Two-stage revision for periprosthetic joint infection after hip and knee arthroplasty.

Aims: Histology is widely used for diagnosis of persistent infection during reimplantation in two-stage revision hip and knee arthroplasty, although data on its utility remain scarce. Therefore, this study aims to assess the predictive value of permanent sections at reimplantation in relation to reinfection risk, and to compare results of permanent and frozen sections. Methods: We retrospectively collected data from 226 patients (90 hips, 136 knees) with periprosthetic joint infection who underwent two-stage revision between August 2011 and September 2021, with a minimum follow-up of one year. Histology was assessed via the SLIM classification. First, we analyzed whether patients with positive permanent sections at reimplantation had higher reinfection rates than patients with negative histology. Further, we compared permanent and frozen section results, and assessed the influence of anatomical regions (knee versus hip), low- versus high-grade infections, as well as first revision versus multiple prior revisions on the histological result at reimplantation. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), chi-squared tests, and Kaplan-Meier estimates were calculated. Results: Overall, the reinfection rate was 18%. A total of 14 out of 82 patients (17%) with positive permanent sections at reimplantation experienced reinfection, compared to 26 of 144 patients (18%) with negative results (p = 0.996). Neither permanent sections nor fresh frozen sections were significantly associated with reinfection, with a sensitivity of 0.35, specificity of 0.63, PPV of 0.17, NPV of 0.81, and accuracy of 58%. Histology was not significantly associated with reinfection or survival time for any of the analyzed sub-groups. Permanent and frozen section results were in agreement for 91% of cases. Conclusion: Permanent and fresh frozen sections at reimplantation in two-stage revision do not serve as a reliable predictor for reinfection.

Tolerability of N-chlorotaurine in comparison with routinely used antiseptics: an in vitro study on chondrocytes.

BACKGROUND: Currently, povidone-iodine (PVP-I) and hydrogen peroxide (H2O2) are frequently used antiseptics in joint infections, but the cytotoxic effects of these solutions are already reported. N-chlorotaurine (NCT) shows a broad-spectrum bactericidal activity and is well tolerated in various tissues, but its effect on human chondrocytes is unknown. The purpose of this study was to assess the cytotoxic effect of NCT, PVP-I, and H2O2 on human chondrocytes compared to a control group in an in vitro setting to get first indications if NCT might be a promising antiseptic in the treatment of septic joint infections for the future. MATERIAL AND METHODS: Chondrocytes extracted from human cartilage were incubated with various concentrations of NCT, PVP-I, and H2O2 for 5 and 30 min respectively. EZ4U cell viability kit was used according to the manufacturer's recommendations determining cell viability. To assess cell viability based on their nuclear morphology, cells were stained with acridine-orange and identified under the fluorescence microscope. RESULTS: EZ4U kit showed after 5 and 30 min of incubation a significant decrease in cell viability at NCT 1%, NCT 0.1%, PVP-I, and H2O2, but not for NCT 0.001% and NCT 0.01%. Acridine-orange staining likewise presented a significant decrease in vital cells for all tested solutions except NCT 0.001% and NCT 0.01% after 5 and 30 min of incubation. CONCLUSION: Our results demonstrate that NCT is well tolerated by chondrocytes in vitro at the tested lower NCT concentrations 0.01% and 0.001% in contrast to the higher NCT concentrations 1% and 0.1%, PVP-I (1.1%), and H2O2 (3%), for which a significant decrease in cell viability was detected. Considering that the in vivo tolerability is usually significantly higher, our findings could be an indication that cartilage tissue in vivo would tolerate the already clinically used 1% NCT solution. In combination with the broad-spectrum bactericidal activity, NCT may be a promising antiseptic for the treatment of septic joint infections.