Background: The aim of this study was to identify an inflammatory marker with fast and predictable kinetics to enable future discrimination between normal postoperative inflammation and potential infection after total hip and knee arthroplasty cases. Methods: Changes in serum levels of C-reactive protein (CRP), interleukins (IL) 1β, 6 and 8 and NT-proCNP peptide were measured before and during first 5 postoperative days in 100 patients undergoing total hip or knee arthroplasty. We also compared two methods to describe the magnitude of inflammation – applying separate two sample tests at each time point, and summary measures – area under the curve (AUC). Results: IL-6 showed a similar kinetics pattern to the CRP in response to surgical trauma. Significantly greater level changes in all markers but NT-proCNP were observed in knee patients. Persisting high levels of CRP, but not other markers, were observed in obese hip patients. IL-6 was found to be an adjunct to routine CRP use. Conclusions: IL-6 has faster kinetics and is less influenced by patient weight, therefore it seems to be more useful in clinical practice. Summary measures describe the inflammatory response well and are easier to analyze than multiple analyses of single time points.

Background: D-lactic acid is a specific marker produced almost exclusively by bacterial species; thus, the appearance of this marker in synovial fluid may indicate periprosthetic joint infection (PJI). Recently, studies have investigated the accuracy of enzyme-linked laboratory tests that detect D-lactic acid in synovial fluid to diagnose PJI. However, to our knowledge, no studies have determined the usefulness of rapid strip tests that detect D-lactic acid in synovial fluid in the diagnosis of PJI. Questions/purposes: (1) What is the best cutoff value for the rapid D-lactic acid strip test for diagnosing PJI? (2) What are the diagnostic accuracies (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) of the rapid D-lactic acid strip test and two different rapid leukocyte esterase (LE) strip tests? Methods: This prospective study enrolled 157 patients who underwent revision THA or TKA from May 2021 to February 2022 at a single orthopaedic center. Seventy percent (110 of 157) were eligible for analysis; 10% of these patients (15 of 157) were excluded based on the exclusion criteria (causes of revisions and additional comorbidities that may interfere with the results), and 20% (32 of 157) of the synovial fluid samples could not be tested (dry taps and blood-contaminated samples that could not be centrifuged). We performed the following off-label diagnostic tests on synovial fluid samples collected from all patients: the D-lactic acid strip test (QuantiQuick^TM, BioAssay System), two different LE strip tests (10 EA from ARKRAY and BM 10 from BioMaxima). Differently colored strips were marked with symbols (from [-] to [++++] for D-lactic acid and from [-] to [+++] for LE tests) according to the manufacturers’ instructions. For the LE tests, results were different for (++), which corresponds to a minimal value of 250 leu/mL for 10 EA and 125 leu/mL for BM 10 tests. The diagnostic standard for the presence or absence of PJI in this study was the International Consensus Meeting (ICM) 2018 criteria; based on these criteria (without the application of an LE test as a minor criterion), all patients were assessed and divided into two groups. Patients who did not meet the criteria for PJI and underwent revision for aseptic loosening, implant malposition, instability, or implant damage were included in the aseptic revision total joint arthroplasty group (68 patients). Patients with a fistula penetrating the joint, those with two positive culture results of the same pathogen, or those with ≥ 6 points according to ICM 2018 minor criteria were enrolled in the PJI group (42 patients). To ascertain the best cutoff value for the rapid D-lactic acid and both LE strip tests for diagnosing PJI, we used collected results, generated a receiver operating characteristic curve, and calculated the Youden index. To determine the accuracies of the diagnostic tests, we calculated their sensitivities, specificities, PPVs, and NPVs against the diagnostic standard (the ICM 2018 criteria). Results: The best cutoff value for D-lactic acid was 22.5 mg/L, which corresponded to a reading of (+) on the test strip. For D-lactic acid, in the diagnosis of PJI, the sensitivity was 83% (95% confidence interval [CI] 68% to 92%) and specificity was 100% (95% CI 93% to 100%). For both LE strip tests, the best cutoff value was the same as that proposed in the ICM 2018 criteria. For LE (10 EA), the sensitivity was 81% (95% CI 66% to 91%) and specificity was 99% (95% CI 91% to 100%); for LE (BM 10), sensitivity was 81% (95% CI 65% to 91%) and specificity was 97% (95% CI 89% to 100%). Conclusion: A rapid off-label D-lactic acid strip test is valuable for diagnosing PJI. The results of this study indicate very good accuracy with comparable sensitivity and specificity for both LE strip tests. The usefulness of the test in a group of patients with chronic inflammatory diseases and the reproducibility of the reading by different researchers were not analyzed in this study and require further investigations. Before a rapid D-lactic strip test is routinely used for diagnosing PJI, multicenter studies on a larger group of patients should be conducted. Level of Evidence Level II, diagnostic study.

Background: Hereditary multiple osteochondromas (hereditary multiple exostoses, HME) is a rare genetic disease characterized by the development of benign osteocartilaginous tumors that may cause severe limb deformities and early onset osteoarthritis. Total knee arthroplasty (TKA) is the method of choice for the treatment of advanced gonarthrosis, however the surgical management with coexisting severe axial limb deformity remains unclear.Case presentation: 65-year-old man with HME and extra-articular multi-axial limb deformity was admitted to the orthopedic department due to chronic knee pain and limited range of motion caused by secondary osteoarthritis. Regarding to the clinical and radiological examinations, after preoperative planning he was qualified to a one-stage TKA combined with tibial shaft osteotomy (TSO). In a one year follow-up full bone union was confirmed with no signs of implant loosening or prosthesis displacement. Patient was very satisfied, did not report any joint pain and has sufficient range of motion without knee instability.Conclusion: The improvement of mechanical axis during TKA is a crucial factor for achieve operative success and long implant survival. Despite the higher risk of complication rate in comparison to two-stage treatment, one-stage TKA with simultaneous TSO should be a considerable method for patients with osteoarthritis and multiaxial limb deformities. This method can give a good clinical and functional outcomes, however should be performed subsequently to careful preoperative planning and proper patient qualification.

Background: The aim of this study was to analyze the treatment results of fungal periprosthetic joint infections (PJI) caused by Candida species from a single orthopedic center and to compare them with reports from other institutions. Methods: Eight patients operated on from January 2014 to December 2021 met the inclusion criteria and were analyzed in terms of clinical outcomes. A systematic review of the literature identified 153 patients with Candida PJIs extracted from 12 studies according to the PRISMA (Preferred Reporting Item for Systematic Reviews and Meta-Analyses) guidelines. Results: The success rate of the treatment in the case series was 50%. The most frequent pathogens were Candida albicans (three cases; 37.5%) and Candida parapsilosis (three cases; 37.5%). In one patient (12.5%), bacterial co-infection was noted, and in five patients (62.5%) significant risk factors of PJI were confirmed. The overall success rate on the basis of data collected for systematic review was 65.5%. A sub-analysis of 127 patients revealed statistically significant differences (p = 0.02) with a higher success rate for the knees (77.6%) than for the hips (58%). In 10 studies the analysis of risk factors was performed and among 106 patients in 77 (72.6%) comorbidities predispose to fungal PJI were confirmed. Bacterial co-infection was noted in 84 patients (54.9%). In 93 patients (60.7%) Candida albicans was the culprit pathogen, and in 39 patients (25.5%) Candida parapsilosis was the culprit pathogen. Based on these two most frequent Candida species causing PJI, the success rate of the treatment was statistically different (p = 0.03), and was 60.3% and 83.3%, respectively. The two-stage strategy was more favorable for patients with Candida parapsilosis infections (94.4% success rate) than the one-stage protocol (50% success rate; p = 0.02); as well as in comparison to the two-stage treatment of Candida albicans (65% success rate; p = 0.04). Conclusions: The analysis of the literature showed no differences in the overall success rate between one- and two-stage surgical strategies for all Candida species, but differed significantly comparing the two most frequent strains and concerning PJI localization. The frequent presence of bacterial co-infections makes it necessary to consider the additional administration of antibiotics in the case of fungal PJI.

Background: Despite the fact that many synovial fluid biomarkers have found application in the routine diagnosis of periprosthetic joint infection (PJI), this process still remains a challenge for orthopaedic surgeons. To simplify this process, fast point-of-care (POC) tests can be used during ambulatory visits and in operating room conditions. However, before such tests can be routinely used in clinical practice, they require validation. The purpose of the present study was to evaluate the diagnostic accuracy of different fast POC tests for detecting C-reactive protein (CRP) in synovial fluid for the diagnosis of PJI. Methods: Synovial fluid samples were collected from 120 consecutive patients who underwent revision total joint arthroplasty (TJA). The patients were divided into 2 groups. The first group included 76 patients who underwent revision for reasons other than infection (the aseptic revision TJA [arTJA] group), and the second group included 44 patients who underwent revision because of periprosthetic joint infection (PJI). The diagnosis of infection was made according to the International Consensus Meeting (ICM) 2018 criteria. All patients were operatively treated at a single orthopaedic center from January 2022 to February 2023. Four fast CRP tests with different cutoff values (1 and 3 mg/L, ≥8 mg/L, ≥10 mg/L [cassette], ≥10 mg/L [strip]) were used off-label for synovial fluid testing. Tests were performed on the same synovial fluid samples, and the results of these tests were compared with those obtained with the laboratory method. Results: The cassette test with a minimum cutoff value of ≥8 mg/L demonstrated the best accuracy for the diagnosis of chronic PJI, with a sensitivity and specificity of 90.9% and 90.8%, respectively. For the cassette test with a cutoff value of >3 mg/L, the sensitivity and specificity were 68.2% and 77.6%, respectively. For the tests with a minimum cutoff value of ≥10 mg/L, the sensitivity and specificity were 77.3% and 94.7%, respectively, for the cassette test and 77.3% and 96.1%, respectively, for the strip test. The laboratory method with the statistically calculated threshold (2.7 mg/L) revealed the highest AUC (area under the receiver operating characteristic curve) value (0.95), with 90.9% sensitivity and 94.7% specificity. Conclusions: The cassette POC test with the minimum cutoff value of ≥8 mg/L had very good accuracy for the diagnosis of chronic PJI. This test had comparable sensitivity and slightly lower specificity in comparison with the laboratory method with the calculated threshold of 2.7 mg/L. Level of Evidence: Diagnostic Level III. See Instructions for Authors for a complete description of levels of evidence.

The purpose of this study was to compare radiological outcomes of total knee arthroplasty (TKA) in mechanical alignment implant positioning in the coronal and sagittal planes depending on surgeons' handedness and their position at the operating table. A total number of 200 consecutive patients with idiopathic osteoarthritis and varus knees who underwent TKA were retrospectively included in this research. Patients were operated on by 4 surgeons (50 for each surgeon) selected according to their handedness and position at the operative table. Surgeon I (right-handed, standing at the operating table always on the right side); Surgeon II(left-handed, standing at the operating table always on the left side); Surgeon III (right-handed, standing at the operating table on the side of the operated limb); Surgeon IV (left-handed, standing at the operating table on the side of the operated limb). Comparing postoperative radiological results statistically significant differences were calculated in the case of deviation from HKA angle (left TKA -1.5°; Interquartile Range [IQR] = -2.6-[-1] vs right TKA -3°; IQR = -4.5-[-2]; p = 0.01) for surgeon II and MPTA for surgeon IV (left TKA 0°; IQR = -1-0.5 vs right TKA 1°; IQR = 0-2; p < 0.01). Higher deviation from the mechanical alignment angles and implant positioning was revealed for a less convenient operation site for the surgeon. We recommend that all surgeons performing TKAs from the less comfortable side should take great care in establishing the MPTA and HKA angles to avoid surgical errors in implant positioning and limb alignment.