The Diagnostic Utility of Fast Tests for Detecting C-Reactive Protein in Synovial Fluid in Periprosthetic Joint Infections.

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.

Results of 198 primary total hip arthroplasties using the Delta PF-FIT system with ceramic-on-ceramic articulating surfaces with average seven years follow up.

BACKGROUND: The lifetime implants is a key parameter that the surgeon should take into account at the time of the primary total hip arthroplasty (THA). The aim of this study was a clinical and radiographical evaluation of the Delta PF-FIT (LimaCorporate, Italy) THA system with ceramic-on-ceramic articulations. We have not found a clinical or radiographical assessment of this implant in available published literature. METHODS: A total of 197 (F = 94, M = 103) primary THAs were evaluated in 163 patients with a mean follow-up of 7.7 years (range 5.1-11.2 years (SD ± 1.5)) Harris hip Score (HHS) and the Western Ontario and McMaster Universities Arthritis index (WOMAC) were used for the clinical evaluation. The statistical evaluation was processed by standard statistical methods. The study was approved by Ethic Committee of the University Hospital Motol (Reference No. EK-73/19). RESULTS: The mean HHS score was found to be 97.59 points (61-100 range with a ± 5.13 SD, preoperative HSS was 51.21, range 28-73 with a ± 4,77 SD). 186 THAs were evaluated as excellent (90-100 points), 9 THAs rated as good (80-89 points), 1 THA was rated as fair (70-79) points and 1 THA rated as poor (less than 70 points). The mean WOMAC score was 97.38 points (65-100 range with a ± 5.18 SD, preoperative was 50,12, range 27-69 with a ± 4.85 SD). We documented an overall 99.49% Kaplan-Meier survival with a mean follow-up of 7.7 years with the FIT (LimaCorporate) stem revision and any component revision as the endpoint. With the Delta PF (LimaCorporate) cup revision as the endpoint, the survival was 100%. We have not found a previously published clinical or radiographical review of this THA system, the study shows a comparison with other THA implants. CONCLUSION: Evaluation of the Delta-PF-FIT (LimaCorporate, Italy) THA system with the use of ceramic-on-ceramic BIOLOX®Delta articulation surfaces shows very good outcomes.

Testing the efficacy of antimicrobial peptides in the topical treatment of induced osteomyelitis in rats.

Joint replacement infections and osteomyelitis are among the most serious complications in orthopaedics and traumatology. The risk factors for these infections are often bacterial resistance to antimicrobials. One of the few solutions available to control bacterial resistance involves antimicrobials, which have a different mechanism of action from traditional antibiotics. Antimicrobial peptides (AMP) appear to be highly promising candidates in the treatment of resistant infections. We have identified several AMP in the venom of various wild bees and designed analogues that show potent antimicrobial activity and low toxicity against eukaryotic cells. The aim of the present study was to test the efficacy of one of those synthetic peptide analogues for the treatment of acute osteomyelitis invoked in laboratory rats. Femoral cavities of 20 laboratory Wistar rats were infected with Staphylococcus aureus. After 1 week, eight rats received an injectable calcium phosphate carrier alone, another eight rats were treated with a calcium phosphate mixed with AMP, and four rats were left without any further treatment. After another week, all rats were euthanized and radiographs were made of both the operated and healthy limbs. The animals with the carrier alone exhibited more severe acute osteomyelitis on radiographs in comparison to the recipients of the calcium phosphate carrier loaded AMP and untreated infected individuals. Based on the results of the above mentioned experiment, it was concluded that when injected directly into the site of femoral acute osteomyelitis, the calcium phosphate carrier mixed with AMP reduced osteomyelitis signs visible on radiographs.

Magnification of digital hip radiographs differs between clinical workplaces.

Preoperative planning for total hip arthroplasty includes templating on anteroposterior radiographs. It is necessary to consider radiographic magnification in order to scale templates accurately. Studies dealing with hip templating report different values of radiographic magnification. It is not clear if the observed difference in magnification between the studies is caused by variability in studied groups, methodology or instrumentation. We hypothesize that there is a difference in magnification between clinical workplaces. Within this study, radiographic magnification was estimated on 337 radiographs of patients after total hip surgery from five orthopaedic departments in the Czech Republic. Magnification was determined for each patient as a ratio between diameter of implanted femoral head measured on radiogram and its true size. One-way ANOVA revealed significant differences in magnification between workplaces (F(4,332) = 132, p≤0.001). These results suggest that radiographic magnification depends on the workplace where it is taken or more precisely on radiographic device. It indicates potential limits in generalizability of results of studies dealing with preoperative planning accuracy to other institutions.

Study of the variability of scapular inclination and the glenoid version - considerations for preoperative planning: clinical-radiological study.

BACKGROUND: Preoperative planning with the aid of imaging methods is a principal factor in successful surgery on the shoulder. This work aims to evaluate the variability of glenoid version, spiralling twist and scapular inclination in relation to the frontal axis. Studies focusing on measuring the variability of scapular inclination in the standardised rest position are lacking in the literature. METHODS: We evaluated 104 CT scans of the shoulder. We measured the glenoid version with respect to the scapular axis at three levels. We measured the scapular inclination angle in relation to the sagittal plane and we determined scapular inclination in relation to the frontal axis. Statistical evaluation was performed using the marginal linear model and parameters were estimated using the generalised least squares method, which enables the dependency of measurements performed on the same subject to be taken into consideration. RESULTS: The highest values of retroversion are attained by the glenoid in the cranial section (average -9.96°, range -29.7 to +13.2°). Proof of the spiralling twist is the decline in retroversion at the centre of the glenoid (average -2.09°, range -16.7 to +11.6°). Retroversion decreases further in the inferior direction (average -0.5°, range -20.9 to +17.5°). The average thoracoscapular angle is 45.46°, ranging from 13.1 to 69.0°. The average scapular inclination in relation to the frontal plane is 44.54°, ranging from 21.0 to76.9°. CONCLUSIONS: During preoperative planning, the surgeon should take into consideration not only the glenoid version in relation to the scapular axis, but also the value of the scapular inclination so as to eliminate possible surgical errors, optimise prosthesis implantation and thus decrease the risk of functional restrictions of the joint. CLINICAL TRIAL REGISTRATION: Ethics Committee for Multi-Centric Clinical Trials (EK-554/14,29thApril 2014).

Quantification of structural changes of UHMWPE components in total joint replacements.

BACKGROUND: At present time the number of implantations of joint replacements as well as their revisions increases. Higher demands are required on the quality and longevity of implants. The aim of this work was to determine the degree of oxidative degradation and the amount of free/residual radicals in selected ultra-high molecular weight polyethylene (UHMWPE) components of the joint replacements and demonstrate that the measured values are closely connected with quality and lifetime of the polymer components. METHODS: We tested both new (4 samples) and explanted (4 samples) UHMWPE polymers for total joint replacements. The samples were characterized by infrared spectroscopy (IR), electron spin resonance (ESR) and microhardness (MH) test. The IR measurements yielded the values of oxidation index and trans-vinylene index. The ESR measurements gave the free radicals concentration. RESULTS: In the group of new polyethylene components, we found oxidation index values ranging from 0.00-0.03 to 0.24. The trans-vinylene index values ranged from 0.044 to 0.080. The value of free radical concentration was zero in virgin and also in sample of Beznoska Company and non-zero in the other samples. In the group of explanted components, the measured values were associated with their history, micromechanical properties and performance in vivo. CONCLUSIONS: We demonstrated that measuring of oxidative damage may help the orthopaedic surgeon in estimating the quality of UHMWPE replacement component and thus radically to avoid early joint replacement failure due to worse polyethylene quality.