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Background: We evaluated the reliability of intraoperative assessment of leukocyte esterase (LE) in synovial fluid samples from patients undergoing reimplantation following implant removal and spacer insertion for periprosthetic joint infection (PJI). Our hypothesis was that a positive intraoperative LE test would be a better predictor of persistent infection than either serum C-reactive protein (CRP) or erythrocyte sedimentation rate (ESR) or the combination of serum CRP and ESR. Methods: The records of 76 patients who received a 2-stage exchange for PJI were retrospectively reviewed. Synovial fluid was collected for LE measurement during surgery before arthrotomy in 79 procedures. Receiver operating characteristic curves were generated. Sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under the curve (AUC) of LE, CRP, ESR, and CRP + ESR were calculated. Results: Sensitivity, specificity, positive predictive value, and negative predictive value of the LE assay were 82%, 99%, 90%, and 97%, respectively. Receiver operating characteristic analysis revealed an LE threshold of 1.5 between the first (negative) and the second (positive) level of the ordinal variable, so that a grade starting from 1+ was accurate for a diagnosis of persistent infection (AUC 0.9044). The best thresholds for the CRP and the ESR assay were 8.25 mg/L (82% sensitivity, 84% specificity, AUC 0.8416) and 45 mm/h (55% sensitivity, 87% specificity, AUC 0.7493), respectively. Conclusion: The LE strip test proved a reliable tool to diagnose persistence of infection and outperformed the serum CRP and ESR assays. The strip test provides a valuable intraoperative diagnostic during second-stage revision for PJI.

Background:To diagnose periprosthetic joint infection (PJI) preoperatively, ultrasound-guided joint aspiration (US-JA) may not be performed when effusion is minimal or absent. We aimed to report and investigate the diagnostic performance of ultrasound-guided periprosthetic biopsy (US-PB) of synovial tissue to obtain joint samples in patients without fluid around the implants. Methods:One-hundred nine patients (55 men; mean age: 68 ± 13 years) with failed total hip arthroplasty (THA) who underwent revision surgery performed preoperative US-JA or US-PB to rule out PJI. Results:Sixty-nine of 109 patients had joint effusion and underwent US-JA, while the remaining 40 with dry joint required US-PB. Thirty-five of 109 patients (32.1%) had PJI, while 74/109 (67.9%) had aseptic THA failure. No immediate complications were observed in both groups. Technical success of US-PB was 100%, as the procedure was carried on as planned in all cases. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of US-JA were 52.2%, 97.8%, 92.3%, 80.3%, and 82.6%, while for US-PB, they were 41.7%, 100%, 100%, 80%, and 82.5%, respectively, with no significant difference (P = .779). Using the final diagnosis as reference standard, we observed a moderate agreement with both US-JA (k = 0.56) and US-PB (k = 0.50). Conclusion:We present a novel US-guided technique to biopsy periprosthetic synovial tissue of failed THA to rule out PJI. We found similar diagnostic performance as compared with traditional US-JA. This supports future larger studies on this procedure that might be applied in patients without joint effusion.

The complexity of bone tissue, its hierarchical multi-scale structure and the delicate mechanobiological equilibrium that regulates its architecture make the analysis of bone local mechanical characteristics highly challenging. The strong dependence between bone’s mechanical properties and meso- and micro-architectural arrangement is particularly evident in the human femur, where loads are transmitted from the pelvis along the stress trajectories. An alteration in loads distribution generates a consequent deterioration in the structural pattern of trabecular groups, that worsen in presence of pathologies such as osteoporosis. Considering this complexity, it is crucial to map femur’s local strength values, in order to capture their variability and to evaluate the possible causes of fragility and fracture. For this purpose, a portable micro-compression device compatible with a synchrotron is designed and realized: it allows to test millimetric samples cut along the stress trajectories from three healthy and three osteoporotic femoral heads and to real-time monitor the apparent stress-apparent strain curves. Intra-patients variability shows increased resistance to compression in the proximal sub-region, anatomically close to the acetabulum, where the loads are transmitted from the pelvis to the femur. Inter-patients variability show an interesting trend: non-osteoporotic femoral heads are characterized by a more uniform distribution in terms of Young moduli in the whole head, while non-uniform values are present in osteoporotic subjects.

Background Coronavirus disease 2019 (COVID-19) pandemic poses an important risk to global health. Methods This study surveyed 370 international orthopedic surgeons affiliated with the American Association of Hip and Knee Surgeons to help identify the global impact of the COVID-19 pandemic on patient care. Results A total of 99 surgeons (27% of those surveyed) completed the questionnaire representing 32 different countries. Except for surgeons in Japan, all respondents noted that their practice had been affected to some degree and 70% of the surgeons have canceled elective procedures. More than a third of the surgeons have had to close their practices altogether and the remaining open practices were estimated to be sustainable for 7 weeks on average given their current situation. Conclusion The COVID-19 pandemic has resulted in marked changes to the majority of international arthroplasty practices.

Resume Introduction La legitimite du recours a l’usage des couples de frottement Metal–Metal (MM) est une question d’actualite du fait des incertitudes sur les effets deleteres locaux et generaux dus a l’usure et la corrosion de ces couples. En depit de diverses recommandations nationales, l’obtention d’une harmonisation internationale sur des recommandations specifiques basees sur l’evidence afin d’ameliorer les pratiques n’a toujours pas ete tentee. Hypothese Organiser une conference de consensus internationale, de preference a l’echelon europeen, afin d’elaborer des recommandations sur l’usage et le suivi des couples MM par une approche multidisciplinaire integrant les points de vue de diverses parties concernees. Materiel et methodes Vingt et un experts de huit pays et representant trois groupes d’interets ont participe a ce travail comprenant une conference de consensus, une discussion structuree et un vote consensuel. Resultats Ce rapport definit en premier lieu les benefices, les risques locaux et generaux, ainsi que les incertitudes des couples MM. Les recommandations de securite apres implantation MM concernent tous les patients. Cependant, un suivi plus etroit est recommande pour le couple MM a grosses tetes (≥ 36 mm) et les resurfacages. Pour ces implants, le suivi de base devrait comporter des radiographies et un dosage de cobalt dans le sang total, realise par technique GF-AAS ou ICP-MS. Des anomalies cliniques et/ou radiologiques de meme que des niveaux d’ions eleves necessitent une imagerie complementaire (echographie, TDM ou MARS-IRM). Un taux de cobalt inferieur a 2 μg/L est probablement sans consequence, la valeur seuil au-dela de laquelle un retentissement clinique doit etre envisage se situant entre 2 et 7 μg/L. Discussion Il s’agit de la premiere tentative d’elaboration d’une recommandation multinationale, pluriprofessionnelle et interdisciplinaire sur l’usage et la surveillance des couples MM en arthroplastie totale de hanche. Ces propositions sont partiellement en accord avec les avis anterieurs sur la duree du suivi et les techniques d’imagerie. En revanche, elles different de certaines propositions passees concernant le dosage des ions metalliques, en particulier sur le milieu a tester, les techniques recommandees et les valeurs seuil proposees. Niveau de preuve V, expert opinion/agreement conference.