Serum D-Lactate, a Novel Serological Biomarker, Is Promising for the Diagnosis of Periprosthetic Joint Infection

Background: Although many markers are used for diagnosis of periprosthetic joint infection (PJI), serological screening and diagnosis for PJI are still challenging. We evaluated the performance of serum D-lactate and compared it with ESR, coagulation-related biomarkers and synovial D-lactate for the diagnosis of PJI.Methods: Consecutive patients with preoperative blood and intraoperative joint aspiration of a prosthetic hip or knee joint before revision arthroplasty were prospectively included. The diagnosis of PJI was based on the criteria of the Musculoskeletal Infection Society, and the diagnostic values of markers were estimated based on receiver operating characteristic (ROC) curves by maximizing sensitivity and specificity using optimal cutoff values.Results: Of 52 patients, 26 (50%) were diagnosed with PJI, and 26 (50%) were diagnosed with aseptic failure. ROC curves showed that serum D-lactate, fibrinogen (FIB) and ESR had equal areas under the curve (AUCs) of 0.80, followed by D-dimer and fibrin degradation product, which had AUCs of 0.67 and 0.69, respectively. Serum D-lactate had the highest sensitivity of 88.46% at the optimal threshold of 1.14 mmol/L, followed by FIB and ESR, with sensitivities of 80.77% and 73.08%, respectively, while there were no significant differences in specificity (73.08%, 73.08% and 76.92%, respectively). Conclusion: Serum D-lactate showed similar performance to FIB and ESR for diagnosis of PJI. The advantages of serum D-lactate are pathogen-specific, highly sensitive, minimally invasive and rapidly available making serum D-lactate useful as a point-of-care screening test for PJI.

Failure Analysis in Multiple TKA Revisions—Periprosthetic Infections Remain Surgeons’ Nemesis

Background: The aim of this study was to categorize reasons for failure and to analyze the survivorship of multiple total knee arthroplasty (TKA) revisions. Methods: The study retrospectively evaluated all multiple TKA revisions performed between 2005 and 2015 at the authors’ institutions. Sixty-three patients (35 female, 28 male, age 64 ± 10 years, follow-up 55 ± 36 months) underwent a total of 157 re-revision TKA surgeries (range 2–5). The revision indications were divided up into main diagnoses. Survivorship was evaluated by mixed model analysis. Results: The main overall reason for re-revision was periprosthetic joint infection (PJI) (48%), followed by instability (12%), polyethylene wear (11%), malpositioning (8%), and aseptic loosening (8%). Survivorship shortened with an increasing number of revision surgeries (p = 0.003). While PJI was in 38% of all cases, the reason for the first revision, incidence increased constantly with the number of revisions (48% at second revision, 55% at third revision, 86% at fourth revision, and 100% at fifth revision, p = 0.022). If periprosthetic infection caused the first revision, patients showed an average of two more septic revisions at follow-up than patients with an aseptic first revision indication (p < 0.001). In 36% of cases, the reason for follow-up surgery in case of periprosthetic infection was again PJI. Conclusion: The probability of survival of the implanted knee arthroplasty is significantly reduced with each subsequent revision. Periprosthetic infection is the main cause of multiple revisions.

Prevention of Periprosthetic Joint Infection in Total Hip and Knee Replacement: One European Consensus

Periprosthetic joint infection (PJI) is a devastating complication in total hip and knee replacement. Its prevention is key to decrease the incidence and avoid some consequences that seriously impact patients and health systems. In view of the variety of recommendations and guidelines, we decided to conduct an expert, peer-reviewed European consensus analysis about the pre-, intra-, and postoperative prevention of PJI. A multinational group of practicing orthopedic experts developed a series of 47 consensus statements in 6 main groups of intervention, and a 2-stage Delphi approach was launched with a threshold for agreement at 75% and for very high agreement at more than 90%. A total of 306 orthopedic surgeon responses were gathered from 9 countries. Consensus was reached for 42/47 statements, 31/47 of which achieved a very high consensus. Many preoperative actions gathered strong consensus, although areas like the use of alcoholic chlorhexidine or the timing of hair removal did not attain strong consensus, despite available evidence. Intra- and postoperative actions showed more variability regarding incise drapes, skin suturing techniques, and wound follow-up. This study confirms an important consensus among orthopedic surgeons across Europe in many areas well known to contribute to the prevention of PJI; however, there are still grounds for improvement.

18F-FDG and 68Ga-FAPI PET/CT for Evaluating Periprosthetic Joint Infection and Aseptic Loosening in Rabbit Models

Purpose We built a loosening model based on the original infection model of rabbit and evaluated the performance characteristics of 18F-FDG and 68Ga-FAPI in infection and loosening. Methods After surgery, the rabbits were divided into four groups, six in the control group and 10 in the loosening, S. aureus and S. epidermis groups. PET/CT and serological examination were performed every two weeks for three times. After sacrificed, micro-CT, tissue culture, pullout test and scanning electron microscope were performed. Results As for 18F-FDG, performances of control and loosening groups were similar. SUVmax of S. aureus had been consistently in the high range than that of S. epidermis. As for 68Ga-FAPI, control group had the lowest SUVmax in the second week and increased gradually. SUVmax of loosening group began exceed control group since the second week. SUVmax of S. aureus in the second week was the lowest among four group and raised as the number of weeks increased and equalled to SUVmax of S. epidermis in the sixth week. Linear regressions between SUVmax and serology showed that 18F-FDG was positively correlated with CRP and IL-6 while 68Ga-FAPI revealed negative and positive correlation with CRP and IL-6 in the second and sixth week. Besides, both SUVmax and MTV of 18F-FDG or 68Ga-FAPI were negatively correlated with BV/TV and BS/TV. Conclusion In this longitudinal observation, 68Ga-FAPI showed greater sensitivity than 18F-FDG in detecting diseases, and 68Ga-FAPI had not intestinal and muscular uptake. MTV of 68Ga-FAPI were larger than 18F-FDG, which meant that 68Ga-FAPI had the potential to define the scope of lesions more accurately. Finally, SUVmax could not differentiate loosening and infection in 68Ga-FAPI, further study about diagnostic criteria was warranted.