Patient-specific articulating spacer for two-stage shoulder arthroplasty exchange.

OBJECTIVE: Two-stage exchange with an antibiotic-loaded polymethylmethacrylate (PMMA) spacer is standard treatment for chronic periprosthetic joint infection of the shoulder. We present a safe and simple technique for patient-specific spacer implants. INDICATION: (Chronic) periprosthetic joint infection of the shoulder. RELATIVE CONTRAINDICATIONS: Known allergy against components of PMMA bone cements. Inadequate compliance for two-stage exchange. Patient is unfit to undergo two-stage exchange. SURGICAL TECHNIQUE: Hardware removal, histologic and microbiologic samples, and debridement. Preparation of targeted or calculated antibiotic-loaded PMMA. Tailoring of patient-specific spacer. Spacer implantation. POSTOPERATIVE MANAGEMENT: Rehabilitation protocol. Antibiotic treatment. Reimplantation after successful eradication of infection.

Does radiolucency really predict loose components in revision shoulder arthroplasty?

OBJECTIVE: The number of shoulder arthroplasties is increasing along with the need for revision surgeries. Determining the stability of the implant is crucial in preoperative planning. This study aims to investigate whether radiolucent lines (RLL) in preoperative radiographs predict component loosening. MATERIALS AND METHODS: Preoperative radiographs of 93 cases in 88 patients who underwent shoulder arthroplasty revision were evaluated regarding the presence of RLL. Correlation analyses were performed for radiographic findings and demographic factors (age, gender, BMI, prior surgeries) compared to intraoperative findings. RESULTS: The presence of RLL around the humeral component correlated with loosening (p < 0.001, Phi 0.511), and the distal zones 3 and 5 showed the strongest correlation (Phi 0.536). While RLL in only one zone did not predict loosening (p = 0.337), RLL present in two or more zones showed correlation with loosening (p < 0.001). Risk factors associated with loosening were a higher age at the time of revision surgery (p = 0.030) and the number of zones with RLL (p < 0.001). The glenoid component was loose in 39.0% of the cases; 5.5% of the glenoid components with RLL were stable. Nevertheless, the presence of RLL was highly associated with loosening (p < 0.001, Phi 0.603). A longer time between implantation and revision correlated with loosening of the glenoid component (p = 0.046). CONCLUSION: While RLL do not predict loosening of the implant in general, occurrence in more than one zone correlates with loosening. If located in distal zones and with increasing number of zones with RLL, the correlation becomes even stronger and loosening is more likely.

Defining a Synovial Fluid White Blood Cell Count Threshold to Predict Periprosthetic Infection after Shoulder Arthroplasty.

BACKGROUND: The diagnosis of periprosthetic shoulder infection (PSI) requires a thorough diagnostic workup. Synovial fluid aspiration has been proven to be a reliable tool in the diagnosis of joint infections of the lower extremity, but shoulder specific data is limited. This study defines a threshold for synovial fluid white blood cell count (WBC) and assesses the reliability of microbiological cultures. METHODS: Retrospective study of preoperative and intraoperative fluid aspiration of 31 patients who underwent a revision of a shoulder arthroplasty (15 with PSI defined by IDSA criteria, 16 without infection). The threshold for WBC was calculated by ROC/AUC analysis. RESULTS: WBC was significantly higher in patients with PSI than in other patients. A threshold of 2800 leucocytes/mm3 showed a sensitivity of 87% and a specificity of 88% (AUROC 0.92). Microbiological cultures showed a sensitivity of 76% and a specificity of 100%. CONCLUSIONS: A threshold of 2800 leucocytes/mm3 in synovial fluid can be recommended to predict PSI. Microbiological culture has an excellent specificity and allows for targeted antibiotic therapy. Joint aspiration presents an important pillar to diagnose PSI.

Myocardial infarction triggers cardioprotective antigen-specific T helper cell responses.

T cell autoreactivity is a hallmark of autoimmune diseases but can also benefit self-maintenance and foster tissue repair. Herein, we investigated whether heart-specific T cells exert salutary or detrimental effects in the context of myocardial infarction (MI), the leading cause of death worldwide. After screening more than 150 class-II-restricted epitopes, we found that myosin heavy chain alpha (MYHCA) was a dominant cardiac antigen triggering post-MI CD4+ T cell activation in mice. Transferred MYHCA614-629-specific CD4+ T (TCR-M) cells selectively accumulated in the myocardium and mediastinal lymph nodes (med-LN) of infarcted mice, acquired a Treg phenotype with a distinct pro-healing gene expression profile, and mediated cardioprotection. Myocardial Treg cells were also detected in autopsies from patients who suffered a MI. Noninvasive PET/CT imaging using a CXCR4 radioligand revealed enlarged med-LNs with increased cellularity in MI-patients. Notably, the med-LN alterations observed in MI patients correlated with the infarct size and cardiac function. Taken together, the results obtained in our study provide evidence showing that MI-context induces pro-healing T cell autoimmunity in mice and confirms the existence of an analogous heart/med-LN/T cell axis in MI patients.