Does a computed tomography-based navigation system reduce the risk of dislocation after total hip arthroplasty in patients with osteonecrosis of the femoral head? A propensity score analysis.

This study aimed to investigate whether use of a computed tomography (CT)-based navigation system reduce the risk of dislocation after total hip arthroplasty (THA) in patients with osteonecrosis of the femoral head (ONFH). A total of 271 hips from 192 consecutive patients that underwent primary THA for ONFH were included. There were 110 hips in non-navigation group, and 161 hips in navigation group. After applying exclusion criteria, 209 hips from 149 patients were selected for analysis. Clinical outcomes and complication rates were evaluated, and implant alignments were also calculated. To identify whether the navigation system was useful to prevent dislocation, the inverse probability of treatment-weighted Cox regression analysis using a propensity score in relationship to sex, age at surgery, body mass index, and femoral head size was performed. No significant difference was observed in clinical scores between both groups. Dislocation was significantly lower in the navigation group (3 hips, 2.7%) than in the non-navigation group (11 hips, 11.2%; p = 0.012), whereas periprosthetic joint infection and aseptic loosening did not differ between the groups. Variance of cup inclination and anteversion angles was smaller in the navigation group than in the non-navigation group (p < 0.001). Use of the CT-based navigation system (hazard ratio; 0.26, 95% confidence interval, 0.07-0.98; p = 0.047) turned out to be the predictor for preventing dislocation. In conclusion, use of the CT-based navigation system provided a precise placement of components, and thus helps to prevent dislocation in patients with ONFH in the propensity score analysis.

Association of CYP2C19 Polymorphisms With Clopidogrel Reactivity and Clinical Outcomes in Chronic Ischemic Stroke.

BACKGROUND: CYP2C19variants are associated with the antiplatelet effects of clopidogrel against recurrent cardiovascular events. However, it remains unknown whether the elapsed time from stroke onset affects the relationship between the genetic variants and such events. To address this, we conducted a prospective cohort study to determine the effect ofCYP2C19variants on clinical outcomes in the chronic phase.Methods and Results:In total, 518 Japanese non-acute stroke patients treated with clopidogrel were registered at 14 institutions. Patients were classified into 3 clopidogrel-metabolizing groups according toCYP2C19genotype: extensive metabolizer (EM:*1/*1), intermediate metabolizer (IM:*1/*2or*1/*3), and poor metabolizer (PM:*2/*2,*2/*3, or*3/*3). Antiplatelet effects of clopidogrel were assessed by adenosine diphosphate (ADP)-induced platelet aggregation and vasodilator-stimulated phosphoprotein (VASP) phosphorylation. The endpoint was composite cerebrocardiovascular events (CVEs). In 501 successfully followed-up patients, the median time from index stroke to enrollment was 181 days. There were 28 cardiovascular and 2 major bleeding events. There were no significant differences in the rates of cardiovascular events among the groups. CONCLUSIONS: Despite associations betweenCYP2C19variants and on-clopidogrel platelet reactivity, there was no significant difference in rates of CVEs in the chronic stroke phase among the 3 clopidogrel-metabolizing groups ofCYP2C19variants.