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Background Myocardial injury after noncardiac surgery (MINS) is common and of prognostic importance. Little is known about MINS in orthopaedic surgery. The diagnostic criterion for MINS was a level of ≥0.03 ng/mL on a non-high-sensitivity troponin T (TnT) assay due to myocardial ischemia. Methods We undertook an international, prospective study of 15,103 patients ≥45 years of age who had inpatient noncardiac surgery; 3,092 underwent orthopaedic surgery. Non-high-sensitivity TnT assays were performed on postoperative days 0, 1, 2, and 3. Among orthopaedic patients, we determined (1) the prognostic relevance of the MINS diagnostic criteria, (2) the 30-day mortality rate for those with and without MINS, and (3) the probable proportion of MINS cases that would go undetected without troponin monitoring because of a lack of an ischemic symptom. Results Three hundred and sixty-seven orthopaedic patients (11.9%) had MINS. MINS was associated independently with 30-day mortality including among those who had had orthopaedic surgery. Orthopaedic patients without and with MINS had a 30-day mortality rate of 1.0% and 9.8%, respectively (odds ratio [OR], 11.28; 95% confidence interval [CI], 6.72 to 18.92). The 30-day mortality rate was increased for patients with MINS who had an ischemic feature (i.e., symptoms, or evidence of ischemia on electrocardiography or imaging) (OR, 18.25; 95% CI, 10.06 to 33.10) and for those who did not have an ischemic feature (OR, 7.35; 95% CI, 3.37 to 16.01). The proportion of orthopaedic patients with MINS who were asymptomatic and in whom the myocardial injury would have probably gone undetected without TnT monitoring was 81.3% (95% CI, 76.3% to 85.4%). Conclusions One in 8 orthopaedic patients in our study had MINS, and MINS was associated with a higher mortality rate regardless of symptoms. Troponin levels should be measured after surgery in at-risk patients because most MINS cases (>80%) are asymptomatic and would go undetected without routine measurements. Level of evidence Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Background: Improvements in perioperative care have markedly decreased mortality after total joint replacement. Acute myocardial infarct (MI) is the most common clinically significant complication after total joint replacement (TJR) and the most common cause of 30-day mortality after TJR, which remains a concern especially in light of an older population with advanced comorbidities. In spite of this, little evidence exists in regard to its effect on TJR functional outcomes. Methods: To assess the potential impact, if any, of acute MI on the clinical outcomes of patients undergoing primary TJR, a matched cohort study of MI and non-MI patients was conducted to determine 1-year Oxford, Harris Hip and Knee Society score outcomes. Results: Of 12,739 primary TJR patients identified over a 9-year period, 0.9% (114; 95% CI, 0.75-1.1) experienced a perioperative MI. A greater proportion of MI than non-MI patients had ≥1 cardiac risk factor (P=0.001) and an American Society for Anesthesiologist (ASA) 4 status (P=0.037). Length of hospital stay was longer for MI cases (MI=11.5±9.8 vs. Non-MI=5.4±2.7, P 0.05). One-year cardiac mortality rate was 6.1% compared to 0 non-MI deaths (P Conclusions: While functional outcomes of MI after TJR are equivalent to non-MI, 1-year mortality remains high, and targeted cardiac screening and long-term monitoring for this patient population should be implemented.

Background While serum interleukin-6 (IL-6) clearly has been established as a marker of physiologic stress, the validity of IL-6 as a reliable measure of the degree of trauma or stress suffered by an individual with total knee replacement (TKA) remains in question. We hypothesized that if serum IL-6 is a marker of surgical stress, then we would observe marked increases in IL-6 levels in sequential bilateral TKA as compared with unilateral TKA. Methods The study design was a single-surgeon prospective case-control pilot study of sequential bilateral TKA cases and unilateral TKA controls to assess changes in serum IL-6 levels preoperatively, during, at wound closure, and up to 48 hours postoperatively. IL-6 levels were analyzed using a one-way mixed models analysis of variance. Results Eleven patients with unilateral and 12 with bilateral TKA comprised the study sample. IL-6 levels at peak (24 hours postoperatively) for the unilateral control group was 12 times higher compared with baseline (4.6 pg/mL compared with 55.0 pg/mL), while the bilateral TKA group saw a 116-fold increase in IL-6 from baseline to peak at 12 hours postoperatively (2.9 pg/mL compared with 335.0 pg/mL). At “peak,” IL-6 was 6.1 times higher for the bilateral group compared with the unilateral group. Conclusions This pilot study supports the notion that sequential bilateral TKA produces a far greater surgical stress, as measured by IL-6. Careful patient selection, counseling, and consideration of staging procedures are advised.