Survival of anterior cruciate ligament reconstructions in active-duty military populations.

PURPOSE: Anterior cruciate ligament tears and anterior cruciate ligament reconstruction (ACLR) are common in young athletes. The modifiable and non-modifiable factors contributing to ACLR failure and reoperation are incompletely understood. The purpose of this study was to determine ACLR failure rates in a physically high-demand population and identify the patient-specific risk factors, including prolonged time between diagnosis and surgical correction, that portend failure. METHODS: A consecutive series of military service members with ACLR with and without concomitant procedures (meniscus [M] and/or cartilage [C]) done at military facilities between 2008 and 2011 was completed via the Military Health System Data Repository. This was a consecutive series of patients without a history of knee surgery for two years prior to the primary ACLR. Kaplan-Meier survival curves were estimated and evaluated with Wilcoxon test. Cox proportional hazard models calculated hazard ratios (HR) with 95% confidence intervals (95% CI) to identify demographic and surgical factors that influenced ACLR failure. RESULTS: Of the 2735 primary ACLRs included in the study, 484/2,735 (18%) experienced ACLR failure within four years, including (261/2,735) (10%) undergoing revision ACLR and (224/2,735) (8%) due to medical separation. The factors that increased failure include Army Service (HR 2.19, 95% CI 1.67, 2.87), > 180 days from injury to ACLR (HR 1.550, 95% CI 1.157, 2.076), tobacco use (HR 1.429 95% CI 1.174, 1.738), and younger patient age (HR 1.024, 95% CI 1.004, 1.044). CONCLUSION: The overall clinical failure rate of service members with ACLR is 17.7% with minimum four-year follow-up, where more patients are likely to fail due to revision surgery than medical separation. The cumulative probability of survival at 4 years was 78.5%. Smoking cessation and treating ACLR patients promptly are modifiable risk factors impacting either graft failure or medical separation. LEVEL OF EVIDENCE: Level III.

Long-range chemical sensitivity in the sulfur K-edge X-ray absorption spectra of substituted thiophenes.

Thiophenes are the simplest aromatic sulfur-containing compounds and are stable and widespread in fossil fuels. Regulation of sulfur levels in fuels and emissions has become and continues to be ever more stringent as part of governments' efforts to address negative environmental impacts of sulfur dioxide. In turn, more effective removal methods are continually being sought. In a chemical sense, thiophenes are somewhat obdurate and hence their removal from fossil fuels poses problems for the industrial chemist. Sulfur K-edge X-ray absorption spectroscopy provides key information on thiophenic components in fuels. Here we present a systematic study of the spectroscopic sensitivity to chemical modifications of the thiophene system. We conclude that while the utility of sulfur K-edge X-ray absorption spectra in understanding the chemical composition of sulfur-containing fossil fuels has already been demonstrated, care must be exercised in interpreting these spectra because the assumption of an invariant spectrum for thiophenic forms may not always be valid.