Determining the stress biomarker profile in patients undergoing total knee replacement and the relationship with outcome at 12 months.

BACKGROUND: Total knee replacement (TKR) is the commonest joint arthroplasty procedure worldwide. Despite excellent outcomes, some studies have reported dissatisfaction in up to 20% of patients. There is evidence of an association between the biochemical stress response to surgery and outcomes. The objective of this study is to describe the stress biomarker profile for TKR, and correlate this with patient outcomes. METHODS: A prospective cohort study of 50 patients undergoing primary TKR was conducted. Serum IL-6, TNF-α, neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) were measured immediately pre- and post-operatively, and on Days 1 and 3. Follow-up questionnaires including the Oxford Knee Score (OKS) and EuroQol five dimensions (EQ-5D) were completed at 12-months. Univariate analysis was completed using a linear regression model (p < 0.05). RESULTS: Serum IL-6, NLR, and PLR all increased to Day 1 post-operatively, and decreased by Day 3. TNF-α values increased across all time points. Statistical analysis found a significant negative correlation (r = -0.414; p = 0.005) between pre-operative IL-6 and 12-month OKS. There was a significant positive correlation between pre-operative NLR and 12 month OKS (r = 0.272; p = 0.039) and 12 month EQ5D (r = 0.268; p = 0.043). CONCLUSION: This is the first study to describe the biochemical stress response to TKR. The results raise the potential for a pre-operative risk stratification tool for patients based on IL-6 and NLR measurements. Further research should be conducted to explore the underlying mechanisms involved, and investigate interventions to reduce pre-operative physiological stress with a view to improving post-operative outcomes.

Conservation management options and actions: putative decline of coral cover at Palmyra Atoll, Northern Line Islands, as a case study.

Localised loss of live coral cover at Palmyra Atoll (central Pacific Ocean) has been attributed to increased temperature and/or sedimentation arising from alterations made to the lagoon system. It has been hypothesised that a causeway spanning the lagoon hinders water circulation, resulting in warmer and/or more turbid water flowing towards a site of high coral cover and diversity (Coral Gardens). Analyses of a multi-site and multi-year data set revealed no differences in mean temperature or turbidity values on either side of the causeway and provided no evidence of significantly warmer or more turbid water at Coral Gardens. We conclude that the putative decline in live coral cover cannot be attributed to the presence of the causeway and that proposed management actions involving modification to the causeway cannot achieve the conservation outcomes suggested of them.