Increased Levels of Cortisol in Patients Undergoing Total Joint Arthroplasty may be Associated with Stress and Inflammatory Processes

Abstract

IntroductionOsteoarthritis is a condition in which joint cartilage and its adjacent bone degenerate progressively over time due to inflammatory processes involving activation of matrix degrading enzymes. Total joint arthroplasty (TJA) is a common surgical treatment for osteoarthritis of the hip or knee. Cortisol is a steroid hormone in the class of glucocorticoids which is produced in the adrenal gland. Cortisol is generated in response to inflammation and physical or emotional stress. This study aims to investigate the cortisol levels in patients undergoing TJA.Materials and MethodsPlasma samples were prospectively collected from 71 TJA patients at baseline (pre‐surgery), 24 hours post‐operation, and 5 days post‐operation. Normal controls represented plasma samples from drug free health individuals (n=50). Cortisol and TNFa levels were measured in each sample using a commercially available ELISA kit. All results were compiled as group means ± SD.ResultsThe plasma cortisol level in normal individuals were 67 ± 11 ng/mL. In contrast, the pre‐surgical and 24‐hour post‐surgical samples showed a marked increase in cortisol levels (> 200ng/mL). The blood samples drawn at the 5th day after surgery showed a downward trend reaching near normal levels (74 ± 12 ng/mL). There was no significant difference between cortisol levels pre‐operatively and within 24 hours post‐TJA, however there was a significant difference in comparison to the levels on the 5th day and normal. The TNFa levels were elevated in TJA patients in the pre‐surgical (18.6 ±3.2 pg/ml), at 24 hours post‐surgical (24.2 ± 7.6 pg/ml) and on the 5th day (11.3 ± 3.1 pg/ml) in comparison to normals (5.1 ± 2.1 pg/ml).Discussion and ConclusionAt 5 days post‐operation, cortisol levels were significantly lower than at baseline or 24 hours post‐operation. This finding differs from previous findings, which reported increased levels post‐operatively relative to at baseline. The TNFa levels also showed elevated levels in the pre‐ and post‐surgical samples which followed a downward trend on the 5th day. These results are consistent with the previous reports that such biomarkers as IL‐6 and TNFa are upregulated in TJA patients prior to surgery suggesting a role of inflammatory process. Furthermore the increased level of cortisol may be related to not only the inflammation but pre‐surgical emotional stress in TJA patients. The near normalization of the cortisol levels on the 5th post‐surgical day is suggestive of differential down‐regulation of the inflammatory process and stress levels in TJA patients.