Presentation Abstract

Session: 001-015-Adult Reconstruction Knee I
Date/Time: Tuesday, Mar 19, 2013, 9:18 AM - 9:24 AM
Location McCormick Place, Room N427
Presentation Number: Paper 11
Title: Subclinical Systemic Inflammation in Obese Total Knee Arthroplasty Patients
Classification: +Basic Science/Biologics (Knee)
Keywords: Basic Science; Total Knee Arthroplasty General Outcome
Author(s): Syed Azim, MD, Stony Brook, New York
James J. Nicholson, MD, Setauket, New York
Ruth A. Reinsel, PhD, Stony Brook, New York
Mario Rebecchi, PhD, Stony Brook, New York
Helene Benveniste, MD, PhD, Stony Brook, New York
Abstract: INTRODUCTION: Thirty percent of adults are classified as obese with a body mass index (BMI) >30. High BMI is linked to development of osteoarthritis of the knee and there is a hypothesized association between obesity, subclinical systemic inflammation and pain in these patients. Subclinical inflammation develops because fat tissue actively produces cytokines such as interleukin 6 (IL-6) in addition to leptin. For example, leptin, an adipocyte-derived protein hormone also acts as a cytokine and can induce a heightened inflammatory state. The average BMI of patients undergoing total knee arthroplasty (TKA) is reported to be ≥ 30 and it is likely therefore that these patients present with subclinical inflammation prior to surgery. There is limited information regarding differences in inflammatory status in obese and non-obese patients prior to TKA surgery; and we therefore conducted a prospective study to test the hypothesis that obese TKA patients (BMI ≥ 30) have higher levels of IL-6, TNF-alpha and leptin than non-obese TKA patients BMI<30.
METHODS: The local Institutional Review Board approved our study protocol; and all patients gave written informed consent. We prospectively enrolled 20 patients scheduled for elective unilateral TKA under combined spinal and femoral nerve block. Serum and cerebrospinal fluid (CSF) samples were collected at the time of the spinal anesthesia procedures. The samples were flash frozen in liquid N2 and stored at -80oC until analysis. Quantikine and Quantikine HS immunoassay kits were used to measure the levels of IL-6, TNF-alpha and leptin in the samples according to the manufacturer’s instructions.
RESULTS: A total of 20 patients were recruited. Serum and CSF data from 19 patients were available for analysis. The mean BMI of obese versus non-obese patients was 26.9 ± 3.2 (N=5) and 34.8 ± 1.6 (N=14), respectively. Interleukin-6: The serum concentration of IL-6 was significantly higher in the obese patients compared to non-obese patients (Obese: 2.6 ± 1.3 vs. Non-obese: 1.1 ± 0.8, p=0.03); however there was no CSF differences in IL-6 between the two groups. TNF-alpha: No serum or CSF differences in TNF-alpha were observed between the two groups. Leptin: The ratio between the concentration of leptin in CSF [Leptin]CSF and serum [Leptin]serum was calculated and regression analysis demonstrated a strong negative correlation between [Leptin]CSF: [Leptin]serum and BMI (R2=0.40, p=003). Further analysis revealed that [Leptin]CSF:[Leptin]serum was significantly lower in the obese compared to non-obese patients (p<0.01) as a consequence of higher [Leptin]serum in the obese group.
CONCLUSIONS: This preliminary study investigated the leptin, IL-6 and TNF-alpha in serum and CSF of obese and non-obese patients prior to elective TKA surgery. We demonstrated higher serum levels of IL-6 and leptin in addition to higher CSF levels of leptin in obese patients compared to non-obese patients indicating the presence of subclinical inflammation prior to surgery. A heightened inflammatory state prior to surgery may adversely affect obese patient’s post-operative recovery including pain status and warrants further investigation. We are in the process of following TKA patients’ inflammatory state in parallel with pain and functional status post-surgery.
Disclosures: Presenting Author
1 - Kinamed; 3A - Bristol-Myers Squibb
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