Poster 136: Measurement Properties of Circulating Interleukin-6 and Oncostatin-M For Quantifying Musculoskeletal Injury

Abstract

Objective: This study was performed to examine changes in serum concentrations of interleukin-6 (IL-6) and oncostatin M following total knee replacement (TKR) surgery in order to examine biomarker measurement properties including sensitivity to injury and variability across individuals in time to peak concentrations. Design: Repeated measures, measurement evaluation. Setting: Orthopedic surgery clinic in a teaching hospital in Hamilton, ON, Canada. Participants: 4 men and 10 women undergoing unilateral TKR. Interventions: Not applicable. Main Outcome Measures: Serial blood samples were taken in the preoperative waiting areas, immediately after surgery, at 6, 12, and 24 hours, and then at 24-hour intervals to 7 days. IL-6 and oncostatin-M concentrations were measured by enzyme-linked immunosorbent assay. Data on individual subjects were plotted over time to visualize the injury response curves. Results: Mean peak IL-6 (651pg/ml; range, 96–2750) significantly exceeded mean presurgery baseline (2pg/ml; range, 0–22). There were no sex differences in baseline or peak IL-6 concentrations. Time to peak ranged between 12 to 48 hours across individuals. There were no sex differences in the timing of the peak. The time window remained the same for low IL-6 secreters (peak below 130pg/ml), moderate secreters (peak 131–400pg/ml), and high secreters (peak >400pg/ml). There was no serum Oncostatin M injury response detectable in any subject. Conclusions: IL-6 has good sensitivity to the state of injury following TKR. The variable time course of IL-6 indicates potential problems with the previous comparison of surgical procedures at common time points (eg, 24h) and necessitates serial measures within 12 to 48 hours to estimate the peak. Oncostatin M did not provide a biochemical index of musculoskeletal injury.