Marco S. Caicedo, 1 Lauryn Samelko, 1,2 and Nadim J. Hallab 3 Lymphocyte Reactivity to Nickel Correlates with Reported High-Pain Levels in Patients with Total Joint Arthroplasties: Implications for Pain-Related Hypersensitivity Responses REFERENCE: Caicedo, Marco S., Samelko, Lauryn, and Hallab, Nadim J., “Lymphocyte Reactivity to Nickel Correlates with Reported High-Pain Levels in Patients with Total Joint Arthroplasties: Implications for Pain-Related Hypersensi- tivity Responses,” Metal-On-Metal Total Hip Replacement Devices May 8, 2012, in Phoenix, AZ; STP 1560, Steven M. Kurtz, A. Seth Greenwald, William H. Mihalko, and Jack E. Lemons, Editors, pp. 1–14, doi:10.1520/STP156020120025, ASTM International, West Conshohocken, PA 2013. ABSTRACT: The growing number of total joint replacements performed every year has led to an increase in the number of patients experiencing unexplained pain around their joint replacement post-operatively. Infections and implant dislocations are common complications from joint replacement surgery; however, excessive aseptic immune activation in response to implant materials (i.e., metal hypersensitivity to nickel) can also occur and induce painful outcomes, but are more challenging to diagnose. We hypothe- size that higher pain levels reported from patients with total joint anthroplasty (TJA) will correlate with a higher degree and incidence of nickel hypersensi- tivity, as determined by metal lymphocyte transformation testing (metal-LTT). We retrospectively reviewed nickel hypersensitivity results from 209 TJA subjects where infection and mechanical problems have been ruled out and plotted their lymphocyte stimulation index against their self-reported pain levels at the time of the test. TJA patients with no previous history of Manuscript received April 13, 2012; accepted for publication August 1, 2012; published online February 11, 2013. 1 Dept. of Orthopedic Surgery, Rush Univ. Medical Center, Chicago, IL 60612, United States of America. 2 Dept. of Immunology, Rush Univ. Medical Center, Chicago, IL 60612, United States of America. 3 Ph.D., Associate Professor, Dept. of Orthopedic Surgery, Rush Univ. Medical Center, Chicago, IL 60612, United States of America (Corresponding author), e-mail: nhallab@rush.edu Copyright V C 2013 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. Metal-On-Metal Total Hip Replacement Devices STP 1560, 2013 Available online at www.astm.org DOI:10.1520/STP156020120025