A. Brozovich (Houston, US)
HMRI & Texas A&M Orthopedics & Sports MedicinePresenter Of 1 Presentation
P151 - Metal Allergy as a Potential Cause of Primary Total Knee Replacement: Evidence of a Type IV Hypersensitivity Reaction
Abstract
Purpose
Implant related allergy is emerging as a causative factor as a potential source of total knee arthroplasty (TKA) failure, Mechanistically, this type IV hypersensitivity reaction (T4HR) is mediated by effector T cells, macrophages, and leukocytes that infiltrate to the site of metal exposure and induce inflammatory tissue damage. We aimed to detect the presence or absence of a true allergic response to metal implants and compare these results to LTT and patch test results.
Methods and Materials
Cortical bone obtained at for patients operated on for primary TKA in which metal allergy was suspected, and for revision TKA cases done for presumed metal allergy. Cytof was used to determine cell density of inflammatory cells, specifically Th1, Th2, M1, and M2 cells. Th2 and M1 cells are indicative of an allergic response.
Results
When evaluating for differences between the mean cell density among primary vs. revision TKA, revision TKA patients had significantly higher number of Th2 cells compared to Th1 cells (p-value=0.0043). Among revision cases, there was significantly more M1 vs M2 macrophages (p-value=0.034) within a patient. When comparing mean cell density of M1 vs M2 macrophages, there was a significant difference in both primary and revision TKA surgeries (p-value=0.0041 primary, p-value<0.001 revision). Among revision patients that had a predominate of Th2 cells, 4/9 (44%) of the patients had a negative LTT/ patch test.
Conclusion
This data supports metal allergy, mediated by a T4HR, for some cases of TKA failure. Current methods to screen patients for metal allergy prior to primary TKA are inadequate as systemic T4HR does not appropriately mimic the inflammatory reaction within the knee joint. This study demonstrates the need for a more sensitive screening test from specimens found in the knee joint, to more accurately identify patients that will exhibit a T4HR to metal.
Presenter Of 1 Presentation
P151 - Metal Allergy as a Potential Cause of Primary Total Knee Replacement: Evidence of a Type IV Hypersensitivity Reaction
Abstract
Purpose
Implant related allergy is emerging as a causative factor as a potential source of total knee arthroplasty (TKA) failure, Mechanistically, this type IV hypersensitivity reaction (T4HR) is mediated by effector T cells, macrophages, and leukocytes that infiltrate to the site of metal exposure and induce inflammatory tissue damage. We aimed to detect the presence or absence of a true allergic response to metal implants and compare these results to LTT and patch test results.
Methods and Materials
Cortical bone obtained at for patients operated on for primary TKA in which metal allergy was suspected, and for revision TKA cases done for presumed metal allergy. Cytof was used to determine cell density of inflammatory cells, specifically Th1, Th2, M1, and M2 cells. Th2 and M1 cells are indicative of an allergic response.
Results
When evaluating for differences between the mean cell density among primary vs. revision TKA, revision TKA patients had significantly higher number of Th2 cells compared to Th1 cells (p-value=0.0043). Among revision cases, there was significantly more M1 vs M2 macrophages (p-value=0.034) within a patient. When comparing mean cell density of M1 vs M2 macrophages, there was a significant difference in both primary and revision TKA surgeries (p-value=0.0041 primary, p-value<0.001 revision). Among revision patients that had a predominate of Th2 cells, 4/9 (44%) of the patients had a negative LTT/ patch test.
Conclusion
This data supports metal allergy, mediated by a T4HR, for some cases of TKA failure. Current methods to screen patients for metal allergy prior to primary TKA are inadequate as systemic T4HR does not appropriately mimic the inflammatory reaction within the knee joint. This study demonstrates the need for a more sensitive screening test from specimens found in the knee joint, to more accurately identify patients that will exhibit a T4HR to metal.