Metal Hypersensitivity Is Associated with Inferior Implant Survivorship in Total Knee Arthroplasty, but Not Total Hip Arthroplasty: A Large-Database Matched-Cohort Analysis.

Abstract

The purpose of this study was to determine if a preoperative diagnosis of metal hypersensitivity (MHS) is a risk factor for worse implant survivorship following total hip arthroplasty (THA) or total knee arthroplasty (TKA). A retrospective cohort study was performed using United States national claims data from January 2010 to October 2022, sourced from a large national database. A cohort of 524 patients undergoing THA and 1,559 patients undergoing TKA who had an MHS diagnosis were 1:4 propensity score-matched to 2,075 THA and 6,189 TKA controls on age, sex, and Charlson Comorbidity Index (CCI). All patients were at least 18 years old at the time of surgery, underwent primary procedures, and had a minimum two-year follow-up. Time to revision surgery at up to five-year follow-up for all causes, for periprosthetic joint infection (PJI), and for mechanical loosening was compared between groups using the Cox proportional hazards model. Hazard ratios (HR) with 95% confidence intervals were calculated. P-values < 0.05 were considered significant. For the THA analysis, the five-year cumulative incidence of revision was low in both groups (MHS 4.8 versus control 3.0%), and the MHS group had a higher risk of revision for PJI (HR 3.19 [1.29 to 7.88], P = 0.01), but there was no significant difference in risk of all-cause revision or revision for mechanical loosening (P > 0.05). For the TKA analysis, the five-year cumulative incidence of all-cause revision was high in the MHS group (MHS 13.1 versus control 3.8%), and the MHS group also had a higher risk of all-cause revisions (HR 3.63 [3.00 to 4.39], P < 0.001), revision for PJI (HR 4.11 [2.81 to 6.02], P < 0.001), and revision for mechanical loosening (HR 4.96 [3.82 to 6.46], P < 0.001). Preoperative MHS was associated with a higher risk of all-cause revision by five-year follow-up following TKA, but not THA, though the present study could not establish a causal relationship between MHS and the need for revision surgery.