What Host Factors Affect Aseptic Loosening After THA and TKA?

Aseptic loosening is the most common cause for revisions after lower-extremity total joint arthroplasties, however studies differ regarding the degree to which host factors influence loosening. We performed a systematic review to determine which host factors play a role in the development of clinical and/or radiographic failure from aseptic loosening after (1) THA and (2) TKA. Two searches on THA and TKA, respectively, using four electronic databases (EMBASE, CINAHL Plus, PubMed, and Scopus) were conducted. We identified a total of 209 reports that encompassed nine potential host factors affecting aseptic loosening. Inclusion criteria for consideration of scientific clinical reports were that 20 or more patients were involved, with more than 1-year followup, with at least three studies pertaining to each factor, and at least six of the Methodological Index for Non-randomized Studies criteria met, and with raw data for odds ratio (OR) calculations. Twenty-one studies (16 THA studies with 45,779 hips and five TKA studies with 288 knees, respectively) were used to calculate weighted OR and CIs (using the random effects theory) and study heterogeneity for four different host factors in THAs (male sex, high activity level, obesity defined as BMI a parts per thousand yen 30 kg/m(2), and current or former tobacco use) and one factor in TKA (BMI a parts per thousand yen 30 kg/m(2)), which were placed in a forest plot. For THA, male sex (OR, 1.39; 95% CI, 1.22-1.58; p = 0.001) and high activity level (University of California Los Angeles [UCLA] activity score a parts per thousand yen 8 points; OR, 4.24; 95% CI, 2.46-7.31; p = 0.001) were associated with aseptic loosening. However, obesity (OR, 1.01; 95% CI, 0.73-1.40; p = 0.96), and tobacco use (OR, 1.96; 95% CI, 0.43-8.97; p = 0.39) were not associated with an increased risk of aseptic loosening after THA with the numbers available. For TKA, we found no host factors associated with loosening. In particular, obesity (BMI a parts per thousand yen 30 kg/m(2)) was not associated with aseptic loosening with the numbers available (OR, 2.28; 95% CI, 0.60-8.62; p = 0.22). Patients undergoing a lower-extremity total joint arthroplasty who engage in impact sports should be counseled regarding their potential increased risk of aseptic loosening; however, given the weak evidence available, we believe that higher-level studies are necessary to clearly define the risk factors, particularly with newer-generation constructs. Level IV, therapeutic study.