Leukocyte Esterase: Metal-on-Metal Failure and Periprosthetic Joint Infection.

BACKGROUND: Adverse local tissue reactions (ALTRs) and periprosthetic joint infection can occur after metal-on-metal total hip arthroplasty (THA), both potentially generating purulent synovial fluid (SF) and elevated white cell count. This makes it difficult to distinguish between diagnoses; therefore, we evaluated leukocyte esterase (LE) strip test's reliability in ruling out periprosthetic joint infection in ALTR revision THA.

METHODS: Sixty-one patients with ALTRs and an LE strip test were evaluated, excluding 15 cases with SF metallic debris. LE strip tests were classified -/trace, + (mildly positive), and ++ (strongly positive).

RESULTS: LE strip tests were ++, +, -/trace in 8 patients (13.1%), 14 (23.0%), and 39 (63.9%), respectively. Means and ranges of SF white cell count and polymorphonuclear percentage were 1291.4 (0-10,886 cells/μL), and 46.1% (0%-94%), respectively.

CONCLUSION: ++ LE strip test, in conjunction with preoperative work-ups, reliably rules out infection in 92.9% of patients undergoing THA revision secondary to ALTR.