399. Treatment and Outcome of Prosthetic Joint Infection in Unicompartmental Knee Arthroplasty

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an increasingly popular alternative to total knee replacement due to easier recovery and greater satisfaction. However, limited evidence guides the management of periprosthetic joint infection (PJI) in UKA specifically. We retrospectively reviewed the largest cohort of UKA PJI to date, providing our experience in a high volume tertiary institution. METHODS: An institutional PJI database was queried from 2008 to 2016 to identify all PJI cases with an index procedure of UKA. Treatment, diagnostic criteria, Charlson Comorbidity Index (CCI) and microbiology data were collected. Success was defined as no further surgical treatment for infection at 2 years. A chi-square test or Fisher’s exact test was used for comparisons between treatment success and failure groups. Survival probability was calculated using the Kaplan–Meier method. RESULTS: A total of 24 UKA PJIs were identified with 22 meeting MSIS criteria. Median age at infection was 65.9 years (range, 50.8–87.4), median BMI was 26.7 kg/m(2) (range, 21.2–49.5), 75% male (18/24).The average follow-up time was 2.83 years. 9 patients presented with early (4 weeks of symptoms). 63% (15/24) of PJI cases were staphylococcal and 8.3% (2/24) were culture negative. Patients were either treated with 1 stage exchange (n = 3, 100% success), two-stage exchange (n = 5, 80% success) or implant retention (n = 16, 75% success). Overall survivorship was 79% at 2 years (95% confidence interval [CI], 63%–95%). Overall there was no significant association between success and CCI (P = 0.46), infection type (P = 0.29), surgical therapy (P = 0.62), and microorganism (P = 0.05). CONCLUSION: In this series, UKA PJIs tended to present more often as early post-operative or hematogenous infections. We observed no significant benefit with revision surgery and therefore conclude that implant retention should be considered as first-line surgical treatment. Outcomes of UKA PJI appear comparable to those in TKA PJIs. DISCLOSURES: All authors: No reported disclosures.