THU0504 EARLY JOINT REPLACEMENT IN JIA: TREND OVER TIME AND FACTORS INFLUENCING IMPLANT SURVIVAL

Abstract

Background:Juvenile idiopathic arthritis (JIA) is the most common chronic rheumatic condition in childhood. New therapies acting on specific targets have led to a significant improvement in the management of JIA. However, when medical therapy fails, total joint replacement represents the standard treatment to obtain pain relief and improve functional outcomes.Objectives:To describe early prosthesis in a JIA cohort followed in a tertiary referral hospital and to analyze any possible factors influencing implant survival, including surgical improvements over time.Methods:This is a monocentric retrospective cohort study; patients were enrolled from January 1992 to June 2019. All patients who underwent total joint replacement and were followed in our institute were included.Results:Eighty-five patients met the inclusion criteria, with a median follow-up of 17.2 years. The total number of replaced joints over 27 years was 198 (Figure 1). Clinical features and implant data are reported in Table 1.Table 1.Patients’ clinical features and implants dataTotal number of patients/ implants85/198JIA categories16 Oligoarticular37 Polyyarticular (7 RF postive)24 Systemic8 otherAge at first arthroplasty median (mean+SD; range)22.7 y (25.1±6.9;14.3-46.5)Disease duration at I arthroplasty median (mean+SD; range)17.4 y (18.6±8.1;1.88-43.7)Location of arthroplasty121 Hips66 Knees11 AnklesType of arthroplasty156 Regular6 Custom31 Hybrid implant5 unknownArthroplasty complications8 Intraoperative fracture3 Infections14 Aseptic mobilizationRevisions13 (9 hips, 4 knees)Figure 1.Numbers of arthroplasties performed for each year.We grouped all arthroplasties by the year of surgical procedure: before 2000 (group A; 28 implants), between 2000 and 2010 (group B; 94 implants) and after 2010 (group C; 76 implants).A significant difference of age at arthroplasty was found between group A and group B (21.93 y vs 26.82; p = 0.03) and between group A and group C (21.93 y vs 27.81 y; p = 0.00).The same upward trend was found with regard to disease duration before arthroplasty: a significant difference between group A and group B (16.98 y vs 21.66 y; p = 0.03) and between group A and group C (16.98 y vs 22.93 y; p= 0.00).The rate of implant survival at 5, 10 and 15 years were comparable (from 84% to 89%); whereas 50% of eligible implants lasted 20 years or more (Figure 2).Figure 2.Kaplan Meier survival curve of implants.The year of surgery was found to be significantly related to implant survival [Hazard Ratio (HR) 1.001, confidence interval (CI) 1.0001-1.0006; p< 0.001] as well as the presence of complications (HR 3.69, CI 1.82-7.48; p < 0.001) in multivariate analysis. Furthermore, prostheses of polyarticular RF-neg patients had more possibilities to last longer than those of S-JIA patients (HR 0.23, CI 0.09-0.53; p= 0.00) as well as implants of all polyarticular JIA (RF-pos and neg together) (p < 0.001).Conclusion:We observed an upward trend of both age at arthroplasty and disease duration before the first arthroplasty over time. JIA category, year of implants and the presence of complications significantly affected implant survival. Future researches should assess functional outcome and survival of implants according to medical therapy and different surgical approaches.Disclosure of Interests:None declared