BackgroundMany patients suffer from osteoarthritis in multiple joints, possibly resulting in multiple total joint arthroplasties (MJA). Primarily, we determined the cumulative incidence (Cin) of MJA in hip and knee joints up to 10 years. Secondly, we calculated the mean time between the first and subsequent joint arthroplasty, and evaluated the different MJA trajectories. Lastly, we compared patient characteristics and outcomes (functionality and pain) after surgery between MJA patients and single hip or knee arthroplasty (HA and KA) patients. MethodsPrimary index (first) HA or KA for osteoarthritis were extracted from the Dutch Arthroplasty Register. The 1, 2, 5, and 10-year Cin (including competing risk death) of MJA, mean time intervals, and MJA-trajectories were calculated and stratified for primary index HA or KA. Sex, preoperative age, and BMI were compared using ordinal logistic regression. Outcomes, measured preoperatively, 3, 6, and 12 months postoperatively (function: Hip Disability or Knee Injury and Osteoarthritis Outcome Score; Pain: Numerical Rating Scale), were compared using linear regression. ResultsA total of 140,406 HA-patients and 140,268 KA-patients were included. One, 2, 5, and 10-year Cin for a second arthroplasty were respectively 8.9% [95% confidence interval (CI): 8.7 to 9.0], 14.3% [95%CI: 14.1 to 14.5], 24.0% [95%CI: 23.7 to 24.2], and 32.7% [95%CI: 32.2 to 33.1] after index HA, and 9.5% [95%CI: 9.4 to 9.7], 16.0% [95%CI: 15.9 to 16.2], 26.4% [95%CI: 26.1 to 26.6], and 35.8% [95%CI: 35.4 to 36.3] after index KA. The 10-year Cin for > 2 arthroplasties were small in both the index HA and KA groups. Time-intervals from first to second, third, and fourth arthroplasty were 26 [95%CI: 26.1 to 26.7], 47 [95%CI: 46.4 to 48.4], and 58 [95%CI: 55.4 to 61.1] months after index HA, and 26 [95%CI: 25.9 to 26.3], 52 [95%CI: 50.8 to 52.7], and 61 [95%CI: 58.3 to 63.4] months after index KA. There were 83% of the second arthroplastiesplaced in the contralateral cognate joint (i.e., knee or hip). Differences in postoperative functionality and pain between MJAs and single HAs and KAs were small. ConclusionThe 10-year Cin showed that about one-third of patients received a second arthroplasty after approximately 2 years, with the majority in the contralateral cognate joint. Few patients received > 2 arthroplasties within 10 years. Being a women, having a higher BMI, and being younger increased the odds of MJA. Postoperative outcomes were slightly negatively affected by MJA.