Abstract Background The purpose of this study was to compare pre- and post-surgical healthcare costs in commercially insured total joint arthroplasty (TJA) patients with osteoarthritis (OA) in the United States (U.S.). Methods Using a large healthcare claims database, we identified patients over age 39 with hip or knee OA who underwent unilateral primary TJA (hip or knee) between 1/1/2006 and 9/30/2007. Utilization of healthcare services and costs were aggregated into three periods: 12 months "pre-surgery," 91 days "peri-operative," and 3 to 15 month "follow-up," Mean total pre-surgery costs were compared with follow-up costs using Wilcoxon signed-rank test. Results 14,912 patients met inclusion criteria for the study. The mean total number of outpatient visits declined from pre-surgery to follow-up (18.0 visits vs 17.1), while the percentage of patients hospitalized increased (from 7.5% to 9.8%) (both p < 0.01). Mean total costs during the follow-up period were 18% higher than during pre-surgery ($11,043 vs. $9,632, p < 0.01), largely due to an increase in the costs of inpatient care associated with hospital readmissions ($3,300 vs. $1,817, p < 0.01). Pharmacotherapy costs were similar for both periods ($2013 [follow-up] vs. $1922 [pre-surgery], p = 0.33); outpatient care costs were slightly lower in the follow-up period ($4338 vs. $4571, p < 0.01). Mean total costs for the peri-operative period were $36,553. Conclusions Mean total utilization of outpatient healthcare services declined slightly in the first year following TJA (exclusive of the peri-operative period), while mean total healthcare costs increased during the same time period, largely due to increased costs associated with hospital readmissions. Further study is necessary to determine whether healthcare costs decrease in subsequent years.

Background: Debilitating pain associated with knee osteoarthritis (OA) often leads patients to seek and complete total knee arthroplasty (TKA). To date, few studies have evaluated the relation of functional impairment to the risk of TKA, despite the fact that OA is associated with functional impairment. Questions/purposes: The purpose of our study was to (1) evaluate whether function as measured by WOMAC physical function subscale was associated with undergoing TKA; and (2) whether any such association varied by sex. Methods: The National Institutes of Health-funded Multicenter Osteoarthritis Study (MOST) is an observational cohort study of persons aged 50 to 79 years with or at high risk of symptomatic knee OA who were recruited from the community. All eligible subjects with complete data were included in this analysis. Our study population sample consisted of 2946 patients with 5796 knees; 1776 (60%) of patients were women. We performed a repeated-measures analysis using baseline WOMAC physical function score to predict the risk of TKA from baseline to 30 months and WOMAC score at 30 months to predict risk of incident TKA from 30 months to 60 months. We used generalized estimating equations to account for the correlation between two knees within an individual and across the two periods. We calculated relative risk (RR) of TKA over 30 months by WOMAC function using a score of 0 to 5 as the referent in multiple binomial regressions with log link. Results: Those with the greatest functional impairment (WOMAC scores 40–68; 62 TKAs in 462 knee periods) had 15.5 times (95% confidence interval [CI], 7.6–31.8; p < 0.001) the risk of undergoing TKA over 30 months compared with the referent group (12 TKAs in 3604 knee periods), adjusting for basic covariates, and 5.9 times (95% CI, 2.8–12.5; p < 0.001) the risk after further adjusting for knee pain severity. At every level of functional limitation, the RR for TKA for women was higher than for men, but interaction with sex did not reach significance after adjustment for covariates including ipsilateral pain (p = 0.138). Conclusions: Baseline physical function appears to be an important element in patients considering TKA. Future studies should examine whether interventions to improve function can reduce the need for TKA. Level of Evidence: Level III, observational cohort study.