Time trends in the characteristics of patients undergoing primary total knee arthroplasty

Abstract

Objective: To study the time trends in sociodemographic and clinical characteristics of patients undergoing primary total knee arthroplasty (TKA).

Methods: We used the Mayo Clinic Total Joint Registry to examine the time trends in patient demographics (body mass index [BMI] and age), underlying diagnosis, medical (Deyo-Charlson Index) and psychological comorbidity (anxiety and depression), and examination findings of primary TKA patients from 1993-2005. We used the chi-square test and analysis of variance.

Results: In total, 7,229 patients constituted the primary TKA cohort; 55% were women. The mean age decreased by 1.3 years (69.3 to 68.0 years), mean BMI increased by 1.7 kg/m(2) (30.1 to 31.8 kg/m(2) ), and mean Deyo-Charlson Index increased by 36% (1.1 to 1.5) over the 13-year study period (P ≤ 0.001 for all). Compared with 1993-1995, significantly more patients (by 2-3 times) in 2002-2005 had a BMI ≥40 kg/m(2) (4.8% versus 10.6%), age <50 years (2.9% versus 5.2%), Deyo-Charlson Index of ≥3 (12% versus 22.3%), depression (4.1% versus 14.8%), and anxiety (4.1% versus 8.9%), and significantly fewer patients had an underlying diagnosis of rheumatoid/inflammatory arthritis (6.4% versus 1.5%; P < 0.001 for all). Compared with 1993-1995, significant reductions were noted in 2002-2005 for the physical examination findings of anteroposterior knee instability, mediolateral knee instability, moderate to severe knee synovitis, severe limp, fair or poor muscle strength, and absent peripheral pulses (P ≤ 0.001 for all).

Conclusion: In this large US total joint registry study, we found significant time trends in patient characteristics, diagnosis, comorbidity, and knee/extremity examination findings in primary TKA patients over 13 years. These secular trends should be taken into account when comparing outcomes over time and in policy-making decisions.

Conflict of interest statement

Financial Conflict: There are no financial conflicts related directly to this study. J.A.S. has received research and travel grants from Takeda and Savient; and consultant fees from Savient, Takeda, Regeneron and Allergan. D.G.L. has received royalties/speaker fees from Zimmer, Orthosonic and Osteotech, has been a paid consultant and owns stock in Pipeline Biomedical and his institution has received research funds from DePuy, Stryker, Biomet and Zimmer.

Copyright © 2014 by the American College of Rheumatology.