The Benefit in Patient-Reported Outcomes After Total Knee Arthroplasty was Comparable Across Income Quartiles

Area of Science:

• Orthopedic Surgery
• Health Services Research
• Health Economics

Background:

• Socioeconomic status (SES) impact on patient-reported outcomes (PROMs) after total knee arthroplasty (TKA) is understudied.
• This study investigates how median ZIP code income levels affect PROMs post-TKA.

Purpose of the Study:

• To evaluate the influence of socioeconomic status, specifically median ZIP code income, on patient-reported outcomes following total knee arthroplasty.
• To determine if income level affects functional improvements and overall outcomes after TKA.

Main Methods:

• Retrospective cohort study of 1,267 patients undergoing primary, unilateral TKA (2017-2020).
• Patients stratified into four income quartiles based on US Census Bureau data for their home ZIP code.
• Collection of preoperative, 12-week, and one-year postoperative PROMs, alongside demographic data, length of stay, discharge disposition, readmissions, and revisions.

Main Results:

• Higher income quartiles showed significantly better Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOSJR) scores preoperatively and postoperatively (P < .001).
• No significant differences were observed in the *improvement* of KOOSJR scores from baseline to one year postoperatively across income quartiles.
• Length of stay, discharge disposition, readmission rates, and revision rates did not differ significantly between income groups.

Conclusions:

• While patients from lower income areas present with worse preoperative knee function and outcomes, they experience comparable functional gains after TKA.
• The study suggests that TKA provides similar therapeutic benefits across different socioeconomic strata, despite initial outcome disparities.
• Income level, as a proxy for SES, does not appear to limit the rehabilitative potential or overall success of TKA in terms of functional improvement.