BACKGROUND: As the number of primary total knee arthroplasties (TKAs) performed in the United States increases, policymakers have questioned whether the indications and timing of TKA have evolved so that surgery is offered earlier.

QUESTIONS/PURPOSES: We analyzed data from a US national TKA cohort to evaluate variation in surgeon selection criteria for elective unilateral TKA based on preoperative patient-reported pain and function scores.

METHODS: Preoperative SF-36 (Physical Component Summary [PCS]/physical function) scores and Knee Injury and Osteoarthritis Outcome Score (KOOS) (pain, activities of daily living/function) of 4900 patients undergoing elective unilateral TKA enrolled in this national database of prospectively followed patients from 22 states were evaluated. The 25(th), 50(th), and 75(th) percentile pain and function scores for patients cared for in 24 orthopaedic offices with 20 or more patients in the database were compared to assess whether consistent preoperative criteria are used in selecting patients undergoing TKA across settings.

RESULTS: The preoperative global function (PCS median, 32.6; national norm, 50; SD, 10) and knee-specific function (KOOS median, 51.5; maximum score, 100; SD, 17) percentile scores represented substantial patient disability, because both values approached 2 SDs below ideal. Consistency in patients across 24 surgeon offices, and more than 100 surgeons, was noted because site-specific medians varied from the national median by less than the minimum clinically important change.

CONCLUSIONS: These data suggest that despite the rapidly growing use of TKA, surgeons in the participating sites use consistent patient criteria in scheduling TKA. Today's patients report significant pain and disability, supporting the need for TKA.