Total knee arthroplasty (TKA) is an effective treatment to relieve pain and restore function in patients with advanced knee osteoarthritis. TKA utilization is growing rapidly, and the appropriateness of current TKA use is of great interest. We examined patient-reported preoperative pain and function profiles to understand symptom severity at the time of TKA decision.
Data were from the Function and Outcomes Research for Comparative Effectiveness in Total Joint Replacement. We included patients undergoing primary, unilateral TKAs between 2011 and 2014 for osteoarthritis and had data on the Knee Injury and Osteoarthritis Outcome Score (KOOS) pain and Short-Form 36-item Physical Component Summary (PCS) score. We compared patient profiles across groupings by symptoms: (1) little pain and high function (KOOS ≥70, PCS ≥40); (2) little pain but poor function (KOOS ≥70, PCS <40); (3) high pain but high function (KOOS <70, PCS ≥40); and (4) high pain and poor function (KOOS <70, PCS <40).
Of 6936 patients, 77% had high pain and poor function (group 4), 19% had high pain "or" poor function (groups 2-3), and 5% had little pain and high function before TKA (group 1). In group 1, 86% were constantly aware of their knee problem, 48% reported pain daily yet 5% experienced severe or extreme pain on stairs, and 1% pain in bed. Over half had a lot of limitations in vigorous activities. Compared with group 4, group 1 were older, less obese, more educated, and included more men and people reporting being healthy, less disabled, and happy (P < .05 for all).
Most patients undergoing TKAs had significant pain and/or poor function. Our results provide critical information given the current debate of potentially inappropriate TKA utilization in the United States.