Abstract
Patient-reported outcome measures (PROMs) are crucial in evaluating the success of
primary total knee arthroplasty (TKA). This study aimed to determine the individual
significance of each question of the Knee Osteoarthritis Outcome Score (KOOS) and
the Veterans RAND 12 (VR-12) Mental Composite Score (MCS) in achieving a Patient Acceptable
Symptom State (PASS). A prospectively collected cohort of 9,942 unilateral elective
TKAs was analyzed. Responses were collected for 17 KOOS questions (KOOS-Pain subscore,
KOOS-Physical Function Short form [PS], and KOOS-Joint related [JR]) and 6 MCS questions
preoperatively and 1-year postoperatively. Achievement of PASS was assessed through
a positive response to a binary satisfaction-related question. The association between
responses to questions and outcomes was examined via multivariable logistic regression
models. A poorer preoperative response to knee pain frequency (odds ratio [OR] = 0.86
[0.77–0.97], p = 0.017) and knee pain while sitting or lying (OR = 0.88 [0.79–0.99], p = 0.029) was independently associated with reduced odds of achieving PASS at 1-year
post-TKA. A more favorable preoperative response in knee pain during full knee straightening
was independently associated with an increased odds of PASS attainment (OR = 1.10
[1.01–1.19], p = 0.035). No other metric was independently associated with PASS attainment at 1
year. Individual KOOS questions evaluating knee pain frequency, knee pain while sitting
or lying down, and knee pain during full knee straightening were linked to patient
satisfaction 1 year following TKA. Patients experiencing frequent or persistent knee
pain at rest may represent those with more advanced joint disease or heightened pain
sensitivity, contributing to lower postoperative satisfaction. Conversely, patients
reporting minimal or no pain during specific movements, such as full knee straightening,
likely had a less severe baseline condition, making their postoperative expectations
more easily attainable, thereby leading to higher satisfaction.
Level of evidence III.
Keywords total knee arthroplasty - KOOS - PASS - TKA - Knee Injury and Osteoarthritis Outcome
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