TABLE IV.

Patient-Reported Outcome Scores at Baseline and 2 Years Postoperatively, Stratified by Preoperative Kellgren-Lawrence (KL) Score^*

Patient-Reported Outcome	KL <4	KL = 4	Difference Between Groups (95% CI)
WOMAC pain
Baseline	43.0 (18.0)	36.9 (16.4)	6.1 (1.6, 10.6)
2 yr	9.2 (15.5)	6.2 (11.1)	3.0 (−0.5, 6.4)
Change from baseline to 2 yr	−33.8 (16.2)	−30.7 (17.1)	−3.1 (−7.6, 1.3)
KOOS ADL
Baseline	57.8 (16.8)	61.8 (16.2)	−4.0 (−8.4, 0.3)
2 yr	88.5 (17.4)	91.6 (11.6)	−3.1 (−6.8, 0.6)
Change from baseline to 2 yr	30.7 (16.9)	29.8 (17.9)	0.9 (−3.7, 5.6)

^*Patient-reported outcome scores are reported separately for individuals with milder radiographic arthritis (KL <4) and more severe radiographic arthritis (KL = 4). Continuous variables are given as the mean, with the standard deviation in parentheses. “Difference between groups” indicates the difference in mean outcome scores between KL categories as assessed by t test or Wilcoxon rank-sum test, as appropriate. WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) pain is scaled 0 to 100, with 100 being the worst pain. KOOS ADL (Knee injury and Osteoarthritis Outcome Score activities of daily living) is scaled 0 to 100, with 100 being the best function. CI = confidence interval. Bold indicates a significant association.