. Author manuscript; available in PMC: 2022 Jul 21.

Published in final edited form as: J Bone Joint Surg Am. 2021 Jul 21;103(14):1328–1334. doi: 10.2106/JBJS.20.01586

TABLE IV.

Comparison of WOMAC Scores at 24 Months Between Low and High-Severity Heterotopic Ossification According to Brooker Classification

WOMAC Score^†	Adjusted Mean Difference in Score at 24 Months (99% CI)^*
WOMAC Score^†	Class I/II vs. Class III (N = 282)	Class I/II vs. Class III/IV (N = 287)
Total	11.40 (2.18 to 20.61)^‡	10.77 (1.70 to 16.63)^‡
Pain	2.15 (0.43 to 3.86)^‡	2.06 (0.38 to 3.75)^‡
Stiffness	0.46 (−0.39 to 1.30)	0.41 (−0.42 to 1.25)
Function	8.41 (1.48 to 15.36)^‡	7.95 (1.13 to 14.76)^‡

The mean difference was adjusted for baseline scores and obtained from the multilevel model.

^†

The minimal clinically important difference (MCID) was set at 7 points for the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

^‡

P < 0.01.