Table 1.

Rates of one-year change in the femorotibial subregion with the greatest change in each knee (OV1), according to radiographic strata based on the OAI site and central readings

	Site readings						Central readings (Boston Univ.)
	n=	OV1 MC		FTJ MC		FTJ	n=	OV1 MC		FTJ MC		FTJ
		(µm)	CI 95%	(µm)	CI 95%	SRM		(µm)	CI 95%	(µm)	CI 95%	SRM
Healthy	112	−115	[−126; −105]	9	[−17;35]	0.07	101	−111	[−122; −100]	13	[−15;40]	0.09
KLG0	n.a.	-		-		-	93	−120	[−132; −108]	−12	[−35;10]	−0.11
KLG1	n.a.	-		-		-	101	−138	[−156; −120]	−33	[−67;2]	−0.19
KLG1 −JSN							61	−150	[−176; −125]	−55	[−101; −10]	−0.30
KLG1 +JSN							40	−119	[−143; −95]	1	[−50;52]	0.01
KLG2	308	−136	[−148; −125]	−20	[−37; −4]	−0.14	308	−160	[−176; −145]	−40	[−59; −20]	−0.23
KLG2 −JSN							98	−134	[−155; −115]	−25	[−54;5]	−0.16
KLG2 +JSN							210	−172	[−193; −152]	−46	[−72; −21]	−0.25
KLG3	299	−180	[−197; −164]	−69	[−91; −47]	−0.35	161	−203	[−225; −181]	−109	[−142; −77]	−0.52
KLG4	111	−201	[−222; −179]	−107	[−147; −67]	−0.50	61	−195	[−223; −166]	−84	[−137; −32]	−0.40

MC = mean change; CI 95% = [lower bound; upper bound] of the 95 confidence interval; SRM = standardized response mean = mean/SD change; KLG = Kellgren Lawrence grade of radiographic knee osteoarthritis; JSN = OARSI grade of (medial or lateral) radiographic joint space narrowing The numbers of site readings (n = 830) and central readings (n = 825) differ, because 6 cases were not classified in our previous paper on the site readings, but were here. In addition we found that from the healthy reference subjects only 101 had bilateral normal knees according to the central readings, explaining the total difference of n = 5.