Familial, structural, and environmental correlates of MRI-defined bone marrow lesions: a sibpair study

Table 2 Heritability estimates for the prevalence and severity of bone marrow lesions

Parameter	Step 1		Step 2		Step 3		Step 4
	h ²	p	h ²	p	h ²	p	h ²	p
Lateral compartment
Severity of BML	60 ± 26	0.01	53 ± 28	0.03	45 ± 28	0.06	45 ± 28	0.06
Prevalent BML	100	<0.01	100	0.02	99	0.04	99	0.05
Medial compartment
Severity of BML	20 ± 25	0.21	65 ± 32	0.03	46 ± 31	0.07	56 ± 31	0.04
Prevalent BML	100	0.01	100	<0.01	99	0.02	99	0.01

Where errors are shown, values are means ± SD. BML, bone marrow lesions; h², heritability estimate. In step 1, h² was estimated after adjustment for age, sex, height and weight; in step 2, further adjustment was made for muscle strength, knee pain and knee alignment; in step 3, further adjustment was made for chondral defects; in step 4, further adjustment was made for radiographic osteoarthritis.

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