Familial, structural, and environmental correlates of MRI-defined bone marrow lesions: a sibpair study
1 Menzies Research Institute, University of Tasmania, Level 2, Surrey House, 199 Macquarie Street, Hobart, TAS 7000, Australia
2 Twin Research and Genetic Epidemiology Unit, St Thomas's Hospital, Lambeth Palace Road, London, SE1 7EH, UK
3 The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC 3050, Australia
4 Department of Epidemiology and Preventive Medicine, Monash University Medical School, 89 Commercial Road, Alfred Hospital, Melbourne, VIC 3004, Australia
Arthritis Research & Therapy 2006, 8:R137 doi:10.1186/ar2027Published: 3 August 2006
The aim of this study was to estimate the heritability and describe the correlates of bone marrow lesions in knee subchondral bone. A sibpair design was used. T2- and T1-weighted MRI scans were performed on the right knee to assess bone marrow lesions at lateral tibia and femora and medial tibia and femora, as well as chondral defects. A radiograph was taken on the same knee and scored for individual features of osteoarthritis (radiographic osteoarthritis; ROA) and alignment. Other variables measured included height, weight, knee pain, and lower-limb muscle strength. Heritability was estimated with the program SOLAR (Sequential Oligogenetic Linkage Analysis Routines). A total of 115 siblings (60 females and 55 males) from 48 families, representing 95 sib pairs, took part. The adjusted heritability estimates were 53 ± 28% (mean ± SEM; p = 0.03) and 65 ± 32% (p = 0.03) for severity of bone marrow lesions at lateral and medial compartments, respectively. The estimates were reduced by 8 to 9% after adjustment for chondral defects and ROA (but not alignment). The adjusted heritability estimate was 99% for prevalent bone marrow lesions at both lateral and medial compartments. Both lateral and medial bone marrow lesions were significantly correlated with age, chondral defects, and ROA of the knee (all p < 0.05). Medial bone marrow lesions were also more common in males and were correlated with body mass index (BMI). Thus, bone marrow lesions have a significant genetic component. They commonly coexist with chondral defects and ROA but only share common genetic mechanisms to a limited degree. They are also more common with increasing age, male sex, and increasing BMI.