RESEARCH - Knee joint cartilage loss linked to bone marrow lesions

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Knee joint cartilage loss linked to bone marrow lesions

6/7/2006

By: Reuters Health

NEW YORK (Reuters Health), Jun 7 - Cartilage loss in the knee more often

than not is accompanied by bone marrow lesions, investigators with a

multicenter study report in the May issue of Arthritis and Rheumatism.

" Bone marrow lesions are invoked by repeated mechanical stress.... It is

unclear how much cartilage is lost before bone marrow lesions appear, " lead

investigator Dr. J. Hunter of Boston University told Reuters Health.

" It may be they occur before cartilage is lost. "

Dr. Hunter and colleagues performed magnetic resonance imaging (MRI) of the

knee at baseline and at 15- and 30-months follow-up in 217 patients with

primary knee osteoarthritis. Long-limb films were obtained at the 15-month

follow-up visit to assess limb alignment.

The researchers scored cartilage morphologic features of the medial and

lateral tibiofemoral joints at all three time points. Subchondral bone

marrow abnormalities of the medial and lateral aspects of the knee, defined

as poorly marginated areas of increased signal intensity in the marrow, were

scored at all three examinations.

Dr. Hunter reports that 57% of knees had bone marrow lesions at baseline.

Lesions either stayed the same or progressed in 99% of cases. High baseline

lesion score correlated with significant cartilage loss. Progression in

lesion size was closely linked to further loss of cartilage. Enlargement and

appearance of new bone marrow lesions occurred primarily in malaligned limbs

on the side of the malalignment.

" It is likely that the lesions will resolve with therapies to realign the

limb, like braces or osteotomies, but this is as yet unknown, " Dr. Hunter

speculated.

" What we know of the natural history is that once you have a bone marrow

lesion, it either stays the same in size or gets larger, " Dr. Hunter

continued. " There is still a long way to go in our understanding of these

lesions. "

He concludes in the journal these study findings " should prompt further work

evaluating the impact of therapeutic approaches that correct malalignment

... on the long-term structural change in knee osteoarthritis. "

By Martha Kerr

Last Updated: 2006-06-06 15:16:27 -0400 (Reuters Health)

Arthritis Rheum 2006;54:1529-1535.

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