'Distal radial metaepiphysis' means the part of the radius bone near the hand. The medullary canal is the space within the bone which contains bone marrow. It normally shows up as a somewhat clearer area than the surrounding bone since it is less dense than the bone.
In relation to bones, 'Sclerosis' means that there is a slow growing part of the bone in that area which is less dense than the surrounding bone. And an area of lucency means a clear area, and that that area contains minimal bony tissue.
Essentially, your Xray suggests that there could be a tumor or a growth of some kind in the bone which has lead to slow growing bony tissue near it and a secondary fracture of the bone.
Or it could mean that a fracture of the bone has lead to infection which is showing up as the areas of sclerosis and lucency.
I hope this helps.
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