red marrow reconversion

Recently I had an MRI for my right knee. It showed "tears of the posterior horn over the medial meniscuc, changes of grade 3 chondromalacia over the medial patellar facet/patellar apex.... and changes of red marrow reconversion". What does all this mean, especially the red marrow part?" Thankyou

[Sumer K Sethi, MD]

Normal bone marrow has yellow marrow and red marrow. Yellow marrow is more of fat and red marrow is more of haematopoitic tissue. in infants marrow is predominantly hematopoietic with the exception of epiphyses & apophyses, which are predominantly fatty throughout life. with skeletal growth, red marrow is gradually replaced by fat. red marrow persists longer in the vertebrae, pelvic bones, sternum, & proximal ends of the long tubular bones, during normal marrow conversion, residual islands of red marrow may subsist in the yellow marrow, as may fatty foci in red marrow.islands of red marrow residue may be a normal variant especially in obese women, cigarette smokers, marathon runners.  It may be pathological some times in cases of hemolytic processes / anemia/hypoxia.