1. Is trabecular (spongy) bone mass the same as bone matrix?
Trabecular bone is a gross/microscopic description of the bone. It's where - as the name suggests - trabeculae are found. Bone matrix, on the other hand, is a microscopic/molecular description - it's the hardened partion of the bone containing both inorganic (e.g. hydroxyapatite crystals) and organic (e.g. type I collagen) parts.
So both trabecular and cortical bone contains bone matrix. Since osteoporosis is the loss of bone matrix, both trabecular and cortical bone will be affected.
2. I'm confused by the discrepancy between normal mineralization (according to FA) and loss in mineralization (according to Goljan). Can someone explain?
Actually, Goljan says "Loss of both organic bone matrix and minerals". So, you may say if there's a loss of minerals, that means there's a loss in mineralization, right? The answer is no - they're two different concepts.
Loss of minerals is simple - It means there's a demonstrable absence of minerals in the bone. Loss of mineralization means that something prevents from normal formation of bone matrix. For example, if there's defect in the gene coding COL1A1 (osteogenesis imperfecta), there'll be impairment of bone mineralization (since type I collagen is a part of organic bone matrix).
Think of it like this: If I were to take DEXA scans of the lumbar vertebra and hip joint and found a T score of <-2,5, can I conclusively say that there's a loss of minerals? Sure. But can I conclusively say that there's a problem with mineralization? No.
Or another example: Loss of minerals means that your bank account is empty. Loss of mineralization means that your income can no longer make your bank account afloat. Hey, if you can't get any paychecks, your bank account will drain eventually. But there are other ways to empty a bank account as well (like an accountant stealing money from your account every month).
Hope this helps.
