Yeah! Fair warning, a lot of these papers use terms that the trans community no longer sees as appropriate. The language standards that the medical community uses are not the same as the trans community at large (I’m sure any trans person can tell you that!) so you’ll see terms like “transsexual” a lot.
The TL:DR from all of this: there is good evidence for skeletal changes during adult-initiated HRT. We know that these changes occur, but there isn’t a whole lot of literature about exactly what occurs. Many of these changes are minute and you may not see them in a living trans human, but are more discernible in a skeleton. We need to study this more.
A nice Sapiens article proposing how to improve trans visibility within bioarchaeology/forensics: https://www.sapiens.org/biology/transgender-intersex-forensic-anthropology/
Why it’s important to be able to talk about the bodily changes trans people go through as an anthropologist: https://journals.upress.ufl.edu/fa/article/view/1409
Studies of skeletal development in trans people taking hormones
Bone health as a part of trans healthcare: https://www.sciencedirect.com/science/article/pii/S8756328208007722?casa_token=Q0yyPHewOLIAAAAA:f6VKhwq1uVylVHkVZtAX6c-t3WADx8aaymmIWtiUeci1dqVuYAMH9OXn2ofmm4T1thKw5dkutuw
Hormones and bone density: https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1365-2265.1998.00396.x?casa_token=o2l0Y9Nt4qoAAAAA:tO3_aIeM4RqBE0xyNpC8Ns8d7vipYNFzsdMdaX5ZcodO9JShKdEkh-Vw-66FKJAW13bDG2pCCKKUYeyc
Interesting paper on pelvic morphology changes: https://asbmr.onlinelibrary.wiley.com/doi/full/10.1002/jbmr.4262
(this one’s about people who started HRT before 18, but it’s still a really interesting read even if it isn’t directly applicable to OP’s situation since they transitioned as an adult)
10 year bone health study in transgender individuals: https://asbmr.onlinelibrary.wiley.com/doi/full/10.1002/jbmr.3612
Not hormones, but stuff on how FFS affects skeletal remains:
https://pubmed.ncbi.nlm.nih.gov/32200173/
Ok, so we’ve identified that there ARE bone changes. How does muscle affect bone structure?
Explains the bone/muscle relationship in typical cis men and typical cis women: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3189615/ (Note: by typical, we mean that their hormones are generally within the range that’s expected for their chromosomal composition.)
Comparing trans men on long-term HRT to cis women of the same age and looking at bone mass, body composition, etc: https://academic.oup.com/jcem/article/97/7/2503/2834495
Facial masculinization of the female cranium with age: https://digital.library.txstate.edu/bitstream/handle/10877/5250/NAPARSTEK-THESIS-2014.pdf?sequence=1
Cranial remodeling with age: https://onlinelibrary.wiley.com/doi/full/10.1111/joa.12247
(The aging stuff is important because hormonal composition changes drastically with age and it’s a useful analogue, if not direct analogy.)
Some interesting reads on the relationship between sex hormones and cartilage
Estrogen and osteoarthritis (aka cartilage loss): https://www.mdpi.com/1422-0067/23/5/2767/htm
More sex hormones and osteoarthritis: https://faseb.onlinelibrary.wiley.com/doi/abs/10.1096/fasebj.27.1_supplement.1053.15
Generally speaking, HRT isn’t going to do too much to the cartilage. If you think your nose looks different, it’s probably because you’re seeing it in a new context since the fat deposits on your face rearrange themselves. They’re very close to the surface, after all.
Pelvic Scarring and how it’s not strictly based in pregnancy
Oops we found it in men: https://onlinelibrary.wiley.com/doi/10.1002/oa.2887
It’s also found in women who have never given birth: https://digital.library.txstate.edu/bitstream/handle/10877/8481/GALEA-THESIS-2018.pdf?sequence=1
Identifying transgender people within archaeology
https://miami.pure.elsevier.com/en/publications/the-fallacy-of-the-transgender-skeleton (good read on how human sexual dimorphism... isn’t. The spectrum of traits overlaps too much.)
surgery piece: https://www.sciencedirect.com/science/article/pii/S0379073820300827?casa_token=jy_vbV7_fXkAAAAA:nz2d-xCUT-JoYACam3CDliKmto1UFkB8-ft837QzSpjLZJ0uiH5DHNSH7M_fG_b5XWsln3yZZKk
As for the mechanism, it’s a combination of remodeling and changes in bone density. The bones don’t unfuse, so you’re basically stuck with the same structure, just with different sizes and densities. This is more notable in trans men- they can lose some height from bone density loss if they’re not careful. It’s usually not a lot and isn’t as noticeable in living people as it is in skeletons, because there’s a lot more tissue to you than just bone! It’s the same mechanism that happens in cis women with osteoporosis. Fortunately, most endocrinologists take that into consideration these days.
Right now, most of the research on skeletal changes is focusing on FFS because it’s much more visible and dramatic. There’s a lot of reasons we don’t really understand everything that HRT does to the skeleton- we know a lot of it, but not everything- and how any of it shows up in the archaeological record. One of them is that HRT is relatively new and we don’t have the representation in skeletal collections. Another is that most of our standards are written based on studying white people, and while you can’t truly identify race from a skeleton, you can associate a skeleton with certain genetic groups based on suites of traits. By only including white skeletons in a study, you miss out on a TON of variation.
I know this is a little disjointed, but I think it’ll help as a starting place for people interested in doing more research on the relationship between HRT and the human skeleton and how we can see some of these changes in the archaeological or forensic context!
