Some tortuous logic goes on when asking these kinds of questions in medical and legal fields.
From personal experience:
The "can only ever occur in child abuse" metaphyseal fracture has also been observed in collagen disorders such as but not limited to Osteogenesis Imperfecta - there are a few relatively rare such conditions which cause bone fragility, and it can fluctuate depending on age, hormones etc. These conditions are still not very well understood.
When my sons case was ongoing, I discovered this. There were a few familial traits on both sides that sounded familiar. I got my solicitor to brooch the subject with all parties, and to possibly ask for permission for a skin biopsy for my son.
I was subsequently told that asking for said biopsy bolstered their suspicions that I had FII, and pushing for it could indicate further abuse on my part, as "on the balance of probabilities" the fractures were caused by abuse. In addition it was pointed out that children with medical conditions / disabilities are over-represented in child abuse cases.
Needless to say, I backed down, if I hadn't it would have added weight to their case I was arrogant and had a problem with authority. Which I didn't until "authority" bulldozed through my life and that of my sons.
My son is in his 30s and has had various joint and ligament issues throughout his life, but being a typical bloke, hasn't had them properly evaluated. I have selective hypermobility, with sacroiliac joint dysfunction and TMJ. Like my grandmother I can still put my hands flat on the floor from a standing position with straight legs.
Things like maternal Vitamin D syndrome and any possible impact of the effects of being my Dad beinh exposed to radiation were all dismissed as irrelevant, because metaphyseal fractures can only be caused by abuse in a baby, except actually..... that's not true.
And everything got circled back to my having a psychological problem with zero previous pathology.