The original Lock Hospitals were as described for treating venereal diseases. However, they were much more than this and certainly not pleasant places for their patients, they were predominantly for treating women with venereal diseases.
Have just read an article about one in Glasgow, based on Rottenrow is described as akin to an internment camp. The origin of the name is from English "Loke" meaning home for lepers. Many of these women were fallen women working as prostitutes locally. But many were children of school age upwards.
It is believe a lot of these children were from Glasgows, Magdalene Asylum for fallen women. In one year around a dozen children were transferred from the asylum to the lock. A vile belief at this time was that men could cure themselves from venereal diseases by having intercourse with a young virgin.
Patients were kept in isolation with no contact. Treatment included the use of Mercury, which we all know is a poison. Many never had chance to return to normal life as they were seen as contaminated those that did returned to prostitution. Victorian cases of child abuse were rarely discussed and often just swept under the carpet. The Lock hospital in Rottenrow only closed for good in 1947. Many of the horrors that took place we will never know. I can imagine that the one in Birmingham had a similar horror story to tell.