The term 'crookback' was certainly used to describe the outward-bending spinal condition of kyphosis.
The Times Literary Supplement (2013)
She had profound and multiple learning difficulties and complex health needs as a result of a spinal condition.
Times, Sunday Times (2012)
A source said: 'The pal actually suffers from a spinal condition which means he has difficulty walking.
The Sun (2007)
I've got a rare spinal condition called syringomyelia.
Times, Sunday Times (2014)