Well, hypermobility isn't the same as contortion. Contortion is just stretching, a lot, so you train yourself to stretch far.

From what I understand hypermobility is a joint issue which can lead to arthritis due to damage.

Contortionists don't need to be hypermobile, anyone can learn contortion as long as they don't have some issue that stops them from stretching. It is just years and years of practice that leads to the extreme flexibility.

What my dear friend Wiki says about hypermobility:

People with hypermobility syndrome may develop other conditions caused by their unstable joints. These conditions include:

*Joint instability causing frequent sprains, tendinitis, or bursitis when doing activities that would not affect the normal individual

*Early-onset osteoarthritis

*Subluxations or dislocations, especially in the shoulder

*Knee pain

*Back pain, prolapsed discs or spondylolisthesis

*Joints that make clicking noises

*Susceptibility to whiplash

*Temporomandibular Joint Syndrome also known as TMJ

*Increased nerve compression disorders (e.g. carpal tunnel syndrome)

*The ability of Finger Locking

*Do not respond well to normal doses of anaesthetic or pain medication

*"Growing pains" as described in children in late afternoon or night

Considering contortion is a circus act, the symptoms of hypermobility sound like they could be a serious disadvantage if someone had it and wanted to actually perform regularly.