Complications; as per conventional implants, more volume, more interventions does mean more potential problems.
Even with exercise, in time, your back might give out.
Your skin might reach its elastic limit.
Blood flow might thin out over time ... so, tissue necrosis (!)
There’s a wave of MRSA that has happened in many PS clinics & hospitals.
The string might also create a toxic reaction, that can go a variety of ways.
If you’re lucky, none of that happens.
Best choose a surgeon that is available & nearby. (Always good to check his track record too)