I'm sure if the bone healed properly it could be removed. Do you not have free health care in the uk? The reason you get autoimmune from the screws is because bacteria grow around the screw and causes a immune response.
The bacteria also grow a biofilm to protect it the immune system. That is why Antibiotics are unlikely to work. If you can not get them removed try ozone iv treatment and high dose vitamin c IV treatment.
Both will kill the bacteria causing the autoimmune