Which part of the spine is it that surgeons are reluctant to operate on?

Thoracic spine: This region is difficult to access unless the chest cavity is entered. With thoracotomy, incision into the chest, most common complication is irritation of the nerve between the ribs (intercostal) and pain. This can be worse than the pain being treated in the first place. So, surgery is often withheld unless pain is severe or spinal cord function is compromised.