My surgeon said there would be extreme pain but I had NO idea just how bad the pain would be. It is the spreading of the ribs alright. That was 25 years ago. I still have achiness especially stormy weather. It isn't just the spreading of the ribs but it also pinches the nerves around the ribs. I grew up on dairy farm and been hurt around big animals and machinery and I've had appendix and hysterectomy surgery but that pain was a Sunday picnic in the park compared to thoracotomy.