View full size photo »

According to Heavy.com, Shane Carwin did not undergo knee surgery,

Heavy.com has learned that, contrary to recent reports, Shane Carwin did not recently undergo knee surgery. We spoke with sources close to Carwin's camp, who indicated that the number-one contender for the heavyweight title is simply rehabbing his knee and did not undergo any surgical procedures.

Recently published reports indicated that Carwin had undergone knee surgery to fix an ailing knee while waiting for Brock Lesnar to recuperate from his bout with mononucleosis. Carwin did undergo an MRI, which came back as a grade II MCL strain. Carwin was told not to do any grappling for three weeks, which made him unavailable for UFC 108. He is available to fight on any card after UFC 108, but with Brock Lesnar out for an unknown amount of time, Carwin remains in limbo.

Initially it was believed that Carwin underwent knee surgery when Lesnar became unavailable for UFC 108. With news of Lesnar's deteriorating health it appears that the UFC may have to move on without Brock and Carwin's availability will be instrumental in the UFC's future plans for the heavyweight division. 

The obvious solution is an interim heavyweight title. Cain Velasquez and Shane Carwin are prime contenders to fight for an interim belt as Antonio Rodrigo Nogueira is out with a staph infection.

Ironically these two fighters were initially scheduled to fight at UFC 104 in a number one contender bout but Carwin was then granted a title shot at UFC 106 and Cain fought and defeated former IFL standout Ben Rothwell at 104.