MMAFighting.com first reported the injury and several outlets have since confirmed the news.
Kyle is 2-2 under the Strikeforce banner, holding a win over another former titleholder — Rafael “Feijao” Cavalcante. His two losses have come against heavyweights Antonio Silva and Fabricio Werdum.
Mousasi hasn’t competed for Strikeforce since his April 2010 loss to Muhammed “King Mo” Lawal. Following they loss, he competed two more times last year for DREAM in Japan, defeating Tatsuya Mizuno and Jake O’Brien.