Minimally Invasive Transforaminal Lumbar Interbody Fusion: Meta-analysis of the Fusion Rates. What is the Optimal Graft Material?. Issue 6 (1st December 2017) - Parajón, Avelino; Alimi, Marjan; Navarro-Ramirez, Rodrigo; Christos, Paul; Torres-Campa, Jose M; Moriguchi, Yu; Lang, Gernot; Härtl, Roger