In State ex rel. Wyo. Worker's Comp. Div. v. Roggenbuck, 938 P.2d 851, 853 (Wyo. 1997), the Court articulated that the causation determination required asking whether "it was the work effort that brought the need for surgery to a head and forced the surgery to be done at this time." Id. In Roggenbuck, an order awarding benefits to a claimant who had a history of back problems, two previous back surgeries and a permanent partial disability of sixty percent was upheld. Under the substantial evidence standard of review, we determined that comparisons of MRI reports showing a worsening of claimant's condition, the treating physicians' statements, and the worsening of pain experienced supported the agency's decision by showing that the work-related injury forced the need for immediate surgery. Roggenbuck, 938 P.2d at 854. The evidence presented in Roggenbuck squarely addressed the issue of whether the last injury was a material aggravation of the pre-existing condition causing the need for surgery. The Court upheld the hearing examiner's finding that, even with a lengthy history of back problems, the work effort "brought the need for surgery to a head." 938 P.2d at 853.