Opinion ID: 1414232
Heading Depth: 1
Heading Rank: 5

Heading: the commission's apportionment of liability for garcia's disability between simplot and isif was correct.

Text: ISIF asserts that the Commission incorrectly apportioned the liability for Garcia's total permanent disability between Simplot and ISIF. We disagree. This Court has stated that the appropriate solution to the problem of apportioning the non-medical factors in an odd-lot case where [ISIF] is involved, is to prorate the non-medical portion of disability between the employer and [ISIF], in proportion to their respective percentages of responsibility for the physical impairment. Carey v. Clearwater County Road Department, 107 Idaho 109, 118, 686 P.2d 54, 63 (1984). Here, the Commission was faced with two pre-existing impairments and two work-related impairments. The Commission used the Carey formula in determining that Simplot was liable for 86.11 percent of Garcia's disability, with ISIF being liable for the balance. In arriving at the respective percentages of responsibility for physical impairment the Commission relied on the testimony of an orthopedic surgeon about combining impairment ratings. This physician combined the fifty-seven percent impairment rating for the loss of Garcia's arm with the twelve percent impairment rating for her injured knee by adding fifty-seven percent to twelve percent multiplied by forty-three percent. (57% + (12% X .43) = 62.16%, rounded to 62%) This forty-three percent is the difference between one hundred percent and the fifty-seven percent impairment due to the loss of her arm. Using the same approach, the impairment attributed to the combined effects of Garcia's back and her thumb was determined to be ten percent. (5% + (5% X .95) = 9.75%, rounded to 10%) The Commission added the sixty-two percent allocated to the arm and the knee to the ten percent attributed to the back and the thumb in arriving at a total of seventy-two percent permanent physical impairment. As provided in Carey, the Commission then assigned 62/72 (86.11%) of the twenty-eight percent disability attributed to non-medical factors to Simplot. The only part of this calculation that is novel as compared to the formula developed in Carey is the method of combining the impairment of the arm with that of the knee and the impairment of the back with that of the thumb. The orthopedic surgeon upon whose testimony the Commission relied for the method of combining these impairments testified that this method was the one used in the combined value tables published by the American Medical Association. The evaluation of the degree of impairment is a medical question. The Commission had substantial competent evidence to find that this is the appropriate method to combine the effects of multiple work-related injuries and to combine the effects of pre-existing permanent physical impairments. Using the impairment ratings produced by this method, the apportionment of the non-medical disability factors between Simplot and ISIF was correctly calculated as required by Carey.