Employee claims that he sustained tears of both his medial and lateral menisci of his right knee as a result of the work-related accident of September 13, 2000. Employer/insurer contend that those tears were degenerative and preexisted the work-related accident and that he sustained at most a temporary aggravation of his underlying degenerative osteoarthritis.
The employee must establish a causal connection between the accident and the claimed injuries. Davies v. Carter Carburetor Div., 429 S.W.2d 738 (Mo. 1968); McGrath v. Satellite Sprinkler Systems, 877 S.W.2d 704, 708 (Mo. App. 1994); Blankenship v. Columbia Sportswear, 875 S.W.2d 937, 942 (Mo. App. 1994); Fisher v. Archdiocese of St. Louis, 793 S.W.2d 195, 198 (Mo. App. 1990); Cox v. General Motors Corp., 691 S.W.2d 294 (Mo. App. 1985); Griggs v. A.B. Chance Company, 503 S.W.2d 697, 703 (Mo. App. 1974); Smith v. Terminal Transfer Company, 372 S.W.2d 659, 664 (Mo. App. 1963).
Amendments made to Section 287.020 .2 in 1993 require that the injury be "clearly work related" for it to be compensable. An injury is clearly work related "if work was a substantial factor in the cause of the resulting medical condition or disability. An injury is not compensable merely because work was a triggering or precipitating factor." The Supreme Court held in Kasl v. Bristol Care, Inc., 984 S.W.2d 852 (Mo. 1999) that the foregoing language overruled the holdings in Wynn v. Navajo Freight Lines, Inc., 654 S.W.2d 87 (Mo. 1983), Bone v. Daniel Hamm Drayage Company, 449 S.W.2d 169 (Mo. 1970), and many other cases which had allowed an injury to be compensable so long as it was "triggered or precipitated" by work. Injuries which are triggered or precipitated by work may nevertheless be compensable if the work is found to be a "substantial factor" in causing the injury. Kasl, supra at 853. A substantial factor does not have to be the primary or most significant causative factor. Bloss v. Plastic Enterprises, 32 S.W.3d 666, 671 (Mo. App. 2000); Cahall v. Cahall, 963 S.W.2d