SIF liability is premised on synergistic combination of the primary and pre-existing disabilities. Synergy is the concept in which the current PPD and the pre-existing PPD are found, in combination, to create a "substantially greater" disability, or an increased overall disability, and for which the employer should not be held liable. Section 287.220.1 RSMo (2000). The SIF is not responsible for subsequent deterioration, i.e. during the period 2012 and date of hearing. Lawrence v. Joplin R-VIII School Dist., 834 S.W.2d 789 (Mo.App. 1992).
A claimant must prove all the essential elements of his claim. Fischer v. Archdiocese of St. Louis, 793 S.W.2d 195, 198 (Mo.App. 1990). Dolen v. Bandera's Cafe, 800 S.W.2d 163, 164 (Mo.App. 1990). Dunn v. Treasurer, 272 S.W.3d 267, 272 (Mo.App. 2008). Regarding SIF benefits requirements under Section 287.220.1 RSMo (2000), the Supreme court held in 2013 that there must be at least one pre-existing permanent partial disability (PPD) that meets the statutory threshold in order to trigger SIF liability and, further, the threshold requirement does not apply to the last (or primary) injury. Treasurer v. Witte, 414 S.W.3d 455, 467 (Mo. banc 2013).
In addition, it has been held that in the determination of SIF liability "the level of permanent disability associated with an injury cannot be determined until it reaches the point of maximum medical improvement." A finding of when "no further progress may be attained" is essential in ascertaining when permanency occurs and, thus, when payment can be calculated. Hoven v. Treasurer, 414 S.W.3d 676, 678 (Mo.App. 2013), citing Cardwell v. Treasurer, 249 S.W.3d 902, 910 (Mo.App. 2008).
The SIF is liable for permanent total disability benefits when that disability is the result of a combination between the primary injury and the prior disabilities. The fact finder need not rely exclusively on expert testimony but may consider the whole record and any reasonable inferences that may be made from the evidentiary record. Carkeek v. Treasurer, 352 S.W.3d 604, 608 (Mo.App. 2011).