The permanent nature of an injury must be shown to a reasonable certainty, and such proof may not rest on surmise and speculation. See *Farmer-Cummings v. Future Foam*, 44 S.W.3d 830, 834 (Mo. App. 2001); *Sanders by Carmean v. St. Clair Corp.*, 943 S.W.2d 12, 16 (Mo. App. 1997).
We have found, based on Dr. Lichtenfeld's uncontested testimony, that employee is not at maximum medical improvement for the primary work injury. It follows that we cannot determine the nature or extent of any permanent disability resulting from the primary injury. As the court explained in *Cardwell v. Treasurer of Mo.*, 249 S.W.3d 902, 910 (Mo. App. 2008): "One cannot determine the level of permanent disability associated with an injury until it reaches a point where it will no longer improve with medical treatment. ... Although the term maximum medical improvement is not included in the statute, the issue of whether any further medical progress can be reached is essential in determining when a disability becomes permanent ..." Here, the essential issue of whether further medical progress may be reached has not been resolved by the proof put forward by employee. The only doctor to testify opined that employee is not at maximum medical improvement and that he would benefit from further evaluation. The notes from Dr. Schlafly and employee's own testimony support the proposition that employee remains in need of further treatment for the primary injuries. Employee did not testify as to whether he intends further significant treatment, and his only mention of further surgery is inconclusive.
Simply put, we don't know whether employee's medical condition or any disability referable to the primary injury are permanent. As a result, any determination of permanent partial disability referable to the primary injury would necessarily hinge upon surmise and speculation.
In light of the foregoing considerations, we conclude that employee has failed to show that he sustained a "subsequent compensable injury" resulting in permanent partial disability for purposes of § 287.220.1.