Claimant appeals from the Workers’ Compensation Board’s denial of his claim. The issue is whether claimant proved that his back strain arose out of and in the course of his employment.1 We conclude that he did not and thus affirm.
Claimant was not able to identify the precise source of his back problems. On August 14,1978 he jarred his back and neck at work when he backed a truck into something projecting above an unfinished road surface. He was free of back symptoms for about the next two weeks.
Dining the balance of August and early September claimant, a cement mason, was constructing curbs. This required that he bend over a substantial percentage of the time and do some heavy lifting. He began to experience pain in his back and neck that worsened as the job progressed. Claimant sought medical attention in mid-September.
Claimant does not contend that the August 14 incident caused his back problems. Rather, he argues that the constant bending and lifting while working on curbs over the following month caused his back strain.
None of the medical evidence supports claimant’s theory. A five-sentence letter from Dr. Johnson just reports that claimant was examined three times; it does not state a diagnosis or express an opinion on the cause of claimant’s back problem. A letter from Dr. Struckman states:
"* * * [Claimant] is certain that this pain is [job-related] because everybody else on the job has a sore back. I am not so sure it is job-related. * * *
*282"* * * * *
"* * * without a specific history of iAjury, I think it would be difficult to establish a definite etiologic cause for his pain. * * *”
Dr. Raaf reported:
"Neurological examination fails to reveal any objective evidence of injury to the central or peripheral nervous system. I think he sustained a mild cervical, dorsal, and lumbar strain. * * *”
Dr. Raaf did not express any opinion on the cause of claimant’s back strain.
Some cases have suggested or held that medical evidence is essential to establish that a given disability was caused by a claimant’s employment.2 Other cases have suggested or held that such medical evidence is not necessarily essential.3 There are two ways to interpret these cases. First, they might establish firm rules of law. Second, they may merely explain the reasoning of courts, on de novo review, as to what was found persuasive or unpersuasive in the individual case.
The second possibility is sufficient to dispose of this case. Given the absence of a specific injury, Dr. Stuck-man’s blunt skepticism, Dr. Johnson’s silence, and Dr. Raaf’s silence, we are not persuaded that claimant’s ordinary work activities in August and September of 1978 caused his back strain.
Affirmed.
Claimant correctly points out that some language in the referee’s decision, which was adopted by the Board, is inconsistent with Hutcheson v. Weyerhaeuser, 288 Or 51, 602 P2d 268 (1979). We are, however, reviewing de novo the result reached below, not the reasoning used.
Orr v. Industrial Acc. Com., 217 Or 249, 342 P2d 136 (1959); Landauer v. State Inc. Acc. Com., 175 Or 418, 154 P2d 189 (1944); Hart v. SAIF, 31 Or App 181, 570 P2d 92 (1977); Foley v. SAIF, 29 Or App 151, 562 P2d 593 (1977).
Uris v. Compensation Department, 247 Or 420, 427 P2d 753, 430 P2d 861 (1967); Mueller v. SAIF, 33 Or App 31, 575 P2d 673 (1978); Volk v. Birdseye Division, 16 Or App 349, 518 P2d 672, rev den (1974).