
69 Wn.2d 893 (1966)
421 P.2d 362
ELMER SAYLER, Respondent,
v.
THE DEPARTMENT OF LABOR AND INDUSTRIES et al., Appellants[*]
No. 38292.
The Supreme Court of Washington, Department Two.
December 8, 1966.
*894 The Attorney General and Gayle Barry, Assistant, and George J. Tichy, for appellants.
Fredrickson, Maxey & Bell, for respondent.
WEAVER, J.
Claimant has received a series of awards for an industrial injury to his ankle, which injury occurred June 24, 1954, during his employment at Long Lake Lumber Company. The more than 10-year procedural history of his claim is set forth in the appendix.
Claimant seeks an additional award for permanent partial disability of 75 per cent of the maximum allowable for unspecified injuries for a back condition allegedly resulting from his ankle injury of June 24, 1954. Claim for the back condition was first made March 5, 1962.
Claimant was born with congenital club feet. During childhood claimant had surgery on the heel cord tendons of his feet and a "fusion or a stiffening of the calcaneal-cuboid and tarsal-scaphoid joints" of the right foot. April 14, 1955, in the course of treatment after his industrial accident of June 24, 1954, the ankle joint of his right leg was fused and made fixed.
The trial court found that claimant "had a defect in the bony structure of the back termed spondylolisthesis,"[1] which condition was dormant before his ankle injury. One medical expert testified that a vertebra having slipped, the "back is then held entirely by muscles or ligaments rather than by bony support." Another medical expert defined the condition as "a congenital defect in the spine"; and still another testified that the condition was possibly due to a severe trauma.
*895 On several occasions claimant testified that he had not experienced any back trouble prior to June 24, 1954, the date his ankle was injured. At subsequent hearings claimant finally admitted that he had sustained an industrial injury (back strain) on February 3, 1954, while employed by the Ross Tire Company in Spokane; that he filed a claim with the Department of Labor and Industries; that he was treated by Dr. Joseph Finney for an injury to his back occurring 4 1/2 months prior to the injury to his ankle. The accident was described in this way: "Putting a truck tire on the back of a truck, slipped, tire falling on patient."
August 20, 1964, the Board of Industrial Insurance Appeals found that claimant's back condition did not result from his ankle injury and denied recovery. This finding affirmed the February 14, 1962 order of the Supervisor of Industrial Insurance.
The trial court, sitting without a jury, reversed, entered findings of fact, conclusions of law and judgment directing defendant,
Department of Labor and Industries, to reassume jurisdiction of plaintiff's claim and to accept responsibility for plaintiff's back condition and complaints and to provide treatment therefor, together with such other and further relief as may be indicated or authorized....
The trial court's conclusion is, of course, contrary to the finding of the hearing examiner of the Board of Industrial Insurance Appeals
that any back complaints the claimant was suffering from on or about the closing date were not the result of any condition resulting from the 1954 industrial injury.
This appeal is by the Department of Labor and Industries and by Long Lake Lumber Company, claimant's employer at the time of the industrial injury to claimant's ankle. The appeal raises one issue: Is there substantial evidence to support the trial court's determination that claimant's back condition was either caused or made symptomatic as the result of his right ankle injury of June 24, 1954?
Although there is no litmus paper test which resolves *896 the issue, our former decisions have laid down certain guidelines.
[1] RCW 51.52.115 provides that the findings and decision of the Board of Industrial Insurance Appeals are prima facie correct; the burden of proof is upon the party attacking them; the appellant must produce sufficient substantial facts, as distinguished from a mere scintilla of evidence, to make a case for the trier of fact. Sawyer v. Department of Labor & Indus., 48 Wn.2d 761, 769, 296 P.2d 706 (1956), and cases cited.
[2] A claimant must establish by the testimony of competent medical experts that there is a probable (as distinguished from a possible) causal relationship between an industrial injury and a subsequent physical condition. Sawyer v. Department of Labor & Indus., supra; Parr v. Department of Labor & Indus., 46 Wn.2d 144, 278 P.2d 666 (1955). Specifically, in the instant case, the burden is upon claimant to show by the testimony of medical experts that his back condition, for which he first made claim in 1962, was probably caused by his 1954 ankle injury.
[3] An expert medical opinion concerning causal relationship between an industrial injury and a subsequent disability must be based upon full knowledge of all material facts. An expert opinion given in response to a hypothetical question is without probative value if it is based upon the existence of conditions or facts not included in the question or established by the evidence and not necessarily inferable therefrom. Berndt v. Department of Labor & Indus., 44 Wn.2d 138, 265 P.2d 1037 (1954); Cyr v. Department of Labor & Indus., 47 Wn.2d 92, 286 P.2d 1038 (1955). The same rule applies to medical opinions based upon incomplete or inaccurate medical history. Parr v. Department of Labor & Indus., 46 Wn.2d 144, 278 P.2d 666 (1955). If the doctor has not been advised of a vital element bearing upon causal relationship, his conclusion or opinion does not have sufficient probative value to support an award. This court said in Parr, supra:
A claimant does not prove such causal relationship by the testimony of a doctor whose information is shown by *897 the claimant's own testimony to be neither complete nor accurate.
We turn now to the record before us.
Dr. Leonard A. Dwinnell, claimant's medical witness, testified that "... at the time I examined him in 1961 he stated that he did not have back pain either prior to the accident of 1954 or immediately after the accident of 1954 [the ankle injury]." His original diagnosis that the ankle injury caused the back injury was based on the fact that there was no prior back trouble. The doctor admitted that had he known of the prior back trouble, he would have changed his diagnosis because the earlier back injury could have "precipitated or caused" the back condition. Finally, Dr. Dwinnell, after knowing all the facts, was forced to conclude that he was not sure whether claimant's faulty gait did or did not cause the latest back pain.
Dr. Robert W. Maris also had been told by the claimant that he had no back trouble prior to his ankle injury. Dr. Maris felt that if in fact claimant had a prior back injury, his present back condition was more likely caused by the prior back injury than by the ankle injury. He concludes that the ankle injury was unrelated to the back injury.
The prior back injury of February 1954 is a material omission from the medical history.
Considered in its entirety, the record does not support the conclusion that there is a causal relationship between claimant's industrial injury and his present back condition.
The judgment is reversed and the case remanded with directions to dismiss claimant's appeal.
ROSELLINI, C.J., DONWORTH and FINLEY, JJ., and BARNETT, J. Pro Tem., concur.

APPENDIX


  Dec. 20, 1954  Supervisor closed claim with a permanent partial
                 disability award of 50% of amputation value of
                 right leg below the knee.
  Feb. 25, 1955  Application to reopen for aggravation.
  Apr.  6, 1955  Reopened for authorized treatment.
*898  Mar.  9, 1956  Claim closed without additional permanent partial
                 disability award.
  Mar. 26, 1956  Appeal to Board of Industrial Insurance Appeals.
  Apr. 17, 1956  Supervisor entered order holding order of Mar. 9,
                 1956 in abeyance pending investigation.
  Apr. 19, 1956  Board denied appeal.
  May  22, 1956  Supervisor entered order adhering to provisions of
                 March 9, 1956 order.
  June  5, 1956  Claimant appealed to Board.
  Nov. 30, 1956  Board entered an order directing Department to pay
                 claimant additional 10% permanent partial
                 disability of amputation value of right leg below
                 the knee.
  Dec. 12, 1956  Supervisor complied with Board order and closed
                 claim.
  Feb.  9, 1960  Application to reopen claim for aggravation.
  May  23, 1960  Supervisor's order reopening claim to pay 10%
                 additional permanent disability award of
                 amputation value of right leg below knee and
                 closing claim.
  June  6, 1960  Order of May 23, 1960 appealed.
  June 16, 1960  Appeal granted.
  Apr. 28, 1961  Board order remanding claim to Department for
                 treatment and other indicated action.
  May  16, 1961  Supervisor reopened claim effective May 24, 1960.
  Feb. 14, 1962  Order of Supervisor terminating compensation as
                 paid to August 28, 1961 and closing claim without
                 additional disability award.
  Mar.  5, 1962  Claimant's notice of appeal from order of Feb. 14,
                 1962. Claimant alleges 75% permanent partial
                 disability of amputation value of right leg at the
                 knee, and that he had a permanent partial
                 disability of 75% of the maximum allowable for
                 unspecified injuries for a back condition
                 allegedly resulting from his injury of June 24,
                 1954. This is the first time claimant placed in
                 issue the causal relationship of a back condition
                 to his right ankle injury of June 24, 1954.
  Mar. 22, 1962  Appeal granted.
  May  14, 1964  Proposed decision of hearing examiner that Feb.
                 14, 1962 order of Supervisor should be sustained.
  May  27, 1964  Claimant filed exceptions to proposed decision and
                 order.
  Aug. 20, 1964  Board affirmed and adopted proposed decision and
                 order of May 14, 1964.
                 Notice of Appeal to Superior Court.
  Dec.  3, 1964  Trial before Superior Court.
  Jan. 29, 1965  Trial court signed findings of fact, conclusions
                 of law and judgment remanding case to Department
                 for investigation and treatment of claimant's back
                 condition.
*899  Feb.  1, 1965  Findings, conclusions and judgment filed in Superior
                 Court.
  Mar.  1, 1965  Employer-defendant, Long Lake Lumber Co. appealed
                 to Supreme Court.
  Mar.  2, 1965  Defendant, Department of Labor and Industries,
                 appealed to Supreme Court.

NOTES
[*]  Reported in 421 P.2d 362.
[1]  "Spondylolisthesis"  a slipping and falling. Forward subluxation of the body of one of the lower lumbar vertebrae on the vertebra below it, or upon the sacrum. Stedman's Medical Dictionary (Unabridged Lawyers' Ed. 1961).
