Appeal from a decision and award of the Workmen’s Compensation Board. Claimant was engaged in a wrecking operation and testified that while using a stairs on his way to reach a lower floor on the job “my leg twisted ”, Although his leg “ swelled up ” he continued working, but the next day “ the knee was like a balloon ” and he saw a doctor. Claimant had a prior injury to this knee, dating back to boyhood. But the occurrence on the job could be found to be an accident and there is medical proof indicating that this event on the job, as well as the earlier pathology played a part in the claimant’s disability. It could well be found to be a physical condition upon which a decision to make a surgical exploration was based. Conditions which antedated the accident were found on surgical exploration; but conditions attributable to the accident also were found and an orthopedic physician having available all the surgical data expressed an opinion of causal relationship to the accident. Even appellant’s orthopedist testified he could not deny that the accident was “ a competent cause for the operation and the sequella thereof ”. Decision and award unanimously affirmed, with costs to the Workmen’s Compensation Board. Present — Bergan, P. J., Gibson, Herlihy, Reynolds and Taylor, JJ.