May 5, 1988 Appeal from the Workers' Compensation Board. Mercure, J. Claimant sustained an injury to his right elbow on May 25, 1975 while working in New York for Kendall Refining Company. Claimant was paid workers' compensation benefits pursuant to Pennsylvania law during subsequent periods of causally related disability pursuant to a supplemental agreement with the employer. Claimant has not worked since October 27, 1978. In May 1979, the employer made a determination that claimant's injury was