LaFleur (P) had his right foot injured in the course of employment. The company doctor told him he had a sprained toe and he entered into a lump sum payment of $4,000 with his employer’s insurer. The agreement stated that it was a complete and final settlement of the claim and that he would not be able to reopen the claim to seek further benefits because of injury. P experienced increasing pain and was eventually diagnosed as having arterial occlusive disease (Buerger’s disease). Eventually, P had to have both of his legs amputated above the knees and was permanently confined to a wheelchair. P sued to set aside the agreement. Dr. Frank, an expert from Harvard Medical School, attested that the disease existed at the time of the accident and had not been diagnosed because the disease is rare but that the forklift accident aggravated the pre-existing condition. The Dr. then testified that the accident was causally related to the amputation of P’s legs. The judge denied P’s motion for summary judgment and entered judgment for D on the grounds that P had simply made an incorrect prediction of the future and had failed to establish a basis for setting aside the release. P appealed.