In October 1988, appellant submitted a claim of entitlement to a rating higher than the 20% rating which had been assigned for his left knee condition in September 1984 (see R. at 55, 63), and on December 12, 1988, the VA requested that a medical examination be conducted to determine whether appellant's service-connected left knee condition warranted an increased rating. R. at 46. Appellant underwent a VA examination on January 25, 1989, which revealed that appellant's left leg was 3/4" shorter than his right, that his left knee had a full range of motion, that he ambulated without limp or pain, and that his left knee showed "no effusion, instability, tenderness, Murray drawer apprehension . . . [or] quad or calf atrophy." R. at 47.