Saunders served on active duty in the Army, 1987-1994. Saunders did not previously experience knee problems but, during her service, sought treatment for knee pain and was diagnosed with patellofemoral pain syndrome (PFPS). Saunders’s exit examination reflected normal lower extremities but noted Saunders’s history of knee swelling. The VA denied Saunders’s 1994 claim for disability compensation because she failed to report for a medical examination. In 2008, Saunders filed a new claim, which was denied. In 2011, a VA examiner noted that Saunders reported bilateral knee pain while running, squatting, bending, and climbing but had no anatomic abnormality, weakness, or reduced range of motion. Saunders had functional limitations on walking, was unable to stand for more than a few minutes, and sometimes required a cane or brace. The examiner concluded that Saunders’s knee condition was at least as likely as not caused by, or a result of, Saunders’s military service but stated there was no pathology to render a diagnosis. The Board of Veterans’ Appeals and Veterans Court rejected her claim under 38 U.S.C. 1110. The Federal Circuit reversed; “disability” in section 1110 refers to the functional impairment of earning capacity, not the underlying cause, which need not be diagnosed. Pain alone can serve as a functional impairment and qualify as a disability, no matter the underlying cause.