Disability Compensation Claims have Three Elements
1. The veteran must currently suffer a disability or have suffered from a disability since the claim was filed;
2. There must have been some incident (for example, injury, disease, symptoms, or event) in service that could have caused the current disability; and
3. There must be a connection between the current condition and the in-service incident.
The veteran almost always needs more than just his or her own testimony to support claims involving medical causation or diagnosis. It is extremely helpful if a medical expert states that the incident in service at least as likely as not caused the disability. For example, if a veteran suffers from a knee condition some 30 years after discharge, then a statement from the veteran’s doctor that it is likely (or at least as likely as not) that the current knee problem was caused by a specific incident in service would support the grant of benefits.