Injury to muscles that bend the hip.
Because the rating levels are defined by the standards in 38 CFR § 4.56, the most helpful evidence is anything that shows how badly the hip flexion muscles are damaged and how that damage affects your function. Medical records documenting the original injury, surgical or treatment history, and imaging or electromyography findings help establish the nature and extent of muscle damage. VA examination findings that describe muscle strength, range of motion, tenderness, spasm, or atrophy directly support the criteria at each level. Records showing how the injury affects your ability to walk, climb, lift, or perform work duties are also relevant. If your symptoms affect daily activities or cause you to limit physical exertion, statements from you or people who observe you regularly can reflect the functional picture that the rating criteria are designed to capture.
Conditions that are often caused or made worse by this one. If you have any of these, they may be claimable as secondary service connection.