Knee Secondary to Knee: Evidence for an Altered-Gait VA Claim

VA can service-connect a condition in your other knee as secondary to a service-connected knee when the evidence shows the first knee caused it or made it worse, usually through a change in how you walk. VA uses a limp from a knee injury leading to hip arthritis as its own example of a secondary claim, and in January 2025 the Board granted both knees and a hip as secondary to service-connected flat feet on an altered-gait opinion. The medical case is harder than the idea sounds: gait research does not show that favoring one knee simply wears out the other, so the opinion has to explain what actually happened in your walking and your joints.

What VA and the gait research say about one knee affecting the other

VA's page on types of claims describes a veteran whose service-connected knee injury causes a limp and who later develops hip arthritis, and says service connection may be established if the arthritis is a result of the knee condition. That is an example of a pathway, not a presumption. VA's evidence page still requires a current condition in the other knee and evidence of the link, usually medical records or an opinion.

The research is less simple than "the other knee picks up the slack." In an exploratory analysis from the Multicenter Osteoarthritis Study, adults with pain in one knee were followed for two years, and 17.1% developed new pain in the other knee. Spending longer on the non-painful leg while walking was associated with lower odds of new pain in that knee, not higher. The pain severity in the first knee was not related to how uneven the walking was. One study does not settle anything for one person, but it is a good reason to expect a rater to ask how, specifically, your gait change affected the other knee.

What the Board did in an altered-gait appeal

In A25008276 (January 30, 2025), the veteran was service connected for flat feet and claimed strain in both knees and a hip condition as secondary to them. VA examiners gave negative opinions. A private clinician explained that the severity of the veteran's foot condition and its pain led to altered posture and gait, that medical literature associates this with biomechanical changes and abnormal gait forces in the joints above, and that this hastened the development of the knee and hip conditions. The Board found the VA opinions inadequate for two reasons: they applied a "proximate cause" standard that the Federal Circuit rejected in Spicer v. McDonough (2023), which uses "but for" causation and allows the service-connected condition to be one contributing cause, and they never addressed aggravation. Resolving doubt in the veteran's favor, it granted both knees and the hip.

The claim here started in the feet rather than the other knee, but the reasoning the Board credited is the same reasoning a knee-to-knee opinion needs: a documented gait change, an explanation of how it loaded the other joint, and a separate answer on aggravation.

Knee appeals are often sent back rather than decided. In Claim Raven's analysis of Board decisions, 1,059 decided records under the single label knee split 30.6% favorable, 27.0% denied and 42.4% remanded, the highest remand share among the labels with 1,000 or more decided records. That label mixes service-connection and rating appeals. Across all conditions, where the Board tied an inadequate VA exam to the outcome (27,680 condition records), 78.0% were remanded. And across secondary claims, opinions the Board described as strong went with favorable outcomes in 94.1% of 2,973 records, against 1.7% where the opinion was weak. All of these figures come from already-disputed Board appeals, mostly from 2024 to 2025. They show where appeals tend to land, not what will happen to yours.

Causation, aggravation and the other knee's own history

Under 38 C.F.R. § 3.310, the other knee can be service connected if the first knee caused its condition or made an existing condition worse. If the other knee already had arthritis, an old injury or earlier complaints, the claim is about aggravation. The regulation's text asks for a baseline from medical records before the worsening, or the earliest records after it, and pays only the increase above it. Under Spicer, VA cannot use that rule to reject a claim where the knee would be less severe today but for the service-connected knee. A prior sports injury or an old complaint in the other knee is therefore evidence to keep, not to hide.

If both knees end up service connected, each is rated on its own findings under the knee codes, and the bilateral factor in 38 C.F.R. § 4.26 adds 10% of their combined value before they combine with your other ratings. The knee condition guide explains the knee codes, and the knee DBQ guide shows what the exam records, including gait.

Records for an altered-gait knee claim

Build three separate histories, then put them side by side:

Look for notes that mention a limp, a brace, a cane, a changed walking pattern or favoring one side, and keep the examiner's words intact even where they differ from your own. Your own description counts as lay evidence of what you observed, such as "I used the handrail and shifted weight to my left leg on stairs from 2021 on." If there was a fall, a sports injury, arthritis or an earlier complaint in the other knee, include it.

Questions for the clinician about the other knee

• What is the current diagnosis in the other knee, and when was it first documented?
• Is the changed gait documented, and has it lasted long enough to matter?
• How, specifically, would this gait change load the other knee, and does the research you rely on fit that mechanism?
• If the other knee had problems first, would it be less severe today but for the service-connected knee, and what earlier records show its baseline?
• What independent causes, such as age, weight, prior injury or occupation, did you weigh?

The guide to nexus letters for secondary conditions explains how to frame causation and aggravation for any secondary opinion.

Sources and scope

Checked September 23, 2026: VA's types-of-claims and evidence pages; the current eCFR text of 38 C.F.R. §§ 3.310 and 4.26; the Spicer opinion; the linked gait study; and the full text of Board decision A25008276, which binds only that appeal. Claim Raven has a commercial interest in this subject because it sells the nexus readiness check on this page.