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Free Viability Check →Knee osteoarthritis is the most common form of arthritis and one of the most prevalent disabling conditions among veterans. Many veterans assume it's just part of aging and never file a claim. The reality is that military service frequently accelerates or causes osteoarthritis, and the VA recognizes this.
Osteoarthritis (OA) is a degenerative joint disease characterized by the breakdown of articular cartilage, the smooth tissue covering the ends of bones inside the joint. As cartilage deteriorates, bone can rub on bone, causing pain, swelling, stiffness, and loss of range of motion.
The knee joint is particularly vulnerable because it bears the full weight of the body and is subjected to significant rotational and shear forces during movement. On imaging (X-ray or MRI), osteoarthritis appears as:
These findings confirm the diagnosis, but the key question for a VA claim is not whether you have OA, it's whether service caused or accelerated it.
Osteoarthritis naturally progresses with age, but research is clear that heavy physical loading throughout early adulthood significantly accelerates that progression. Veterans who spent careers performing high-impact activities (infantry, airborne, combat arms, deck operations, heavy equipment operation) accumulated joint loads that would far exceed those of civilian counterparts of the same age.
The legal and medical argument is not that service caused OA from nothing. The argument is that service accelerated the onset and severity of OA beyond what would have occurred on a normal aging timeline.
This is a distinct and often stronger pathway. When a joint sustains a significant injury (ligament tear, meniscus tear, fracture), the joint environment changes. Inflammation, altered mechanics, and cartilage damage from the initial injury trigger an accelerated degenerative cascade that leads to post-traumatic OA.
If you tore your ACL, MCL, or meniscus during service and that was service-connected or documented, the subsequent knee OA is a direct secondary condition. See our article on ACL and MCL tears in veterans for how those initial injuries connect forward to arthritis claims.
Even if you had early arthritic changes before service (common in athletes), military service can aggravate those changes. The VA must rate the additional disability caused by service, not deny the claim entirely because some OA existed before enlistment.
The VA rates osteoarthritis under Diagnostic Code 5003 (degenerative arthritis established by X-ray findings). Under DC 5003, the rating depends on the number of major and minor joints involved and whether there is limited motion:
Crucially, if limited range of motion exists, the condition is rated under the limitation of motion codes (DC 5260 for flexion, DC 5261 for extension) because those ratings often yield higher evaluations than DC 5003 alone. See our full explanation of knee VA rating criteria for how these interact.
The VA is required to apply whichever rating is higher, so it's important that your C&P examiner documents both the arthritic changes and any range of motion limitations.
DC 5003 produces its highest rating (20%) when two or more major joint groups are affected with frequent incapacitating episodes. This means DC 5003 is most advantageous for veterans with bilateral knee arthritis or arthritis in multiple major joints who experience frequent episodes severe enough to require bed rest or equivalent incapacity.
For a veteran with moderate range of motion limitation (flexion to 60 degrees, rated 10% under DC 5260) but frequent incapacitating episodes affecting two major joints, DC 5003 at 20% would be the higher evaluation and should be applied. The distinction matters at the C&P exam: document both the range of motion measurements and the frequency and severity of incapacitating episodes. Providing both data points gives the rater what they need to apply whichever code benefits the veteran most.
A successful OA claim requires:
This is where most claims succeed or fail. The VA's own examiner may focus narrowly on whether a single traumatic event is documented. A well-constructed independent medical opinion will instead explain the cumulative biomechanical mechanism of service-accelerated degeneration, cite the veteran's specific occupational history, and reach a properly worded conclusion.
A vague nexus letter ("could be related to service") is not sufficient. The opinion must reach at least a 50/50 probability expressed in appropriate legal language.
If you have service-connected flat feet, a service-connected back condition, or a prior service-connected knee injury, knee OA may be ratable as a secondary condition to any of those. Secondary claims sometimes bypass the need to establish direct service connection and can result in the same rating and compensation.
If you're working on a knee osteoarthritis claim, Flat Rate Nexus offers physician-signed independent medical opinions at flatratenexus.com. The site also includes a free nexus letter grader and a C&P exam prep tool.
Thinking about your own claim? Every nexus letter we write goes through a full physician record review, cites peer-reviewed research, and is built around the actual evidence in your case.
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