VA Bilateral Factor for Knee Conditions: How the 10% Boost Works (2026)

What Is the Bilateral Factor?

The bilateral factor is a rating adjustment found in 38 CFR 4.26. It recognizes that disabilities affecting both sides of the body have a greater combined impact than the same disabilities would have if they were on opposite sides or unpaired. Put simply: having two bad knees is more disabling than having one bad knee plus one bad elbow, even if the individual ratings are identical. The regulation accounts for this through a 10 percent upward adjustment applied specifically to the combined value of paired disabilities.

The adjustment is applied before the final combined rating is determined, and it is rounded to the nearest 10 percent along with the rest of the combined rating per 38 CFR 4.25. Even a small bilateral factor can tip a rating up to the next 10 percent bracket, which can translate into meaningfully higher monthly compensation.

Why the Bilateral Factor Exists

The regulation's reasoning is functional. A veteran with service-connected bilateral knee disabilities cannot compensate for one weak knee by favoring the other - both are impaired. Walking, standing, climbing, kneeling, squatting, and carrying loads all suffer more than the individual ratings suggest. The same rationale applies to bilateral ankles, bilateral hips, bilateral hands, bilateral shoulders, and bilateral radiculopathy of the lower or upper extremities.

The regulation has been part of the VA rating framework for decades. It is neither a "bonus" nor a "trick" - it is a structural recognition that paired extremity impairment compounds functional disability.

When Does It Apply?

The bilateral factor applies when all of the following are true:

• The veteran has service-connected compensable disabilities (typically 10 percent or higher) of both paired extremities
• The disabilities affect paired skeletal muscles, joints, or nerves - both legs, both arms, or their components
• The disabilities are not already combined into a single bilateral diagnostic code that inherently reflects both sides

Common qualifying pairs for which veterans should verify application of the bilateral factor include:

• Bilateral knee strain, meniscal tear, or osteoarthritis
• Bilateral ankle sprain residuals or arthritis
• Bilateral hip strain or degenerative joint disease
• Bilateral plantar fasciitis
• Bilateral shoulder impingement or rotator cuff condition
• Bilateral carpal tunnel syndrome
• Bilateral radiculopathy of the upper or lower extremities

How to Calculate the Bilateral Factor

The calculation follows a specific sequence under 38 CFR 4.25 and 38 CFR 4.26:

1. Combine the paired ratings using the combined ratings table in 38 CFR 4.25. The VA does not simply add percentages - it uses an efficiency-based formula that accounts for the fact that subsequent disabilities can only impair the portion of the body that remains unimpaired.
2. Multiply the combined value by 10 percent. This is the bilateral factor.
3. Add the bilateral factor back to the combined value. The result is the adjusted combined rating for the paired disabilities.
4. Combine that adjusted value with any other non-bilateral disabilities using the combined ratings table.
5. Round the final result to the nearest 10 percent (per 38 CFR 4.25).

Worked Example: Bilateral Knee Ratings

Consider a veteran with service-connected disabilities rated at:

• Right knee - 10 percent
• Left knee - 20 percent
• Tinnitus - 10 percent
• Lumbar strain - 10 percent

The bilateral factor quietly changed the combined rating - without it, the arithmetic would have landed the veteran at a lower rounded rating. That is why verifying its application is worth the effort.

When It Does Not Apply

The bilateral factor does not apply in several common situations:

• Only one side is service-connected. A veteran with only a service-connected right knee does not get the bilateral factor, even if the left knee is also impaired but not service-connected.
• Non-paired body systems. A service-connected right knee and a service-connected left wrist are not paired extremities - they do not trigger the factor.
• Conditions already rated together. When a single diagnostic code inherently accounts for both sides (for example, certain neurological codes), the bilateral factor is not applied a second time.
• Non-compensable ratings. A 0 percent rating does not generally trigger the bilateral factor.

How to Check If It Was Applied to Your Rating

VA rating decision letters sometimes obscure the bilateral factor within the combined ratings math. To check whether it was applied, look for:

• Language in the "Reasons for Decision" section mentioning the bilateral factor or 38 CFR 4.26
• A line in the combined rating worksheet (when provided) showing a bilateral factor addition
• Combined ratings that appear higher than the straight combined-ratings-table math would suggest

If you believe the bilateral factor should have been applied and was not, the rating is subject to correction through a Higher-Level Review (38 CFR 3.2601) or a supplemental claim with evidence that both extremities are service-connected.

If Only One Knee Is Service-Connected

Many veterans with bilateral knee disability have only one knee service-connected - often because the second knee deteriorated after service and was never formally tied back to military activity. In those cases, a secondary service connection claim under 38 CFR 3.310 is often the right path. The theory: the service-connected knee caused an altered gait that transferred load to the opposite knee, accelerating degenerative changes.

A secondary nexus letter for this scenario typically addresses:

• The current diagnosis of the contralateral knee (arthritis, meniscal tear, instability)
• The biomechanical pathway from the service-connected knee to the contralateral knee - described with reference to the clinical literature on compensatory gait and contralateral joint loading
• A records-based review anchoring the opinion in the veteran's imaging, clinical notes, and functional history
• The "at least as likely as not" opinion phrasing

Once both knees are service-connected, the bilateral factor applies automatically to the combined rating.