By Dr. Drew Brennes, DC | Nexus Letter Doctor
You filed for back pain. Maybe you filed for knee pain. But did you know that the real origin of your entire musculoskeletal chain of suffering might be a condition you overlooked — one you've been walking on, literally, since your first day in basic training?
Flat feet — formally known as pes planus — is one of the most underrated and under-claimed service-connected conditions in the VA system. And what makes it especially significant is this: once flat feet are service connected, every condition it causes up the kinetic chain becomes a secondary service-connected disability too.
That could mean your knee pain, your hip pain, your lumbar strain, your sciatica — all flowing from a single root condition I can connect directly to your military service.
In this article, I'm going to break down exactly how this works, what the VA recognizes, and what you need to do to make sure you're not leaving significant back pay and monthly compensation on the table.
What Is the Kinetic Chain — And Why Should Veterans Care?
The kinetic chain is a concept from sports medicine and chiropractic care that describes how the body's joints and muscles work together as a connected system. Think of it like a row of dominoes: when one joint is out of alignment or malfunctioning, the stress doesn't stay there. It shifts. It compensates. And the joints above and below begin to absorb forces they were never designed to handle.
Your feet are at the foundation of that entire chain. When the arch of the foot collapses — which is exactly what happens with flat feet — the ankle rolls inward (overpronation), the knee tracks incorrectly, the hip rotates to compensate, and the lumbar spine bears uneven load. Over time, that uneven load causes structural breakdown at every level above the foot.
As a Doctor of Chiropractic, I see this pattern constantly. And as someone who has spent years writing nexus letters for veterans, I know that the VA will not connect these dots for you automatically. You have to show them the chain — and that is exactly what I help veterans do.
Why Are Flat Feet So Common in Military Veterans?
The answer is simple: the military is extraordinarily hard on feet. I've seen this in veteran after veteran who comes to me. Consider what military service demands of your feet on a daily basis:
- Prolonged standing and marching — often 8–12+ hours on hard pavement or uneven terrain
- Heavy load carrying — rucksacks, body armor, weapons, and gear can add 50–100+ lbs of force with every step
- Non-supportive footwear — military boots, while durable, are not always optimally fitted or arch-supportive for every foot type
- High-impact activities — running on concrete, jumping, rapid direction changes during training and combat operations
- Extended deployments — months or years of continuous stress on the plantar fascia and arch structures with little recovery time
The result? The plantar fascia — the connective tissue that maintains your foot's arch — gradually weakens and flattens. Many veterans I work with developed flat feet during service and never had it documented, never had it treated, and never thought to file for it. They just pushed through the pain. That's what you do. But the condition doesn't disappear when you're discharged. It progresses — and as it progresses, it drags everything above it down with it.
What the Research Actually Shows
I want to take a moment here to point to two peer-reviewed studies that I find particularly relevant to this conversation — because what I see clinically in veterans is backed up by the science.
The first is a 2024 study published in the Journal of Men's Health titled "Static and Dynamic Plantar Foot Shape Following Long-Term Use of Military Boots" (Sobhani et al., 2024). Researchers compared thirty military personnel who had been wearing military boots for the past 12 years against thirty non-military subjects. What they found was striking: military personnel showed significantly lower arch indices — meaning measurably flatter feet — compared to their civilian counterparts. The study's conclusion put it plainly: military personnel have low arches, making them susceptible to musculoskeletal disorders, and the authors specifically recommended that military boots be reassessed or that insoles be used. That is a peer-reviewed research team saying exactly what I tell veterans every day: the boots changed your feet, and the VA should recognize that.
The second study hits even harder from a clinical standpoint. Published in Military Medicine in 2013, "Shock-Absorbing Insoles Reduce the Incidence of Lower Limb Overuse Injuries Sustained During Royal Marine Training" (House, Reece & Roiz de Sa, 2013) compared injury data across 2,754 recruits — one group issued standard flat insoles, the other issued shock-absorbing insoles. The result: the standard insole group suffered lower limb overuse injuries at a rate of 31.7%, while the group with better insoles came in at 19.0% — a statistically significant reduction. The injuries that decreased included stress fractures, tibial periostitis, Achilles tendinopathy, and anterior knee pain.
Think about what that means for your claim. If better insoles reduced injuries by that margin, then the standard flat insoles issued to you during service were, by definition, a contributing factor in the injuries that occurred. This is not speculation — it is the logical and legal implication of the data. And it is exactly the kind of evidence that belongs in a nexus letter.
The Domino Effect: How Flat Feet Damage the Body From the Ground Up
Step 1: The Foot and Ankle
When the arch collapses, the ankle rolls inward — a motion called overpronation. This shifts the weight distribution across the entire foot and changes the angle at which forces travel upward into the leg. Conditions I commonly see at this level include plantar fasciitis, Achilles tendinopathy, posterior tibial tendon dysfunction, and ankle instability.
Step 2: The Knee
Overpronation causes the tibia (shinbone) to rotate inward, which in turn pulls the kneecap medially — a condition called patellar maltracking or patellofemoral syndrome. The medial compartment of the knee begins to absorb disproportionate load. Over years and decades, this leads to medial compartment osteoarthritis, IT band syndrome, meniscal degeneration, and chronic patellofemoral pain.
Step 3: The Hip
The inward rotation from the knee travels upward into the hip, causing the femoral head to sit incorrectly in the acetabulum (the hip socket). The muscles that stabilize the hip are forced to overwork to compensate, leading to hip flexor tightening, labral irritation, trochanteric bursitis, hip impingement, and eventually hip osteoarthritis.
Step 4: The Lumbar Spine and Lower Back
With the hip out of alignment, the pelvis begins to tilt anteriorly — which increases the lumbar curve and compresses the posterior elements of the lumbar spine. Veterans with this pattern develop lumbar spondylosis, degenerative disc disease, facet arthropathy, lumbar radiculopathy, and chronic lumbosacral strain. In my experience writing nexus letters, this is one of the most common and most missed secondary chains in the entire VA system.
Step 5: Beyond the Lumbar Spine
In many veterans, the compensatory pattern continues upward into the thoracic and even cervical spine, contributing to mid-back pain, shoulder imbalances, and neck conditions. The body is remarkably adaptive, but those adaptations come at a cost that accumulates over a lifetime.
What Does the VA Say About Secondary Service Connection?
Under 38 CFR § 3.310, the VA recognizes secondary service connection when a disability that is already service connected causes or aggravates another disability. The legal standard requires a "nexus" — a documented medical link between the service-connected condition and the secondary condition.
Here's what I want every veteran reading this to understand: the VA will not draw this connection for you automatically. You need a qualified medical professional to produce a written nexus opinion stating, to at least a 51% degree of medical certainty, that the secondary condition is "at least as likely as not" caused or aggravated by the primary service-connected condition.
Without that nexus letter, the rater reviewing your file has no obligation to connect the dots — even when the medical relationship is clinically obvious to any provider looking at it. I've seen veterans denied again and again on conditions I could have connected in a single letter.
2026 Update — Secondary Causation Standard: Effective May 1, 2026, the VA updated the secondary service connection framework following Spicer v. McDonough. Nexus letters for secondary claims — including flat feet and all downstream kinetic chain conditions — must now satisfy a "but for" causation standard. See The VA Changed the Rules on Secondary Claims: What the New 'But For' Standard Means for Your Nexus Letter (2026) for what this means for your letter.
VA Ratings for Flat Feet (Pes Planus) — 38 CFR § 4.71a, DC 5276
- 0% — Mild: symptoms are controlled by arch supports
- 10% — Moderate: pain on use, not controlled by arch supports
- 20% — Severe: marked pronation, severe pain, tenderness of plantar surface
- 30% — Pronounced: extreme tenderness, marked pronation, unable to use feet effectively
Note: ratings apply per foot — bilateral (both feet) conditions can be rated separately.
Which Conditions Can Be Claimed Secondary to Flat Feet?
If you have documented flat feet from military service — or can establish your flat feet developed during service — here are the conditions I regularly help veterans connect in a nexus letter:
- Plantar fasciitis — Direct mechanical consequence of arch collapse
- Achilles tendinopathy — Overpronation places excess tension on the Achilles
- Patellofemoral syndrome — Medial patellar tracking caused by tibial rotation
- Knee osteoarthritis — Medial compartment overloading from gait abnormality
- IT band syndrome — Lateral hip/knee friction from altered biomechanics
- Trochanteric bursitis — Hip bursa irritation from compensatory gait patterns
- Hip osteoarthritis — Femoral head maltracking in the hip socket
- Lumbar spondylosis / DDD — Posterior element compression from pelvic tilt
- Lumbar radiculopathy — Nerve root compression secondary to disc changes
- Facet arthropathy — Posterior joint degeneration from increased lordosis
- Chronic lumbosacral strain — Muscle overuse compensating for pelvic imbalance
Why a Nexus Letter Is the Most Important Document in Your Claim
I've written nexus letters for hundreds of veterans in exactly this kinetic chain scenario. What I see over and over again is that the VA denies these secondary conditions not because the connection doesn't exist — it does — but because no one has formally documented it in their file.
A well-written nexus letter will:
- Establish the biological and biomechanical mechanism by which flat feet caused or aggravated your secondary condition
- Cite peer-reviewed medical literature supporting the connection
- Apply the appropriate legal standard ("at least as likely as not")
- Use the specific language VA raters and the Board of Veterans' Appeals are trained to look for
My letters are medically rigorous, legally precise, and written specifically to give you the best possible chance at the rating you've earned. As a Doctor of Chiropractic, I understand musculoskeletal medicine at the level of detail that VA raters need to see — and I know how to translate that into a document that moves claims forward.
The Bottom Line
If you served in the military, you marched. You ran. You carried weight. You put your body through things most civilians will never experience. And if your feet bore the brunt of that service — if your arches gave way, if you ignored the pain and kept going because that's what you do — the effects of that sacrifice may still be rippling upward through your body today.
You deserve to be rated for every condition your service caused. The kinetic chain is real. The secondary connection is real. And the compensation you've earned is real.
Don't leave it on the table.
Think This Applies to You? Let's Talk.
I've helped hundreds of veterans establish secondary service connection for exactly this kind of kinetic chain scenario. If you have a foot condition from service and pain up the chain, you may be leaving significant compensation on the table. I'd be honored to help you connect the dots.
>> Order Your Nexus Letter at NexusLetterDoctor.com <<
I am Dr. Drew Brennes, DC, founder of Nexus Letter Doctor. I hold a Doctor of Chiropractic degree and specialize in writing VA disability nexus letters and DBQ opinions for veterans nationwide. It is nothing but an honor when a veteran trusts me to help fight for what they've earned.
