Back Pain Secondary to Knee Pain

If your knee is service connected and your lower back now hurts, you can claim the back as secondary to the knee. Veterans search for this as "back pain secondary to knee pain," but VA service connects a diagnosed back condition, such as a lumbosacral strain or degenerative arthritis of the spine, and rates it under the spine formula. The theory behind most of these claims is compensation: a bad knee changes how you stand and walk, and over years the lower back takes the load. The research supports parts of that theory and leaves gaps, and this page is honest about both.

Can knee pain cause back pain?

The research shows that knee problems and back problems often occur together and that knee disease goes with changes in posture and gait. It does not show, for any one person, that the knee caused the back condition.

• Japanese surgeons described a "knee-spine syndrome" in 366 patients (Murata and colleagues, Journal of Bone and Joint Surgery, British volume, 2003). Knee extension was more limited in patients with a flatter lumbar curve, and the lumbar curve was smaller in patients whose knee lacked more than 5 degrees of extension. The authors concluded that lumbar symptoms may be caused by degenerative changes in the knee.
• A 2019 review of 32 studies with 2,037 participants (Iijima and colleagues, Journal of Biomechanics) found that people with knee osteoarthritis lean the trunk more toward the side of the affected knee when they walk. The authors suggested this could lead to problems such as low back pain, called for studies to test it, and graded the evidence very low.
• Among 1,389 people with symptomatic knee osteoarthritis in the Osteoarthritis Initiative (Suri and colleagues, Arthritis Care and Research, 2010), 57.4% reported low back pain, and those with back pain had worse knee pain. It measured both at the same time, so it cannot show which came first.
• Treating the knee helps some backs. In 45 knee replacement patients (Kechagias and Grivas, Cureus, 2024), 62.22% had moderate to very severe low back pain before surgery, and it improved in half of them. The study was small, and the authors found no clear link between the back pain and either knee pain or a sideways tilt of the pelvis.
• Not every finding points the same way. A review of 6 studies with 475 knee replacement patients (Jain and colleagues, World Journal of Orthopedics, 2025) found that only pelvic tilt changed after surgery, not the lumbar curve. A cohort study of joint replacement patients (Staibano and colleagues, Journal of Arthroplasty, 2014) found less back pain improvement after knee replacement than after hip replacement, and warned that back pain may continue after a successful replacement.
• Leg length is a weak theory on its own. A 1984 case-control study (Grundy and Roberts, Lancet) found no link between a difference in leg length and chronic low back pain, and a 2025 review of 46 studies (Sugavanam and colleagues, Disability and Rehabilitation) found no difference in leg length between people with and without low back pain.

In my read, the strongest version of this claim rests on a knee that changed your posture or gait for years, documented in your records, with a back condition that started or worsened after that. A doctor has to connect those facts to the research.

How VA decides back pain secondary to knee pain

Secondary service connection is in 38 CFR § 3.310. VA grants it in two ways.

• Caused by. Your service-connected knee condition caused the back condition, at least as likely as not.
• Aggravated by. Your back condition is aggravated by your service-connected knee condition, meaning it would be less severe but for the knee condition (M21-1 V.ii.2.D). VA rates only the part above the baseline, so the opinion should describe the baseline, from the earliest medical evidence of the back's severity before the worsening. The text of § 3.310(b) still mentions natural progress, but VA's current manual no longer applies that part, and the worsening does not have to be permanent.

The claim needs three things in the file: a diagnosed back condition, a service-connected knee condition, and a medical opinion linking the two with reasoning. A lumbosacral strain counts: it is DC 5237, rated under the same spine formula as arthritis and disc disease.

VA rating for back pain secondary to knee pain

The back is rated under the General Rating Formula for Diseases and Injuries of the Spine in 38 CFR § 4.71a, which applies "with or without symptoms such as pain (whether or not it radiates)." For the thoracolumbar spine, these are the levels.

• 100%: unfavorable ankylosis of the entire spine
• 50%: unfavorable ankylosis of the entire thoracolumbar spine
• 40%: forward flexion 30 degrees or less, or favorable ankylosis of the entire thoracolumbar spine
• 20%: forward flexion greater than 30 but not greater than 60 degrees; or combined range of motion not greater than 120 degrees; or "muscle spasm or guarding severe enough to result in an abnormal gait or abnormal spinal contour"
• 10%: forward flexion greater than 60 but not greater than 85 degrees; or combined range of motion greater than 120 but not greater than 235 degrees; or muscle spasm, guarding or localized tenderness without abnormal gait or contour; or a vertebral body fracture with loss of 50 percent or more of the height

Normal forward flexion is 90 degrees, and each measurement is rounded to the nearest five degrees. A disc herniation that compresses or irritates a nerve root (DC 5243) can instead be rated on incapacitating episodes, which require "bed rest prescribed by a physician and treatment by a physician." Nerve findings in the legs are rated separately under Note (1); see radiculopathy. The back VA rating page covers all of this in depth.

Pain and repeated use count. Section 4.40 says "a part which becomes painful on use must be regarded as seriously disabled," § 4.45 counts excess fatigability, incoordination and pain on movement, and § 4.59 treats "actually painful, unstable, or malaligned joints, due to healed injury, as entitled to at least the minimum compensable rating for the joint."

The back and knee ratings combine under 38 CFR § 4.25, larger rating first. A 20% back rating and a 10% knee rating combine to 28, because the 10% takes its share of the remaining 80. VA rounds 28 to 30%. The bilateral factor does not apply to the spine.

The C&P exam for back pain secondary to knee pain

The examiner is asked whether your back condition is at least as likely as not caused by your knee condition and, separately, whether the knee aggravated it. An opinion that answers only the first question is inadequate under El-Amin v. Shinseki (2013).

A careful examiner looks at these things.

• When the back symptoms started compared with the knee injury or surgery
• How long you have limped, favored one leg or used a brace or cane
• Whether the knee lacks full extension or bends less than normal, and whether the back exam shows guarding or an abnormal gait
• Other causes, such as age, a separate back injury, heavy work and weight

Watch for three lines in unfavorable VA opinions: your gait looked normal at the exam, the literature does not support the link, or your knee condition does not affect the lumbar spine. In Board decision A25037377 (April 2025), a VA examiner relied on a normal gait at the exam and a claim that few studies support the link. The Board granted the back anyway: private doctors had tied decades of altered gait after the veteran's knee surgery to the back, and a later VA opinion was inadequate because it did not address the reported altered gait. Board decisions are not precedential, but they show what the Board accepts. C&P exam prep can help you describe how you walk on bad days, not just on exam day.

Why back pain secondary to knee pain claims get denied

The gaps that lead to a denial are predictable.

• The only medical opinion is a negative VA opinion, and nothing in the file answers it.
• A private opinion names a mechanism without explaining it. In Board decision A25010382 (February 2025), the Board summarized a private opinion as saying the knee condition "disrupted the kinetic chain, placing added stress on surrounding tissue." The Board gave it little weight because it did not say whether it addressed causation or aggravation, did not identify the tissue, and did not explain how that stress led to the back conditions. A second opinion in the same case cited a study and case law but discussed no details of the veteran's knee or back conditions.
• No opinion addresses aggravation.
• The records do not show a gait change, a limp or a brace, so the theory has no facts under it.
• The opinion ignores a separate back injury or other cause in the file.

Nexus letter for back pain secondary to knee pain

A strong nexus letter for this claim does six things.

1. States that the doctor reviewed your records, including the knee history, the back diagnosis and imaging, and any notes on gait, braces or canes.
2. Lays out the time course: when the knee problem began, how long your gait or posture changed, and when the back symptoms started or worsened.
3. Gives an opinion on causation: your back condition is at least as likely as not caused by your service-connected knee condition.
4. Gives a separate opinion on aggravation: your back condition is aggravated by your service-connected knee condition, meaning it would be less severe but for the knee condition, and describes the baseline.
5. Explains the mechanism in your case, such as lost knee extension and a flatter lumbar curve, trunk lean or years of favoring one leg, and cites the research, including its limits.
6. Deals with the other causes in your file directly.

These opinions break down when they name a mechanism without walking through it, skip aggravation, or ignore the other causes. Raven Nexus can organize your records and the research into a draft for your doctor to review. If the knee also affects your hip, see hip pain secondary to knee pain, and for every condition claimed secondary to the knee, see secondary conditions to knee pain.

Questions veterans ask about back pain secondary to knee pain

Can back pain be secondary to knee pain?

Yes. VA can grant a diagnosed back condition secondary to a service-connected knee under 38 CFR § 3.310 when the knee caused it or made it worse. The claim needs a medical opinion that explains how the knee affected your back.

What is the VA rating for back pain secondary to knee pain?

The same as any back condition under the General Rating Formula: 10, 20 or 40 percent based mostly on forward flexion, with 50 and 100 percent for ankylosis. It combines with your knee rating under 38 CFR § 4.25.

Does a lumbar strain count, or do I need arthritis?

A strain counts. Lumbosacral strain is DC 5237 and is rated under the same spine formula.

My gait looked normal at the C&P exam. Does that end the claim?

No. A normal gait on one day does not show how you walked for years. Your records, your statement and a private opinion can show the longer history.

Can I claim my back secondary to both knees?

Yes. The opinion should explain how each knee affected your gait. If both knees have compensable ratings, the knees get the bilateral factor; the back rating does not.

Sources

• 38 CFR § 3.310, secondary service connection; M21-1 V.ii.2.D, aggravation of a nonservice-connected disability by a service-connected one.
• 38 CFR § 4.71a, General Rating Formula for Diseases and Injuries of the Spine and its notes, DC 5237 and DC 5243 with the Formula for Rating Intervertebral Disc Syndrome Based on Incapacitating Episodes; 38 CFR §§ 4.25, 4.26, 4.40, 4.45 and 4.59 (eCFR text as of October 1, 2026).
• El-Amin v. Shinseki, 26 Vet. App. 136 (2013), an opinion must address aggravation.
• Murata Y, Takahashi K, Yamagata M, et al. The knee-spine syndrome. Association between lumbar lordosis and extension of the knee. Journal of Bone and Joint Surgery, British volume. 2003;85(1):95-99. PMID 12585585.
• Iijima H, Shimoura K, Ono T, et al. Proximal gait adaptations in individuals with knee osteoarthritis: A systematic review and meta-analysis. Journal of Biomechanics. 2019;87:127-141. PMID 30904334.
• Suri P, Morgenroth DC, Kwoh CK, et al. Low back pain and other musculoskeletal pain comorbidities in individuals with symptomatic osteoarthritis of the knee: data from the osteoarthritis initiative. Arthritis Care and Research. 2010;62(12):1715-1723. PMID 20799265.
• Kechagias VA, Grivas TB. Hip-Spine and Knee-Spine Syndrome: Is Low Back Pain Improved After Total Hip and Knee Arthroplasty? Cureus. 2024;16(4):e57765. PMID 38716012.
• Jain M, Pal DK, Narayan Sahu R, et al. Effect of total knee arthroplasty on the spinopelvic parameters: A systemic review and metanalysis. World Journal of Orthopedics. 2025;16(7):107869. PMID 40698278.
• Staibano P, Winemaker M, Petruccelli D, de Beer J. Total joint arthroplasty and preoperative low back pain. Journal of Arthroplasty. 2014;29(5):867-871. PMID 24211057.
• Grundy PF, Roberts CJ. Does unequal leg length cause back pain? A case-control study. Lancet. 1984;2(8397):256-258. PMID 6146810.
• Sugavanam T, Sannasi R, Anand PA, Ashwin Javia P. Postural asymmetry in low back pain - a systematic review and meta-analysis of observational studies. Disability and Rehabilitation. 2025;47(7):1659-1676. PMID 39166267.
• Board of Veterans' Appeals citations A25037377 (April 23, 2025, granted) and A25010382 (February 5, 2025, denied). Board decisions are not precedential.
• Board figures on this page: Claim Raven's read of every Board decision from 2021 to 2026 that it holds, and of every decision since 1992 for the longer view.