Pre-Existing Injuries and Your Personal Injury Claim

A prior injury or chronic condition does not disqualify you from recovering compensation after an accident. But it does give insurers a powerful argument to minimize what they pay. This guide explains the legal rules that protect you, the tactics insurers use, and exactly how to document your claim when you have a pre-existing condition.

What Counts as a Pre-Existing Condition?

A pre-existing condition is any health problem, injury, or degenerative change that existed before the accident at issue. Common examples include:

• Prior back injuries, herniated discs, or spinal stenosis
• Previous knee, shoulder, or hip injuries from sports or prior accidents
• Arthritis, osteoporosis, or degenerative disc disease
• Old fractures or surgical repairs
• Neurological conditions such as chronic migraines or prior concussions
• Mental health diagnoses including pre-accident depression or PTSD

Importantly, a condition does not need to be formally diagnosed before the accident for it to be called pre-existing. If an MRI reveals degenerative changes that the defense's radiologist says "pre-date" the incident, the insurer will argue those changes are not compensable.

The Eggshell Skull Rule

The eggshell skull doctrine (also called the "thin skull rule") is a bedrock principle of American tort law: a defendant must take the plaintiff as they find them. If the at-fault party's negligence causes a far greater injury than it would have to a healthy person — because the victim had a fragile or weakened condition — the defendant is still fully liable for all resulting harm.

This matters because insurers often argue, "Any reasonable person would not have been this badly hurt." Under the eggshell skull rule, that argument fails. If a rear-end collision ruptures a disc that was already degenerated, the negligent driver owes compensation for the full rupture, not just the incremental damage to a healthy spine.

The rule applies across all U.S. states, though the specific jury instruction language varies. Most instructions tell jurors something like: "You must compensate for all injuries that were proximately caused by the defendant's conduct, even if the plaintiff was more vulnerable than an ordinary person."

Aggravation vs. Exacerbation vs. a New Injury

Courts and medical experts distinguish between several scenarios when a pre-existing condition is involved:

Aggravation of a Pre-Existing Condition

The accident permanently worsens a prior condition beyond its natural progression. For example, a chronic but stable back injury now requires surgery after a collision. You are entitled to compensation for the worsening — the difference between where you were before the accident and where you are after.

Exacerbation or Flare-Up

The accident temporarily intensifies a pre-existing condition, but you return to baseline. Compensation typically covers pain, treatment costs, and lost income during the flare period — not permanent damages if the evidence shows you returned to your pre-accident state.

Coincidental New Injury at the Same Body Site

Sometimes an accident causes a distinct new injury to an area that was already damaged. This requires careful medical documentation to separate the new trauma from the old condition — MRI comparisons, before-and-after functional assessments, and treating physician testimony are essential.

How Insurers Use Prior Medical Records Against You

Adjusters are trained to request broad medical authorizations that let them pull years — or decades — of your records. Their goal is to find any prior treatment, complaint, or diagnosis they can attribute your current symptoms to. Common tactics include:

• Blanket records requests — seeking records far beyond the affected body part to find unrelated issues they can conflate with your claim
• Defense medical examinations (DMEs) — having their hired physician characterize your injuries as entirely pre-existing
• Low settlement offers — presenting a lowball figure on the grounds that "most of your condition existed before the accident"
• Recorded statement traps — asking you to describe prior symptoms in ways that suggest your current pain is not accident-related
• Surveillance — monitoring your physical activity to show the insurer you are "not as injured as you claim" relative to your baseline

Never sign a blanket medical authorization without attorney review. An experienced personal injury attorney can limit the scope to records actually relevant to your claim. Learn more about how insurance companies handle injury claims and their standard delay and deny strategies.

Documentation That Protects Your Claim

Strong documentation is how you neutralize the pre-existing condition defense. Focus on establishing a clear "before and after" picture:

Pre-Accident Baseline Records

Gather records from your own treating physicians showing the state of the prior condition before the accident. Notes indicating you were "stable," "asymptomatic," or "functioning normally" are powerful because they establish the baseline that the accident disrupted.

Immediate Post-Accident Treatment

Seek medical care immediately after the accident, even if you think your symptoms are "just" a flare of an old problem. A gap in treatment gives insurers a strong argument that the accident did not cause meaningful harm. Emergency records, urgent care notes, and imaging ordered shortly after the crash create the critical temporal link.

Treating Physician Causation Opinion

Ask your treating physician to document in their notes the relationship between the accident and your current condition — specifically, whether the accident aggravated a pre-existing condition and to what extent. A written causation opinion in your medical records is far more persuasive to an adjuster or jury than verbal testimony alone.

Comparative Imaging

If you have pre-accident MRI or X-ray images, compare them to post-accident imaging. A radiologist's report noting new findings — new disc herniation, new fracture, increased disc bulge — objectively distinguishes what the accident caused from what was already there.

What Damages You Can Still Recover

Even with a documented pre-existing condition, you can typically recover:

The key principle is apportionment: you recover for what the accident caused or worsened, not for the underlying pre-existing condition itself. A skilled attorney and medical expert work together to quantify the aggravation component and present it clearly to the insurer or jury. See our guide on how pain and suffering is calculated for more on how these figures are built.

When You Need a Personal Injury Attorney

Pre-existing condition cases are among the most complex in personal injury law. An attorney is strongly recommended when:

• The insurer is denying or significantly reducing your claim citing prior records
• Your treating physician is being pressured to retract causation opinions
• The defense has scheduled a DME with their hired physician
• You have a significant gap between prior treatment and the accident
• Damages are substantial — surgery, long-term disability, or lost career capacity

Most personal injury attorneys handle these cases on contingency — no fee unless you win. The attorney brings in medical experts, limits record subpoenas to relevant materials, and develops the causation narrative that defeats the "it was pre-existing" defense.