Pre-existing conditions don’t doom a personal injury claim. They change it. The heart of the case becomes aggravation (what worsened, by how much, and for how long?) and whether the proof lines up across records, imaging, and believable voices.
Picture this: someone with a cranky lower back from an old warehouse job gets rear-ended at a stoplight. The insurer’s adjuster says it’s all pre-existing. The treating doctor says the crash lit the fuse. Which story wins when a case like this reaches a courtroom?
How Insurers Use Pre-Existing Conditions as a Defense
First, they frame the injury as old news: degenerative disc disease, prior shoulder tear, long-standing knee arthritis. Next, they comb records for inconsistencies – maybe the pain level dipped for two weeks, or physical therapy notes mention mowing the lawn. Then comes an apportionment: if anything is new, they argue that only a sliver is crash-related.
A favorite tactic is the independent medical exam (IME). The report often says the crash caused a temporary strain that resolved in six to eight weeks, and any ongoing symptoms are baseline degeneration. Juries see a lot of those reports. The question becomes one of credibility: Which story matches the timeline, the scans, and common sense?
The “Eggshell Skull” Rule
The eggshell skull doctrine (sometimes called the thin skull rule) is simple in theory: a negligent driver takes the victim as they find them. If a relatively minor crash causes major harm because the plaintiff was susceptible, the defendant is still on the hook for that harm. If the new incident aggravates the old condition, the damages can reflect that aggravation.
What the doctrine does not do is relax the burden of proof. Plaintiffs still must show – more likely than not – that the crash aggravated the pre-existing condition and to what degree. That’s where causation testimony earns its keep. A treating orthopedist who can point to a clean MRI from last year and a distinctly messier study after the collision is persuasive. So is a pain diary that tracks function before and after: sleep, work shifts, stairs, lifting the grandkids – the real-world stuff jurors understand.
Medical Records and Expert Testimony
Juries trust paper and scans more than speeches. Three evidence categories usually carry the day:
- Historical Records: Prior charts aren’t the enemy; they’re context. If the plaintiff was active with minimal pain six weeks pre-crash (say, walking two miles nightly), and after the crash they need injections just to sit through a workday, that delta matters. Consistency across primary-care notes, PT progress reports, and pharmacy refills helps.
- Imaging: MRIs and CTs don’t tell the whole story, but radiology can corroborate change: a new annular tear, increased protrusion size, nerve root edema.
- Testimony by Expert Witnesses: Treating doctors often carry more weight than retained experts because they saw the patient before any lawsuit existed. But retained experts – biomechanical or orthopedic – can explain aggravation mechanics: how a rear-end jolt loads facet joints, why pre-existing narrowing makes nerve impingement more likely, how a meniscus with fraying tears outright under torsion. Good experts teach, not just argue.
And yes, the defense will have its own experts. Expect debates over mechanism (delta-V), alternative causes (work, sports, age), and medical necessity of care. Ultimately, jurors look for a clean chain: crash → symptoms → objective findings → reasonable treatment → documented limitations.
Practical Tips for Plaintiffs
- Be candid about the past. Hiding a prior injury is the fastest way to tank credibility. Disclose everything – prior claims, old scans, the time you tweaked your back moving apartments. Honesty beats cross-examination surprises.
- Track symptoms like it’s your second job. A simple daily log – pain level, sleep quality, activities tolerated – creates a timeline that can be matched to treatment. Those patterns tell a story that sterile records can’t.
- Avoid gaps in treatment. Courts and juries will notice if you stop PT for three months. If you must pause care, document why and resume when possible.
- Follow medical advice (and clarify limits). Try home exercises. Take meds as prescribed. If work restrictions are needed, get them in writing. Not following through gives the defense a causation opening.
- Mind your social media. A photo of smiling at a barbecue doesn’t prove pain-free living, but it will appear on a blow-up board with a caption. Context gets lost; be cautious.
- Document objective impacts. Missed workdays, reduced hours, task accommodations, help from family members – these aren’t side notes; they’re damages.
- Choose counsel thoughtfully. Many plaintiff-side firms work on contingency (no fee unless they recover), offer free initial consultations, and schedule meetings by phone or Zoom. That kind of access helps organize records early and avoids avoidable mistakes – like missing a statute-of-limitations deadline because nobody returned a call. If your case also involves questions about negligent medical care, a medical malpractice attorney can evaluate whether a separate claim should be pursued alongside the injury case.
What “Aggravation” Really Looks Like to a Jury
Aggravation cases aren’t about perfect spines or pristine knees. Most adults have some degeneration on imaging by middle age. Jurors, many of whom wake up with their own aches, get this. The question they actually answer feels practical: Did this crash make this person measurably worse? If yes, how much and for how long?
That’s why damages often break into two parts: (1) the difference-maker period – weeks or months when pain and disability sharply increased – and (2) any lingering deficit that never returned to baseline. Apportionment can apply; courts sometimes ask jurors to separate pre-existing impairment from new aggravation. The better the records, the easier that math.
Settlement vs. Trial
Most personal injury tort cases settle. That’s not a cop-out; it’s recognition that juries are unpredictable and medical disputes are expensive to try. Insurers weigh risk after discovery – once they’ve seen the prior MRI and the new one, deposed the treating doctor, and heard the plaintiff explain daily life changes. Plaintiffs weigh their own risk, including the time, stress, and costs of trial.
A quiet truth: strong aggravation evidence tends to move numbers. Clear before-and-after function, consistent treatment without big gaps, and credible testimony narrow the defense playbook. That’s when realistic settlement ranges appear.
Pre-Existing Conditions Don’t Sink a Case
Pre-existing conditions don’t doom a personal injury claim. They change it. The heart of the case becomes aggravation (what worsened, by how much, and for how long?) and whether the proof lines up across records, imaging, and believable voices. Insurers will press the “it-was-already-there” button; plaintiffs answer with timelines, scans, and clinicians who connect dots without overselling.
Early organization is half the battle. Gather prior records, track symptoms, stay consistent with treatment, and get advice from qualified counsel about strategy and deadlines in your state. Not a sales pitch, just practical reality. Good lawyers help put puzzle pieces in the right order so a judge or jury can see the full picture.
Join the conversation!