It is one of the most common moves an insurer makes in a serious injury case: point to a degenerative finding on a scan, call the injury “pre-existing,” and argue the crash changed nothing. It sounds devastating. In reality it collides with two things — a rule of law that has protected vulnerable victims for over a century, and the medical fact that degenerative findings live in the spines and brains of most healthy, pain-free adults. This is how that defense actually works, and how it is answered.
Almost everyone who is catastrophically hurt in a crash and then files a claim eventually hears some version of the same sentence: “This was already there.” The defense radiologist finds a bulging disc, a narrowed joint space, or a patch of the brain that looks older than the crash, and the insurer builds its entire theory around it — the harm you are describing, it argues, is just the aging you were already carrying, not anything a collision caused. For an injured person who was living a normal life the day before impact, few arguments feel more unfair or more disqualifying.
It is also one of the most misunderstood arguments in injury law, because it fails in two independent ways at once. The first is legal: the rule that a wrongdoer takes an injured person exactly as it finds them — frailties and all — is one of the oldest and most durable principles in tort law. The second is medical: the imaging findings insurers wave around are so common in people with no pain whatsoever that their mere presence proves almost nothing about when your pain began. Understanding both is how a “pre-existing” label stops being an ending and becomes just another disputed fact in the case.
The pre-existing condition defense is the argument that an injured person’s current symptoms come from a condition that predated the crash rather than from the crash itself. Insurers rely on it because it attacks the one element every injury claim must prove — causation — and because degenerative findings are easy to locate on the imaging of any adult. If the defense can convince a jury that the herniated disc, the shoulder tear, or the cognitive change was already present and simply discovered after the collision, it can argue the defendant owes nothing.
The tactic works on intuition. A juror hears “degenerative disc disease” and pictures a problem the plaintiff was always going to have. What the label conceals is the difference between a finding that exists on a film and a finding that was actually causing a person pain and disability before the crash. Those are not the same thing, and the gap between them is exactly where these cases are won.
The eggshell plaintiff rule — also called the eggshell skull doctrine — holds that a defendant is liable for the full extent of the harm it causes, even when a victim’s pre-existing condition made that harm far greater than it would have been for someone else. In the classic image, if you negligently strike a person whose skull is as thin as an eggshell, you are responsible for the catastrophic result even though the same blow to an ordinary person would have caused only a bruise. You take your victim as you find them.
This is not a fringe theory. The Restatement (Third) of Torts: Liability for Physical and Emotional Harm states it directly at § 31: when tortious conduct causes harm that, because of a person’s pre-existing physical or mental condition, is of a greater magnitude or a different type than might reasonably be expected, the actor is nevertheless liable for all of that harm. The prior Restatement (Second) contained materially the same rule at § 461, and courts across the country have applied the principle for well over a century. The doctrine exists precisely because the alternative — letting a wrongdoer pay less because its victim happened to be vulnerable — would punish people for being human.
The practical consequence is important: a defendant does not get a discount because the person it hurt was older, had a prior surgery, had a healed injury, or had a silent condition on a scan. In a catastrophic case, where the injured person may have carried some ordinary wear-and-tear in their spine or a prior concussion in their history, that protection is often the difference between a full recovery and a gutted one.
Yes. This is the doctrine of aggravation of a pre-existing condition, and it is the companion to the eggshell rule. The law does not let you recover for the underlying condition you brought to the crash — the arthritis or degenerated disc you already had. But it does let you recover when the crash accelerated that condition, made it meaningfully worse, or converted something that had been silent and painless into a symptomatic, disabling problem. A disc that was quietly degenerating and never bothered you, then herniated and compressed a nerve root in the collision, is a compensable injury, not a free pass for the at-fault driver.
Where a condition truly was already causing symptoms, courts and juries handle it through apportionment: the defendant pays for the aggravation attributable to the crash, and not for the baseline the person walked in with. That line — baseline versus aggravation — is a medical question before it is a legal one, which is why precise causation testimony from a physician who has actually read the records carries so much weight. The defense wants the jury to see one undifferentiated “old” problem. The task on the other side is to show, in the medicine, exactly what the crash added.
Here is the fact the “it was already there” argument depends on you not knowing: degenerative changes on imaging are normal, and they are nearly universal as people age. A widely cited 2015 systematic review in the American Journal of Neuroradiology, led by Dr. Waleed Brinjikji, pooled imaging from more than 3,000 people who had no back symptoms at all and measured how often degenerative findings showed up by decade of life.
The authors’ conclusion is the point exactly: these findings are “likely part of normal aging and unassociated with pain,” and must be interpreted in the context of the patient’s clinical condition. In plain terms, if roughly a third of healthy, symptom-free young adults already have disc degeneration on a scan, then finding degeneration on your post-crash MRI tells no one whether your pain existed before the collision. The finding is background noise that nearly everyone carries. What matters is the correlation between the imaging and a person who was functioning normally, got hit, and has not been the same since.
A degenerative finding and an acute injury do not look the same to a trained reader, and the distinction is written into the images. Long-standing degenerative disc disease follows a slow, recognizable arc: the disc gradually dehydrates and loses the bright signal it normally shows on T2-weighted MRI, and the disc space narrows as height is lost over years. Those are the fingerprints of time, not trauma. By contrast, as the imaging literature notes, a herniation occurring without surrounding degeneration is unusual and tends to point toward an acute, high-energy force — the kind a serious collision delivers.
The endplates tell their own story through Modic changes, the reactive signal shifts in the bone next to a disc. Modic Type 1 changes — dark on T1, bright on T2 — reflect an active, inflammatory, comparatively recent process, while Modic Type 2 changes — bright on T1 — reflect chronic fatty change that has been settling in over a long period. A reader who understands the difference can often say something meaningful about the age of what they are looking at rather than lumping everything under “degenerative.” The single most powerful tool, when it exists, is a prior scan: comparing imaging from before the crash with imaging after it can separate what was already present from what is new with a clarity no verbal argument matches.
The same logic governs brain injuries. An insurer may point to age-related atrophy or an old, healed area of the brain and call a new cognitive problem “pre-existing.” But acute findings have their own signature — a fresh contusion, or the microscopic bleeding that specialized sequences pick up — and they read differently from the smooth, chronic changes of prior events. This is the same interpretive discipline that separates an acute finding from a normal-looking scan in a diffuse axonal injury, and it is the work at the center of how a physician reads a head CT after a brain injury.
A pre-existing condition defense is answered on two tracks at once, which is why it fits the way this firm is built. On the medical side, Herb Borroto, M.D., J.D., the firm’s medical-legal expert, does the work a defense radiologist’s summary is designed to skip: he reads the actual films, distinguishes chronic degenerative signal from acute injury, hunts down any prior imaging that establishes a true baseline, and correlates all of it with what the person could do before the crash and cannot do now. A finding is not a diagnosis, and a diagnosis is not a cause — separating those three is medicine, not argument.
On the legal side, Alex Alvarez, Managing Partner and Board Certified Civil Trial Lawyer, frames that medicine inside the rules that govern it: the eggshell instruction that forbids a discount for a vulnerable victim, the aggravation instruction that makes worsening a compensable harm, and the apportionment analysis that holds a defendant to what its collision actually caused. Paired, the two answer the defense’s single undifferentiated “old problem” with a specific account of what was baseline, what was aggravated, and what was brand new — the same evidence-first approach the firm brings to the traumatic brain injury and spinal cord injury cases it handles.
If you have been told your injury was “pre-existing,” the label is a starting position, not a verdict. The law does not reward a wrongdoer for hurting someone who was already vulnerable, and the imaging findings used to sell the “it was already there” story are the same findings that quietly sit in the scans of most pain-free adults. What decides these cases is not the presence of a degenerative finding but the honest medical accounting of what changed — and that accounting depends on records that are complete and preserved early, including any prior imaging that can anchor a baseline. As with every serious case, the evidence is most persuasive when it is gathered before it scatters, a theme we return to in the first 24 hours after a crash. This article is general information about a common defense, not legal or medical advice about any particular case.
Yes. Under the eggshell plaintiff rule, a person who causes harm is liable for the full extent of that harm even if a pre-existing condition made the person more vulnerable to serious injury. A defendant takes the victim as found. You cannot recover for the pre-existing condition itself, but you can recover for a new injury and for the aggravation or worsening of a prior condition that the crash caused. The Restatement (Third) of Torts states this rule at Section 31.
No. Degenerative changes are extremely common in people with no symptoms at all. A 2015 systematic review in the American Journal of Neuroradiology found disc degeneration on imaging in 37 percent of asymptomatic 20-year-olds, rising to 96 percent of 80-year-olds, and disc bulges in 30 percent of 20-year-olds. Because these findings appear in most pain-free adults, their presence on a scan does not establish that your current pain existed before the crash. It has to be interpreted against your clinical history.
By reading the specific features. Long-standing degenerative disc disease shows gradual dehydration, loss of the normal bright T2 signal, and loss of disc height. A herniation occurring without any surrounding degeneration is unusual and points toward an acute traumatic force. Modic endplate changes are also informative: Type 1 changes reflect an active, inflammatory process, while Type 2 changes reflect chronic fatty change. Comparing a post-crash study with any earlier imaging is often the clearest way to separate what is new from what was already there.
Aggravation means the crash made an existing condition meaningfully worse, accelerated it, or turned something that was silent and painless into a symptomatic, disabling problem. The law treats that worsening as a compensable injury. Where a condition was already causing some symptoms, courts and juries apportion damages so the defendant pays for the aggravation attributable to the crash rather than the underlying condition, which is why precise medical causation testimony matters so much in these cases.
Why “no acute abnormality” is the start of the analysis, not the end.
How a catastrophic injury can be real even when the standard scan reads normal.
What each level of injury means for function — and for the case.
Why the records and imaging that anchor a case have to be locked down early.
How a brain injury is proven when the defense calls it something older.
The catastrophic spine cases where “degenerative” is the first defense raised.
A degenerative label is a starting position, not a verdict. Herb Borroto, M.D., J.D., reads the actual imaging; Alex Alvarez applies the eggshell and aggravation rules that protect an injured person. Free, confidential.
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