An old injury does not end a Texas car accident claim. What the law lets you recover is the harm the crash added: new or worse symptoms, new treatment, new limits. The work in these cases is proving where the line sits between your condition before the collision and your condition after it, usually with medical records and a treating doctor’s opinion.
The short version
- Aggravation is recoverable. A Houston appeals court approved a jury instruction defining injury to include “aggravation of any disease, infirmity, or condition, previously or subsequently existing” (Weidner v. Sanchez, 14th Court of Appeals, 2000).
- The burden is yours. The Texas Supreme Court has said the plaintiff must prove the crash caused the injuries and exclude other plausible causes the record supports (JLG Trucking v. Garza, 2015).
- Doctors usually have to connect the dots. Expert testimony is needed for medical conditions outside jurors’ common knowledge.
- A scan alone does not settle it. A 2015 review of 3,110 people with no symptoms found disk degeneration in 37 percent at age 20 and 96 percent at age 80.
- A bill affidavit is not proof of cause. Under Civ. Prac. & Rem. Code § 18.001(b), it supports reasonableness and necessity of charges, not causation.
Can you still recover if you were already injured before the crash?
Yes, for the part the crash caused. Texas courts allow a jury to be told that an injury includes the aggravation of an existing disease, infirmity or condition. You are not paid for the condition as it stood before the collision, only for what the collision made worse.
The clearest Houston example is Weidner v. Sanchez, a Fourteenth Court of Appeals opinion filed February 17, 2000, from a Harris County court at law. A Liberty Cab driver ran a stop sign and collided with another vehicle while carrying a passenger home from her doctor. The passenger had arthritis before the crash. She testified that she never needed more than Advil for it before the crash and that Advil was no longer enough. The jury was instructed that “injury” means damage to the body “or the incitement, acceleration, or aggravation of any disease, infirmity, or condition, previously or subsequently existing, by reason of such damage or harm.” The court of appeals noted the definition is not generally included in a negligence charge but “correctly states the law” given the pleadings and evidence, and it affirmed. You can read the opinion on the Texas courts site (read 16 October 2026).
That is one court’s treatment of one record; your claim still needs the proof described below. For the overall claim, see our Houston car accident lawyers page, the step-by-step claim walkthrough and the car accident FAQ.
How is an aggravation different from a pre-existing condition?
The pre-existing condition is what was already there: a degenerated disc, an earlier surgery, an old joint injury. The aggravation is the change after the crash: new symptoms, new findings, treatment you did not need before. Only the change is the subject of the claim.
Think of two snapshots: your health before the collision, as the records show it, and your health afterward. The claim lives in the difference, which must be linked to the crash rather than to age, a second incident or the natural course of the condition. Fault is a separate question; the percentage of blame each person bears is in our article on shared fault under Chapter 33, and a person with no fault still has to prove the injury came from the crash.
The same two-snapshot logic applies to injuries that do not show on a scan; see brain injury claims.
What does the injured person have to prove?
That the other driver’s conduct caused the crash and that the crash caused the injuries claimed, including which conditions produced each medical expense. If the record shows another plausible cause, the injured person must also exclude it with reasonable certainty.
In JLG Trucking, LLC v. Garza (decided April 24, 2015), a woman rear-ended by an 18-wheeler on U.S. Highway 83 in Zapata County said the crash herniated discs in her neck. Three months later she was in a second collision. The Supreme Court restated the framework: a plaintiff must “prove that the conduct of the defendant caused an event and that this event caused the plaintiff to suffer compensable injuries,” and, to recover medical expenses, must show “what all the conditions were” and “that all the conditions were caused by the accident.” It also held that part of the plaintiff’s burden “was to exclude with reasonable certainty other plausible causes of her injuries supported by the record.” The case was sent back for a new trial. The full opinion is on the Texas courts site (read 16 October 2026).
For an aggravation claim, the evidence must show which conditions the crash made worse and why a competing explanation, such as a later accident or natural progression, does not account for the change. See preparing for a case evaluation and what to do in an auto accident.
When does a case need a doctor’s testimony?
When the medical condition is outside what jurors know from everyday experience. The Texas Supreme Court has held that expert testimony “is necessary to establish causation as to medical conditions outside the common knowledge and experience of jurors,” and that timing alone does not by itself support an inference of medical causation.
Both statements come from Guevara v. Ferrer (Tex. 2007), as restated in JLG Trucking. In Guevara the plaintiff had hypertension, heart disease and kidney failure, and the family sought over $1 million in medical bills without expert proof. The court found the evidence legally sufficient for some expenses, such as emergency-room care right after the crash, but not for “what the conditions were that generated all the medical expenses or that the accident caused all of the conditions.” The court also confirmed that evidence of temporal proximity is not irrelevant to causation.
Lay evidence can still matter. In Weidner, the court listed three routes a jury may use to find the link: general experience and common sense, expert testimony tracing a chain of causation, or expert testimony showing probable cause. It found “a strong and logically traceable connection” in the plaintiff’s own account together with the treating orthopedic surgeon’s opinion that the crash aggravated her arthritis. When a case involves more than one possible source, plan on a doctor. Our article on expert witnesses in a truck-crash case shows how experts are used.
What records and evidence show the before and after?
Medical records from before the crash, emergency and first-visit records from right after it, imaging from both periods, the treating doctor’s opinion, and non-medical proof of what you could do before and cannot do now. Each answers a different part of the comparison.
| Evidence | What it can show | Court example |
|---|---|---|
| Records and prescriptions from before the crash | How often the condition was treated and how bad it was | In Weidner, the defense expert relied on a doctor’s record that the plaintiff had neck, shoulder and back pain for years and had seen a chiropractor for fifteen years. |
| Emergency-room and first-visit records | New complaints close in time to the collision | In JLG, records from the second accident’s emergency treatment showed neck pain; the plaintiff’s doctor had not reviewed them. |
| Imaging before and after | Structural change, read in the patient’s clinical context | In JLG, an MRI after the second accident showed herniated discs. |
| Treating doctor’s opinion | Whether the crash, in medical probability, caused the change and what care it requires | In Weidner, an orthopedic surgeon testified the crash aggravated a pre-existing arthritic condition. |
| Your own account | What you could do before and what you cannot do now | In Weidner, the plaintiff testified Advil had been enough before the crash and was not afterward. |
Sources: Weidner v. Sanchez, Tex. App.—Houston [14th Dist.] 2000 and JLG Trucking v. Garza, Tex. 2015, both read 16 October 2026. The table lists kinds of evidence; what exists in your case depends on your own history.
Gathering them usually means signing an authorization; weigh the scope using our records-release guide. Unconventional treatment raises its own questions: alternative medicine and a crash claim.
Records from a Harris County public hospital come from Harris Health’s Release of Information office in Bellaire, which takes an authorization form or a written request with a photo ID and says complete requests can be filled within 15 business days (Harris Health, Medical Records, read October 16, 2026). Keep copies for the insurance claim and for any written statement to the insurer.
What will the insurance company argue?
Typically that the problem was already there, that something else caused it, or that the records do not connect it to the crash. Reported cases show all three: degeneration, a second accident, and a long history of treatment for the same pain.
Degeneration is the first argument. The defense expert in JLG testified the plaintiff’s disc problems were degenerative and not trauma-related, and the plaintiff’s own doctor testified he relied on that expert to rule out the second accident. Imaging evidence cuts both ways. A systematic review of 33 studies covering 3,110 people without symptoms, published in the American Journal of Neuroradiology in April 2015, found disk degeneration in 37 percent of 20-year-olds and 96 percent of 80-year-olds, disk bulges in 30 and 84 percent, and concluded that many imaging-based degenerative features are “likely part of normal aging and unassociated with pain” and must be read in the context of the patient’s clinical condition (record read 16 October 2026). A report that says “degenerative changes” therefore begins the analysis; it does not end it.
A second event is the other argument. In JLG the Supreme Court held the later accident was relevant to whether the first crash caused the herniations, and that excluding it was harmful error, in part because it curtailed the defense’s ability to probe why the plaintiff’s doctor discounted the second accident, when he had not reviewed the records from her emergency treatment after it. Our overview of common insurer strategies after a crash and the note on insurers that stall describe what to expect.
Why can’t a medical bill affidavit settle the question of cause?
Because the statute says so. Unless a counteraffidavit is served, a Section 18.001 affidavit is sufficient evidence that a charge was reasonable and the service necessary, but “is not evidence of and does not support a finding of the causation element,” and a counteraffidavit cannot be used to dispute causation either.
Subsection (b) of § 18.001 confines the affidavit to cost and necessity, and subsection (f) runs the limit the other way: a counteraffidavit “may not be used to controvert the causation element.” Deadlines for serving each are set by § 18.001(d) and (e). For an aggravation case the consequence is simple: the bills can come in on one track, but the link between this crash and this worsening still rests on testimony and records. The statute is on the Texas Legislature’s site (read 16 October 2026).
What damages can the worsening of an old injury support?
Losses tied to the aggravation: the added medical care and lost income, which Texas classes as economic damages, and the added pain, impairment and loss of enjoyment of life, which fall under noneconomic damages. Medical expenses are limited to what was actually paid or incurred.
Under the damages chapter, economic damages repay pecuniary loss (§ 41.001(4)), noneconomic damages cover pain and impairment among other things (§ 41.001(12)), and § 41.0105 caps medical expenses at what was “actually paid or incurred.” Chapter 41 text (read 16 October 2026). Each category is walked through in types of crash damages, value in valuing a Houston crash claim, a spouse’s separate loss in loss of consortium, and timing in how long a case takes. The general limitations period is in § 16.003; see how long you have to file and confirm your date with an attorney.
What should you tell your doctors and your lawyer about an old injury?
All of it, from the first visit. A treating doctor who knows the full history can explain the change; one who learns of a prior injury or a second incident for the first time under cross-examination has a credibility problem that can reach the whole case.
The JLG record shows how that plays out. The plaintiff’s doctor testified he did not think he had asked about other accidents, his July note recorded no other history of injury, and he had not reviewed the second accident’s emergency records; the Supreme Court said the exclusion kept the defense from probing why he discounted that accident. The same rule applies to your own statements. Before you answer an adjuster’s question, read why to speak with a lawyer first, and keep a written list of earlier treatment so nothing is left out of your account.
If an old injury is part of your story, compare lawyers with these five hiring questions, read the auto accident and personal injury pages, and see this article on cost for how fees are handled. Whether an injury qualifies as a claim at all is explained in this overview of Texas injury cases. Bring the list of earlier treatment when you describe the new injury.
Frequently asked questions
How do you prove a car accident made a pre-existing condition worse?
By comparison. The claim needs records showing the condition before the crash, records showing it afterward, and a doctor who can explain, in medical probability, what changed and why the collision caused it. Bills alone do not do this, and a second incident must be accounted for.
What happens if a car accident aggravates a pre-existing condition?
The claim is for the worsening, not the old condition. In the Houston case Weidner v. Sanchez, the jury was told injury includes aggravation of an existing condition, and the court of appeals affirmed. The worsening still has to be proved as caused by the crash.
What should I expect from a car accident claim with a pre-existing condition?
Expect questions about your earlier treatment and requests for older records. Courts look at whether the crash caused each condition and each expense, so your medical history becomes part of the case. Providing a full, accurate history early is usually safer than having it surface later.
My MRI report says “degenerative changes.” Does that end my claim?
No. A 2015 review found degenerative findings in many people with no pain, and said they must be read with the clinical picture. The question is whether the crash made a quiet or stable condition symptomatic or worse, which comparison of records and a doctor’s opinion answer.
Should I tell my doctor about my old injury after the crash?
Yes. In a reported Texas Supreme Court case, a plaintiff’s doctor testified he did not think he had asked about other accidents and had not reviewed records of a later one, and the Supreme Court said excluding the later accident kept the defense from probing why he discounted it. A complete history lets your doctor explain the change.
If I was hurt again after the crash, can I still recover?
Possibly, but the later event will be examined. In JLG Trucking v. Garza, the Supreme Court held a second accident was relevant to whether the first caused the injuries. The plaintiff must still prove the first crash caused the harm claimed, and exclude other plausible causes.
Does the lawyer for the other driver get my old medical records?
Not automatically. Records come through an authorization you sign or through the discovery process once a suit is filed. Review any authorization with your attorney first, because how broadly it is written decides how much of your history is released.
About the authors
Sam A. Maida, Jr.
Owner and Managing Attorney
Sam A. Maida, Jr. has represented injured Texans in the greater Houston area since the firm opened in 1993.
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Bernard G. Johnson III
Litigation Managing Attorney
Bernard G. Johnson III is a board certified trial lawyer licensed in Texas since 1996 and a graduate of South Texas College of Law.