When Does a Pre-Existing Condition Matter to Injury Causation?
By Dr. Steven B. Ross, DC, FASBE, DAAPM
Chiropractic Physician | Fellow, American Academy of Applied Spinal Biomechanical Engineering | Diplomate, American Academy of Pain Management.
When Does a Pre-Existing Condition Matter to Injury Causation?
In personal injury cases, the presence of a pre-existing condition can make injury causation more difficult to evaluate.
A patient may have had an underlying spinal condition before an accident. That does not, by itself, establish whether the accident caused a new injury, aggravated an existing condition, or had little relationship to the symptoms being reported.
The important question is not simply whether a condition existed before the event.
The question is what the available evidence shows about the relationship between the condition and the reported event.
Pre-Existing Condition and Injury Causation Require Careful Analysis
A pre-existing condition can be relevant to an injury causation analysis, but it should not automatically determine the conclusion.
A careful evaluation may require consideration of several factors, including:
The individual's medical history before the incident
The mechanism of the reported injury
The timing and development of symptoms
Objective clinical findings
Diagnostic imaging
Changes in functional status
Prior treatment and complaints
The nature and severity of the reported event
Other potential explanations for the condition or symptoms
Looking at these factors together can provide a more complete picture than focusing on any single piece of information.
A Pre-Existing Condition Does Not Automatically Answer the Causation Question
One common assumption is that if a condition existed before an accident, the accident could not have contributed to the person's current symptoms.
That conclusion may be too simplistic.
Similarly, the absence of documented symptoms before an accident does not automatically establish that the accident caused every condition identified afterward.
Both situations require analysis.
For example, an individual may have an underlying degenerative condition without experiencing significant symptoms before an event. Following an accident, the person may report new or increased symptoms.
The relevant analysis is whether the evidence supports a connection between the event and the subsequent condition or symptoms, and if so, what that relationship may be.
Timing Matters, But Timing Alone Is Not Enough
The appearance of symptoms after an event can be an important part of the history.
However, temporal sequence alone does not necessarily establish causation.
A sound analysis considers the timing alongside the mechanism of injury, clinical findings, prior history, diagnostic information, and other reasonable explanations.
This is particularly important when evaluating spinal injuries, where imaging may identify conditions that existed before the reported event.
The presence of an abnormality on imaging does not necessarily tell us when that abnormality developed or what caused the individual's current symptoms.
The Role of Evidence in Causation Analysis
This is where experience can be valuable, but it should not replace evidence.
An experienced expert may recognize patterns, identify questions that require closer examination, and notice inconsistencies that deserve further consideration.
But the final opinion should remain grounded in the available evidence.
The analysis should ask:
What does the evidence actually support?
That question can help distinguish between a diagnosis and a conclusion about causation.
What Should Attorneys Look For?
When a case involves a pre-existing condition, attorneys may benefit from asking whether the expert has considered the complete clinical picture rather than relying on a single factor.
Useful questions may include:
What was known about the condition before the reported event?
Is the reported mechanism consistent with the claimed injury?
What objective findings support the opinion?
How did symptoms change following the event?
Were reasonable alternative explanations considered?
These questions can help clarify how the expert arrived at the opinion rather than simply focusing on the conclusion.
A More Complete Approach to Causation
Pre-existing conditions are not necessarily a reason to accept or reject a causation opinion.
They are a reason to examine the evidence more carefully.
The strongest medical-legal analyses consider the patient's history, the reported event, clinical findings, diagnostic information, biomechanics, timing, and alternative explanations as part of a broader evidence-based assessment.
Ultimately, the goal is not to make the evidence fit a predetermined conclusion.
The goal is to understand what the evidence supports.
About the Author
Dr. Steven B. Ross, DC, FASBE, DAAPM is a chiropractic physician, spinal biomechanical injury analyst, Independent Medical Examiner, and expert witness with more than 40 years of clinical experience. His practice focuses on injury causation analysis, spinal biomechanics, chiropractic and medical malpractice, independent medical examinations, and evidence-based medical-legal consulting.
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