Pre-Existing Conditions and Injury Causation: What Attorneys Should Consider

By Dr. Steven B. Ross, DC, FASBE, DAAPM

Chiropractic Physician | Fellow, American Academy of Applied Spinal Biomechanical Engineering | Diplomate, American Academy of Pain Management.

A pre-existing condition does not automatically mean that a reported injury is unrelated to a subsequent accident.

At the same time, the presence of symptoms after an accident does not automatically establish that the accident caused the condition.

For attorneys evaluating a personal injury case, the more important question is whether the available evidence supports a causal relationship between the event and the patient's current condition.

That distinction can become particularly important when a patient has documented pathology, previous symptoms, or a history of treatment before the reported incident.

Understanding Injury Causation in the Presence of a Pre-Existing Condition

A pre-existing condition can complicate the evaluation of injury causation, but it does not necessarily resolve the question.

The analysis may require consideration of several factors, including:

• The nature and extent of the pre-existing condition

• Whether symptoms were documented before the incident

• The mechanism of the reported event

• The timing of new or worsening symptoms

• Clinical findings following the incident

• Changes in treatment or functional status

• Diagnostic findings before and after the event

• Other potential explanations for the patient's condition

Looking at these factors together can provide a more complete picture than relying on any single fact.

Pre-Existing Does Not Automatically Mean Unrelated

One of the common assumptions in medical-legal cases is that if a condition existed before an accident, the accident could not have contributed to the patient's symptoms.

That conclusion may be too simplistic.

A patient may have an underlying condition that was previously asymptomatic or relatively stable and then experience new or increased symptoms following an event. Determining whether the event caused, aggravated, accelerated, or otherwise contributed to the patient's condition requires an evidence-based analysis.

The question is not simply whether the condition existed before the accident.

The question is what changed, when did it change, and does the evidence support a relationship between that change and the reported event?

Why Timing Matters

The timing of symptoms can be an important part of the analysis.

For example, an attorney may encounter a case where a patient reports no significant symptoms before an accident but develops symptoms afterward. That information may be relevant, but it should be evaluated alongside the rest of the medical record.

The medical history may reveal prior imaging findings, previous treatment, intermittent symptoms, or other factors that provide additional context.

Likewise, a patient with an established condition before an accident may experience a significant change afterward. The existence of the prior condition does not, by itself, answer whether the accident contributed to that change.

The Role of Objective Evidence

A strong medical-legal evaluation should move beyond assumptions and examine the available evidence.

Medical records, diagnostic findings, clinical examinations, treatment history, reported symptoms, and the mechanics of the incident may all contribute to understanding the case.

The goal is not to automatically attribute a condition to the accident.

It is also not to automatically dismiss the possibility of causation because a pre-existing condition exists.

The goal is to determine what the available evidence actually supports.

Questions Attorneys Can Ask

When reviewing a case involving a pre-existing condition, attorneys may find it useful to ask:

1. What was documented about the patient's condition before the incident?

2. What changed following the reported event?

3. Is the reported mechanism capable of producing the claimed injury or aggravation?

4. Do the clinical and diagnostic findings support the reported change?

5. Have other potential explanations been considered?

These questions can help identify where additional medical or biomechanical analysis may be appropriate.

Conclusion

Pre-existing conditions can make medical-legal cases more complex, but complexity does not eliminate the possibility of causation.

The most useful approach is to examine the complete picture rather than relying on a single assumption.

The presence of a pre-existing condition is a fact to be evaluated, not an automatic conclusion about causation.

For attorneys, understanding that distinction can lead to more informed case evaluation and more focused questions when reviewing medical evidence.

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.