New Comp Law Defines “Preexisting Conditions”

Under a 1995 change in the workers’ compensation law, when a work injury “combines” with a “preexisting condition,” the work injury must be the major cause of the disability or need for treatment for the “combined condition” to be compensated.

There are no easy “rules of thumb” to provide guidance under this new law. It’s a case-by-case call by the medical experts. Your testimony as treating physician is key.

To understand how this works, we first must look at the new definition of “preexisting condition”: “any injury, disease, congenital abnormality, personality disorder or similar condition that contributes or predisposes a worker to disability or need for treatment and that precedes [the claim].”

What does “similar condition” mean? No one knows for sure. But note that what is similar about all the listed conditions is that something is wrong or not normal. The term “congenital abnormality” is also troubling in its potential to thwart injured workers’ claims. For example, if a worker is overweight, may this be said to be a “congenital abnormality”? This question has actually come up already, as we will see later. Consider carefully whether in your medical opinion any of these classifications applies to your patient.

The mere presence of one of these conditions is not enough. To be a “preexisting condition”, the identified injury, disease, etc. must contribute to or predispose the worker to disability or the need for treatment in a causal way. The bottom line is that the preexisting condition(s) has to be a cause of the need for treatment you are providing or of the disability from which your patient is suffering. Remember, the standard is whether the injury is the major cause of treatment or the condition, when there is a preexisting condition. Obviously, benign non-causes or non-causal predispositions or non-causal preexisting conditions are causes of nothing, and, therefore, cannot be limiting factors to compensability!

For example, a person may have totally benign degenerative changes that are not consistent with symptoms or disability at all. The question is: Are these degenerative changes causal, if the patient was totally asymptomatic prior to the injury for which the worker seeks treatment caused by the benign preeesisting condition? In such cases, is the preexisting condition causal or is it just a benign backdrop to the injury?

The next question is whether one of these conditions actually “combines with” the, work injury in causing the need for treatment, the disability or the prolonging of a disability. If your medical opinion is that such a combination has occurred, then you must determine whether the injury or the preexisting condition is the major contributing (51% or more) cause of the condition or need for treatment or the disability or its prolonging.



Here are some illustrations of the potential uses and abuses of these new laws. A woman had developed the occupational disease of bi-lateral carpal tunnel syndrome (CTS). The independent medical examiners hired by the insurance carriers identified that the worker’s “being female and slightly overweight” were predispositions to the development of CTS. However, based on the persuasive opinion of the worker’s attending physician the Board found that the worker did not have any conditions which contributed or predisposed her to disability or the need for treatment for her CTS to any causative degree. Therefore, she did not have a “preexisting condition” which was actually causative.

“Being female” was not a preexisting condition because it was not an “injury, disease, congenital abnormality, personality disorder or similar condition.” Also, the medical examiners did not explain why being “slightly overweigh” predisposed her to disability or the need for treatment for CTS. (What if the medical examiners did explain and the attending physician was not so persuasive?)

Another case involved a woman with a left knee injury who had a patellar dislocation two or three years prior. The insurance carrier contended that her injury had “combined” with her preexisting, left knee condition, and the work injury was not the major contributing cause of her need for treatment. However, relying on an unrebutted opinion from the worker’s treating surgeon, the Board found that the old patellar dislocation had stabilized and the current dislocation was caused solely by the work incident. There was no persuasive medical evidence that the work injury had “combined” with her preexisting condition (patellar subluxation and tracking problems).

Since there was no “combined condition,” there was no need to show that the work injury was the major contributing cause. Since there was no question of the relative amount of cause contributed by a preexisting condition, the work injury to the knee was clearly compensable.


We frequently see situations where a worker has had few or no previous problems with his/her back, and then suffers a significant work trauma with ongoing symptoms. Subsequent scans show degenerative changes. What has to be assessed, in the event of persisting symptoms, is the role of the injury in converting an asymptomatic condition into a new symptomatic condition, which is now in need of treatment, but was not before.

Did the work injury strain or sprain spinal ligaments which have not healed back to their original length causing instability at the affected joint? Has the injury created a new symptomatic condition by setting off the arthritis? If so, what is the pathogenesis of the symptoms? Is the body responding to the trauma by splinting of the muscles or additional bone growth, pathologically seeking stabilization? What happens if there is a serious strain or sprain of ligaments and they are rendered lax as a result of the injury? These are the types of questions which must be considered in order to put into proper perspective the relative roles of the impact of the work trauma and the preexisting. condition. The existence of a “preexisting condition” calls for more careful analysis.


In summary, your opinion as treating doctor is key when a worker’s injury may he combined with a preexisting condition. You should ask yourself: 1) Given my patient’s pre-injury status (a complete history is essential), is this work injury the major (51% or more) reason he/she needs treatment and or is disabled (has a prolonged disability) now? If so, your records should clearly state your view of the major role of this work trauma.

If and only if, you think some prior problem could be the major cause of the need for treatment or of the disability, then consider: 2) Prior to the work trauma, did my patient have a condition of the type described above? 3) If yes does the condition contribute or predispose my patient to disability or the need for treatment, that is, is it a cause? 4) If yes, does this preexisting condition “combine with” the work injury/condition? 5) If yes, is the pre-existing condition portion of this combined condition” the major contributing (51% or more) cause of the disability (or its prolonging) or the need for treatment?

Be prepared to state persuasively the reasons for your answers. If you answer “no” to questions two, three or four, then the work injury is probably compensable since no preexisting condition will be competing with it for major causation status. However, if all the criteria for a combining preexisting condition are met, then you must be able to state that the work injury/exposure was the major contributing (51% or more) cause of the disability or need for treatment for the claim to be compensable.

This article was prepared by Arthur W. Stevens, III