Prior problems do not prevent you from being eligible for workers compensation. In order to have a workers' compensation claim you must (1) have an injury by accident (2) arising out of and (3) in the course of employment. This standard applies even if you have a pre-existing condition. At the time you are hired, an employer takes you as you are regardless of your prior knee problem and prior back problem. At least for the purposes of workers compensation in Arizona.
An aggravation of a preexisting problem can be an original or a "new" workers' compensation claim. If a work activity causes the need for new medical treatment or increased disability then there is a workers' comp claim. Additionally, an organic (physical) change could be a new workers' compensation claim. Essentially, you have a claim if a work activity combines with your pre-existing condition to create a bigger or more serious injury. Any work related exacerbation of symptoms that require further medical treatment, create a compensable workers' compensation claim.
Whether or not you have a pre-existing condition, if you are injured at work, you should receive, at the very least, more medical care. If you have a decreased ability to work as a result of the work injury, you should also be entitled to compensation. Ideally, you would have comparative MRIs from before and after the workplace injury.
For example, if you were hiking a lot in Flagstaff five years ago and you developed Chondromalacia, more commonly known as runners' knee. You have knee pain on and off for the next 5, years and you seek treatment for it. Last week, at work in Phoenix, you were carrying a box down the stairs, missed a step and overextended your knee injuring your ACL. You immediately tell your supervisor and seek medical attention. Let say for this example, the doctor puts you on light duty. You have a new work related injury regardless of the pre-existing chondromalacia. You may be able to get compensation for the medical treatment you need. Not only that, you may be able to get compensation because you have an increase in disability as evidenced by your light duty status.
Even if you have a pre-existing degenerative condition, if your work caused an increase in your symptoms or accelerated your need for further treatment or required you to seek more frequent medical attention, you should be compensated.
Unfortunately sometimes the insurance company will take a brief look through your records or a questionnaire and hear the word pre-existing and automatically deny the claim. You will essentially need to prove that the disability you have now, is greater than it would have been without the work contribution. What you are then forced to do is filing for a hearing request protesting the denial of your claim. It will also most likely require medical testimony. It shouldn't be this way, but it is a fairly common reality.
Questions to ask yourself are whether or not the work injury caused your preexisting condition to reoccur, to get worse, to spread to other body parts. Do you have more or new work restrictions? Do your diagnostic tests from before and after your work injury show different things? If your answer to any of these questions is yes, you should contact Fendon Law Firm for a free consultation.