The answer is "yes," so long as the activity that caused the subsequent exacerbation 1) was reasonably foreseeable, and 2) was a result of a weakened condition created by the original injury. Examples of foreseeable activities include lifting, bending, walking, etc. Examples of non-foreseeable (and threfore non-related) activities include a subsequent car collision, battery, etc.
The following is taken from my recent brief on the issue:
If the negligent actor is liable for an injury which impairs the physical condition of another's body, the actor is also liable for harm sustained in a subsequent accident which would not have occurred had the other's condition not been impaired, and which is a normal consequence of such impairment.
Similarly, Uniform Civil Jury Instruction 20.07, provides:
We at Dwyer Williams Potter, Attorneys feel that this is a good rule. Boiled down to the nut, it provides protection for a worsening of the underlying injuries while performing normal acts that would not have caused pain had the original injury never occurred. At the same time, it offers protection to the person who caused the original injury, in that only exacerbating activities that are reasonably foreseeable are included in the rule, thus striking a balance for both sides.
If you find the defendant was negligent and that such negligence caused injury to the plaintiff, the defendant would also be liable for any additional injury caused by the subsequent conduct of another person or entity, even if such conduct was negligent or wrongful, as long as the subsequent conduct and risk of additional injury were reasonably foreseeable.
- Tim Williams