Yes, if the work accident caused aggravation of the prior condition, then what has been aggravated should be covered.
Aggravating a prior injury or condition
Aggravation of a prior injury or condition is covered if the aggravation occurs by accident, arising out of and in the course of employment. However, the employer is only responsible for the part that was aggravated and the increase in impairment that may result. The extent of aggravation is typically left up to a doctor to clarify.
Example:
Cheryl has had problems with her right elbow since childhood. However, her condition was not serious enough to require surgery.
Recently, Cheryl slipped on some ice in the employee parking lot on her way into work which caused further injury to her right elbow. As a result, she underwent several surgeries and was assigned a permanent partial impairment rating to her right elbow by the orthopedic surgeon.
There are a couple of points to note from this example.