Medical records
Aggravation of a preexisting condition
Aggravation of a preexisting condition is the legal theory that an incident worsened a condition the claimant already had — compensable in most jurisdictions, but only to the extent of the worsening, which makes the medical baseline the whole fight.
Tort law takes plaintiffs as it finds them — the “eggshell plaintiff” rule — so a defendant whose negligence worsens a bad back is liable for the worsening. But the corollary defines the battleground: the defendant owes for the delta, not the baseline. Some clinicians distinguish exacerbation (a temporary flare that returns to baseline) from aggravation (a permanent worsening); the legal significance of the distinction varies by jurisdiction, but the trajectory question it encodes — back to baseline, or not? — is universal.
Why it matters in practice
Aggravation cases are baseline-reconstruction cases. The pre-incident chart controls: how often was the condition treated, what did imaging show, what could the claimant do? Then the same questions after. Plaintiff teams want the fullest possible pre-incident record (a documented quiet baseline makes the post-incident change vivid); defense teams want the same record for the opposite reason. The classic failure mode is discovering the prior injury late — from the defense, at deposition.
In the fact record
This is the exact split FactMarshal’s medical analysis renders: treatment history divided at the incident date, baseline on one side, claim on the other, each visit cited — so the delta argument is built from the record instead of asserted at it.