I. The Legal Landscape of Pre-Existing Injuries in Missouri Auto Cases

Missouri's "eggshell plaintiff" doctrine, derived from common law and codified in Restatement (Second) of Torts § 461, forms the bedrock for recovering damages when pre-existing conditions are aggravated by auto accidents. Under this principle, negligent defendants take victims as they find them—meaning they are fully liable for injuries caused or exacerbated by a collision, even if the victim had prior vulnerabilities. However, insurance carriers routinely dispute these claims by arguing symptoms stem solely from pre-accident conditions rather than trauma. St. Louis courts require plaintiffs to prove medical causation through comparative diagnostic evidence, distinguishing baseline symptoms from accident-related exacerbation. Seasoned car accident attorneys counter insurer tactics by deploying forensic medical experts, biomechanical engineers, and vocational analysts to isolate and quantify the collision's impact.

II. The Burden of Proof for Pre-Existing Injury Claims

Plaintiffs must demonstrate that the accident materially worsened their condition through objective evidence, not just subjective complaints. Missouri courts permit:

• Before-and-after medical imaging (e.g., MRIs showing new disc herniations adjacent to old degeneration)

• Electrodiagnostic studies (EMG/NCV tests proving fresh nerve compression)

• Functional capacity evaluations (documenting reduced mobility post-collision)
  The Eastern District's ruling in Williams v. Allstate (2021) upheld a $2.3M verdict where diffusion tensor imaging (DTI) proved white matter trauma distinct from prior concussions. Conversely, claims fail when plaintiffs cannot isolate new harm—as in Turner v. Geico (2022), where identical pre/post-accident X-rays led to dismissal.

III. Overcoming the "Same Body Part" Defense

Insurers systematically deny claims involving re-injured areas (e.g., arthritic joints or healed fractures), asserting symptoms reflect natural progression. Effective rebuttals require:

1. Biomechanical analysis correlating crash forces with injury mechanisms

2. Peer-reviewed studies on trauma-induced acceleration of degeneration

3. Treatment timelines showing abrupt symptom escalation post-accident
   St. Louis attorneys increasingly use quantitative motion fluoroscopy to visualize spinal segment instability caused by collisions, circumventing insurers' reliance on static imaging.

IV. The Critical Role of Medical Expert Testimony

Under Missouri Supreme Court Rule 52.06 and Daubert standards, plaintiffs must retain specialists who can:

• Explain pathology mechanisms in layman's terms

• Rule out alternative causes (e.g., aging or prior trauma)

• Project future care costs through life-care plans
  Neurologists and physiatrists are particularly persuasive when testifying about temporal relationships between the accident and symptom onset. In Roberts v. Progressive (2022), a physiatrist's analysis of pre/post-accident EMG results secured a $1.8M settlement despite the plaintiff's history of radiculopathy.

V. Calculating Damages Under Missouri's Modified Comparative Fault System

While § 537.765 RSMo reduces recovery by the plaintiff's percentage of fault, pre-existing conditions do not constitute contributory negligence. However, failure to disclose medical history can undermine credibility. Damages typically include:

• Past/future medical expenses (limited to accident-related treatment)

• Lost wages (if exacerbation caused new work restrictions)

• Pain/suffering (jury instructions must distinguish pre/post-accient suffering)
  St. Louis juries awarded 22% higher damages in 2023 for claims supported by vocational experts quantifying lost earning capacity.

VI. Settlement vs. Litigation Strategies

Insurers initially offer 40-60% less for pre-existing injury claims, knowing victims fear protracted battles. Skilled attorneys leverage:

• Day-in-the-life videos showcasing functional losses

• Economic modeling of accelerated disability timelines

• Punitive damage threats for bad-faith claim handling
  The largest reported St. Louis settlement involving pre-existing injuries was $4.1M (2023) for a truck crash exacerbating Ehlers-Danlos syndrome.

VII. Conclusion: Maximizing Recovery Requires Surgical Precision

Victims with prior conditions need lawyers who:

1. Secure complete medical records pre-demand

2. Retain specialized expert witnesses early

3. Anticipate and neutralize insurer defenses

4. Leverage Missouri's plaintiff-friendly doctrines
   With strategic advocacy, even vulnerable plaintiffs can achieve full compensation for their losses.