Detailed answer — how South Dakota law treats aggravated pre‑existing conditions

Under general tort principles applied in South Dakota, a person who negligently injures another is responsible for the full extent of the harm that their conduct causes, even if the plaintiff had a prior vulnerability or illness. Courts often describe this as the rule that a defendant “takes the plaintiff as he finds him.” Practically, that means if an accident materially aggravates a pre‑existing back problem, you can recover damages for the aggravation and any new or intensified symptoms, treatment costs, lost earnings, and non‑economic losses (like pain and suffering) that flow from the aggravation.

Causation: the core requirement

Two elements matter most: (1) the defendant’s breach (for example, negligent driving) must have caused an injurious event, and (2) that event must be a legal cause of the increased harm to your back. You do not need to prove that the accident was the sole cause of your condition — only that it was a substantial factor in making it worse.

Proof: medical and expert evidence

Because a pre‑existing condition already existed, you will usually need medical records and an opinion from a treating physician or medical expert linking the aggravation to the accident. Useful proof includes:

• Pre‑accident medical records and imaging showing baseline condition.
• Post‑accident records, notes, and imaging showing new or worsened findings.
• A medical opinion that the accident more likely than not caused or materially aggravated your back condition and that any additional treatment was necessary because of the accident.

Damages you may recover

Typical categories include:

• Reasonable and necessary medical expenses for diagnosis, treatment, surgery, rehabilitation, and future care tied to the aggravation.
• Lost wages and reduced earning capacity caused by the worsened condition.
• Pain, suffering, loss of enjoyment of life, and mental anguish resulting from the aggravation.
• Costs for assistive devices, home modifications, or in‑home care if required because of the aggravated condition.

Comparative fault and apportionment

If you were partly at fault for the accident, South Dakota applies comparative‑fault principles that reduce a plaintiff’s recovery in proportion to the plaintiff’s share of fault. The defendant cannot escape liability simply because the plaintiff had a pre‑existing condition; however, the jury or judge may consider the plaintiff’s own conduct when apportioning responsibility and damages.

Common defenses to expect

Defendants and insurers commonly argue:

• The pre‑existing condition, not the accident, caused the current symptoms.
• The aggravation would have happened regardless of the accident (progression of disease).
• Medical records do not support the claimed increase in symptoms or recommended treatment.

How a hypothetical claim might look (illustrative example)

Imagine a person had intermittent low‑back pain for years and saw a doctor twice before an automobile collision. After the crash, the pain became constant, new leg numbness appeared, MRI shows new herniation at the same level, and the person required a fusion. In that situation, a claim would focus on the new symptoms, the changed imaging, the necessity of the surgery, and a medical opinion tying the surgery to the accident. The victim could seek compensation for the additional medical costs, lost wages while recovering, and pain and suffering due to the worsened condition.

Practical steps to protect your claim

1. Get prompt medical care and follow all treatment recommendations. Early and consistent treatment creates a clear causal record.
2. Save and organize all medical records, imaging, and bills — include pre‑accident records to show baseline status.
3. Document your symptoms and how they changed after the accident (daily pain logs, impact on activities, photographs of scars or mobility aids).
4. Keep work records showing missed time and any loss in earning capacity.
5. Identify witnesses (passengers, bystanders, employers) who can corroborate changes in function or pain after the accident.
6. Ask your treating provider for a written opinion that links the aggravation to the accident; if necessary, retain an independent medical expert who can testify to causation and future needs.
7. Contact an attorney experienced in personal injury as soon as possible — many attorneys will evaluate whether the aggravation is compensable and help preserve evidence and testimony.

Helpful hints

• Do not delay care. Gaps between the accident and treatment make it harder to prove causation.
• Pre‑existing records are useful: they can show the degree of pre‑existing injury and make the argument for increased damages more credible.
• Insurers often dispute causation; objective records (imaging, consistent provider notes) strengthen your position.
• Keep all correspondence from insurers and do not sign releases without advice from a lawyer.
• Ask whether your attorney will consult medical experts and whether expert fees are advanced or handled through contingency arrangements.