"The surgery made it worse."

The basic rule first

A compensable consequence is compensable. If the employer's obligation to provide treatment led to that treatment, and the treatment caused new harm, the new harm belongs to the claim. That is settled and it is not controversial.

This covers more than a bad surgical outcome. A fall while on prescribed medication. A reaction to a drug. An infection acquired during treatment. A second injury sustained travelling to a required appointment. Nerve damage from a procedure. A frozen shoulder from immobilization.

The apportionment argument — this is the valuable part

Normally the carrier can reduce what it owes by attributing part of your disability to something else, under Labor Code §§ 4663 and 4664. That is apportionment, and it is the most common way case value is cut.

Hikida v. WCAB (2017) held that where the employer's medical treatment itself causes new permanent disability, that disability is not subject to apportionment — the employer takes responsibility for the consequences of the treatment it provided. But Hikida was narrowed.* County of Santa Clara v. WCAB (Justice) *(2020) 49 Cal.App.5th 605 [85 Cal.Comp.Cases 467] holds that it "precludes apportionment only where the industrial medical treatment is the sole cause of the permanent disability." Where pre-existing pathology also contributes, §§ 4663 and 4664 apportionment still applies.

Later authority has narrowed how broadly that applies, particularly where the treatment addressed a condition that was itself partly non-industrial. So this is a real argument rather than an automatic answer. But it is a strong one, it is worth a great deal when it lands, and it is frequently not raised at all.

If your permanent disability was substantially caused by a failed surgery, and the carrier is apportioning your rating, that is a fight worth having. How apportionment works.

What decides it

The medical record has to connect the disability to the treatment. A physician needs to say, with reasoning, that the current impairment arises from the surgery or the complication rather than from the underlying condition.

Pre-operative baseline matters enormously. Range of motion, strength, and function documented before the surgery are what the post-operative findings get measured against. If nobody documented the baseline, get the records that show it anyway — physical therapy notes, prior QME reports, the surgeon's own pre-op exam.

And the treatment has to have been for the industrial injury, which is usually obvious but occasionally is the whole dispute.