Workers' Compensation

California: Apportionment of Permanent Disability Per Benson

What Happens When One AME Cannot Apportion Permanent Disability Per Benson and Five Other AMEs Can?

In Mills v. American Medical Response, 2019 Cal. Wrk. Comp. P.D. LEXIS 84, the WCAB affirmed the WCJ’s finding that applicant was entitled to a single, unapportioned award of 100 percent permanent disability as a result of four separate specific and cumulative industrial injuries incurred during his employment as a paramedic.

The WCAB found no legal basis to apportion applicant’s permanent disability between his separate industrial injuries pursuant to Labor Code § 4663 and Benson v. W.C.A.B. (2009) 170 Cal. App. 4th 1535, 89 Cal. Rptr. 3d 166, 74 Cal. Comp. Cases 113, notwithstanding that the orthopedic agreed medical examiner was able to apportion applicant’s orthopedic permanent disability consistent with Benson, where the agreed medical examiner in internal medicine was unable to apportion applicant’s internal disability between his separate dates of injury, and because there was no unanimity amongst the physicians indicating that it was appropriate to apportion between the dates of injury.

The WCAB further found that pursuant to Hikida v. W.C.A.B. (2017) 12 Cal. App. 5th 1249, 219 Cal. Rptr. 3d 654, 82 Cal. Comp. Cases 679, applicant’s permanent total disability arose directly from the effects of surgery to treat his industrial injuries, including implantation and removal of spinal cord stimulator, and, therefore, it could not be apportioned between injuries or to any other source.


The Mills case is a good, recent example of when the WCAB will allow a single award with multiple dates of injury but where evaluating physicians cannot each provide an apportionment analysis that is required under the Benson case. This case is interesting for the fact that five out of six AME physicians could do an apportionment analysis originally. Only one could not, and it appears the WCAB panel here would still award 100% permanent total disability despite the one hold-out physician who could not provide apportionment by concluding in his opinion that permanent disability cannot be parceled out. This case provides a road map for applicant’s counsel to follow to obtain an award without apportionment when there are multiple injuries and at least one evaluating physician cannot parcel out apportionment. Here are considerations that stand out in the Mills case:

  1. Long term employment of the injured employee: Applicant worked for this employer for 25 years.
  2. A heavy or arduous job: Applicant here was a paramedic where significant injurious exposure is obvious.
  3. Multiple orthopedic surgeries that result in compensable consequential parts of body injured – psychiatric, internal, urological, all of which have objective medical evidence to support the diagnosis.
  4. AME or PQME physicians do not adopt each other’s apportionment analysis: Each physician in his or her own specialty has to make an independent assessment of apportionment of permanent disability within his or her own specialty. It is not enough, for example, for a psychologist or psychiatrist to say “apportionment of psychiatric disability follows the findings of the orthopedic evaluator.”
  5. The fact that Applicant returned to his usual and customary duties after major orthopedic surgeries starting in 2003. The injurious exposure continued as there was no evidence that Applicant worked under restrictions despite the earlier orthopedic surgeries.
  6. A vocational expert opined that Applicant was not amenable to vocational rehabilitation and was totally disabled due to the failed spinal and shoulder surgeries. Most importantly, the vocational expert reviewed all of the AME reports and commented on each physician's apportionment findings.
  7. The probability that the permanent total disability is iatrogenic under the Hikida case. In this case, Applicant was left with a separate diagnosis caused by his medical treatment: a disastrous result from a spinal stimulator placement and removal.
  8. The terminology “permanent disability is inextricably intertwined” is nowhere in the Benson case. The WCAB in Benson instead says physicians need to “parcel out” approximate percentages of causation of permanent disability between injuries.

Applicants’ attorneys need to use this case as one of many that provides a roadmap to success on getting a 100% award when there are multiple dates of injuries. The WCAB panel gives you case references and some hints about deposing doctors on apportionment issues. This case should stay on your quick reference shelf.

Practitioners should check the subsequent history of any cases before citing to them.

Any information or opinions contained in this commentary are not necessarily endorsed by LexisNexis® or its affiliates.

© Copyright 2019 LexisNexis. All rights reserved.