Workers' Compensation

California: Elements for Rebuttal of a Strict Rating of the AMA Guides

One of the primary goals and foundation of the workers’ compensation system is to provide adequate medical treatment for injured workers, enabling them to promptly return to their usual and customary jobs. Hence, it is not unusual for a worker to be injured, receive appropriate medical treatment, and return to “base line,” ready to return to his or her usual and customary job. It’s logical that those cases might result in a 0% whole person impairment (WPI) in accordance with the rating guidelines of the AMA Guides, since fortunately, although the worker suffered an industrial injury, he or she is not permanently disabled. 

Pursuant to page five of the AMA Guides, an injury rated at 0% WPI “… does not limit the performance of the common activities of daily living as indicated in Table 1-2.” However, over the years since the AMA Guides has been used for rating industrial injuries, it was discovered that in some 0% WPI cases, the injured worker’s ability to perform daily activities was significantly and negatively impacted. In these situations, the 0% strict AMA Guides rating would not seem consistent with the definition of a 0% rating as set forth in the AMA Guides.

Editor’s Note: The citations below link to Lexis Advance.

Parties used this inconsistency as one of many arguments in favor of allowing a rebuttal to a strict rating under the AMA Guides. Eventually, the courts resolved this issue by allowing the medical evaluator to offer an alternate and in her or his opinion a more accurate WPI rating, as long as certain guidelines were met. (See Milpitas Unified School District v. WCAB (Guzman), (2010) 187 Cal. App. 4th 808; 75 Cal. Comp. Cases 837 – 6th DCA) Recently, this standard was tweaked a bit by the 3rd DCA in the case of City of Sacramento v. WCAB (Cannon), (2013 – ordered published on 1/15/2014) 222 Cal. App. 4th 1360; 79 Cal. Comp. Cases 1, to clarify that this principle was not limited to “complex and extraordinary” cases. The Cannon case also provided a roadmap for rating impairments not listed in the Guides.

The “Guzman rebuttal” concept has evolved a bit over the years and the WCAB has continued to issue panel decisions illustrating what is required to rebut a strict rating of the AMA Guides. One such case is Lobdell v. California Department of Corrections & Rehabilitation, 2014 Cal. Wrk. Comp. P.D. LEXIS 65.

The Lobdell case dealt with a thirty-eight year old accounting officer, Trixie Lobdell, who spent a great deal of time operating a computer on an industrial basis. As a result of these “repetitive hand motions at work,” as assessed by Dr. Joel Renbaum, the AME in this case, Ms. Lobdell sustained a cumulative trauma injury to her right upper extremity.

After a thorough medical evaluation, the AME diagnosed Ms. Lobdell with the following:

1. Epicondylitis in her right upper extremity

2. “tardy ulnar nerve palsy” and

3. Repetitive stress injury

Dr. Renbaum noted that the injured worker’s injury would rate at 0% using a “strict interpretation of the Guides. He also noted that the injury significantly impacted Ms. Lobdell’s ability to perform her activities of daily living (ADLs) listed in Table 1-2 which are as follows:

> Self-care, personal hygiene

> Communication

> Physical activity

> Sensory function

> Non-specialized hand activities (such as grasping and lifting)

> Travel

> Sexual function

> Sleep

Therefore, Dr. Renbaum set forth an alternate rating, pursuant to the instructions in the Guzman case.

First, Dr. Renbaum reviewed Chapter 16, the chapter of the Guides which deals with Ms. Lobdell’s injured body part, the right upper extremity. Epicondylitis is mentioned in Section 16.7d as follows:

Several syndromes involving the upper extremity are variously attributed to tendinitis, fasciitis, or epicondylitis…. Although these conditions may be persistent for some time, they are not given a permanent impairment rating unless there is some other factor that must be considered.

As explained in the Judge’s Opinion on Decision, “Dr. Renbaum stated that there was “no ratable impairment for the right elbow, forearm or hand/wrist based on todays’ examination per the AMA Guides” (Joint Exhibit 1, at page 6). Dr. Renbaum stated that “[t]his rating was obtained using a strict interpretation of the Guides.

Dr. Renbaum took a thorough history and performed all required diagnostic testing. In addition, he explained in depth how the work injury resulted in a “significant grip loss,” as well as significant levels of pain, all of which impacted her activities of daily living.

Noting that Chapter 16 did not provide a measurement for accurately rating Ms. Lobdell’s injury, Dr. Renbaum turned to Chapter 13, which deals with “The Central and Peripheral Nervous System.” Specifically, he selected Table 13-22 at page 343 as the appropriate metric to use in this case. Table 13-22 is entitled, “Criteria for Rating Impairment Related to Chronic Pain in One Upper Extremity.”  There are four classes of impairment levels included in Table 13-22, with ratings from 1% WPI to 45% WPI.

Dr. Renbaum concluded that Ms. Lobdell’s injury best fit within Class I which is described as “Individual can use the involved extremity for self-care, daily activities, and holding, but is limited in digital dexterity.” He further explained “how” and “why” Ms. Lobdell’s injury fit best within this category. He selected 9% WPI from Class I, which is at the top of range of 1-9% WPI, because that level best reflected the significant impact of the injury on Ms. Lobdell’s activities of daily living.

This resulted in the following rating string:–9% - [5] - 11–111G-13–13%.

Dr. Renbaum explained his conclusion for rejecting the 0% WPI as follows:

It is my opinion that this impairment rating would not be an accurate measurement of this patient’s permanent disability based on my clinical experience and in consideration of the effects of the residuals of the work injury on the patient’s Activities of Daily Living. These include her ability to do repetitive gripping, grasping, pinching, because of pain, and result in the use of the Almaraz/Guzman II decision. In this case, the patient would fall into a cohort of patients whose level of impairment is greater than that obtained using a strict interpretation of the Guides. Taking into account the Almaraz/Guzman decision, the most accurate measurement of the patient’s impairment is obtained by using Table 13–22, page 343, Class I, dominant extremity = 9% WPI.

Ms. Lobdell’s primary treating physician, Dr. Lin, also provided a “rebuttal rating” of 2% WPI, based on applicant’s level of pain “using Chapter 18 of the AMA Guides.” However, the 2005 PDRS bars a stand-alone rating based on a subjective complaint of pain only. At page 1 – 12 of the 2005 Permanent Disability Rating Schedule, it is very clear that a WPI rating “may be increased… up to 3% WPI if the burden of the worker’s condition has been increased by pain-related impairment in excess of the pain component already incorporated in the WPI rating in Chapters 3-17. (AMA Guides p. 573.)” If there is no initial WPI rating, then there can be no 1-3% pain “add-on.”

The 6th DCA in Guzman stated that a rebuttal rating must be based on a medical report that constitutes substantial evidence. The court quoted a checklist of sorts regarding “substantial medical evidence” from the decision of E.L. Yeager Construction v. WCAB (Gatten), (2006) 145 Cal. App. 4th 922; 71 Cal Comp Cases 1687 and explained, the physician’s medical opinion “must constitute substantial evidence” of WPI and “therefore … must set forth the facts and reasoning [that] justify it.” “In order to constitute substantial evidence, a medical opinion must be predicated on reasonable medical probability. [Citation.] Also, a medical opinion is not substantial evidence if it is based on facts no longer germane, on inadequate medical histories or examinations, on incorrect legal theories, or on surmise, speculation, conjecture, or guess. [Citation.]”

The WCJ analyzed the facts in Lobdell in accordance with the mandate of the DCA in Guzman and adopted Dr. Renbaum’s analysis as the most accurate reflection of Ms. Lobdell’s industrial injury.


Before filing a Declaration of Readiness to proceed to trial on a Guzman rebuttal issue, counsel should thoroughly review the medical evidence in the case and confirm that it constitutes substantial evidence pursuant to the following checklist derived from the quote in the Gatten case, cited above:

> The physician must explain how and why the alternate rating is a more accurate reflection of the injured worker’s impairment than the strict AMA Guides impairment rating;

> The physician’s medical opinion must set forth the facts and reasoning that justify the alternative rating;

> The medical opinion must be based on facts that are germane;

> The medical opinion must be based on an adequate medical history and examination;

> The medical opinion must be based correct legal theories;

> The medical opinion may not be based on surmise, speculation, conjecture, or guess; and

> The physician must base his medical opinion as to the alternate rating on reasonable medical probability.

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