Mazzuca: Later Treating Reports Were Admitted While the 52% Disability Award Remained

A serious shoulder injury can leave you dealing with weakness, continuing treatment and uncertainty about benefits at the same time. Different parts of one medical report may answer different questions. A supported impairment rating does not automatically establish a proposed reduction for preexisting conditions, and admitting a new report does not necessarily change the award.

In Mazzuca v. City of San Bernardino, No. ADJ18038876 (WCAB Dec. 16, 2025), the Workers’ Compensation Appeals Board kept a 52 percent permanent-disability award and the accepted medical-stability date. It rejected the employer’s rating challenge, found the QME’s apportionment explanation insufficient and admitted two later treating reports. The decision shows why those questions need separate analysis.

Both sides challenged different parts of the decision

William Mazzuca, an equipment mechanic, injured his right shoulder and arm at work on February 11, 2022. The judge found that he reached maximum medical improvement, or MMI, on November 18, 2023, and awarded 52 percent permanent disability.

The petitions described in Mazzuca raised different objections. Mazzuca challenged exclusion of two treating reports and the MMI finding. The employer challenged strength testing, combining strength and motion impairment, apportionment and the rating procedure. The Board evaluated the supporting medical reasoning and the evidentiary issues rather than treating either side’s preferred report as controlling on every point.

The Board accepted the explained strength rating

Panel QME Alexander Peterson, M.D., examined Mazzuca and reviewed the complex shoulder history. The rating discussion in Mazzuca describes limited motion, weakness in identified shoulder muscles and impairment associated with a distal-clavicle excision. Dr. Peterson found that Mazzuca gave maximal effort and that pain did not prevent that effort. He explained why strength loss represented an impairment not adequately accounted for by the other methods used.

The accepted analysis combined 29 percent upper-extremity impairment for strength, 14 percent for motion and 10 percent for the clavicle procedure. These combined to 45 percent upper-extremity impairment and converted to 27 percent whole person impairment, or WPI. The judge corrected the doctor’s strength arithmetic from 28 to 29 percent upper-extremity impairment. The 27 percent WPI was the medical impairment measure, not the final 52 percent permanent-disability rating.

The Board’s account of the medical explanation in Mazzuca identified the failed shoulder repair and particular muscle deficits supporting the rare-case analysis for separately rating strength loss. The result depended on that explanation and examination record. The useful question in another report is what distinct loss the strength measure captures and why the chosen methods avoid counting the same impairment twice.

A private rater could not replace the medical opinion

The employer’s private rater, Tim Null, proposed reducing the strength component in proportion to the lost motion. He reasoned that a worker should not receive credit for strength in a range of motion the worker no longer had. The discussion of the private rating in Mazzuca explains why the judge rejected that approach: It changed the medical impairment opinion, and the question had not been put to the reporting physicians.

The panel applied Blackledge v. Bank of America, 75 Cal.Comp.Cases 613, 615–616 (WCAB en banc 2010), which separates the physician’s assessment, the judge’s findings and the rater’s work. Here, the judge had obtained a consultative DEU rating, rather than a formal one. Rule 10166 provides that consultative rating determinations are inadmissible in judicial proceedings. The Board rejected the argument that a formal DEU rating was required in this case; a judge may rate independently when the result rests on substantial evidence.

That distinction separates Mazzuca from our Keteles analysis, which involved formal rating instructions and an amended DEU recommendation. In both, a medical disagreement needed medical support. In Mazzuca, the private rater’s proposed proportional reduction did not displace the physician’s supported impairment explanation.

Supported impairment did not make the apportionment opinion sufficient

The same QME assigned 20 percent of disability to preexisting conditions based on degeneration shown in diagnostic studies and Mazzuca’s age. The apportionment analysis in Mazzuca found that explanation insufficient. The doctor needed to explain the condition or disease process, how it was causing permanent disability at evaluation and why it accounted for the selected percentage. The Board left the award unapportioned.

Labor Code section 4663 bases apportionment on causation of permanent disability. Here, the Board applied Escobedo v. Marshalls, 70 Cal.Comp.Cases 604, 621 (WCAB en banc 2005), requiring a reasoned explanation of the causal allocation. Identifying age or degeneration did not supply the missing explanation on this record. The impairment findings and the apportionment opinion had to stand on their respective reasoning.

Further treatment did not change the accepted MMI date

The MMI discussion in Mazzuca compared the doctors’ actual records and explanations. An earlier treating physician declared MMI in July 2023 but also provided a steroid injection that day, without a later evaluation of its effect. A new treating physician initially declared temporary total disability without the complete earlier records. Dr. Peterson reviewed the history and records, examined Mazzuca in November 2023 and maintained his conclusion after reviewing additional material.

The Board accepted November 18, 2023 as the MMI date. It agreed with the judge’s explanation that later treatment recommendations had not established a change from the static condition on this record. A recommended procedure had been authorized but had not taken place. Mazzuca continued to receive future treatment; the need for that care was not itself proof that the accepted stability date was wrong.

For someone facing this issue, compare the medical explanation for continuing temporary disability with the reports supporting MMI, the treatment actually provided and any documented change in condition. Mazzuca turned on that record. Decisions about surgery and your own benefit status require advice based on your medical circumstances and current reports.

The later treating reports belonged in the record

The mandatory settlement conference occurred in March 2025. Dr. Jonathan Nassos issued new treating reports on May 8 and May 23, after the first trial session. The judge’s opinion treated them as inadmissible because of the pretrial disclosure issue, but the Board ordered both admitted.

The evidence-admission discussion in Mazzuca distinguished these reports from the old, available QME reports at issue in DPR Construction v. Workers’ Compensation Appeals Board (McClanahan), 111 Cal.App.5th 1136, 1145 (2025). These were readily anticipated treating reports that did not exist at the discovery cutoff. The panel relied on the physician-report evidence provision and ongoing treating-physician reporting duties when finding good cause to admit them.

The distinction is about actual availability and diligence. Section 5502(d)(3) closes discovery at the mandatory settlement conference and states the exception for evidence unavailable or not discoverable with due diligence beforehand. Rule 9785(f)(8) requires progress reports during continuing medical treatment. Preserve when a report was created, its treatment purpose and why it could not have been listed earlier. Those facts help counsel address admission rather than assume that every later report qualifies.

What changed in the final order

The operative decision in Mazzuca denied the employer’s petition, granted the worker’s petition, added the omitted February 11, 2022 injury date and admitted the two treating reports. It otherwise affirmed the findings and award. Admission of those reports did not change the 52 percent award or the accepted MMI date.

Read the reports for the particular question they answer

Review the complete QME and treating reports with counsel, separating the impairment calculation, the cause of any proposed apportionment and the medical basis for stability or temporary disability. Compare the examination findings, what records each doctor reviewed and the explanation for each conclusion. Identify a disputed medical question for the physician to answer rather than expecting a rating calculation to resolve it.

For a later treating report, keep the report date, conference statement, service history and admission ruling together. Admission and persuasive weight are separate questions. Mazzuca is useful because the worker succeeded in adding reports to the record while the Board kept the substantive award in place. Our Blackledge analysis explains the broader division of rating responsibilities.