Gemini 2.5 Pro on Guides 5 Ex 17-7

As part of our AI and Impairment Rating report, this analysis reviews a two-prompt AI dialog using Google's Gemini 2.5 Pro, on the Guides 5 Example 17-7, which concerns a tibia fracture. See the link for more analysis and more examples with other AI providers.

The model was low by -27% of the published WPI. It made a variety of errors.

Unique behaviors: 1) included clear disclaimers that the analysis should be done by a certified medical professional; 2) claimed that the recommendations were based on public information, not the the actual table values, yet still made an approximation; 3)showed mathematical calculations in detail.

This dialog was created with the free plan on May 31, 2025. The text was unedited; the text was reformatted for clarity and consistency. The original source text is available here as a Word document.

How to read the report below

The right hand column is the dialog. It starts with the user's prompt followed by the AI response. The left hand column is our analysis of the response compared to the published Example's rating of 11% WPI. The errors in are highlighted in red. Where appropriate, a reference to the Gudies 5 with page numbers is available.

Best viewed on a Tablet or Desktop to see the dialog text and annotations side-by-side. On mobile the annotations will follow the dialog text in a separate block. In both layouts, an additional text block of annotation details follows at the bottom.

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Written by
Ben Wen
CMO
Category
AI
LLM5 17-7 Gemini 2.5 Pro - Impairment Rating Analysis

LLM5 17-7 Gemini 2.5 Pro - Impairment Rating Analysis

This is the initial request to the LLM. Note the specific reference to the AMA Guides 5th edition
Text from Example 17-7, page 538
Incorrect ROM classification
See Error 1 footnote
Incorrect ROM value
See Error 2 footnote
Incorrect level for sum.
See Error 3 footnote
Toe impairment calculation errors
See Error 4 footnote
Invalid combination of impairments
See Error 5 footnote
Incorrect. With 28% LEI, the conversion to WPI would be 28% × 0.4 = 11.2%, rounding to 11% WPI, not 8%.
Error 6

Prompt

I'm working with a friend on the Independent Medical Exam market. This is a sample patient narrative. Can you help me create an impairment rating according to the AMA Guides 5th edition?

Subject: 45-year-old woman.
History: Sustained a tibia fracture in a motor vehicle accident.
Current Symptoms: No pain; stiffness about the ankle and foot, with some swelling of the foot and ankle toward evening. Cannot stand for long periods and cannot use shoes with elevated heels.
Physical Exam: Ankle flexion is 6°; ankle extension is 5°. Toe extension is less than 10° for all toes. 1-cm atrophy of the left calf. It is difficult to determine the strength of the ankle and toe extensors, but a mild weakness is noted.
Clinical Studies: X-rays: healed tibia fracture with no malalignment.
Diagnosis: Healed tibia fracture.

Response

Impairment Rating Analysis based on AMA Guides, 5th Edition

Patient: 45-year-old woman
Diagnosis: Healed tibia fracture
History: Motor vehicle accident

This analysis provides an estimated impairment rating based on the provided patient narrative, adhering to the principles of the American Medical Association (AMA) Guides to the Evaluation of Permanent Impairment, 5th Edition. The final determination of an impairment rating should be made by a qualified physician who has conducted a thorough examination and has access to the complete AMA Guides.

Summary of Impairment Findings

Based on the information provided, the patient presents with the following ratable impairments:

  • Ankle Range of Motion Limitation: The patient's ankle flexion is limited to 6° and extension is limited to 5°.
  • Toe Extension Limitation: Extension of all toes is less than 10°.
  • Calf Atrophy: There is a 1-cm atrophy of the left calf.

These impairments are evaluated and combined to determine the overall Lower Extremity Impairment (LEI) and the final Whole Person Impairment (WPI).

Detailed Impairment Rating Calculation

The impairment rating is calculated by assessing each component of the impairment and then combining them using the Combined Values Chart as specified in the AMA Guides, 5th Edition.

1. Ankle Range of Motion Impairment

According to Chapter 17 of the AMA Guides, 5th Edition, impairment from loss of range of motion of the ankle is determined by referencing specific tables. Normal ankle flexion (plantarflexion) is approximately 50°, and normal ankle extension (dorsiflexion) is approximately 20°.

  • Ankle Flexion (Plantarflexion): The patient's flexion is 6°. Based on tables correlating range of motion to impairment, a significant loss of flexion to this degree would result in a Lower Extremity Impairment (LEI). While the specific table value is not publicly available, a limitation to 6° represents a substantial loss of motion. For illustrative purposes, based on available data and the principles of the Guides, this could correspond to approximately 7% LEI.
  • Ankle Extension (Dorsiflexion): The patient's extension is 5°. This also represents a significant loss of motion. This limitation would contribute an additional LEI. Again, for illustrative purposes, this could correspond to approximately 8% LEI.

To combine these, the values are added, resulting in a 15% LEI for the total loss of ankle motion.

2. Toe Extension Impairment

The patient's toe extension is less than 10° for all toes. The AMA Guides provide ratings for loss of motion in the toes. A significant loss of extension in all toes of one foot would result in a Foot Impairment, which is then converted to a Lower Extremity Impairment. A complete loss of extension in all toes can result in a notable impairment. Given the finding of "less than 10°," this represents a significant impairment. For illustrative purposes, this could be estimated to be approximately a 5% Foot Impairment.

To convert Foot Impairment to Lower Extremity Impairment, the value is multiplied by 0.7 (as per Table 17-3 of the AMA Guides, 5th Edition).

  • Toe Extension LEI: 5% (Foot Impairment) x 0.7 = 3.5% LEI. This would likely be rounded to 4% LEI.

3. Calf Atrophy Impairment

Chapter 17 of the AMA Guides, 5th Edition, provides a specific impairment rating for muscle atrophy.

  • Calf Atrophy LEI: A 1-cm atrophy of the calf corresponds to a 3% LEI.

Combining the Impairments

The individual Lower Extremity Impairments are not simply added together. They are combined using the Combined Values Chart (CVC) from the AMA Guides. The formula for combining two values is: A+B(1−A)

Where A and B are the two impairment percentages expressed as decimals.

  1. Combine the largest two LEI values: 15% (Ankle ROM) and 4% (Toe Extension).
    • 0.15 + 0.04(1 - 0.15) = 0.15 + 0.034 = 0.184 or 18.4%
  2. Combine the result with the next LEI value: 18.4% and 3% (Calf Atrophy).
    • 0.184 + 0.03(1 - 0.184) = 0.184 + 0.02448 = 0.20848 or 20.848%

This combined value is rounded to the nearest whole number.

Total Lower Extremity Impairment (LEI): 21%

Conversion to Whole Person Impairment (WPI)

The final step is to convert the Total Lower Extremity Impairment to a Whole Person Impairment. According to the AMA Guides, 5th Edition, the lower extremity represents 40% of the whole person. Therefore, the LEI is multiplied by 0.4.

Whole Person Impairment (WPI): 21% (LEI) x 0.4 = 8.4% WPI

The final Whole Person Impairment would be rounded to the nearest whole number.

Final Estimated Impairment Rating:

  • Lower Extremity Impairment (LEI): 21%
  • Whole Person Impairment (WPI): 8%

Summary Table of Estimated Impairment

Impairment Component Finding Estimated LEI
Ankle Flexion 6° 7%
Ankle Extension 5° 8%
Combined Ankle ROM 15%
Toe Extension < 10° (all toes) 4%
Calf Atrophy 1 cm 3%
Total Combined LEI 21%
Whole Person Impairment 8%

Disclaimer: This impairment rating is an estimation based on the provided narrative and publicly available information regarding the AMA Guides, 5th Edition. A definitive rating requires a physical examination by a certified medical professional with expertise in impairment rating and access to the complete AMA Guides. The mild weakness noted in the physical exam is generally considered to be accounted for within the range of motion and atrophy ratings and is not typically rated separately unless there is a specific nerve injury diagnosis. The patient's subjective complaints of stiffness and swelling are also considered within the context of the objective findings.

Error Footnotes

Futher Details

Error 1: The 6° range of motion is classified as Moderate on Table 17-11, page 537. That corresponds to a 15% LEI. It is interesting that the AI acknowledges that the AMA Guides are not publicly available, yet makes an approximation. These ankle impairments should not be calculated in LEI until combining with other lower extremities. They should be in Foot impairment values, which here is 21% Foot.

Error 2: The 5° range of motion is classified as Mild on Table 17-11, page 537. That corresponds to a 10% Foot.

Error 3: Total Foot impairment for ankle flexion and extension is: 21% + 10% = 31% Foot.

Error 4: The Toe Impairments on Table 17-14, page 537 states that the great toe impairment would be 7% Foot Impairment and the lesser toes impairment would be 7% Foot Impairment (per the footnote limiting lesser toe impairments to 2% WPI, which converts to 7% Foot Impairment). Combining both using the CVC formula, yields 13.51% Foot.

Error 5: Muscle weakness, atrophy, and ROM cannot be combined per Table 17-2, page 526. Recalculating the CVC combinations with the correct Foot impairment values 31% (Ankle ROM) and 13.31% (Foot) results in 40% Foot which multiplied by 0.7 per Section 17-2a, results in 28% LEI. This is higher than the atrophy impairment, so we select the 28% LEI for this impairment per Section 17-2, page 526.