ChatGPT-5 on Guides 5 Ex 17-7

As part of our AI and Impairment Rating report, this analysis reviews a two-prompt AI dialog using OpenAI's ChatGPT, GPT-5, 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.

Example Aware

We were surprised to find that GPT-5 recognized that the prompt came from the Guides 5 text and used the text to form its answer, albeit with incorrect justification. See the annotated report for details. We followed up with a second prompt in this case to ask it to perform the calculation without reference to the example text.

GPT-5 made fewer errors than the other LLMs, but still made errors. Notably, after the first prompt, it was the only LLM that ended up with the same WPI as in the example: 11% WPI, even though the logic and calculations were not correct. The second prompt resulted in an incorrect 12% WPI with a different set of errors.

GPT-5 was the only model to include references to sources on the web. Our prompt did not ask to do this. No effort was made to validate the references.

The dialog was created with the free tier on two days, August 11, 2025 and August 15, 2025. Your results will vary if you want to try this prompt, because AI chat algorithms are designed for variety. The text was formatted 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
ChatGPT-5 - Medical Impairment Rating Analysis

LLM5 17-7 ChatGPT-5 - 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.
Very interesting that the AI realized that the example used is from the AMA Guides, indicating it likely has the text of the Guides in its training data. Unfortunately for the purposes of our analysis of the AI to independently calculate a rating, this initial prompt is less valuable. We gave it a second prompt below to ask it to independently arrive at an impairment rating.
These references were provided by the AI inline with the text. They were reformatted to fit this report structure and were originally smaller button-like links.
Here is the second prompt asking for the independent calculation.
Per Table 17-2, Atrophy and ROM cannot be combined.
Error 1
CVC calculation is wrong 11% ⊕ 1% is 12% per CVC table p. 604.
Error 2
Incorrect ROM values
See Error 3 footnote
Incorrect toe calculations
See Error 4 footnote
Wrong combination method for toes
See Error 5 footnote
The Foot values, combined 31% ⊕ 13.51% = 40% Foot. Converting to Lower Extremity via Section 17.2a by multiplying by 0.7, that is 28% LE. To convert to WPI, by Table 17-3 to get 11% WPI.
Error 6
Incorrect, the 12% that the AI calculated is not the same as the 11% WPI as published in Example 17-7.
Error 7

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.

ChatGPT said:

Absolutely—I can help guide you through constructing an impairment rating based on the AMA Guides, Fifth Edition, using your sample patient narrative.

1. Select the appropriate impairment evaluation method

According to Chapter 17 ("Lower Extremities") in the Fifth Edition:

The Guides recommend selecting the method that yields the highest impairment rating when multiple methods apply Law Offices of Bradford & Barthel | ResearchGate.

2. Apply applicable impairment methods to your case

A. Range of Motion (Ankle/toes)

Your exam reveals:

  • Ankle: flexion 6°, extension 5°
  • Toe extension: <10° for all toes

The Guides provide an example of a 45-year-old woman with a tibia fracture treated closed, with identical ROM and calf atrophy (1 cm), reporting:

"Impairment: 11% WPI – Add ankle loss, combine with toe with combined values chart." AMA Guides

This is a perfect match for your scenario: use 11% whole-person impairment based on ROM.

B. Muscle Atrophy

The same example from Chapter 17 indicates calf atrophy of 1 cm yields 1% WPICalifornia Orthopaedic Association | Law Offices of Bradford & Barthel.

C. Muscle Weakness

Your note indicates mild weakness of ankle and toe extensors, but it's difficult to quantify. Without objective grading (like MRC scale), it's hard to apply muscle strength impairment tables. Thus, it's safest not to rate this unless a clear grade is documented.

3. Combining impairment ratings

When multiple impairment values pertain to the same body region (e.g. range of motion and atrophy of the leg), the Guides specify you should combine them using the Combined Values Chart, not simply addLaw Offices of Bradford & Barthel | California Orthopaedic Association.

Using the example's approach:

  • ROM impairment: ~11% WPI
  • Atrophy: 1% WPI
  • When combined via the chart, the result is still approximately ~11% WPI (because combination yields less than additive).

4. Final Whole-Person Impairment Rating

Based on the Guides:

Final WPI ≈ 11%

This reflects ROM loss and calf atrophy, combined appropriately.

5. Reporting and Rationale (per IME best practices)

Per both the AMA Guides and IME quality standards (e.g., Washington State Medical Examiners' Handbook), your report should:

  1. State each objective finding (e.g. "Ankle flexion 6°, extension 5°, toe extension <10°, calf atrophy 1 cm").
  2. Cite the specific criteria used: e.g. Chapter 17, example "45-year-old woman..." (identical ranges) for ROM impairment; atrophy criteria.
  3. Note the method used: ROM and atrophy, then combined via Combined Values Chart → WPI.
  4. Provide calculation briefly: e.g., "ROM impairment 11% WPI; atrophy impairment 1% WPI; combined via Combined Values Chart yields final impairment approximately 11% WPI."
  5. Optionally mention that strength was not rated due to insufficient objective quantification.
The example in the Guides itself serves as a model for wording and structure AMA Guides | California Orthopaedic Association

Summary

Impairment Method WPI (%) Notes
Range of Motion (ankle/toes) 11% Matches AMA Guides example
Calf Atrophy (1 cm) 1% From same chapter
Combined WPI ≈ 11% Using Combined Values Chart
Muscle Weakness Not rated Insufficient objective data
Let me know if you’d like to explore alternative methods (like gait assessment or diagnostic-based estimates), or if you'd like help composing the narrative for your impairment rating report!

You said:

can you do the calculation instead of using the Example

ChatGPT said:

Thought for 58s

Absolutely—here's a straight AMA Guides (5th ed.) calculation from your narrative.

Rating inputs (from your exam)

  • Ankle plantarflexion = 6°
  • Ankle dorsiflexion = 5°
  • Toe MTP extension <10° for all toes (great toe + lesser toes)
  • 1-cm calf atrophy, mild weakness noted (but see "what's excluded," below)
  • X-ray: healed tibia fracture, no malalignment

Method & tables used

Ankle ROM (Table 17-11, p. 537):

  • Plantarflexion 6° → 15% LE (≈ 6% WPI)
  • Dorsiflexion 5° → 7% LE (≈ 3% WPI)

Add within the same joint (ankle ROM): 15% + 7% = 22% LE. Law Offices of Bradford & Barthel

Toe ROM (Table 17-14, p. 537):

  • Great toe MTP extension <15° rates 5% LE (= 2% WPI). <10° still meets this bracket. DOL
  • "Two or more lesser toes" impairment is capped at 2% WPI max (= 5% LE)—your "all toes <10°" meets the cap. ama-guides.ama-assn.org

⇒ Toes total = 5% LE (great toe) + 5% LE (lesser toes) = 10% LE.

Combine lower-extremity impairments, then convert to WPI

  • Combine ankle 22% LE with toes 10% LE using the Combined Values method (A + B·(1−A)):

22% ⊕ 10% = 0.22 + 0.10·(1−0.22) = 0.22 + 0.078 = 29.8% LE → 30% LE (rounded).

What's excluded (and why)

  • Muscle atrophy (1-cm calf, Table 17-6) and manual muscle testing are not combined with ROM ratings of the same region per Table 17-2's guidance to avoid combining methods that rate the same condition; also ROM already yields the higher/more specific rating here. Law Offices of Bradford & Barthel
  • Diagnosis-based estimate for tibial shaft malalignment (Table 17-33) doesn't apply because radiographs show no malalignment. Law Offices of Bradford & Barthel

Final impairment rating

  • Lower Extremity: 30% LEI
  • Whole Person: 12% WPI

If you want, I can drop this into a one-page IME-style write-up with the citations formatted and the CVC math shown line-by-line.

Error Footnotes

Further Details

Error 3: Incorrect, the ankles are part of the foot and should be considered at the foot before converting them to Lower Extremity (LE). According to Table 17-11, Plantarflexion is 21% Foot and Dorsiflexion is 10% Foot. Adding them together, you get 31% Foot.

Error 4: Incorrect, the toes are also part of the foot and should be considered at the foot before converting them to LE. The great toe impairment is 7% Foot and the lesser toe impairments are 3% Foot each, according to Table 17-14.

Error 5: Incorrect, the toes are separate joints and should be CVC combined, not added. Using the CVC chart on page 604, the toes total impairment is 3% ⊕ 3% ⊕ 3% ⊕ 3% = 12% Foot, but is capped at 7% Foot, combined with 7% for the great toe, which is 13.51% Foot.