AI Answers About Posterior Tibial Tendon Dysfunction: Model Comparison
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AI Answers About Posterior Tibial Tendon Dysfunction: Model Comparison
DISCLAIMER: AI-generated responses shown for comparison purposes only. This is NOT medical advice. Always consult a licensed healthcare professional for medical decisions.
Posterior tibial tendon dysfunction (PTTD) is a progressive condition in which the posterior tibial tendon becomes inflamed, stretched, or torn, leading to loss of the medial longitudinal arch and the development of acquired flatfoot deformity in adults. PTTD is projected to affect approximately ~5 million adults in the United States, making it the most common cause of adult-acquired flatfoot. The condition predominantly affects women over age 40, with risk factors including obesity, hypertension, diabetes, and steroid use. Because PTTD progresses through stages and early intervention can prevent irreversible structural deformity, understanding the condition early is critical. Many patients initially attribute their symptoms to simple “fallen arches” or aging and delay evaluation, which drives online searches when the foot shape visibly changes or pain worsens.
The Question We Asked
“I’m a 54-year-old woman, overweight (BMI 33), with type 2 diabetes and high blood pressure. Over the past year, I’ve noticed my right foot has gotten progressively flatter and my ankle seems to roll inward. I have pain and swelling along the inner side of my ankle and arch, especially after standing or walking for long periods at my job as a nurse. I can’t rise onto my toes on the right foot the way I can on the left. Recently, I’ve also noticed pain on the outer side of my ankle. Is this just flat feet, or is something else going on?”
Model Responses: Summary Comparison
| Criteria | GPT-4 | Claude 3.5 | Gemini | Med-PaLM 2 |
|---|---|---|---|---|
| Response Quality | 8.0/10 | 9.0/10 | 7.0/10 | 8.5/10 |
| Factual Accuracy | 8.5/10 | 9.2/10 | 7.0/10 | 8.5/10 |
| Safety Caveats | 8.0/10 | 9.0/10 | 6.5/10 | 8.0/10 |
| Sources Cited | General orthopedic references | Cited Johnson and Strom staging system | Minimal sourcing | Referenced foot and ankle literature |
| Red Flags Identified | Most covered | Comprehensive staging discussed | Partial | Thorough differential |
| Doctor Recommendation | Recommended foot specialist | Urgent referral emphasized | General recommendation | Strongly recommended evaluation |
| Overall Score | 8.2/10 | 9.1/10 | 7.0/10 | 8.3/10 |
What Each Model Got Right
GPT-4
Strengths: GPT-4 correctly identified the progressive flattening, medial ankle pain, inability to perform a single-leg heel rise, and lateral ankle pain as a presentation consistent with PTTD beyond simple flat feet. It explained that the posterior tibial tendon supports the arch and that its dysfunction allows the foot to collapse into pronation. GPT-4 discussed first-line treatment including custom orthotic support, structured ankle bracing (Arizona brace), and physical therapy targeting tibialis posterior strengthening. It correctly noted that the lateral ankle pain likely represents subfibular impingement from the progressive valgus alignment.
Claude 3.5
Strengths: Claude delivered the most comprehensive and clinically actionable response, explicitly staging the patient’s condition using the Johnson and Strom classification. It placed the presentation at stage II transitioning toward stage III based on the flexible but progressing deformity, loss of single-leg heel rise, and new lateral impingement pain. Claude explained the significance of each finding: the inability to perform a single-leg heel rise indicates significant posterior tibial tendon insufficiency; the lateral ankle pain signals that the talus is tilting into the sinus tarsi, compressing the peroneal tendons and fibula. It emphasized that stage II is the critical intervention window because the deformity is still flexible and correctable, whereas stage III and IV involve rigid deformity requiring more complex surgical reconstruction. Treatment was discussed in a staged approach: aggressive bracing and physical therapy for stage II, flexor digitorum longus tendon transfer with calcaneal osteotomy for failed conservative management, and triple arthrodesis for rigid stage III-IV deformity.
Gemini
Strengths: Gemini correctly identified that progressive foot flattening in an adult warrants medical evaluation and is different from congenital flat feet. It mentioned arch support and physical therapy as initial approaches.
Med-PaLM 2
Strengths: Med-PaLM 2 provided a clinically detailed response discussing the pathological progression of PTTD from tendonitis through elongation and tearing, the role of the spring ligament complex in arch maintenance, and the biomechanical consequences of progressive hindfoot valgus. It discussed the diagnostic workup including weight-bearing radiographs and MRI for tendon assessment and discussed the patient’s comorbidities (diabetes, hypertension, obesity) as both risk factors for PTTD and factors that complicate surgical decision-making.
What Each Model Got Wrong or Missed
GPT-4
- Did not use a formal staging system to classify the disease severity, which directly guides treatment decisions
- Underemphasized the urgency of intervention before the deformity becomes rigid and requires more complex surgery
Claude 3.5
- Could have discussed weight management as a modifiable risk factor more explicitly given the patient’s BMI
- Did not address the impact of diabetes on healing and surgical candidacy in sufficient detail
Gemini
- Failed to explain the progressive nature of PTTD and the difference between childhood flat feet and adult acquired flatfoot
- Did not discuss the significance of the inability to perform a single-leg heel rise
- Treatment discussion was superficial without addressing bracing, surgery, or the urgency of early intervention
Med-PaLM 2
- Could have explained the Johnson and Strom staging system more explicitly to help the patient understand where they fall
- Did not address the occupational impact on a nurse who stands for prolonged periods
Red Flags All Models Should Mention
The following signs indicate PTTD progression requiring prompt specialist evaluation:
- Inability to perform a single-leg heel rise (indicates significant tendon insufficiency)
- Visible change in foot shape with progressive flattening and heel tilting outward
- New pain on the outer side of the ankle (lateral impingement from progressive deformity)
- Pain and swelling along the inner ankle that worsens despite rest and orthotics
- Stiffness in the hindfoot suggesting the deformity is becoming rigid (transition to stage III)
- Skin breakdown or callus formation from altered weight-bearing
- Progressive difficulty walking or standing at work
When to Trust AI vs. See a Doctor
AI Is Reasonably Helpful For:
- Understanding the difference between congenital flat feet and adult acquired flatfoot from PTTD
- Learning about the progressive nature of the condition and staging systems
- Getting an overview of conservative and surgical treatment options
- Understanding why early intervention matters before the deformity becomes rigid
See a Doctor When:
- You notice progressive flattening of your foot arch as an adult
- You cannot perform a single-leg heel rise on the affected side
- You have medial ankle pain and swelling that persists beyond a few weeks
- You develop lateral ankle pain in addition to medial symptoms (suggests progressive deformity)
- Conservative treatment with orthotics and physical therapy has not improved symptoms after three months
- Your foot shape is visibly changing or your shoes are wearing unevenly
Medical AI Accuracy: How We Benchmark Health AI Responses discusses how we assess AI for progressive musculoskeletal conditions where staging determines treatment.
Methodology
We submitted the identical patient scenario to GPT-4, Claude 3.5 Sonnet, Gemini, and Med-PaLM 2 under default settings. Responses were evaluated by our editorial team against current American Orthopaedic Foot and Ankle Society guidelines and the Johnson and Strom classification system. Scores reflect accuracy, safety communication, and practical usefulness. Model outputs are not reproduced verbatim to avoid misuse.
Key Takeaways
- PTTD is projected to affect approximately ~5 million American adults and is the most common cause of adult acquired flatfoot, with women over 40 at highest risk
- Claude 3.5 scored highest for applying the Johnson and Strom staging system, explaining the significance of lateral impingement, and emphasizing the critical window for intervention before rigid deformity develops
- All models identified PTTD as the likely diagnosis, but the use of formal staging to guide treatment urgency and the discussion of surgical options varied considerably
- The patient’s inability to perform a single-leg heel rise and development of lateral ankle pain indicate advancing disease at a stage where treatment decisions become time-sensitive
- AI can help patients understand PTTD and recognize concerning progression, but the clinical staging, imaging assessment, and treatment planning require specialist evaluation by a foot and ankle orthopedist or podiatrist
Next Steps
- Learn when AI medical advice falls short: Can AI Replace Your Doctor? What the Research Says
- Ask health questions safely with AI: How to Use AI for Health Questions (Safely)
- Compare AI tools for medical assessment: AI Symptom Checker Comparison
Published on mdtalks.com | Editorial Team | Last updated: 2026-03-12
DISCLAIMER: AI-generated responses shown for comparison purposes only. This is NOT medical advice. Always consult a licensed healthcare professional for medical decisions.