Flat Feet (Pes Planus): A Complete Medical Review for Patients and Clinicians
Flat feet—medically known as pes planus—affect millions worldwide, from children in Abu Dhabi to seniors in Cleveland, Ohio. While often benign, flat feet can evolve into a debilitating condition requiring orthopedic intervention, especially when rigid or acquired in adulthood. This comprehensive, evidence-based review synthesizes current clinical understanding, diagnostic protocols using X-ray imaging, conservative and surgical management strategies (including triple arthrodesis), and practical guidance for both patients and healthcare providers.
What Is Flat Foot (Pes Planus)?
Pes planus describes a foot with a diminished or absent medial longitudinal arch. When standing, the entire sole contacts the ground, leading to biomechanical alterations that may affect the ankles, knees, hips, and lower back. Flat feet are broadly categorized as:
- Flexible flatfoot: Arch is visible when non-weight-bearing but collapses under load.
- Rigid flatfoot: No arch present regardless of position; often painful and structurally fixed.
- Congenital: Present from birth due to developmental anomalies.
- Acquired: Develops later in life, commonly from posterior tibial tendon dysfunction (PTTD).
Did You Know? All infants are born with flat feet. Most develop a normal arch by age 6–10. Persistent flat feet beyond this age warrant evaluation—especially if pain or gait abnormalities emerge.
Epidemiology and Global Relevance
Flat feet affect approximately 20–30% of the general population. Prevalence is higher in certain regions due to genetic, lifestyle, and diagnostic factors:
| Location | Reported Prevalence | Notes |
|---|---|---|
| United States (Ohio, Florida, Nevada) | 25–30% | Higher rates in obese adults and diabetics |
| Canada | 20–25% | Common in pediatric populations; often resolves spontaneously |
| United Kingdom (London) | 22% | NHS data shows increased referrals for adult-acquired flatfoot |
| United Arab Emirates (Abu Dhabi) | 18–24% | Rising due to sedentary lifestyles and high BMI trends |
Causes of Flat Feet
Congenital Causes
- Tarsal coalition (abnormal fusion of foot bones)
- Vertical talus (congenital convex pes valgus)
- Genetic syndromes: Down syndrome, Marfan syndrome, Ehlers-Danlos
Acquired Causes (Adult-Acquired Flatfoot Deformity – AAFD)
- Posterior tibial tendon dysfunction (PTTD) – Most common cause
- Charcot arthropathy (in diabetic neuropathy)
- Inflammatory arthritis (e.g., rheumatoid arthritis)
- Trauma (Lisfranc injury, calcaneal fracture)
- Obesity and aging (ligamentous laxity)
Symptoms and Clinical Presentation
Not all flat feet are symptomatic. However, when pain or dysfunction occurs, patients may report:
- Medial foot or ankle pain, especially during walking
- Swelling along the inner ankle
- Difficulty standing on toes
- Outward deviation of the heel (valgus deformity)
- Shoe wear on the inner edge
- Referred pain to knees, hips, or lower back
In rigid flatfoot, symptoms are often more severe and include:
- Stiffness and limited joint motion
- Subtalar or tibiotalar impingement
- Early-onset osteoarthritis
X-ray Diagnosis of Flat Foot
Weight-bearing radiographs are the cornerstone of flatfoot evaluation. They reveal structural alignment, joint integrity, and degenerative changes critical for surgical planning.
Key Radiographic Measurements
| Parameter | Normal Value | Flatfoot Finding |
|---|---|---|
| Calcaneal Pitch Angle | 17°–25° | <17° indicates flatfoot |
| Talo-First Metatarsal Angle (Meary’s Angle) | 0° to 4° | >4° (downward curve = pes planus) |
| Talar-First Metatarsal Coverage | Complete | Incomplete = uncoverage due to forefoot abduction |
| Subtalar Joint Space | Uniform | Narrowing = osteoarthritis (see Figure 2) |
Advanced imaging like MRI or SPECT-CT may be added if soft tissue pathology (e.g., PTTD tear) or occult coalition is suspected.
Non-Surgical Management
First-line treatment for symptomatic flat feet—especially flexible or early-stage AAFD—includes:
- Custom orthotics: Medial arch support with heel cup and forefoot posting.
- Physical therapy: Eccentric strengthening of tibialis posterior, calf stretching.
- NSAIDs: For pain and inflammation control.
- Bracing: Arizona brace or UCBL orthosis for moderate PTTD.
- Weight management: Reduces mechanical load on the foot.
Success rates exceed 80% in Stage I–II PTTD with conservative care.
Surgical Management of Rigid Flatfoot
When conservative measures fail—particularly in rigid or advanced deformities—surgery becomes necessary. The BOFAS Lectures of Distinction webinar (Ramsay Healthcare, 2025) emphasized that “alignment correction is absolutely paramount—you can't leave these patients in valgus.”
Common Surgical Procedures
| Procedure | Indication | Key Considerations |
|---|---|---|
| Triple Arthrodesis | Rigid flatfoot with subtalar, talonavicular, and calcaneocuboid arthritis | Gold standard; allows 3D correction. Risk: non-union (~10%), adjacent joint stress |
| Double Arthrodesis | When calcaneocuboid joint is preserved | Reduces risk of lateral column complications |
| Pan-Talar Fusion | Severe deformity with ankle involvement | Eliminates ankle motion; reserved for salvage |
| Tibio-Calcaneal Fusion | Neuropathic or failed prior reconstructions | Last-resort; significant functional loss |
| Tendon Transfer + Osteotomy | Flexible flatfoot with PTTD (Stage II) | FDL transfer + medializing calcaneal osteotomy |
Surgical Technique Essentials
- Complete cartilage and subchondral bone removal for fusion surfaces.
- Rigid fixation using cannulated screws (e.g., 6.5mm or 7.0mm), staples (as in Figure 1), or locking plates.
- Combined medial and lateral approaches for optimal exposure and correction.
- Avoid overcorrection into varus—balance is critical.
Complications to Anticipate
- Non-union (5–15%)
- Wound dehiscence (higher in diabetics/smokers)
- Subfibular impingement
- Adjacent joint arthritis (e.g., ankle, midfoot)
Postoperative Rehabilitation
Recovery is staged and multidisciplinary:
- Weeks 0–6: Non-weight-bearing in cast or boot.
- Weeks 6–12: Gradual weight-bearing as fusion consolidates.
- Months 3–6: Physical therapy for gait retraining, proprioception, and strength.
- Long-term: Custom footwear, activity modification, and podiatry follow-up.
Collaboration between orthopedic surgeons, physiotherapists, and podiatrists—as emphasized in the BOFAS lecture—is essential for optimal outcomes.
Frequently Asked Questions (FAQs)
For Patients
Q: Are flat feet genetic?
A: Yes. Family history is a strong predictor. Syndromes like Ehlers-Danlos also increase risk.
Q: Can flat feet cause back pain?
A: Indirectly, yes. Altered biomechanics can lead to compensatory changes up the kinetic chain—knees, hips, and lumbar spine.
Q: Do orthotics cure flat feet?
A: They don’t “cure” but effectively manage symptoms and slow progression in flexible cases.
Q: Is surgery always needed for rigid flatfoot?
A: Not always—but if pain limits daily function and imaging shows joint degeneration, surgery is often the best long-term solution.
Q: Can I run with flat feet?
A: Many elite athletes have flat feet! With proper footwear and conditioning, running is usually safe.
For Clinicians
Q: How do I differentiate flexible vs. rigid flatfoot clinically?
A: Assess the arch non-weight-bearing vs. standing. Rigid flatfoot shows no arch in either position and limited subtalar motion.
Q: When should I order an MRI?
A: Suspect PTTD with pain/swelling but normal X-rays, or when tarsal coalition is suspected in adolescents.
Q: What’s the role of SPECT-CT?
A: It’s invaluable in complex cases—identifying occult impingement, non-unions, or asymmetric arthritis not visible on standard imaging.
Q: Is triple arthrodesis outdated?
A: No. Despite joint-sparing trends, it remains the gold standard for rigid, arthritic flatfoot with reliable pain relief and deformity correction.
Q: How do I prevent overcorrection during fusion?
A: Use intraoperative fluoroscopy to assess heel alignment. The heel should be neutral—not varus. Consider temporary K-wires for trial reduction.
Conclusion
Flat feet span a spectrum—from benign anatomical variants to debilitating rigid deformities. Early recognition of acquired flatfoot, especially posterior tibial tendon dysfunction, allows for timely conservative intervention. In rigid cases with radiographic evidence of arthritis (as shown in Figure 2), surgical realignment through procedures like triple arthrodesis (Figure 1) offers durable pain relief and functional restoration. As orthopedic care evolves, a patient-centered, multidisciplinary approach remains the cornerstone of success.
Whether you're a patient in London seeking relief or a surgeon in Florida planning reconstruction, understanding the nuances of pes planus ensures better outcomes and improved quality of life.
References
- Johnson KA, Strom DE. Tibialis posterior tendon dysfunction. Clin Orthop Relat Res. 1989;(239):196–206.
- Myerson MS. Adult Acquired Flatfoot Deformity: Treatment of Dysfunction of the Posterior Tibial Tendon. Instructional Course Lectures. 1997;46:393–403.
- BOFAS Lectures of Distinction: “The Rigid Flatfoot.” Ramsay Healthcare Webinar, presented by George Smith, David Loveday, moderated by Yasir Gani. 2025.
- Cleveland Clinic. Flat Feet (Pes Planus). Reviewed November 17, 2024. https://my.clevelandclinic.org/
- Kitaoka HB, et al. Outcome of treatment for posterior tibial tendon dysfunction. Foot Ankle Int. 1996;17(8):433–439.
- Neville C, et al. Tarsal coalition: diagnosis with SPECT-CT. Skeletal Radiol. 2020;49(5):721–728.
- Deland JT, et al. Flexor digitorum longus transfer for the treatment of posterior tibial tendon insufficiency. Foot Ankle Int. 2003;24(8):609–614.
- Abu Dhabi Orthopaedic Society. Epidemiology of Foot Deformities in the UAE. Gulf J Orthop. 2023;12(2):45–51.