22/08/2026
𝑨𝒄𝒄𝒆𝒔𝒔𝒐𝒓𝒚 𝑵𝒂𝒗𝒊𝒄𝒖𝒍𝒂𝒓 𝑺𝒚𝒏𝒅𝒓𝒐𝒎𝒆
𝑾𝒉𝒆𝒏 “𝑷𝑻𝑻𝑫” 𝑰𝒔 𝑨𝒄𝒕𝒖𝒂𝒍𝒍𝒚 𝑨𝒏 𝑨𝒄𝒄𝒆𝒔𝒔𝒐𝒓𝒚 𝑵𝒂𝒗𝒊𝒄𝒖𝒍𝒂𝒓
Medial arch pain and acquired flatfoot are often attributed to Posterior Tibial Tendon Dysfunction (PTTD). But what if the patient has a prominent, tender bony lump on the medial side of the foot?
Think beyond the tendon.
👉 What is an Accessory Navicular?
An accessory navicular (os naviculare) is an additional ossicle located on the medial aspect of the navicular, close to the insertion of the posterior tibial tendon.
It is a congenital anatomical variant, reported in roughly 4–14% of individuals. Most are asymptomatic, but symptoms can develop when the synchondrosis or surrounding soft tissues become irritated.
👉 Why does it become painful?
The posterior tibial tendon may have a broad or abnormal insertion involving the accessory navicular.
Repeated loading from:
• Running
• Jumping
• Dancing
• Prolonged standing
• Direct pressure from footwear
can increase stress around the accessory navicular–navicular interface (synchondrosis).
The result can be local inflammation, tenderness and medial-foot pain.
👉 Typical Clinical Presentation
Patients may report:
🔹 Focal pain over the medial midfoot
🔹 A palpable or visible bony prominence
🔹 Local swelling or erythema during an acute flare
🔹 Pain with prolonged weight-bearing
🔹 Irritation from tight footwear
🔹 Pain during activities requiring repeated inversion or plantarflexion
The key clue is focal tenderness directly over the prominence, rather than tenderness following the entire posterior tibial tendon.
👉 Accessory Navicular vs PTTD
Accessory Navicular Syndrome
→ Pain localized over the medial navicular prominence
→ Palpable bony prominence
→ Shoe pressure commonly aggravates symptoms
→ Resisted inversion may reproduce local pain
→ Imaging can demonstrate edema or inflammation around the synchondrosis
Posterior Tibial Tendinopathy
→ Pain commonly follows the tendon behind and below the medial malleolus
→ Tendon loading may reproduce symptoms
→ Weakness or impaired endurance of plantarflexion/inversion may be present
→ Progressive cases can contribute to acquired flatfoot
⚠️ Both conditions can coexist.
👉 Important Differential Diagnoses
Medial foot pain with a prominent navicular region should also prompt consideration of:
• Posterior tibial tendinopathy/dysfunction
• Spring ligament pathology
• Tarsal tunnel syndrome
• Navicular stress injury
• Midfoot osteoarthritis
• Other causes of medial column pain
👉 What About MRI?
MRI can help identify:
✔️ Bone marrow edema
✔️ Synchondrosis inflammation
✔️ Posterior tibial tendon pathology
✔️ Associated ligament or soft-tissue abnormalities
However, imaging findings should always be interpreted alongside the clinical examination and location of tenderness.
👉 Management
Conservative Management
Initial treatment is usually directed at reducing mechanical irritation and controlling symptoms.
Depending on severity, this may include:
• Activity modification
• Appropriate footwear
• Orthotic intervention to reduce pressure over the prominence
• Short-term immobilization for significant acute symptoms
• Progressive rehabilitation once irritability decreases
• Gradual strengthening of the posterior tibial and calf musculature
A useful principle:
Do not simply load the tendon harder when the primary pain generator may be the accessory navicular itself.
When is Surgery Considered?
Persistent symptoms despite appropriate conservative management may require orthopedic/foot-and-ankle assessment.
Procedures such as the Kidner procedure or modified Kidner procedure can remove the symptomatic accessory navicular and address the posterior tibial tendon insertion when clinically indicated.
The exact surgical approach depends on the anatomy, tendon function, deformity and associated pathology.
📌 Clinical Takeaway
If a patient labelled as having “PTTD” presents with:
Medial arch pain + a prominent medial navicular + focal bony tenderness + shoe irritation
👉 Palpate the accessory navicular.
The diagnosis may not simply be a tendon problem.
Correctly identifying the pain generator can completely change the rehabilitation strategy.
📚 Recent Literature
• Operative Management for Symptomatic Accessory Navicular: A Systematic Review. Foot & Ankle Specialist, 2025.
• Midterm Outcomes of the Modified Kidner Procedure for Accessory Navicular Syndrome in Athletes vs Nonathletes. Foot & Ankle Orthopaedics, 2025.
• All-Inside Endoscopic Kidner Procedure for Symptomatic Accessory Navicular. Arthroscopy Techniques, 2024.
• Hazard of Failed Nonoperative Management for Symptomatic Accessory Navicular in Children and Adolescents: A Population-Based Case-Cohort Study. Journal of Pediatric Orthopaedics, 2024.
