This document discusses the accessory navicular bone, a normal anatomical variant seen in around 12% of the population. It presents the case of a patient with a painful bony prominence on their left foot associated with their accessory navicular bone. The document covers the relevant anatomy, classification, pathophysiology, clinical presentation, differential diagnosis, imaging, and treatment options for symptomatic accessory navicular bone. Conservative treatment is usually first-line, while surgical excision may be considered for recalcitrant cases that fail extended nonoperative management.

1. Accessory Navicular Bone
10’ talk
By Jifar J ( OSR Ⅰ)

2. Zewditu Tadesse 35/F
?Lt Accessory Navicular Bone
• Presented with Lt foot mass of 01 year.
• She complains the mass as associated with pain when walking.
• Otherwise, no Hx of trauma to the site/known medical chronic illness
• P/E:
• GA: well, looking
• V/S: stable
• HEENT: PC, NIS
• MSK: there is a bony prominence over Lt medial foot area with
tenderness to palpation. Bilaterally flat foot.

3. X - Ray

5. Introduction
• Accessory navicular is a normal variant seen in up to 12% of
population. ( Symptomatic < 1%)
• Accessory Navicular is a common idiopathic condition of the foot that
presents with a plantar medial enlargement of the navicular bone.

6. Relevant Anatomy
• An extensive network of plantar and dorsal ligaments attaches to the
navicular and rigidly stabilizes the midfoot.
plantar calcaneonavicular (spring) ligament
bifurcate ligament
dorsal talonavicular ligament
• The only tendon that inserts into the navicular is the anterior portion of
tibialis posterior tendon medially.

9. Cont’d
• Blood supply is provided through small branches from the dorsalis
pedis and tibialis posterior arteries from the medial pole and the dorsal
and plantar surfaces.
dorsalis pedis artery (dorsal aspect)
medial plantar artery (plantar aspect)
anastomosis between dorsalis pedis and medial plantar arteries
(medial surface of tuberosity)

10. Classification of Accessory Navicular Bone

11. Pathophysiology
• Pain generator theories
micro-fracture through the cartilaginous synchondrosis.
acute and chronic inflammation - tendinosis
cellular proliferation indicative of attempted repair.
• Chronic chondro-osseous tensile failure can occur in this condition
and is responsible for the clinical findings.

12. Cont’d
• The presence of type I or II accessory navicular is also a cause of
Posterior Tibial tendinopathy.
• Autosomal dominant inheritance has been reported.
• Flat feet and posterior tibial tendon insufficiency have been reported
as the association.

13. Clinical Presentation
Symptoms
• Majority of patients are asymptomatic.
more commonly symptomatic in females
• Medial arch pain – often worse with overuse.
• Condition may also be bilateral.
P/E
• Firm, warmth/redness and tender at the medial and plantar aspect of
the navicular bone.
Reported bilateral incidence is 50-90%

14. Differential Diagnosis
• Flexible pes planovalgus
• Posterior tibial tendon insufficiency ( PTTI )
• Tarsal coalition – talocalcaneal
• Stress fracture
• Bone tumor
• Kohler’s disease

15. Imaging
• X – ray
AP
Lateral
External oblique - best
• Ultrasonography
could detect the osseous contours of the accessory navicular and
medial navicular.
assessment of the integrity of the posterior tibialis tendon.
• MRI
Determine the size and type of AN
Assess posterior tibial tendon
Bone marrow edema

18. Treatment of Accessory Navicular Bone
• Conservative Treatment - first-line of treatment.
Activity restriction
Shoe modification
Anti-inflammatory medications
short period of cast immobilization – pain refractory for above
• Surgical Treatment - excision of the symptomatic, accessory bone.
Recalcitrant cases that have failed extended nonoperative
management
Symptomatic AN in athletes

20. Cont’d
• Conservative treatment should be maintained for at least 4- 6 months
before considering any surgical intervention.
• Most children and adolescents who have a symptomatic accessory
tarsal navicular bone become asymptomatic when they reach skeletal
maturity

24. Complications
• The most common complication is persistent medial prominence and
pain when the body of the navicular is not trimmed sufficiently.

25. Reference
• Orthobullets
• https://boneandspine.com/accessory-navicular-bone/#clinical-
presentation