Mid foot condition

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