Lower extremity ossicles Flashcards
1
Q
Define accessory ossicles?
A
- **Secondary ossification centres that remain separated from the normal bone **
2
Q
Define sesmoids?
A
- Bones that are incorporated into tendons and move with normal and abnormal tendons
3
Q
Name the most common ossicles?
A
- Os trigonum
- Accessory navicular ( os tibiale externum)
- Os intermetatarseum
4
Q
Name most common sesmoids?
A
- Os peroneum- in peroneus longus
- Hallux sesmoids- located in flexor hallucis brevis
5
Q
What is this?
A
- OS trigonium
- Semoid bone representing the separated POSTERIOR TUBERCLE OF TALUS
- Usually asymptomatic but symptomatic -> os trigonium syndrome
6
Q
Describe the epidemiology of Os trigonum?
A
- 10-25 % of population have os trigonium
- Commonly symptomatic in BALLET dancers due to EXTREME PLANTAR FLEXION
7
Q
Describe the pathophysiology of OS trigonium?
A
- Repetitive microfracture- may present as Stress FRACTURE
- Acute forced plantarflexion may present as acute fracture- downhill running, kicking or dancing
8
Q
Name associated conditions of OS trigonium?
A
- FHL Tenosynovitis or entrapement
9
Q
Describe the osteology of os trigonium?
A
- Secondary ossification centre forms posterior to talus between 8-13 years
- Normally fuses with talus within 1 year
- If ossicles fail to fuse, it articulates with talus thru synchondrosis
- Os lies LATERAL to FHL, TIBIAL nerve, PTT, POST tibial artery
10
Q
Describe the symptoms of os trigonium?
A
Symptoms
- Pain en pointe position
O/E
- Posterior lateral ankle pain with passive ankle flexion
- may have swelling & tenderness over FHL is associated with FHL tendonitis
11
Q
What investigations are useful in Os trigonium?
A
- Xrays
- lateral with foot in planar flexion
- show os trogonium impinging between posterior malleolus and calcaneal tuberosity
- MRI
- show os trigonium adn associated inflammationadn oedema in FHL tendon
12
Q
What is the Differential dx of Os trigonium ?
A
- Posterior process of talus fracture - Shepherd’s fracture- see pic
- FHL & Post tibial tendonitis- produce medial ankle pain and tenderness.
13
Q
What is the Tx of Os trigonium?
A
- Non operative
- NSAIDS, rest, immobilisation, restricted WB
- Operative
- Surgical excision
- if non op fails
- through an OPEN LATERAL APPROACH or POST ANKLE ARTHROSCOPY- 80% gd to excellent results at 2-5 yr mark
14
Q
What is this?
A
- Os Subfibulare
- small piece of bone adjacent to inferior fibula
15
Q
What is the epidemiology and pathoanatomy of Os Subfibulare?
A
- 1-2% of population
- May represent Avulsion fx of ATFL that secondarily ossifies
- Accessory ossification centre