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
16
Q
What are the symptoms and signs of Os Subfibulare?
A
Symptoms
- May be asyptomatic
- Ankle pain ( symptomatic os subfibulare)
- Assoc with chronic ankle instability- present with recurrent ankle sprains
Signs
- Focal tendermess & swelling at site of ossicle
- Laxity with anterior draw & inversion/eversion stress test
17
Q
What imaging is helpful in Os Subfibulare?
A
- xrays
- standard ankle series- WB AP, Lateral , Mortise
- varus stress view
- See accessory ossicle
-
Talar tilt on varus stress view- see pic
- suggest ankle instability
- increased separation of os fragment from fibular tip
18
Q
What is DDX of Os Subfibulare?
A
- Acute lateral malleolus avulsion fracture ( by ATFL)
19
Q
What is the Tx of Os Subfibulare?
A
- Non operative
- NSAIDs, Rest, Immobilisation, restricted WB
- intial tx for symptomatic os fibulare
- Operative
- Surgical exicision
- failed non operative treatment
20
Q
What is this?
A
- Os Peroneum
- Sesmoid bone found within PERONEUS LONGUS tendon near the base of the 5th MT
- May represent avulsion/rupture of peroneus longus
21
Q
What is the epidemiology of Os peroneum?
A
- Incidence 9-20%
- Bilateral 60%
- Bipartite 30%
22
Q
Describe the pathophysiology of injury/fracture?
A
- Direct Trauma
- Indirect Trauma- Sudden inversion/eversion
- assoc with peroneus longus tendon rupture
23
Q
What investigations are useful in DDx of Os peroneum?
A
- Xrays
- normal os peroneum
- acute os peroneum fracture
- peroneus longus rupture
- MRI
- Normal os peroneum
- Acute os peroneum fracture
- peroneus longus rupture- see pic
24
Q
What is the DDX of Os peroneum?
A
- Painful os Vesalianum- see pic
- Biparite os peroneum
25
Describe the Tx of OS peroneum?
* Non operative
* **NSAIDS, Rest, immobilisation, restricted weightbearing**
* inital Tx for painful os peroneum syndrome
* minimally displaced os peroneum fractures
* Operative
* **Surgical Excision**
* Painful os peroneum syndrome w consx tx
* os peroneum fracture w displaced fragments
* **Surgical excision w repair of Peroneus Longus Tendon or tenodesis to Peroneus Brevis**
26
What is this?
* **Accessory NAVICULAR**
* Normal variant in **12% population**
* Majority pts are **asymptomatic**
* More common in **females**
27
What is the pathoanatomy of accessory navicular?
* Occurs as a **PLANTAR ENLARGEMENT of navicular bone**
* Navicular ossifies at age 3 in girls, 5 in boys
* **Accessory navicular doesn't ossify until 8 years**
* exists as **secondary bone** or **complete ossified extension to navicular**
28
What is the classification ot the accessory navicular?
* Radiograph
* TYPE 1= Sesmoid bone in substance of TIBIALIS POST tendon- see pic
* TYPE 2= Separate accessory bone attached to native navicular via **synchondrosis**
* Type 3= Complete bony enlargement
29
What are the symptoms and signs of accessory navicular?
* Symptoms
* **Medial Arch pain is worse w OVERUSE**
* due to repetitive microfracture at the synchondrosis or from inflammation of the posterior tibialis tendon insertion
* O/E
* **Tender at medial and plantar** aspect of **navicular** bone
30
Describe the imaging useful for Dx?
* Xrays
* Ap, Lat, obliques
* best seen on **EXTERNAL OBLIQUE**
* **bony enlargement or accessory bone**
* **MRI**
* **Helps delinate insertion of tibialis posterior tendon**
31
What is the TX of accessory navicular?
* Non operative
* **Activity restriction, shoe modification and non- narcotic analgesia**
* use of arch supports/pads over bony prominences
* UCBL orthosis may invert heel during walking and decrease symptoms
* nearly all children & adolsecents who have symptomatic accessory tarsal navicular bone become asymptomatic when they reach skeletal maturity
* **Short period pf cast immobilisation**
* **Operative**
* **Excision of accesory navicular**
* failed consc tx
32
Describe the technique for surgical excision of accessory navicular?
* **Bone needs to be resected flush with MEDIAL CUNEIFORM**
* most common cause of persistent symtpoms post surgery is **INADEQUATE BONE RESECTION**
* other pts may have persistent pain from **SCAR TISSUE** or other causes
* May need to **SPLIT the posterior tibialis** tendon in order to excise the navicular
* **Re- routing the posterior tibialis will NOT CORRECT FLAT FOOT DEFORMITY**
* **CALCANEUS OSTEOTOMY if flatfoot correction is needed.**
