Splint Bones And Proximal Sesamoid Bone Fractures Flashcards
What bones do the splint bones (MC/MT 2 and 4) articulate with ?
They articulate with the carpal and tarsal bones
What kind of support do the splint bones provide?
Axial support to the carpus and tarsus
Which splint bone has minimal articulation and weight transfer With its corresponding bone ?
MT4 has minimal articulation and weight transfer with the 4th tarsal bone
In both the front and hind limb, the ____________splint bone provides less support for the carpus/tarsus.
Which has the least of all
Lateral
MT4 provides the least support of all
If there is damage to MT4 (hind lateral splint bone) there are more ways of dealing with it and better prognosis, Why?
Because MT4 provides the least amount of support!!!
Give some common causes of Splint bone fractures
1) hyperextension of the fetlock
- closed
2) External trauma
- open
Can splint bone fractures be treated successfully?
Many can be treated successfully with REST alone!!!!
Suspensory desmitis may cause persistent lameness
What ligament is intimately related to the splint bones?
The suspensory ligament
What are some treatment options for splint bone fractures?
1) conservative wound management
2) segmental ostectomy
3) removal of distal portion (midbody fx)
4) ORIF. (Open reduction and internal fixation)
5) wound management and removal of loose fragments
6) internal fixation
What are some treatment options for proximal splint bone fractures?
1) wound management and removal of loose fragments
2) internal fixation (proximal splint bone fx)
How much of the distal splint bone can be removed?
Up to 2/3 of the distal splint bone (except MT4)
In theory you can remove the entire MT4, because its so useless at its job (support)
If you need to remove more than 2/3 of the distal splint bone what is required?
Need internal fixation of the proximal fragment
Where do sequestrums form most commonly?
Metacarpus and metatarsus regions
-lack of circulation
How long does a sequestrum take to show up on radiographs?
4-6 weeks
When performing internal fixation (plating) a splint bone fx it is important NOT to engage the MC/MT 3 Why?
- there is movement between splint bones and MC/MT3
- cause persistent lameness
- micro-movements cause more trauma
If the cannon bone must be engaged with internal fixation what must be done?
MUST remove plate 3-4 months post op!!!!
What is suggested when an owner says my horse “popped a splint” or “has a splint”
Splint exostosis
Proliferative periostitis
Usually caused by trauma
-usually on the medially aspect of the cannon bone (MC2)
Where is splint exostosis most commonly seen?
Medial aspect of the front cannon bone (MC2)
-young horses
What causes splint exostosis?
- direct trauma
- ligamentous inflammation
What clinical signs are seen with splint exostosis?
1) lame initially
2) firm swelling at site (MC2)
3) warm and painful to palpate
Become sound with a blemish!!!
How do you treat Exostosis ?
Conservative :
- rest, NSAIDs
- Local DMSO/ or infiltration with corticosteroids
Surgical : (segmental ostectomy)
- /Linear incision over site with en bloc removal
- excellent bandaging required post op
What are the three places you can get a pulse on a horse?
1) transverse facial artery
2) facial artery
3) dorsal metatarsal artery
Where is the dorsometatarsal artery and nerve located?
Between between MT4 and MT3
Lateral splint bone and cannon bone of the hind limb
What should you consider when incising over the cannon bone in the hind limb? Is this a concern in the fore limb?
The location of the dorsometatarsal artery and nerve (between MT3 and MT4)
This is not a concern in the fore limb because there are no arteries or nevers running over the cannon bone
Dorsal cortical fractures of the cannon bone (MC3) is most common in which type of horse?
YOUNG race horses
Bucked shins/ dorsal metacarpal disease/ saucer fractures/ stress fractures all refer to what?
Periostitis and fracture of the dorsal metacarpal 3 (cannon bone)
Are Dorsometacarpal 3 fractures (dorsal cannon bone fractures) preventable?
YES
Allocate more training efforts to regular short distance breezing and less long distance galloping
What is the medical treatment for Dorsometacarpal 3 fractures?
TIME
- rest
- NSAIDs
- REduced exercise program
- radiographic monitoring
What surgical treatment can be done for bucked shins?
OSTEOSTIXIS
- alone or in combo with screws
- advantages of alone (no screw removal required)
COMBO has the best result = more stability
-screws removed at 60days
What kind of screw should be placed for buckle shin?
-difficult to ID fx in sx so put staples pre operatively
drill perpendicular to fracture
- radiographic guidance
-SINGLE unicortical positional screw (22mm)
-6-8 osteostixis holes drilled 10mm apart (towards medullary cavity)
What is the prognosis for stress fractures of the cannon bone to return to race?
GOOD RTR
What is the most common fracture of the proximal sesmoid bones?
Apical fracture
What are some common causes of Proximal sesamoid bone fractures?
1) excessive tension from suspensory ligament
2) trauma
3) primary racing breeds
How would you treat an Apical sesamoid Fracture?
- proximal 1/4-1/3 always articular
1) if less than 1/3 then it can be removed arthroscopically
2) if large fragments then internal fixation is required
What is the prognosis for Apical sesamoid fractures?
GOOOD prognosis
- usually dont cause significant suspensory Dz
- evaluate suspensory ligament with US
Can midbody sesamoid fractures be removed with a scope?
No
- requires internal fixation
- lag screw or circumferential cerclage wire
What is the ideal surgical technique for midbody sesamoid fractures?
Screw fixation in lag fashion
-best for TB to RTR
What surgical technique is reserved for Standard bred horses that have midbody sesamoid fractures?
Circumferential cerclage wire
How are screws placed for midbody sesamoid fractures?
- Arthroscopically
- cortical screws placed in lag fashion
- screw placed at the base of sesamoid bone
- screw placed distally to proximally
How do you verfy accurate screw placement for midbody sesamoid fractures?
Radiographically and arthroscopically
Which technique is better for midbody sesamoid fractures?
Screw fixation vs wire fixation
Screw fixation arthroscopically
Are abaxial (towards the outside of the limb) sesamoid fractures usually displaced?
NO
How do you diagnose an abaxial sesamoid fracture?
Take rads 60 degrees skyline view to see if it is articular
How do you treat an abaxial sesamoid fracture:
A) if it is intra articular
B) if it is extra articular
A) intra-articular => artroscopic removal (depending on size)
B) conservative management
What is the prognosis for Abaxial sesamoid fractures?
Fair to good
What is the prognosis for basilar sesamoid fracutres? WHY?
POOR prognosis
- invovles origin of all distal sesamoidean ligaments
- lag screw fixation is challenging
- inverse relationship between dorsopalmar length and RTR
