Metacarpus/metatarsus Flashcards
Describe the anatomy of the metacarpal/metatarsal region
Cannon bone (3rd metacarpus/tarsus bone) and two splint bones
Which structure runs down the dorsal aspect of the 3rd metacarpal/tarsal bone, how is it different in the FL and HL?
Digital extensor tendon
– made up of the common and lateral in the FL this tendon al extensor tendons in the HL the lateral extensor tendon merges into the long digital extensor tendon to continue down as a single tendon
Which structures are found on the palmar aspect of the 3rd metacarpal/tarsal bone?
- SDFT
- DDFT
- Check ligament/accessory ligament of the DDFT
- Suspensory ligament: divides into two branches that insert onto the proximal sesamoid bones
Describe the Digital flexor tendon sheath
Synovial ‘sleeve’ like structure that allows the SDFT and DDFT to pass through the fetlock canal. Anchored in placed by the annular ligament
What may be found on clinical examination when investigating problems of the metacarpus/metatarsus
Pain/heat/soft tissue swelling
Joint/tendon sheath effusion
Crepitus/pain on percussion
Describe diagnostic analgesia of the metacarpus/metatarsus
- H4/H6 NB
- Subcarpal/subtarsal block
- Lateral palmar nerve/deep branch of lateral plantar
nerve (DBLPN) block
Which radiographic views would you want to take of the metacarpus/metatarsus
Standard projections (DP, LM, DMPLO, DLPMO)
List some bone conditions of the metacarpus/metatarsus
- Fractures of the third metacarpal/metatarsal bone
- Dorsal metacarpal bone disease
- Fractures of the second/fourth metacarpal/metatarsal (“splint”) bones
- Exostosis of the second/fourth metacarpal/metatarsal bones (“splints”)
List some (Palmar) soft tissue conditions of the metacarpus/metatarsus
SDFT/DDFT tendinitis
ALDDFT desmitis
SL desmitis
PAL syndrome
Which 4 types of fractures can occur in the third metacarpus/metatarsus
Condylar fractures (lateral and medial)
Diaphyseal
Transverse
Proximal articular
What are the causes of Fractures of the third metacarpus/metatarsus
Usually single overload injury or external trauma (e.g. kick)
Condylar Fractures of the third metacarpus/metatarsus are usually caused by …?
Condylar fractures usually fail due to repetitive strain cycles
- Pre-existing changes parasagittal to the ridge
How do Fractures of the third metacarpus/metatarsus usually present clinically?
- Lame (moderate/severe, acute), signalment
- Swelling/crepitus/pain on palpation/flexion
- +/- joint effusion
- Displacement (diaphyseal)
- Open/closed
Describe how to carry out radiography for suspected fractures of the third metacarpus/metatarsus
- Standard views plus additional to work out configuration
- Do not over collimate: lateral condylar f# tend to exit laterally above physeal scar whereas medial condylar f# tend to spiral proximally
How do open/closed fractures need to be initially managed?
- Need to make sure a closed fracture doesn’t become an open fracture by stabilising it
- Zone 2 external co-aptation (lateral condylar f# two splints placed lat. and med.)
- Open fractures (especially if infected) have a poor prognosis and are hard to treat
Describe the management options for fractures of the third metacarpus/metatarsus based on the fracture type
- Conservative: Non-displaced, closed, transverse and some proximal articular fractures
- Surgical: Condylar fractures, diaphyseal fractures
- Euthanasia: Displaced, open, comminuted
Dorsal metacarpal disease is also known as?
Also known as “sore shins” or “bucked shin complex” in young racehorses
What is dorsal metacarpal disease?
- Excessive cyclic loading results in painful periosteitis as 2yo
- Some of these horses go on to develop dorsal cortical “stress” fractures as 3yo