26.5.3: Distal phalangeal and distal sesamoidean fractures Flashcards
Causes of navicular and P3 fractures
- Acute onset tauma
- Developmental/ osteochondral fragments
- Repetitive wear and tear
- Chronic disease
Prognosis
Prognosis is poor
* There are multiple fragments, some articular in a very high motion joint
* This is very unstable
* Internal fixation is not possible
* Arthritis of DIP inevitable and often the reason for euthanasia
Treatment and prognosis
- Small non-articular fragment from sole of pedal bone
- Usually repetitive wear and tear (poor foot conformation + concussive forces)
Treatment
* Will heal with rest and shoeing
* If due to acute onset trauma e.g. nail in foot -> need to remove fragment
Prognosis: good because this fracture is small and non-articular.
Considerations for detection of navicular and P3 fractures
- Both of these fractures are enclosed within the hoof capsule -> this means there is often minimal displacement of these fractures
- Identification on physical exam is difficult but important
Clinical signs and detection of navicular and P3 fractures on physical exam
Clinical signs
* Small extra-articular fractures = low grade lameness with minimal localising signs
* Significant/ complete fractures = acute onset severe lameness with localising signs e.g. bounding digital pulses, heat in the hoof, positive response to hoof testers
Physical exam findings
* Carefully palpate hoof and pastern region for heat, pain, swelling (including synovial effusions e.g. DIP, flexor tendon sheath)
* Use hoof testers to identify site of pain
* Articular fragments -> distal interphalangeal joint effusion (pedal bone and navicular bone)
* Tendon involvement -> digital flexor tendon sheath effusion (navicular bone)
Diagnostic approach to navicular fractures
- Radiography
- MRI
- CT
- Gamma scintigraphy
- Nerve and joint blocks - ONLY for mild/chronic cases. AVOID in acute/ severe/ significant fractures.
What is the appropriate treatment option for this fracture?
a) conservative (box rest only)
b) external coaptation (foot cast)
c) fragment removal (bursocopy surgery)
d) internal fixation (screw)
d) internal fixation (screw)
This is a completely transverse fracture and the 2 fragments are unstable and will move unless stabilised.
Challenges in using radiographs to identify distal phalangeal and navicular fractures
- Hoof structures holdbone together -> fracture may not be visible until bone resorption has occurred (7-10 days)
- If you think there is a fracture but it’s not showing, radiograph 10-14 days later and look for radiolucent line
- Some fractures only heal with fibrous union -> line remains on radiographs but fracture is stable
- Therefore chronic fractures may need additional tests to confirm if clinically significant
Where is the extensor process of P3 and why is it important?
- Extensor process = site where extensor tendon attaches. Common site for arthritic change and fragments.
What view of the navicular bone is shown here?
Dorsoproximal palmarodistal 60 degree oblique
What view of the navicular bone is shown here?
Palmaroproximal palmarodistal oblique
Where do the collateral ligaments of the distal interphalangeal joint attach?
Wings of P3
What could a fragment at the site of the extensor process represent?
- Recent fracture
- Previous fracture, now healed and stabilised
- Separate centre of ossification
- Dystrophic mineralisation in the extensor tendon
Standard foot series - radiographic views needed
- Lateromedial
- Dorsopalmar
- Dorsoproximal palmarodistal 60 degree oblique centred on the pedal bone (upright pedal)
- Dorsoproximal palmarodistal 60 degree oblique centred on the navicular bone (upright navicular)
- Palmaroproximal palmarodistal 45 degree oblique (flexor navicular)
^ of both feet (so 10 images minimum) so you can compare.
Can also do additional oblique views of the pedal bone,
