Fractures of the tibia and fibula Flashcards
What are the epiphyses of the tibia and how much growth do they contribute respectively?
Proximal: 40%
Distal: 60%
Medial malleolar: none
Tibial tuberosity: none
The proximal and tibial tuberosity physes typically fuse around 5 months of age. The tibial tuberosity physis may not close to the metaphysis until over 1 year of age in large breed dogs.
What vessel supplies the medullary nutrient artery to the tibia?
The cranial tibial artery.
The medullary artery supplies the inner two-thirds of the tibial cortical circulation, whereas the periosteal arteries supply the outer one-third.
What structures cross obliquely over the diaphysis of the tibia and need to be protected during a surgical approach?
Cranial branch of the medial saphenous artery and vein, and the saphenous nerve.
What are the most common configurations of proximal and distal physeal fractures of the tibia?
Salter Harris type 1 and 2
What are the most common fracture configurations of the tibial diaphysis?
Spiral/oblique, comminuted
What force is thought to result in tibial tuberosity avulsion fracture?
Contraction of the quadriceps muscle with concurrent stifle flexion.
Usually observed in patients 4-8 months of age.
What are the treatment options for avulsion of the tibial tuberosity?
- Conservative management with cast or splint if minimally displaced and a small breed dog.
- Surgical fixation (typically recommended).
a. Pin fixation
b. Pin and TBW
When should removal of pins following fixation of tibial tuberosity avulsion fracture be considered?
In animals with considerable remaining growth potential (large dogs less than 6 months, small dogs less than 4 months)
What are potential complications associated with surgical repair of tibial tuberosity avulsion fracture?
Avulsion of the tuberosity from the implant, wire or pin breakage, bending of a pin, pin migration, entry of a pin into the proximal epiphysis, deformity of the proximal end of the tibia.
What are treament options for Salter Harris fractures of the proximal tibial physis?
- Conservative management if minimally displaced.
- Surgical fixation using cross-pins. If a large metaphyseal fragment is present this may be additionally stabilized using an interfragmentary screw.
The tibial tuberosity is usually involved in conjunction with the proximal epiphysis.
How many pins should ideally be used for repair of a proximal Salter Harris type 2 fracture of the tibia?
Ideally 3 (medial, lateral and third pin through the tuberosity)
What are surgical repair options for proximal metaphyseal fractures of the tibia?
Intramedullary pin, cross-pins, bone plate, ex-fix (type 1b, circular or hybrid)
What is the ideal normograde entry point for a tibial IM pin?
Cranial to the intermeniscal ligament, at a point midway between the tibial tuberosity and medial collateral ligament in the frontal plane.
What is the percentage of medullary canal fill typically recommended for IM pinning of the tibia?
50%
Why is normograde tibial pinning preferred over retrograde?
Less risk of intraarticular penetration
What proportion of fractures of the distal tibia are open fractures?
30-40%
Which side of the distal tibia is more frequently affected by shearing injuries?
The medial side
What are surgical options for distal Salter Harris fractures of the tibia?
Cross pinning if adequate bone stock distally. If inadequate bone stock intramedullary pinning or transarticular pinning can be performed.
Normally approached from the medial aspect.
If cross-pinning of a distal tibial Salter Harris fracture is not possible due to the small size of the distal fragment, what is an alternative?
Transarticular pinning from the talus to the tibia at a normal standing angle. Less ideal as creates articular damage.
Must be supported with rigid immobilization post-operative and the pin should be removed as soon as clinical union is reached.
Are growth disturbances of the distal tibia common or rare following distal physeal Salter Harris fracture?
Rare.
Malleolar fractures commonly occur secondary to what type of injury?
Shearing injury.
What are surgical stabilization methods for malleolar fracture?
Pins/K-wires +/- TBW, screws (depending on size)
Are the lateral or medial malleoli more likely to be fractured?
Equal probability (as well as bilateral fractures)
What should be tested following surgical repair of a malleolar fracture?
Joint stability. If joint instability persists integrity of the ligaments should be further evaluated.