Fractures of the tibia and fibula

Question 1

What are the epiphyses of the tibia and how much growth do they contribute respectively?

Answer 1

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.

Question 2

What vessel supplies the medullary nutrient artery to the tibia?

Answer 2

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.

Question 3

What structures cross obliquely over the diaphysis of the tibia and need to be protected during a surgical approach?

Answer 3

Cranial branch of the medial saphenous artery and vein, and the saphenous nerve.

Question 4

What are the most common configurations of proximal and distal physeal fractures of the tibia?

Answer 4

Salter Harris type 1 and 2

Question 5

What are the most common fracture configurations of the tibial diaphysis?

Answer 5

Spiral/oblique, comminuted

Question 6

What force is thought to result in tibial tuberosity avulsion fracture?

Answer 6

Contraction of the quadriceps muscle with concurrent stifle flexion.

Usually observed in patients 4-8 months of age.

Question 7

What are the treatment options for avulsion of the tibial tuberosity?

Answer 7

1. Conservative management with cast or splint if minimally displaced and a small breed dog.
2. Surgical fixation (typically recommended).
   a. Pin fixation
   b. Pin and TBW

Question 8

When should removal of pins following fixation of tibial tuberosity avulsion fracture be considered?

Answer 8

In animals with considerable remaining growth potential (large dogs less than 6 months, small dogs less than 4 months)

Question 9

What are potential complications associated with surgical repair of tibial tuberosity avulsion fracture?

Answer 9

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.

Question 10

What are treament options for Salter Harris fractures of the proximal tibial physis?

Answer 10

1. Conservative management if minimally displaced.
2. 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.

Question 11

How many pins should ideally be used for repair of a proximal Salter Harris type 2 fracture of the tibia?

Answer 11

Ideally 3 (medial, lateral and third pin through the tuberosity)

Question 12

What are surgical repair options for proximal metaphyseal fractures of the tibia?

Answer 12

Intramedullary pin, cross-pins, bone plate, ex-fix (type 1b, circular or hybrid)

Question 13

What is the ideal normograde entry point for a tibial IM pin?

Answer 13

Cranial to the intermeniscal ligament, at a point midway between the tibial tuberosity and medial collateral ligament in the frontal plane.

Question 14

What is the percentage of medullary canal fill typically recommended for IM pinning of the tibia?

Answer 14

50%

Question 15

Why is normograde tibial pinning preferred over retrograde?

Answer 15

Less risk of intraarticular penetration

Question 16

What proportion of fractures of the distal tibia are open fractures?

Answer 16

30-40%

Question 17

Which side of the distal tibia is more frequently affected by shearing injuries?

Answer 17

The medial side

Question 18

What are surgical options for distal Salter Harris fractures of the tibia?

Answer 18

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.

Question 19

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?

Answer 19

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.

Question 20

Are growth disturbances of the distal tibia common or rare following distal physeal Salter Harris fracture?

Answer 20

Rare.

Question 21

Malleolar fractures commonly occur secondary to what type of injury?

Answer 21

Shearing injury.

Question 22

What are surgical stabilization methods for malleolar fracture?

Answer 22

Pins/K-wires +/- TBW, screws (depending on size)

Question 23

Are the lateral or medial malleoli more likely to be fractured?

Answer 23

Equal probability (as well as bilateral fractures)

Question 24

What should be tested following surgical repair of a malleolar fracture?

Answer 24

Joint stability. If joint instability persists integrity of the ligaments should be further evaluated.

Question 25

What are some options for surgical treatment of distal metaphyseal tibial fractures?

Answer 25

If adequate distal bone stock can use bone plate and screws or ESF.

If the distal bone stock is inadequate can use a transarticular ESF or transarticular IM pin. Arthrodesis is also an option in highly comminuted fractures with no hope of preserving function.

Question 26

What causes pes varus?

Answer 26

Premature closure of the medial aspect of the distal tibial physis.

Question 27

In which breed is pes varus most frequently reported?

Answer 27

Dachshund

Question 28

What causes pes valgus?

Answer 28

Abnormal growth of the distal fibula physis.

Question 29

Which breeds are most commonly affected by pes valgus?

Answer 29

Shetland sheepdogs and large breed dogs

Question 30

How are pes varus and pes valgus most frequently corrected?

Answer 30

Pes varus: medial opening wedge
Pes valgus: medial closing wedge

Fixation can be achieved with bone plates, ESF (hybrid or linear), or plate rod.

Question 31

In a study by Sherman 2022 in Vet Surg, what percentage of tibial fractures in dogs and cats stabilized with linear external fixators had post-op complications? What was the mean time to ex-fix removal?

Answer 31

40% had complications.
71 days was the mean time to ex-fix removal.

Question 32

In a study by Welsh 2023 in Vet Surg, did one single large pin, or two smaller pins have greater biomechanical stability when repairing tibial tuberosity avulsion fractures?

Answer 32

Two small pins (mean strength of 462 N compared to 639 for one single pin).

Question 33

In a study by Gutbrod 2024 in Vet Surg, which of the following constructs was the strongest and most rigid in a feline tibial fracture gap model?
1) 2.4mm LCP and 1mm IM pin
2) 2.4 mm LCP and 1.6 mm IM pin
3) 2.7mm LCP

Answer 33

The 2.4mm LCP and 1.6mm IM pin

Question 34

In a study by Miller 2022 in JAVMA, what was the long term complication rate of tibial tuberosity avulsion repair in immature dogs with the implants left in situ?

Answer 34

14% (patients required implant removal). Compares favourably to previous reports.

Question 35

In a study by Hoffman 2020 in VCOT, were LCP or conical coupling constructs biomechanically superior for fixation of cadaveric feline tibial fractures?

Answer 35

The LCP was stiffer and stronger (yield load and failure load were greater) than the conical coupling plate.

Question 36

In a study by Miraldo 2020 in VCOT, what technique was used for repair of distal tibial physeal fractures in cats and was associated with a good to excellent outcome? What was the primary benefit of this technique?

Answer 36

Modified four cross-pin technique.

No external coaptation was required.

Question 37

In a study by von Pfeil 2021 in VCOT, was the use of negative profile or smooth pins for percutaneous pinning of tibial tuberosity avulsion fractures associated with a higher rate of seromas and implant removal? What horizontal cross pin angle was associated with a decreased incidence of desmitis?

Answer 37

Smooth profile pins had a higher rate of seroma and requirement for implant removal.

A horizontal cross pin angle of 40 degrees resulted in a lower incidence of desmitis (as compared to 26 degrees).