Dealing with Non-Infectious Complications

Question 1

Common complications of internal fixation. (7)

Answer 1

wound dehiscence
seroma
implant failure
necrosis of soft tissue
neurological damage
delayed union/non-union/malunion
infection

Question 2

What specifics about # repair create a favourable environment for bacterial colonisation and multiplication? (3)

Answer 2

Metal implant
Haematoma
Necrotic tissue

Question 3

What are the 3 possible results of inadequate mechanical or biological environment?

Answer 3

retarded healing (delayed union)
unsuccessful healing (non-union)
improper healing (malunion).

Question 4

At what point should a patient be weigh bearing (toe touching) post surgical stabilisation?

Answer 4

48 hours

Question 5

At what stage post-operatively should a more thorough investigation be performed if the animal is not weight-bearing?

Answer 5

3-5 days

Question 6

A client reports that their dog (who has recently undergone fracture repair) has shown sudden deterioration in their lameness over the last 24 hours. What is your advice?

Answer 6

The dog should be seen for a thorough re-examination and may require more investigations, if this is indicated.

Question 7

All animals that have deteriorated post-orthopaedic surgery usually need the following: (3)

Answer 7

• Full physical examination
• Radiographs to check for implant problems, evidence of infection, or bone complication such as fracture
• Samples for cytology and culture (likely arthrocentesis for articular fractures).

Question 8

How to avoid wound dehiscence at tie of surgery? (2)

Answer 8

• Good wound closure
• Careful tissue handling

Question 9

Self-trauma of the wound or surgical site infection can be contributing reasons. If implants are exposed in combination with lack of tissue, reconstruction often fails. What are your options? (3)

Answer 9

Treat as an open wound

May require implant removal for ultimate closure

Alternative stabilisation methods may need to be considered such as an external skeletal fixator.

Question 10

Possible causes of seromas post surgical fixation? (3)

Answer 10

• leaving fascial planes open
• Dehiscence of sutures in middle layers
• Uncontrolled activity

Question 11

Why should you NOT aspirate an FNA?

Answer 11

Introduce bacteria

Question 12

How to reduce a seroma once formed?

Answer 12

Warm pack several times daily

Question 13

If there is a large seroma, causing clinical signs. What may be needed?

Answer 13

A closed drain under aseptic conditions

Question 14

Possible causes of haematoma post surgery? (2)

Answer 14

• Poor surgical technique
• Coagulation problems

Question 15

If Hematomas are not associated with coagulation problems, what should be done?

Answer 15

They will disappear within a couple of days and do not need further therapy.

Question 16

Common reason for implant failure?

Answer 16

Technical error.

Question 17

Common technical errors causing implent failure?

Answer 17

Solitary use of an IM pin

Solitary use of an IM pin with cerclage wires

Use of cerclage wire that is too small in diameter

Use of an insufficient number of cerclage wires

Use of cerclage wires at unsuitable areas/fractures

Excessive or insufficient plate size due to a lack of inventory

Use of a short plate with too few screws

Use of a plate that is too short relative to the length of the bone

Unsuitable plate type

Non-adherence to the rules of plate uses

Erroneous analysis of the forces to neutralise.

Question 18

Where are reconstruction plates not sufficiently strong?

Answer 18

Weight bearing diaphyseal bone

Question 19

The implants used to stabilise a fracture restore the bone’s structure and function A) It is bone healing that restores it B)

Answer 19

A) Temporaily
B) Permanently

Question 20

As a fracture heals, the load taken by the implants A) over time and the load taken by the bone B)

Answer 20

A) Decreases
B) Increases

Question 21

If the bone fails to heal, then implants undergo cyclic fatigue and may A). All metalwork will B) eventually. Successful healing can be considered a race between bone healing and implant failure.

Answer 21

A) Fail
B) Fatigue

Question 22

What are the types of implant failure? (6)

Answer 22

Mechanical failure
Metallurgic imperfections
Manufacturing faults
Acute overload failure
Fatigue failure
Corrosive degradation.

Question 23

What is fatigue failure causes by?

Answer 23

repetitive cyclic loads that in isolation would not cause failure.

Question 24

What is the most important mode of failure?

Answer 24

Fatigue

Question 25

When does fatigue failure occur?

Answer 25

Weeks after successful repair

Question 26

What happens with fatigue failure?

Answer 26

There is progressive microscopic damage to the metal structure and micro-cracks form. These propagate until the crack reaches a length beyond which remaining material cannot withstand the stress of loading.

Question 27

What is the relation of number of stress cycles a metal implant can withstand and magnitude of stress?

Answer 27

The number of stress cycles a metal implant can withstand is inversely proportional to the magnitude of stress (i.e., as stress increases the number of cycles the implant can withstand decreases).

Question 28

The concept of stress concentration is important in fracture repair. In a dynamic compression plate (DCP), the hole is a

Answer 28

‘stress riser’ (i.e., there is a force being applied to a smaller area due to the hole:

Question 29

When is the stress concentration greater? (3)

Answer 29

• Unstable #
• Poorly reduced#
• Plate must withstand all the force

Question 30

Relation of load sharing of the bone and stress concentration.

Answer 30

Load sharing of the bone (i.e., reconstruction with compression) decreases stress concentration.

Question 31

What can neurological damage occur secondary to? (2)

Answer 31

Initial trauma
Surgical approach

Question 32

Which fractures have the highest incidence of sciatic nerve injury? (4)

Answer 32

Displaced ileal,
acetabular,
sacral
caudal #s

Question 33

When do Displaced ileal, acetabular, sacral and caudal #s have a guarded prognosis? (2)

Answer 33

Concurrent anal atony and limb flaccidity.

Question 34

How to reduce Iatrogenic radial nerve injury during humeral fracture repair? (2)

Answer 34

• Early nerve identification
• careful retraction

Question 35

Injury to which nerves is usually NOT catastrophic? (2)

Answer 35

Median n.
Ulnar n.

Question 36

Most common neurological damage?

Answer 36

Neuropraxia

Question 37

What is the outcome with neuropraxia?

Answer 37

In these cases, functional recovery can be expected within days to weeks.

Question 38

How to avoid neurological damage? (3)

Answer 38

Ensure a good work-up pre-surgery to recognise nerve injury.

Avoid iatrogenic damage by employing a careful and prepared surgical approach.

Place IM pins normograde and cut short or leave long enough to protrude through the skin and be tied into an external frame.

Question 39

Predisposing factors to muscle contracture? (5)

Answer 39

Skeletally immature animals

Exuberant bony callus

Extended coaptation

Muscular trauma - initial trauma or iatrogenic

Infection.

Question 40

What # are prone to quadriceps contracture?

Answer 40

Distal femur

Question 41

What are important factors for development of quadriceps contracture? (2)

Answer 41

• Initial trauma
• Misuse of leg

Question 42

What may reduce risk of quadriceps contracture? (2)

Answer 42

Early use of the leg with careful physiotherapy