Stabilisation of Humeral Fractures Flashcards
What % of # are humeral in cats and dogs?
10
Most # of humerus involve which aspect of the bone?
Middle and distal 1/3
Most likely humeral # location with a cat?
more likely to affect mid-diaphysis
Most likely humeral # location with a dog?
most likely in distal part of the bone
What nerve injury needs to be assessed for with the humerus to judge any postoperative neurodysfunction as trauma-related or iatrogenic or a combination of both?
Radial
What type of immobilisation can be used for a temporary option with humeral #?
A spica splint
Humerus anatomy:
A) What shape bone?
B) What about the muscle makes it difficult?
C) What makes accurate plate contouring difficult?
A) S shaped with a twist
B) Large surround muscle mass
C) The ridges proximally and distally
Humerus anatomy:
A) Where does the radial n cross?
B) Where do medial and ulnar nerves run?
A) Distolateral
B) Medial
What passes through the supracondylar foramen in cats? (2)
Median n
Branch of brachial a
The distal third of the humeral shaft in the dog and cat is compressed in what direction?
Craniocaudal
The distal third of the humeral shaft in the dog and cat is compressed; what does this make it prone to? (2)
Communiution
Fissure
Why does the humerus have a limiting intramedullary pin purchase in the condyle of the humerus?
The medullary canal tapers and effectively ends far proximal to the distal aspect of the bone
The surgical approaches are technically demanding because of (2)
Neovascular
Large amount of muscle
Patterns of Fractures of the Humeral Diaphysis (6)
Simple transverse
Spiral
Oblique fractures
Comminuted fractures
Supracondylar:
- Simple
- Comminuted
Combined with condylar fractures:
- Unilateral
- Bilateral.
Views of humerus by xrays?
both humeri in mediolateral and craniocaudal or caudocranial views
How to take a CrCd view of humerus to avoid a foreshortened image or use horizontal beam?
Position animal in dorsal recumbency with the limb pulled caudally and slightly laterally
Approach to the craniolateral aspect of the humerus, combined with an approach to the proximal part of the humerus.
How much of the humerus is exposed?
Proximal 3/4
Lateral approach to humerus, what muscles are exposed:
A) Caudally?
B) Cranially? (3)
A) Triceps brachii
B) Biceps brachii, pectoral, braciocephalicus
Lateral approach to the humerus; how to know which way to reflect radial n with brachialis m?
Cranial/caudal according to position of #
Medial approach to humerus:
Where is the skin incision?
Skin incision along cranial shaft to medial epicondyle.
What blood vessels need to be visualised on the initial medial approach to the humerus? (2)
brachial and collateral ulnar
Medial approach to humerus:
Incise deep fascia directly over distal humeral shaft and between blood vessels, bluntly dissect through subfacial fat and fascia to identify which nerve:
A) Caudally?
B) Cranially?
A) Ulnar
B) Median
Medial approach to the humerus elevate and reflect:
A) What muscle caudally or cranially, if exposure required distally
B) What muscle cranially?
C) What muscle caudally?
A) ) Biceps brachii
B) Brachiocephalicus
C) Triceps
The aims of the IM pin, in combination with a plate are (3)
To help with fracture fragments alignment
To protects against bending forces
To reduce the stress applied to the more abaxially placed bone plate.
The goals of the plate-rod construct are: (3)
The pin should provide some stability
The construct should reduce the chance of plate failure
Should allow adequate room for placement of some bicortical screws
IM pin placement of the humerus in dogs:
A) Where to angle?
B) Size?
A) Towards medial aspect of the humeral condyle
B) 35-45% of diameter
How to use x rays to measure IM pin size in a dog? which x ray? Where?
35-45% diameter of CrCd medullary canal diameter
Lateral x ray
Measured at distal 80th percentile of the humeral length to pass through the medial epicondylar crest into medial aspect of condyle
How direct IM pin in humerus in cats?
Into central area of distal part of diaphysis just proximal to olecranon fossa
Proximal normograde IM pin:
Where is the pin started?
craniolateral aspect of the greater tubercle.
Proximal normograde IM pin:
How to place in # of the mid- or proximal diaphysis?
Drive the IM pin distally to a point just proximal to the supratrochlear foramen
Proximal normograde IM pin:
How to place in # of distal 1/3 of diaphysis?
a pin of smaller diameter and direct it toward the medial side of the shaft. Once the pin has entered the distal bone fragment, bow the bone fragments slightly medially to help direct the tip of the pin down into the medial aspect of the condyle.
Distal normogarde IM pin insertion:
A) Start where and with?
B) Drive where?
C) Advance into?
A) A small pin from the caudal-distal aspect of the medial part of the condyle.
B) Directly across reduced #
C) Into greater tubercle
Tension side of the humerus?
Proximal - Craniolateral
Distal - Caudomedial
Where are plates positioned for proximal or middle dipahysis #?
Cranial or Lateral
Where are plates positioned for distal diaphysis, supracondyle, intracondyle?
Medial
Which approach to the proximal half of the humerus is less invasive?
Lateral
lateral surface of the distal half of the humerus has a marked..?
Curvature
What nerve needs to be preserved on the lateral approach; what can be used for this?
Radial; use of a penrose drain
The straighter shape of the medial epicondylar crest requires minimal plate contouring, allowing also more bone stock to be available for…?
Screw purchase
Accurately contour the plates and use of plates that allow contouring in:
A) How many plane?
B) OR what type of plate?
A) 3
B) Locking
