Ch 51 - Fractures of the Humerus Flashcards
What is anatomically unique about the feline humerus in comparison to the canine?
- Supracondylar foramen, through whicha branch of the brachial artery and median nerve run
How can you best assess nerve function in a humeral fracture?
- toe pinch and skin prick
- If cutaneous sensation is present, will usually regain motor function in 1-6wk
What is the tricipital line?
What is the deltoid tuberosity?
- Tricipital line: A bony ridge extending from the humeral head cranially and distally toward the deltoid tuberosity. Origin of the lateral head of the triceps. Bone cranial and proximal is generally cancellous
- Deltoid tuberosity: The insertion point for the deltoideus muscle
What are the two sides of the humeral condyle called?
- Medial: the trochlea - articulates with the trochlear notch of the ulna
- Lateral: The capitulum - smaller, articulates with the radial head
What percentage of fractures of the humerus are proximal, diaphyseal, supracondylar and condylar in cats and dogs?
When does the proximal humeral physis fuse with the metaphysis?
- Dog: 7.5 - 12m
- Cat: 19 - 26m
At what angle do the humeral head and the greater tubercle fuse?
102 degrees
What are the fixation options of a proximal physeal fracture if the physis is complete?
What are the fixation options of a proximal physeal fracture if the physis has split between the humeral head and the greater tubercle??
What are some potential underlying disease processes of a proximal metaphyseal fracture?
- Nutritional secondary hyperparathyroidism
- Neoplasia
Where should an IM pin be aimed towards in a dog?
What is the recommended size?
- Aimed towards or inserted into the medial aspect of the humeral condyle to increase bone purchase and length
- Optimal pin diameter 36 - 45% of the medullary canal diameter observed from a lateral radiograph, measured at the 80th percentile of humeral length
What percentage of nondirected retrograde IM pins penetrate the shoulder?
20%
What are the most common ESF configurations for the humerus?
- Type I
- Modified type I/II
- ESF tied into IM pin
Usually placed on craniolateral surface
What is the tension surface of the humerus?
- Craniolateral surface proximally
- Caudomedial surface distally
On which side of the humeral condyle is plate application easier?
Medial - straighter epicondylar crest
What is a supracondylar fracture?
What are the repair options?
A fracture which communicates with the supracondylar foramen but not with the articular surface
Repair options:
- Cross pins or Rush pinning
- Unilateral or bilateral plate
- ESF - modified type I/II
When do the medial and lateral aspect of the condyle fuse together?
When does the condyle fuse with the metaphysis?
- Fuse together: 85d (3m)
- Fuse to metaphysis: 5.5 - 6m
Which aspect of the condyle is fractures more frequently?
- Lateral (34 - 67%) (SHIV)
- Followed by T/Y (25.9 - 35%)
- Medial (6.9 - 11%)
How much of the growth of the humerus is the distal growth plate responsible for?
20%
What are the recommended landmarks for transcondylar screw placement?
- Enter craniodistal to lateral epicondyle and exit at similar location on medial side
- Parallel to articular surface
- Perpendicular to fracture line
What adjunctive fixation options are there after transcondylar screw placement for a lateral condylar fracture?
- Antirotation pin
- Supracondylar screw
- Lateral epicondylar plate
What is the complication rate of repair of an olecranon osteotomy?
up to 37%
How ofter are other elbow diseases (eg FMCP) present in dogs with IOHC
23.5 - 25%
What radiograph projection can aid in diagnosis of IOHC
15 degree craniomedial caudolateral oblique
What techniques can be implemented to improve healing in IOHC
- Screw combined with transcondylar bone tunnels to allow vascular ingrowth
- Autogenous cancellous bone graft
- Fenestrated tubular screw
23% have implant fialure and loss of reduction
At what angle do the humeral head and the greater tubercle fuse?
102 degrees
