Ch 13 Elbow Flashcards
Point out: anconeal process, trochlear notch, medial and lateral coronoid process, medial and lateral epicondylar crest
If this is an 8 week old Rottweiler, what are the * indicating?
Future ossification centres of the olecranon (ulna) and medial epicondyle (humerus).
What is the craniolateral–caudomedial oblique (Cr15°L-CdMO) view best for?
Medial structures - MCP, OCDs on the medial humeral condyle
What is the craniomedial–caudolateral oblique (Cr45°M-CdLO) view best for?
Lateral structures - sesamoid of m. supinator longus, IOHC (best seen with 15’ supination, like in the image here)
adult irish wolfhound
arrow: sesamoid of m. supinator longus
There is a fractured MCP on the medial aspect of the joint.
What are the types of humeral condylar fractures and which is more common?
- Lateral is the most common, because it bears the most weight (on the radial head) and its attachment to the diaphysis is weaker.
*Y / T fractures - Medial condylar fractures are rare.
3.5m Yorkie
lateral humeral condylar fracture
3.5m Yorkie
lateral humeral condylar fracture - see its caudal displacement, superimposed over the cranial ulna.
What is a Monteggia fracture?
Proximal ulnar fracture (articular or non-articular) accompanied by a cranial luxation of the proximal radius and distal ulnar fragment
Monteggia fractures
Which muscle is involved with olecranon avulsion fractures?
Triceps, it distracts the fragment proximally.
Avulsed olecranon (fracture)
Where do (typically) olecranon avulsion fractures occur?
In young animals - at the physis.
In mature animals - at the semilunar/trochlear notch (more distally)
Medial epicondyle avulsion fracture: This is usually associated with a traumatic incident, and results in fragments of various sizes seen medially or mediodistally to the medial epicondyle on CrCd or Cr15°L-CdMO views (Figure 13.25). This condition needs to be differentiated from an ununited medial humeral epicondyle, seen occa- sionally in Labrador Retrievers
When does the humeral condyle close (fuse) in dogs?
The humeral condyle is usually closed by 6 to 10 weeks and is considered delayed/incomplete if a linear lucency is evident after 100 days.
90 day labrador, CT at level of semilunar / trochlear notch. Is this normal or delayed?
Should be fused by 10 weeks (70 days), but lit says considered delayed/incomplete if the lucency is visible after 100 days.
elbow subluxation
how will early closure of the distal ulnar physis (e.g. due to trauma) affect the elbow joint?
It will most likely cause subluxation (distal subluxation of the trocheal notch relative to the humeral condyle / radial head), with a widened humeroulnar joint and distal displacement of the MCP, due to the radius continuing to grow normally.
5m labrador
Widened humeroulnar joint > a subluxation due to premature closure of distal ulnar physis
what other pathology (other than trauma) in the distal ulnar physes can cause elbow subluxation?
Retained endochondral cartilage. These will be bilateral, though.
What will result in this appearance?
premature closure of the distal radial physis will result in widening of the humeroradial joint space
what will develop secondary to premature closure of the distal or proximal radial physes?
subluxation of the trochlear notch relative to the humeral condyle and radial head
widened humeroradial joint space
page 197
Which types/breeds may be predisposed to secondary humeroulnar subluxation due to retarded ulnar growth?
Chondrodystrophic breeds
What is a possible sequel of radioulnar fractures (non physeal) that may result in humeroulnar subluxation?
Synostosis
5m JRT
Congenital proximal radial luxation or subluxation usually occurs in larger breeds such as Shetland Sheepdogs and Bulldogs. Clinically, there may be only mild deformity or lameness. The radius usually luxates caudolaterally. The radial head is often underdeveloped and rounded.
Proximal ulnar luxation is the most common form of primary/congenital elbow luxations and presents with marked limb dysfunction. It is mainly seen in small breeds such as the Yorkshire Terrier and Boston Terrier, as well as the Cocker Spaniel, English Bulldog and Staffordshire Bull Terrier. The ulna usually luxates laterally. The anconeal process may be underdeveloped and the ulna rotated 90 degrees, resulting in a lateral projection of the ulna on a CrCd radiograph
What are some causes of elbow lameness that may have normal rads?
6y cat, with a rapidly growing, non-
painful, solitary juxta-articular mass on the craniolateral elbow
extraskeletal osteochondroma (seen as separate on the Cr15’L-CdMO projection). Incidental mineralized flexor enthesopathy is present.
same dog 3 months apart
chronic septic arthritis
top: Extensive periarticular new bone formation with the humeroulnar joint reasonably spared
bottom: progression of (a) the new bone formation, marked humeroulnar subchondral lysis indicative of non- responsive infection.
What are 2 ways to assess elbow joint (in)congruity?
Is there a radioulnar step formation?
Is there a widened humeroulnar joint space?
Kissing lesion - Sclerosis of the medial humeral condyle (arrowed); this accompanies MCP fragmentation