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
Irregular radial incisures/ subchondral cystic lesions - part of MCP disease
Which radioulnar growth disparity leads to FMCP?
Short radius/ long ulna
Which radioulnar growth disparity leads to UAP?
Short ulna/ long radius
What are the cornerstones of ED in dogs?
- FMCP or MCD
- OCD of the medial humeral condyle
- Elbow incongruity
- UAP
whichh all leads to osteoarthrosis/osteophytosis.
The medial coronoid process has a separate centre of ossification which appears at.. ?
FALSE - it does not have a separate centre of ossification. It completes ossification from base to tip by 20-22 weeks (5-5.5 months).
When does MCP ossification finish?
by 20-22 weeks / 5-5.5months
In dogs with ED, why is there an increased pressure on the cartilaginous (developing) MCP?
Either disparate growth between radius and ulna (i.e. long ulna/short radius syndrome), or due to an incongruent trochlear notch.
What is the underlying cause of ED?
OC - e.g. OC of the MCP causes the chondrocytes to undergo chondromalacia, and this is where it fissures/fragments.
If you cannot see a MCP fragment on radiographs (and often you cannot since it is cartilaginous, or non-displaced, or just superimposed), what other radiological clues are usually present in this condition?
- Secondary osteophytic changes
- Subtrochlear sclerosis on the caudal aspect of the
medial coronoid - Associated elbow incongruity
- Poorly defined, convex, flattened or irregular outline of the medial coronoid process.
skeletally mature dog with
an absent or flattened medial coronoid process. Note early osteophyte formation on the anconeal process.
4-year-old
Rottweiler
large separate medial coronoid fragment superimposed on the cranial radius (arrowed). Osteophytic reactions are seen on the cranial margins of the joint and on the anconeal process and subtrochlear sclerosis.
Which is more sensitive for MCD - osteophytosis or subtrochlear sclerosis?
Subtrochlear sclerosis - In a study of 263 dogs with MCD, 29% had no evidence of osteophytic reactions radiographically (Fitzpatrick et al., 2009a). However, 87% of the dogs had subtrochlear sclerosis. Another study showed that subtrochlear sclerosis was strongly correlated with the presence of FMCP (r >0.92) (Lavrijsen et al., 2012).
Kissing lesions of the humerus are located more laterally than OCD lesions - true or false?
True
If elbow joinr inongruity is present after ____ months, it may be present on its own (whereas if present before, may be accompanied by fMCP, OCD and UAP).
6
Which 3 joint spaces make up the elbow?
humeroulnar, humeroradial and radioulnar
Insufficient development of the trochlear notch with resultant incongruity is thus most likely in larger dogs. True or false?
True - Intermediate and heavy-set breeds have a longer proxi- mal ulna, relative to the adjacent radius than other breeds. Morgan et al. (2000) postulated that this reflects the need to accommodate a trochlear notch of sufficient size to encompass a heavier and larger humeral trochlea.
a study by Samoy et al. (2012b) showed that incongruity can be reliably diagnosed on radiographs, particularly on the _______ view and to a lesser extent on the __________view.
ML extended
pronated Cr15°L-CdMO
In incongruent elbows, the ‘radioulnar step’ is between the radial articular surface and which anatomical structure* of the ulna*?
lateral coronoid process
The anconeal process ossification centre
- appears at ____ weeks.
- is united with the olecranon by ____ weeks.
Appears: 11-14w
United: ~ 20-22 weeks (GSD 16-20w, greyhounds EVEN EARLIER 14-15w)
A UAP is always completely separated from the ulna - T or F?
False, it can be joined by fibrous or fiborcartilaginous tissue
GSD at 7.5m and 9m
b) UAP: radiolucent line in the anconeal process and slightly widened humeroanconeal joint space (i.e. displacement of the AP).
c) fusion of the AP following ulnar osteotomy
Which fuses first - the anconeal process or the medial humeral epicondyle?
The anconeal process fuses first, followed by (1-2 mo later), the medial humeral epicondyle.
What are the theories on development of the UAP?
- short ulna / long radius - the AP ossification centre is essentially pushed proximally while its trying to ossify and gets damaged.
- The joint (trochlear notch part) is incongruent from the start and forms an elliptical shape rather than semicircular.
What are likely concomitant pathologies in dogs with UAP?
joint incongruency and MCD, 1/3 of which will have fMCP
Which angle is this?
Cr15°L-CdMO
What are the findings and diagnoses in this 2y Boerboel?
UAP, fMCP, joint incongruency and osteophytosis / arthrosis
OCD and fMCP are heritable through the same genetics - T or F?
False, many breeds are predisposed to both, but they are inherited independently as polygenic traits.
What is a non-ED, congenital elbow disease that occurs mainly in Labrador Retrievers, with an incidence up to 15%?
Ununited medial humeral epicondyle
Ununited medial humeral epicondyle occurs in which breed mainly?
Labrador Retrievers, incidence up to 15%
What does ununited medial humeral epicondyle look like on radiographs, and which view is best?
CC view is best (actually, could be missed on laterals) because there are single/multiple fragments adjacent to the medial epicondyle +/- bone defects
Ununited medial humeral epicondyle
Is ununited medial humeral epicondyle always symptomatic?
No, dogs can be asymptomatic.
If you have both MCD and flexor enthesopathy - which one should be treated as a priority?
MCD
Flexor enthesopathy is mainly seen in juvenile large and giant-breed male dogs - T or F.
F: The etiology is said to be traumatic, and therefore any age, and mainly in med-large dogs, but yes male dogs and rarely in the cat.
Which projection is best for flexor enthesopathy?
You are looking for a medial epicondylar spur, and this is best seen on a flexed ML projection.
What radiological change do you look for in flexor enthesopathy?
A distally-projecting enthesophyte from the most caudodistal aspect of the medial epicondyle of the humerus
cat with an early medial
epicondylar spur and mineralization of the adjacent flexor tendon
4-year-old Boerboel
White arrow - enthesophyte on the medial epicondyle
Black arrow - dystrophic mineralization of the proximal flexor muscles
Image - CC view showing the flexor muscle mineralisation
6y Rottweiler
Flexor enthesopathy, also fMCP
Flexor enthesopathy; flexor origin medial epicondyle enthesopathy with immature new bone formation
ST window: Note the flexor origin inflammation, visible as peripheral contrast enhancement (arrowed) with centrally non- enhancing oedema. The contrast-enhancing structure cranially is the saphenous vein
T1w pre and post
Flexor enthesopathy; T1w hyperintense and contrast-enhancing
When should the ossification centres of the capitulum and trochlea fuse in dogs?
2-3 months of age
What is the mean age of incidence of intracondylar fissures of the humeral condyle?
3-4 years
IOHC in an 8y Springer
image: other elbow
IOHC is usually bilateral. T or F?
True, usually! up to 95% have bilateral involvement.
What is distractio cubiti?
Non-traumatic elbow incongruity due to asynchronous growth of the radius & ulna
Which breeds are predisposed to dysostosis enchondralis?
Also called distractio cubiti, it is common in Basset hounds and other chondrodystrophic breeds (e.g. Corgi, Pekingese).
What is the corrective procedure for this condition?
Condition: Distractio cubiti/dysostosis enchondralis/asynchronous growth of the radius and ulna
Correction: Ulnar ostectomy (lengthening procedure)
8m Rottweiler, acute lameness
patella cubiti
image: post-op
What is the typical signalment of synovial cysts?
Elderly cats
