1.9 Common Conditions of the Forelimb in SA

Question 1

What disease(s) should you expect in a SA with shoulder lameness?

Answer 1

• Young dogs: suspect osteochondritis dissecans (OCD)
• Otherwise, assess for shoulder OA (most common), shoulder soft-tissue (‘rotator cuff’) injuries, trauma, instability

Question 2

What is osteochondrosis?

Answer 2

• Osteochondrosis = conditions of developing cartilage and its supporting bone
• Developmental disease in fast growing often high performance patients
• In dogs it commonly affects the elbow, shoulder, stifle, and tarsus (others possible)

During development, cartilage becomes bone (endochondral ossification), which requires a blood supply. In dogs that grow very quickly, the rapid cartilage growth can outstrip its own blood supply and cause Osteochondrosis. A problem with the cartilage vasculature → cartilage does NOT form bone → thickened, avascular cartilage → necrotic cartilage → possible fissure/flap formation (OCD)

(2) normal cartilage thickness; (3) thickened cartilage with necrotic tissue below

Question 3

What is OCD?

Answer 3

a form of osteochondrosis:

in some cases of osteochondrosis, flaps of diseased cartilage become separated from the remaining cartilage surface. This is called osteochondritis dissecans.

• Large, Giant breeds; Great Danes, Wolfhounds, Bernese Mountain dogs, (Labradors, Collies)
• Males > Females; 50% bilateral (radiographically)
• Heredity factors, but multifactorial (↑calories, ↑calcium, ad lib feeding)

Question 4

What are common OCD history and physcal exam findings?

Answer 4

HISTORY

• 4-8 months old commonly, but may be older
• Progressive forelimb lameness, uni- or bilateral

PHYSICAL EXAM

• Forelimb lameness with pain on shoulder extension or flexion (not usually on palpation)
• May have muscle atrophy shoulder region

Question 5

What diagnostics can be used for OCD?

Answer 5

DIAGNOSTICS

(1) Radiographs: Mediolateral and CdCr of shoulder

• Lesions may be obvious; use
• contrast arthrogram for nonobvious lesions

(2) CT & arthroscopy

Question 6

What is the treatment and prognosis for OCD?

Answer 6

TREATMENT AND PROGNOSIS
Importantly, the OCD flap is the source of pain

(1) Surgical removal and curettage of the defect

• Via arthrotomy (higher morbidity) or via arthroscopic procedure
• If the animal has minimal OA, excellent long term prognosis if treated when young

(2) Some may spontaneously break off – improves comfort, but could interfere with biceps

(3) Conservative: symptomatic improvement often seen (flap removal is better)

Prognosis: bigger lesions and increased age = worse OA

Question 7

What are the other common shoulder conditions?

Answer 7

(5) A shoulder joint allowing too much movement, but not fully dislocating (luxating); (6) Biceps tendon test: extend the elbow as you flex the shoulder. This creates tension which will be painful in a diseased bicep.

Question 8

What is elbow dysplasia?

Answer 8

Umbrella term encompassing several developmental pathologies: AKA developmental elbow disease

• Young medium-giant breeds (smaller chondrodystrophic dogs) are affected most commonly
• Pathology is bilateral in 35% of cases
• Genetic heritability: Rottweilers, Retrievers, Bernese Mountain Dogs
• most common is medial coronoid process disease (e.g., FMCP)

Importantly, all elbow dysplasias cause osteoarthritis (DJD)!

• Elbow dysplasia is a life-long disease process
• OA progresses over time: clinically may have several flareups
• Long-term OA management, however may have many years of good function

Question 9

What are the forms of elbow dysplasia

Answer 9

There are three common developmental problems that are often referred to as elbow dysplasia:

• fragmented medial coronoid process (FMCP)
• ununited anconeal process (UAP)
• osteochondritis dissecans (OCD).

Dogs with elbow dysplasia typically have only one of the three conditions, and it is rare for a single dog to have all three components of elbow dysplasia.

Question 10

How does elbow dysplasia occur?

Answer 10

Growth disturbance → asynchronous growth (radial-ulna incongruity) → abnormal loading

• Short radius = pressure on medial coronoid
• Long radius = pressure on anconeal process
• Trochlea notch dysplasia (‘humero-ulna conflict’)

The pathogenesis is quite unique, as the elbow joint involves paired bones (the radius and ulna)

(a) short radius; (b) long radius; (c) trochlea notch dysplasia

Question 11

How does elbow displasia typically present on history and physical exam?

Answer 11

HISTORY

• Forelimb lameness ‘head nod’
• From 5-7 months; most diagnosed 12 months
• Insidious to chronic lameness
• Worse post-rest or exercise ++
• Possibly shift sides (frequently bilateral)
• improvement on NSAIDs

PHYSICAL EXAM
1. Assess for a rotation of the paw, the elbow may be too close/far from the body (dogs with elbow dysplasia will often have a rotated paw (in either direction)
2. Assess for reduced weight bearing and muscle atrophy of the shoulder
+/- elbow effusion caudal and lateral to the lateral epicondyle

Ensure to isolate the elbow; don’t manipulate the shoulder and/or carpus simultaneously!

Question 12

What diagnostics can you perform to assess elbow dysplasia?

Answer 12

DIAGNOSTICS

(1) Radiographs: 3 views for elbows = CrCd, MLn, MLf

• Can usually diagnose UAP, OCD, incongruity, but superimposition makes diagnosis of MCD difficult
• however, osteoarthritis without UAP or OCD = strong suspicion of MCD, ‘diagnosis of elimination’

(2) CT / arthroscopy (most often via referral)

Question 13

What is the treatment for UAP?

Answer 13

(12) Sometimes it is cut and replaced with screws

Question 14

What is the treatment for OCD of the humerus?

Answer 14

(13) You pick the bone to get bleeding and induce fibrocartilage growth/healing

Question 15

What is the treatment for MCP disease?

Answer 15

(16) All of these are examples of diseased coronoid processes! Not all must have fragments broken off. Some show remodeling while others show fissures. They all have the same symptoms and treatment options.