Elbow Dysplasia

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Elbow Dysplasia

 

Elbow Dysplasia is a series of four developmental abnormalities that lead to malformation and degeneration of the elbow joint.

 

PATHOPHYSIOLOGY

  • Four abnormalities—UAP, OCD, FMCP, and incongruity; alone or in combination; may be seen in one or both elbows; bilateral disease common (50% of cases).
  • UAP—delayed closure of the growth plate between the anconeal process and the proximal ulnar metaphysis (olecranon) by 5 months of age; may be the result of abnormal mechanical stress on the anconeal process.
  • OCD—affects the medial aspect of the humeral condyle; a disturbance in endochondral ossification causes retention of articular cartilage and subsequent mechanical stress leads to a cartilage flap lesion.
  • FMCP—chondral or osteochondral fragmentation or fissure of the medial coronoid process of the ulna; likely a manifestation of osteochondrosis of the coronoid process; the coronoid does not have a separate ossification center; may be the result of abnormal mechanical stress on the medial coronoid process.
  • Incongruity—asynchronous proximal growth between the radius and ulna may lead to abnormal loading, wearing, and erosion of cartilage in the humeroulnar compartment; possible malformation of the trochlear notch of the ulna; a slightly elliptical trochlear notch with a decreased arc of curvature is too small to articulate with the humeral trochlea, which results in major points of contact in areas of the anconeal process, coronoid process, and medial humeral condyle and little or no contact in other areas of the trochlea.

 

SYSTEMS AFFECTED

Musculoskeletal

 

GENETICS

  • Inherited disease.
  • High heritability—heritability index ranges between 0.25 and 0.45.

 

INCIDENCE/PREVALENCE

  • The most common cause for elbow pain and lameness.
  • One of the most common causes for forelimb lameness in large-breed dogs.

 

GEOGRAPHIC DISTRIBUTION

N/A

 

SIGNALMENT

Species

Dog

 

Breed Predilections

Large and giant breeds—Labrador retrievers; rottweilers; golden retrievers; German shepherds; Bernese mountain dogs; chow chows; bearded collies; Newfoundlands.

 

Mean Age and Range

  • Age at onset of clinical signs—typically 4–10 months
  • Age at diagnosis—generally 4–18 months.
  • The onset of symptoms related to DJD—any age.

 

Predominant Sex

  • FMCP—males predisposed
  • UAP, OCD, incongruity—none established

SIGNS

General Comments

  • Lameness—if no distinct abnormalities are noted on physical examination or radiographs, early intervention may demand advanced imaging.
  • Not all patients are symptomatic when young.
  • Intermittent episodes of elbow lameness due to advanced DJD changes in a mature patient—common.

 

Historical Findings

Intermittent or persistent forelimb lameness—exacerbated by exercise; progressed from a stiffness seen only after rest.

 

Physical Examination Findings

  • Pain—elicited on elbow hyperflexion or extension; elicited when holding the elbow and carpus at 90° while pronating and supinating the carpus.
  • Affected limb—the tendency to be held in abduction and supination.
  • Joint effusion and capsular distension—especially noted between the lateral epicondyle and olecranon.
  • Crepitus—may be palpated with advanced DJD.
  • Diminished range of motion.

 

CAUSES

  • Genetic
  • Developmental
  • Nutritional

 

RISK FACTORS

  • Rapid growth and weight gain
  • High-calorie diet

 

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

  • Trauma
  • Septic arthritis
  • Panosteitis
  • Avulsion or calcification of the flexor muscles
  • Synovial sarcoma

 

CBC/BIOCHEMISTRY/URINALYSIS

N/A

 

OTHER LABORATORY TESTS

N/A

 

IMAGING

Radiography

  • The image both elbows—high incidence of bilateral disease.
  • Elbow DJD recognized by osteophytes on the cranial margin of the radial head and epicondyles (medial and lateral), and medial coronoid process; also commonly see sclerosis of the ulna caudal to the coronoid process and trochlear notch and a stairstep between the joint surface of the radius and lateral coronoid; may see these changes with UAP, OCD, FMCP, and incongruity.
  • UAP—best diagnosed from the mediolateral hyper flexed view; may easily see lack of bony union. Comparison to the contralateral elbow may be helpful although the high incidence of bilateral disease should be kept in mind.
  • OCD—best diagnosed from the craniocaudal and craniocaudal-lateromedial oblique views; reveals a radiolucent defect or flattening of the medial aspect of the humeral condyle.
  • FMCP—may not be visualized in some cases; diagnosis is then presumptive based on DJD and the lack of UAP or OCD lesions; commonly see early osteophyte formation on the proximal caudal surface of the anconeal process with FMCP.
  • Other

CT, MRI, and linear tomography—can provide more definitive evidence for fissures and non-displaced fragments. CT is necessary in many cases of FMCP as survey radiographs have low sensitivity.

 

DIAGNOSTIC PROCEDURES

  • Joint tap and analysis of synovial fluid—confirm the involvement of joint.
  • Synovial fluid—should be straw-colored with normal to decreased viscosity; cytology reveals < 5,000 nucleated cells/μL (> 90% are mononuclear cells); normal results do not necessarily rule out the diagnosis.
  • Arthroscopy—may help diagnose UAP, FMCP, and OCD.

 

PATHOLOGIC FINDINGS

  • UAP—fibrous union between anconeal process and proximal ulnar metaphysis; fibrous tissue invasion and degeneration of the anconeal process; DJD.
  • OCD—chondral flap on medial humeral condyle; sclerosis of underlying subchondral bone with fibrous tissue invasion; erosive lesion on apposing coronoid cartilage; DJD.
  • FMCP—chondral or osteochondral fragmentation of the cranial tip or lateral margin of the medial coronoid; erosive lesion on the cartilage of the opposing medial aspect of the humeral condyle; DJD.
  • Incongruity—erosive lesions involving part or all of medial coronoid process and the opposing articular cartilage of the medial aspect of the humeral condyle; DJD; linear striations in the articular cartilage.

 

TREATMENT

APPROPRIATE HEALTH CARE

Surgery—controversial but recommended for most patients

 

NURSING CARE

Cold packing the elbow joint—perform immediately post-surgery to help decrease swelling and control pain; perform at least 5–10 minutes q8h for 3–5 days.

Range-of-motion exercises—beneficial until the patient can bear weight on the limb(s).

 

ACTIVITY

Restricted for all patients postoperatively

 

DIET

Weight control—important for decreasing the load and stress on the affected joint(s).

Restricted weight gain and growth in young dogs—may decrease incidence and severity.

CLIENT EDUCATION

  • Discuss the heritability of the disease.
  • Discuss the likelihood of DJD progression regardless of intervention.
  • Discuss the influence of excessive intake of nutrients that promote rapid growth.

 

SURGICAL CONSIDERATIONS

  • The severity of DJD and advanced age of the patient—negatively influence the outcome. Generally DJD progresses faster without treatment.
  • UAP—four options: removal, lag screw fixation, dynamic proximal ulnar osteotomy, and lag screw fixation plus dynamic proximal osteotomy; base decision on the degree of DJD, patient’s age, and surgical expertise.
  • OCD and FMCP—medial approach to elbow (diagnostic differentiation not necessary); removal of the loose fragment(s).
  • Incongruity—controversial; four options: no surgery, coronoidectomy, dynamic proximal ulnar osteotomy, intra-articular osteotomy; base decision on type of incongruity, degree of DJD, patient’s age, and surgical expertise.
  • Arthroscopic diagnosis and treatment—an excellent option for FMCP, OCD, and incongruity; benefits: superior visualization, minimally invasive.

 

MEDICATIONS

DRUG(S) OF CHOICE

  • None that promotes healing of osteochondral or chondral fragments.
  • NSAIDs—minimize pain, decrease inflammation, symptomatically treat associated DJD.
  • Deracoxib (3–4 mg/kg PO q24h, chewable).
  • Carprofen (2.2 mg/kg PO q12h or q24h).
  • Etodolac (10–15 mg/kg PO q24h).
  • Meloxicam (load 0.2 mg/kg PO, then 0.1 mg/kg PO q24h—liquid).
  • Tepoxalin (load 20 mg/kg, then 10 mg/kg PO q24h).

 

CONTRAINDICATIONS

Avoid corticosteroids—potential side effects; articular cartilage damage associated with long-term use.

 

PRECAUTIONS

NSAIDs—gastrointestinal irritation may preclude use in some patients.

 

POSSIBLE INTERACTIONS

N/A

 

ALTERNATIVE DRUG(S)

Chondroprotective drugs (e.g., polysulfated glycosaminoglycans, glucosamine, and chondroitin sulfate)—may help limit cartilage damage and degeneration; may help alleviate pain and inflammation.

 

FOLLOW-UP

PATIENT MONITORING

Post-surgery—limit activity for a minimum of 4 weeks; encourage early, active movement of the affected joint(s).

Yearly examinations—recommended evaluating the progression of DJD.

 

PREVENTION/AVOIDANCE

Discourage breeding of affected animals.

Do not repeat dam-sire breedings that result in affected offspring.

 

EXPECTED COURSE AND PROGNOSIS

Progression of DJD—expected

Prognosis—fair to good for all forms

miscellaneous MISCELLANEOUS

 

AGE-RELATED FACTORS

Middle-aged to old dogs with advanced DJD are not candidates for surgical intervention.

 

Visit your veterinarian as early recognition, diagnosis, and treatment are essential.

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