Renberg Lecture 12/11 Angular Limb Deformities

What are the causes of malunion and angular limb deformities?

Post trauma - salter harris or untreated fracture

Post surgery - Poor reduction/alignment

Developmental - premature closure of a physis

What salter-harris does not appear on a X-Ray?

5 (crushing)

What do you need to differentiate an angular limb deformity from?

Ligamentous damage

How can you determine if an angular limb deformity is a problem?

Cosmetic only like a basset hound

Check if currently in pain or lame

Evaluate for growth, arthritis, and function later

What 5 things do you look for when you examine a joint?

Crepitus

Effusion

Laxity

Pain

Range of motion

How do dog carpi normally sit?

Slightly over extended

What do radiographs not help you evaluate?

Torsion abnormalities

What does valgus mean?

Deformity going laterally

What does varus mean?

Deformity going medially

What is procurvatum and recurvatum?

Used to describe cranio-caudal movement

What are rads bad at evaluating?

Torsion

What lines can you draw on rads to look at an angular limb deformity?

A line at each joint surface, should be close to parallel

A line down the shaft of the bone to locate the deformity and curvature

What is the benefit of a CT?

3D and lets you evaluate torsion

What is the advantage to 3D printing a limb?

Can practice cuts and hold it

Can print out other models to practice how to fix the problem

What are two important terms to recognize?

Anatomic axis is line of bone

Mechanical axis is line of how limb works

How can you determine if it is actually messed up or normal for that dog?

Check the other side

How can you address angular limb defomities?

Ostectomy (partial)

Osteotomy: opening wedge, closing wedge, other

What is the most common angular limb deformity?

Carpus valgus (radius ulna are the most common bones to have a deformity in)

Why is the radius and ulna the most common location for a deformity?

They have 2 bones that have to grow synchronously which makes it more challenging

Also the distal physis determines of the growth

Where is the main problem with an angular limb deformity?

Incongruity of the joint

What does a partial ostectomy of the ulna do?

If the ulna stop growing it acts as a tether to the radius. By cutting the end of the ulna the radius can keep growing

When can you do a ostectomy of the ulna?

The patient needs to be old enough for the radius to keep growing before the problem is too severe

What physis of the ulna determines most of the growth?

Distal (90%)

What is the main problem when there is incongruity of an ulna and radius?

When it causes incongruity of the joint. Not a problem if the joint works fine

What is required for partial ostectomy of the ulna to be effective?

Patient must be young enough for radius to grow

Problem cannot be too severe

What is the most common angular limb deformity?

Premature close of the distal ulnar physis

What does premature closure of the distal ulnar physis cause?

Capral valgus

Procurvatum of radius

External rotation

How are malunions generally treated?

Same as angular limb deformities

How can you do an osteotomy?

Cut an opening wedge to straighten out the bone

What is the concern for an opening wedge?

Can be torsional so need to correct that too

Big gap in the wedge can be good

How to protect the limb after an opening wedge?

External skeletal fixature

Opening wedge

Closing wedge

What is the benefit of a closing wedge?

Fix most of the problems of a opening wedge

What is a closing wedge osteotomy?

Cut a wedge completely out and close it normally

What is a downside to a closing wedge?

You are shortening the limb which can cause problems depending on the patient and case

What can you do to stabilize a closing wedge?

Circular external fixature but a very complicated procedure that needs to be adjusted as the patient grows (AGE)