The elbow Flashcards
Label the following parts of the elbow joint.
What are the main functions of the three joints comprising the elbow joint?
Humeroradial: main weight bearing axis.
Humeroulnar: restricts elbow motion to the sagittal plane.
Radioulnar: pronation and supination.
What are the sections of the medial coronoid process?
Base, midbody, apex.
What is the main extensor muscle of the elbow and its innervation?
Triceps brachii (+ tensor fascia antibrachii and anconeus). Innervated by the radial nerve.
What are the main flexors of the elbow joint and their innervation?
Biceps brachii and brachialis muscle, innervated by the musculocutaneous nerve
What are the main ligamentous support structures of the elbow?
Lateral and medial collateral ligaments, annular ligament, interosseous ligament.
What is the normal range of motion of the elbow joint?
130 degrees (36 degrees in flexion, 165 degrees in extension)
Beyond how many degrees of elbow extension does the anconeal process articulate with the olecranon fossa, restricting movement in the sagittal plane?
90 degrees
When the elbow is at 135 degrees of extension what structures are the primary stabilizers in pronation and supination?
Pronation: Anconeal process
Supination: Lateral collateral (with secondary stabilization from the anconeal process and medial collateral)
When the elbow is held at 90 degrees what structures are primarily responsible for rotational stability?
Medial collateral ligaments
What is the name of the test that examines the integrity of the medial collateral ligaments?
Campbell’s test.
What are the normal values of elbow supination and pronation as determined by the Campbell’s test?
Supination: 17 - 50 degrees laterally
Pronation: 31 - 70 degrees medially
Luxation of the elbow can only occur if the elbow is flexed beyond how many degrees?
45 degrees
What percentage of traumatic elbow luxations are lateral?
92 - 100%
What are the reasons that lateral traumatic elbow luxation is more frequent than medial?
Large size of the humeral trochlear, inherent weakness of the medial (compared to lateral) collateral
In what percentage of cases is collateral ligament damage reported in conjunction with traumatic elbow luxation?
18 - 50%.
One collateral ligament has to be ruptured for elbow luxation to occur in the dog, both collaterals have to be ruptured in the cat.
How does a patient with traumatic elbow luxation typically carry the affected limb?
Abduction and external rotation of the antebrachium, slight elbow joint flexion.
In what percentage of cases of traumatic elbow luxation does the anconeal process remain within the olecranon fossa?
16%
When is closed reduction of elbow luxation contraindicated?
Concurrent intra-articular or periarticular fracture
How is closed reduction of the elbow performed?
Flex the elbow to 90 degrees and internally rotate and abduct the antebrachium to engage the anconeal process in the olecranon fossa.
Once the anconeal process is engaged extend the elbow joint and adduct and internally rotate the antebrachium.
How can elbow stability be assessed following closed reduction of a luxation?
Stressed radiographs, Campbell’s test (should be compared to the contralateral elbow).
What are some indications for open surgical reduction and stabilization of traumatic elbow luxation?
Avulsion fracture at the site of collateral ligament attachment, fracture involving the articular surface, intra-articular apposition of soft tissues, marked instability or reluxation after closed reduction, and chronic luxation
From what approach is open reduction of the elbow joint performed?
Caudolateral.
Name two methods of stabilization of the elbow joint following open reduction.
- Primary ligament repair and augmentation.
- Ligament replacement with synthetic materials (screws and washers, bone anchors, tunnels).