The elbow

Question 1

What is the main extensor muscle of the elbow and its innervation?

Answer 1

Triceps brachii and radial nerve

Question 2

What are the main flexors of the elbow joint and their innervation?

Answer 2

Biceps brachii and brachialis muscle, innervated by the musculocutaneous nerve

Question 3

What is the normal range of motion of the elbow joint?

Answer 3

130 degrees (36 degrees in flexion, 165 degrees in extension)

Question 4

Beyond how many degrees of elbow extension does the anconeal process articulate with the olecranon fossa, restricting movement in the sagittal plane?

Answer 4

90 degrees

Question 5

When the elbow is at 135 degrees of extension what structures are the primary stabilizers in pronation and supination?

Answer 5

Pronation: Anconeal process
Supination: Lateral collateral (with secondary stabilization from the anconeal process and medial collateral)

Question 6

When the elbow is held at 90 degrees what structures are primarily responsible for rotational stability?

Answer 6

Medial collateral ligaments

Question 7

What is the name of the test that examines the integrity of the medial collateral ligaments?

Answer 7

Campbell’s test.

Question 8

What are the normal values of elbow supination and pronation as determined by the Campbell’s test?

Answer 8

Supination: 17 - 50 degrees laterally
Pronation: 31 - 70 degrees medially

Question 9

What percentage of traumatic elbow luxations are lateral?

Answer 9

92 - 100%

Question 10

What are the reasons that lateral traumatic elbow luxation is more frequent than medial?

Answer 10

Large size of the humeral trochlear, inherent weakness of the medial (compared to lateral) collateral

Question 11

In what percentage of cases is collateral ligament damage reported in conjunction with traumatic elbow luxation?

Answer 11

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.

Question 12

How does a limb with traumatic elbow luxation typically carry the affected limb?

Answer 12

Abduction and external rotation of the antebrachium, slight elbow joint flexion.

Question 13

In what percentage of cases of traumatic elbow luxation does the anconeal process remain within the olecranon fossa?

Answer 13

16%

Question 14

When is closed reduction of elbow luxation contraindicated?

Answer 14

Concurrent intra-articular or periarticular fracture

Question 15

How can elbow stability be assessed following closed reduction of a luxation?

Answer 15

Stressed radiographs, Campbell’s test

Question 16

What are some indications for open surgical reduction and stabilization of traumatic elbow luxation?

Answer 16

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

Question 17

Name two methods of stabilization of the elbow joint following open reduction.

Answer 17

1. Primary ligament repair and augmentation.
2. Ligament replacement with synthetic materials.

Question 18

According to Amadio 2020 in Vet surg what was the effect of PAUL on the mechanical axis of the thoracic limb?

Answer 18

Shifting of the mechanical axis from medial to lateral.

Question 19

According to Danielski 2021 in Vet Surg, what were the three most common complications associated with PAUL for elbow dyplasia?

Answer 19

Non union, implant failure, infection. Body weight was a risk factor for increased complications.

Question 20

In a study by Jones 2024 in Vet Surg, what CT finding was positively correlated with the presence of osteoarthritis in labrador retrievers?

Answer 20

Subchondral bone cysts

Question 21

What treatment is described by von Pfeil 2024 in Vet Surg for correction of too short radius resulting in elbow incongruity?

Answer 21

Arthroscopically assisted ulnar shortening

Question 22

In a study by Danielski 2023 in JAVMA, what were the most common major and minor complications in dogs following proximal bioblique ulnar osteotomy? What 2 factors were associated with an increased risk of complications?

Answer 22

Most common major complication was non-union, delayed union was the most common minor complication.

Increased risk of complications was observed with increasing age or decreased weight of the patient (mainly chondrodystrophic dogs that had issues).

Question 23

In a study by Baud 2020 in JSAP, what were the two types of medial coronoid fragmentation described?

Answer 23

Radial incisure or apex fragmentation

Question 24

In a study by Baud 2020 in JSAP what was the theoretical effect of decreased radioulnar joint space?

Answer 24

Increased risk of radial incisure fragmentation

Question 25

In a study by Williams 2020 in JSAP what percentage of cats with elbow luxation in which closed reduction was performed suffered reluxation? What was the most common surgical technique performed? What was the outcome?

Answer 25

61% of cats with closed reduction suffered reluxation (risk increased with duration from injury).

Transondylar bone tunnels and circumferential suture were most commonly performed (see image).

The outcome (for both closed and open reduction) was considered excellent.

Question 26

In a study by McCarthy 2020 in JSAP, what technique was successfully used for elbow arthrodesis? What was a benefit of this technique in terms of approach?

Answer 26

Medial arthrodesis (rather than caudal) was performed using a 2.7/3.5mm pre-contoured elbow arthrodesis plate or SOP. The mean angle of arthrodesis was 118 degrees.

The main benefit in terms of the approach was no requirement for ulnar osteotomy for debridement of the articular surface. There is also a mechanical advantage as the plate is edge-loaded, and the plate can be precontoured to ensure an accurate standing angle.

Question 27

In a study by Zweifel 2020 in VCOT, what CT slice size was recommended for accurate detection of fragmented MCP?

Answer 27

1mm

Question 28

In a study by Coghill 2021 in VCOT, was there a difference in outcome between dogs with medial compartment disease of the elbow treated with arthroscopy with fragment removal alone as compared to arthroscopy and PAUL?

Answer 28

No - there was no difference in canine brief pain inventory scores or use of NSAIDs.

Dogs greater than 3 years of age at the time of initial surgery had greater NSAID use and higher pain scores regardless of surgery.

Question 29

In a study by Jacqmin 2023 in VCOT, what imaging modality was useful in diagnosing MCP disease in unclear cases based on radiography and CT?

Answer 29

Ultrasound - was able to identify joint effusion and abnormal shape to the medial coronoid process.

Question 30

In a study by Scharpf 2024 in VCOT, did injection of autologous conditioned plasma improve post-operative limb function in patients undergoing subtotal coronoidectomy for MCP disease?

Answer 30

No - there was no change in force plate analysis parameters with the addition of ACP.

While vertical and propulsive parameters gradually improved post-operative, braking parameters remained reduced at 26-weeks, suggesting continued loss of elbow function following subtotal coronoidectomy.

Question 31

In a study by McLarty 2021 in VRU, what imaging technique was used to improve the detection of lesions in dogs with elbow pain?

Answer 31

PET-CT using 18F-Sodium Fluoride. This improved detection rate of lesions over CT alone, and was more correlated to clinical grade.