ch 49 Scapula fracture

Question 1

anatomy

Answer 1

fossae cranial and caudal: origin for the supraspinatus and infraspinatus muscles,

acromion: origin of the acromial head of the deltoideus muscle

supraglenoid tuberosity: which is the origin of the biceps brachii muscle

glenoid cavity: articulation with the humeral head

Question 2

superfical muscles

Question 3

deeper muscles

Answer 3

muscular protection both medially (subscapularis and serratus ventralis muscles) and laterally (omotransversarius, supraspinatus, infraspinatus, deltoideus, trapezius, triceps, and teres minor muscles).

Question 4

nerves

Answer 4

suprascapular nerve
- emerges cranially from the scapular notch
- travels caudally to wrap distal to the scapular spine, deep to the acromion.

axillary nerve
- emerges from the caudal border of the subscapularis muscle
- crosses the caudal aspect of the scapulohumeral joint

Question 5

What percentage of scapular fractures have concurrent injuries?

Answer 5

56 - 70%

thoracic injury, fractures of other bones, and neurologic

Question 6

What is the anatomical classification system of scapular fractures?

Answer 6

Type I: Fractures of the body and spine
Type II: Fractures of the neck
Type III: Glenoid fractures

Question 7

What is the fracture classification scheme as described by Cook et al?

Answer 7

From least to most severe:
- Stable, extra-articular
- Unstable, extra-articular
- Intra-articular

Question 8

What muscles are encountered during the lateral approach to the shoulder?

Answer 8

Omotransversarius and trapezium
Deltoideus
Supraspinatus and infraspinatus

After incision of the deep fascia along the spine of the scapula, the omotransversarius and trapezius muscles are retracted cranially, and the spinous head of the deltoideus muscle is retracted caudally.7 The supraspinatus and infraspinatus muscles are elevated

Question 9

conservative for body #

Answer 9

• Velpeau sling improves patient comfort and minimizes the likelihood of further fracture displacement.
• maintained, along with strict confinement, for 3 to 4 weeks.
• To minimize the risk for flexural contracture of the carpus, some authors advocate not including the flexed carpus in the bandage
• Conservative management is often successful because the extensive muscle-derived blood supply = favorable environment for bone healing.

Question 10

What are the surgical options of fixation of scabular body fractures?

Answer 10

• Plate fixation (Thicker bone at base of spine), a screw angled at 45 degrees to the scapular spine, bone depth was greater cranially in the distal half of the scapular spine and caudally in the proximal half of the scapular spine.
• The implication: fractures within the proximal half should be plated caudally, and fractures in the distal half should be plated cranially.
• Interfragmentary cerclage (not prevent bending, thus sling needed)
• Partial or total scapulectomy - can remove 60% and retain excellent function
• Double plating was stronger but not stiffer and both failed by bending at much greater than clinically expected loads

No significant benefit has been shown with locking plate however study had multiple flaws i.e intact scapulas

Question 11

What are the fixation options for fracture of the acromion?

deltoideus muscle exerts a primarily tensile force on the acromion

Answer 11

2 K-wires and figure of 8 tension band
Interfragmentary wires
Single interfragmentary wire

Question 12

What are the fixation options of scapular neck fractures?

distal neck segment, containing glenoid, is typically displaced medially

Answer 12

Approach laterally or craniolaterally
Osteotomy of acromion usually required (or tenotomy of deltoid, or muscle seperation approach)
Osteotomy of greater tubercle of humerus sometimes required
Cross-pins (substantial exposure is necessary )
Divergent pins
Plate (T- ot L-shaped)

Only after atrophy of the supraspinatus and infraspinatus muscles occurs is suprascapular nerve injury readily evident.

Velpeau sling is advised for approximately 4 weeks with conservative management, and for approximately 2 weeks with surgical stabilization.

Question 13

What percentage of scapular fractures are articular?

Answer 13

28%, most commonly cranial glenoid

Question 14

When does the acccessory ossification of the supraglenoid tuberosity fuse?

Answer 14

By 5mo

Question 15

How do you approach a supraglenoid tuberosity fracture?
What are the repair options?

most common: cranial glenoid fractures 58%, and Y fractures 23%

Answer 15

Approach
- Cranial approach with osteotomy of greater tubercle
- OR - Longitudinal myotomy of supraspinatus muscle from midbelly to humeral insertion

Fixation
- Interfragmentary lag screw and antirotation wire
- 2 K-wires and tension band
- fragment excision and tenodesis (biceps)

pull of the tendon of the biceps brachii muscle, which originates on the supraglenoid tuberosity, results in distal displacement of the fracture fragment.

intra-articular fractures

Question 16

What are the surgical options for a T/Y-fracture of the glenoid?

Answer 16

Craniocaudal lag screw for anatomical reconstruction of articular surface anf then correct neck fracture as previously described

Fractures of medial/lateral labrum can be fixed with lateromedial lag screws if sufficient bone stock

Excision of the glenoid (excisional arthroplasty)

Partial scapulectomy

Arthrodesis

most dogs with intra-articular fractures had residual lameness.

Question 17

partial scapulectomy - in a cat.
A caudolateral approach to the shoulder
The caudal aspect of the medial glenohumeral ligament was then incised near its scapular attachment and the caudodistal portion of the scapula excised with rongeurs (30% of the glenoid). The portion of the caudal glenohumeral ligament attached to the humerus was sutured to the subscapularis muscle using a locking loop pattern to prevent medial shoulder instability.

Question 18

How do you treat scapular avulsion?

Answer 18

Caused by rupture of serratus ventralis +/- trapezius, rhomboideus

Fixation:
- 20-22g cerclage wire around 5th/6th/7th rib and through holes in caudodorsal border of scapula
- +/- reattachment of serratus ventralis through drill holes at craniodorsal scapula
- Velpeau sling 2-3wk
- Prognosis excellent

Question 19

What is this condition?
Is it clinically significant?

Answer 19

Ununited accessory ossification center of the caudal glenoid
Can cause lameness if unstable
Requires arthroscopy to determine stabiliy and can be removed if unstable

Question 20

Outcome of Supraglenoid Tubercle Fractures
in 12 Dogs
Kulendra 2019

articular and classified as type III fractures, hyperflexion of joint

Answer 20

retrospectively for cases of supraglenoid tubercle fracture (n = 12).

Overall success rate was 9/12. Major complication rate was 2/12 and minor
complication rate was 9/12. All fractures that had major complications were comminuted.pin and tension band wire (n ¼ 5), lag screw (n ¼ 2),
plate fixation (n ¼ 2), fragment removal (n ¼ 2) and conservative management (n ¼ 1).

Chronically lame caseswere treated by fragment removal,
in line with the current recommendations in the literature

Good outcomes can be achieved following fractures of the
supraglenoid tubercle, although cases with comminution have a higher complication
rate. Further research into the optimal method of fixation