Chapter 76 - Disorders of the Acromioclavicular Joint

Question 1

horizontal stability of the clavicle at the AC joint is predominately from what structures

Answer 1

posterior (25%) and superior (50%) AC ligaments

Question 2

Vertical stability of the clavicle is provided by what structures?

Answer 2

AC joint at physiologic loads

CC ligaments at supraphysiologic loads
- medial conoid is strongest vertical stabilizer - 46mm from lateral edge of clavicle
- lateral trapezoid ligament provides medial/lateral stability
- 26mm from lateral end of clavicle

Question 3

need to rule out what concomitant neurologic injury in AC separation?

Answer 3

brachial plexus injury

Question 4

Zanca view

Answer 4

AP xr centered at the AC joint with 10-15 degrees of cephalad tilt

Question 5

rockwood classification of AC separation

Answer 5

I: ac ligaments sprained but intact

II: AC ligaments torn, CC ligaments sprained but intact

III: AC and CC torn
IIIA - horizontally stable
IIIB - not

IV: posterior displacement of the clavicle
non-reducible - clavicle is herniated through deltotrap fascia

V: >100% super translation
non-reducible - clavicle herniated thru deltotrap fascia

VI: inferior translation
clavicle stuck under acromion or coronoid

Question 6

rockwood classification of AC separation

Answer 6

I: ac ligaments sprained but intact

II: AC ligaments torn, CC ligaments sprained but intact

III: AC and CC torn
IIIA - horizontally stable
IIIB - not

IV: posterior displacement of the clavicle
non-reducible - clavicle is herniated through deltotrap fascia

V: >100% super translation
non-reducible - clavicle herniated thru deltotrap fascia

VI: inferior translation
clavicle stuck under acromion or coracoid

Question 7

indications for non-op AC separation

Answer 7

type I-III

Question 8

indications for surgical mgmt of AC separation

Answer 8

Type IV-VI
Type III in manual laborers, athletes, younger patients
Type IIIb - horizontally unstable

Question 9

complication of hook plate

Answer 9

acromial erosion -> have to remove them after healing

Question 10

outcomes of acute CC ligament reconstrucion

Answer 10

predictable healing no matter what technique is used
- biomechanically double suture titanium button best replicated CC ligament strength

Question 11

delayed reconstruction

Answer 11

fixation >3-4 weeks

needs tissue grafting

anatomic reconstruction provides better fixation strength and stability than weaver-dunn (transfer of the coracoacromial ligament to the clavicle)

Question 12

when is DCE contraindicated in AC arthritis?

Answer 12

history of low grade separation with persistent horizontal plane instability - higher incidence of persistent pain in these patients

Question 13

open DCE how much bone to resect

Answer 13

10mm

Question 14

arthroscopic DCE - how much bone to resect

Answer 14

5mm