AC pathology

Question 1

Acromio-clavicular (AC) ligaments anatomy

Answer 1

▪ controls horizontal motion and anterior-posterior stability

has superior, inferior, anterior and posterior components

posterior and superior AC ligaments are most important for stability

Question 2

Classification of AC injury

Answer 2

Type I

sprain; AC tenderness; no AC instability ; sling

Type II: torn; sprain; AC horizontal instability

AC joint disrupted; increased CC distance < 25% of contralateral; reducible; sling

Type III: increased CC distance 25-100% of contralateral; reducible; controversial

Type IV

skin tenting, posterior fullness

lateral clavicle displaced posterior through trapezius on the axillary lateral XR

not reducible

surgery

Type V: severe shoulder droop, does not improve with shrug

increased CC distance > 100% of contralateral

not reducible

surgery

Type VI: rare; associated injuries; paresthesias

inferior dislocation of lateral clavicle, lying either in sub-acromial or sub-coracoid position

not reducible

surgery

Question 3

AC injury outcomes for op vs non op

Answer 3

Outcomes

type III treated non-op had higher DASH scores at 6 weeks and 3 months, and equal function at 1 year with lower rate of secondary surgery (removal of hardware) compared to those treated operatively

new studies have shown no difference in outcomes in types III injuries treated surgically after 6 weeks non-op treatment versus immediate surgery

Question 4

What are the surgical options?

When to consider the surgical options?

Answer 4

• Symptomatic or unable to return to sports at 3 to 6 months
• May consider early surgical indication in type IV, V, VI

Question 5

What is the etiology of distal clavicle osteolysis?

Answer 5

Repetitive stress and micro-fracture in distal clavicle which leads to osteopenia

Question 6

Who is the typical patient that presents with clavicle osteolysis?

Answer 6

patients in their 20s, mostly male

commonly seen in weightlifters

Question 7

What are the physical findings of distal clavicle osteolysis?

Answer 7

Palpation: tenderness at the distal end of clavicle and AC joint

provocative test: pain with cross-body adduction

Question 8

What are the radiologic findings of distal clavicle osteolysis?

Answer 8

cysts

osteopenia

resorption and erosion

tapering of distal clavicle

AC joint widening

Question 9

Arthroscopic distal clavicle resection (Mumford procedure)

How much should be resected and why?

Answer 9

should resect only 0.5-1cm of the distal clavicle

too large a resection can lead to horizontal AC joint instability:

• avoid violating the posterosuperior capsule during distal clavicle excision as will lead to horizontal instability

Question 10

What are the risk factors of AC arthritis?

Answer 10

1. trauma
2. post-traumatic (i.e. clavicle fractures, AC instability)
3. distal clavicle osteolysis
4. inflammatory arthropathy (i.e. RA)
5. post-infectious arthropathy (i.e. septic arthritis)
6. Commonly associated with individuals who engage in constant heavy overhead activities

especially in weight-lifters and overhead throwing athletes

Question 11

What ligaments of the AC joint are the most important for stability?

Answer 11

posterior and superior AC ligaments are most important for stability