Chapter 75 - Arthritis and Arthroplasty of the Shoulder

Question 1

what is often contracted in primary GH arthritis

Answer 1

anterior capsule, and subscap

Question 2

pathoanatomy of primary GH arthritis

Answer 2

POSTERIOR glenoid and humeral head wear

Question 3

walch classification of glenohumeral arthritis

Answer 3

A: concentric wear
A1. minor wear
A2. major central erosion

B: posterior wear
B1. narrowing of the posterior joint space
B2. asymmetric loading -> biconcave glenoid
B3. monoconcave and severely worn - at least 15deg retroversion, at least 70% posterior humeral head subluxation

C: dysplastic glenoid with glenoid retroversion (not acquired) >30deg
C1. monoconcave
C2. high pathologic retroversion with acquired posterior bone loss -> appearance of biconcave glenoid

D: any level of glenoid anteversion

Question 4

hemiarthroplasty v aTSA for GH arthritis

Answer 4

pain relief and function (ROM) are generally good but less predictable

pain relief following TSA more predictable than HA

Question 5

indications for aTSA in GH arthritis

Answer 5

intact deltoid
intact or repairable cuff

Question 6

indications for rTSA in GH arthritis

Answer 6

non-repairable cuff

Question 7

which has higher 10yr survival aTSA or rTSA

Answer 7

aTSA (92-95% vs 78-89%)

Question 8

complication for aTSA vs rTSA

Answer 8

aTSA: glenoid loosening
rTSA: instability/dislocation

Question 9

optimal position for shoulder arthrodesis

Answer 9

30FE
30Abd
30IR

Question 10

common complaint post shoulder arthrodesis

Answer 10

pain at the scapulothoracic jcn

Question 11

what is the maximum amount of glenoid retroversion that can be corrected with high side reaming?

Answer 11

15deg

Question 12

normal GH position in space

Answer 12

glenoid is 3degrees retroverted (can range from 10 of retro to 10 of ante)

humerus is 20-30 degrees of retroversion

top of the humeral head should be 8-10mm above the GT

humeral thickness should be 70% of the component diameter

Question 13

Hydroxyapatite crystals

Answer 13

seen in RCA

dx with alizarin red staining

Question 14

Gout crystals

Answer 14

monosodium urate crystals
negatively birefringent needle shaped crystals

Question 15

pseudogout crystals

Answer 15

calcium pyrophosphate dihydrate
positively birefringent
rhomboid shaped

Question 16

pattern of GH arthritis in RA

Answer 16

severe medial, concentric wear of the glenoid

Question 17

what type of humeral prosthesis should be avoided in inflammatory arthropathy?

Answer 17

long stemmed humeral implants bc of likelihood of TEA in the future -> stress riser

Question 18

most common location of osteonecrosis of the humeral head?

Answer 18

superior middle portion of the head -> just deep to the articular cartilage

Question 19

what is the dominant source of vascularity to the humeral head?

Answer 19

posterior circumflex humeral a

Historically thought to be the ascending branch of the anterior circumflex humeral a via the arcuate a to the GT

Question 20

what imaging do you need if you confirm ON to the humeral head?

Answer 20

XRs of the hips

Femoral head is most common location of ON, humeral head is 2nd

Question 21

treatment for stage I or II shoulder ON

Answer 21

stage I and II are PRE collapse (I - no XR evident disease only MRI, II - sclerosis on XR)

core decompression

Question 22

treatment for stage III, IV shoulder ON

Answer 22

Stage III - subchondral fracture/crescent sign
Stage IV femoral head collapse with joint incongruity at the GH joint without glenoid changes

hemiarthroplasty

Question 23

treatement for stage v shoulder ON

Answer 23

TSA - now you have glenoid involvement