Avascular necrosis

Shoulder AVN

 

Epidemiology

 

Second most common site of AVN

- much less common than hip OA

 

Usually presents late as shoulder non weight bearing

 

Typically not isolated - in multiple joints

 

Aetiology

 

Most common non traumatic cause is corticosteroids

 

Similar causes as hip (AS IT GRIPS 3C)

 

Alcohol / Steroids / Idiopathic / Trauma

 

Gout, Gauchers

Rheumatoid / radiotherapy

Infection / increased lipids / inflammatory arteritis

Pancreatitis / pregnancy

SLE / sickle cell / smoking

 

Chronic renal failure / chemotherapy / Caisson's disease

 

Blood Supply

 

Blood supply humeral head

 

1.  Anterior Circumflex Humeral Artery (36%)

- primary blood supply

- becomes arcuate artery

- runs lateral aspect bicipital groove

 

2.  Posterior Circumflex Humeral Artery (64%)

- collateral circulation

- supplies head when GT / LT fracture

 

3.  Via rotator cuff

 

Natural History

 

Variable

- difficult to predict

- somewhat related to aetiology

- sickle cell disease tend not to progress to arthroplasty

- steroid induced far more likely

 

Less severe than femoral

- non weight bearing

- less conforming joint

- scapulothoracic motion

 

Pathology 

 

Superior head collapse at 90° mark 

- area of peak contact stress in abduction

- glenoid rarely affected

- soft tissue and subscapularis rarely contracted

 

Classification / Cruess modification of Ficat-Arlet 

 

Stage I

- pre-xray change

- only seen with MRI

 

Stage II

- sclerotic changes in superior central head

- sphericity maintained

 

Shoulder AVN

 

Humeral AVN Stage 2Humeral AVN Stage 2 MRI

 

Stage III

- "crescent" sign - subchondral fracture

- mild flattening articular surface

 

Shoulder AVN Stage 3

 

Stage IV

- significant humeral collapse with loss integrity joint surface

- loose bodies

 

Shoulder AVN Stage 4Shoulder AVN Stage 4

 

Stage V

- degeneration extends to involve glenoid

 

AVN Shoulder Xray

 

Symptoms

 

Pain is major problem

- pain before significant loss ROM

- difficulty sleeping

 

MRI

 

Shoulder AVN MRIShoulder AVN MRI Sagittal

 

Shoulder AVN 1Shoulder AVN 2Shoulder AVN 3

 

Sensitivity and specificity approach 100%

 

T1

- areas low signal intensity on T1 representing oedema

- areas of high signal intensity thought to represent blood flow

 

T2

 

"Double line sign"

- highly specific for AVN

- inner bright line representing granulation tissue

- outer dark line representing sclerotic bone

 

Management

 

Non Operative

 

Remove insult

 

Corticosteroids, alcohol

 

Maintain current shoulder ROM / Halt Progression

 

A.  Physiotherapy

 

B.  Limit overhead activities

- joint reaction force greatest > 90o

 

C.  Bisphosphonates

 

Agarwala et al. J Orthop Surg Res 2019

- bisphosphonates for non femoral head AVN

- 20 patients, 5 with shoulder AVN

- combined oral and IV treatment

- 50% reduction in analgesia needs after 6 weeks

- MRI showed complete resolution in 17 / 20 (94%) at 1 year

 

Operative

 

Core Decompression

 

Concept

 

Decrease intra-osseous pressure & increase blood flow

 

Indications

 

Stage 1 / 2 - pre-collapse

 

Technique

 

Arthroscopy Technique Article

 

Arthroscopy Technique Article decompression + fibular graft

 

Results

 

La Porte et al. CORR 1998

- core decompression in 63 shoulders all stages

- looked at improvement in UCLA scores

- 94% / 88% / 70%/ 14% success for stage I / II / III / IV

 

Alkhateeb et al. JSES Int 2021

- systematic review of core decompression in sickle cell

- one paper showed evidence of improved pain scores post procedure

- one paper demonstrated all cases went on to collapse

- may not prevent or delay progression of disease

 

Joint replacement

 

Results

 

McLaughlin et al. JSES 2022

- 52 aTSA and 67 rTSA for shoulder AVN

- matched to controls in database

- similar improvements in ROM and PROM's to non AVN patients

 

 

Australian Joint Registry Shoulder Replacement for AVN 2021

- revision rate aTSR 11.4% at 5 years (compared with 7.2% for OA)

- revision rate rTSR 6.5% at 7 years (compared with 4.5% for OA)

- revision rate hemiarthroplasty 9.9% at 7 years (compared with 9.7% for OA)