Avascular necrosis

 

Shoulder AVNShoulder AVN 1

 

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

 

Etiology

 

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 in setting of GT / LT fracture

 

3.  Via rotator cuff

 

Natural History

 

Variable

- difficult to predict

- somewhat related to etiology

- 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 / diagnosed on MRI

 

Stage II - sphericity maintained / sclerotic changes in superior central head / crescent sign

 

Shoulder AVNHumeral AVN Stage 2Humeral AVN Stage 2 MRI

 

Stage III - mild flattening articular surface

 

Shoulder AVN Stage 3

 

Stage IV - significant humeral collapse with loss integrity joint surface

 

Shoulder AVN Stage 4Shoulder AVN Stage 4

 

Stage V - degeneration extends to involve glenoid

 

AVN Shoulder Xray

 

Symptoms

 

Pain is major problem well before loss of range of motion

 

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 edema

- 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

 

Nonoperative management

 

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

 

Arthroplasty

 

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)