Hydroxyapatite Deposition

Types

 

Dystrophic or Metastatic

 

1.  Metastatic 

- hypercalcaemia / hyperphosphatemia

 

2.  Dystrophic 

- more common

- onto damaged connective tissue

- tendon / ligament / cartilage

- calcific tendonitis shoulder

- Pellegrini-Steida lesion MCL

 

Pathology

 

Deposited around chondrocytes & into avascular portion of CT

- crystals grow by accretion

- early on like cream

- later like chalk

- can be inert or surrounded by inflammatory reaction

- crystal shedding into joint causes synovitis

 

Clinical Features

 

Two syndromes

 

1.  Acute or Subacute Periarthritis

 

Pain near a large joint

- not intra articular

- after minor trauma

- warm & swollen tendon / ligament

- calcific tendinitis rotator cuff

- Pellegrini-Stieda lesion MCL

 

Calcific TendonitisPellegrini Steida Lesion

 

2.  Chronic Destructive Arthritis

 

HA crystals found in association chronic erosive arthritis

- unknown if cause or effect

- destructive arthropathy seen in shoulder with cuff arthropathy

- i.e. Milwaukee shoulder

- whether related to HA unknown

 

Aspiration

 

Crystals too small to be seen with light microscopy

- hence will not see on aspiration

 

X-ray

 

Periarthritis seen as calcium in tendon

- especially rotator cuff

- chronic HA arthritis doesn't show on xray as well as CPPD

 

Management 

 

Non operative

 

Periarthritis

- RICE

- NSAID

- HCLA

 

Operative

 

Surgical removal

- calcific tendonitis

- problematic Pellegrini Steida

 

Chronic Arthritis

- treat as OA

- early arthroplasty if rapid bone destruction