CT

Epidemiology

Much less common than hip and knee OA
Patients tend to be younger

Incidence

Dale et al Acta Orthop 2012

- Nordic Arthroplasty Registry of 430,000 THA

Definition

Ossification of the posterior longitudinal ligament (OPLL)

Heterotopic ossification of the posterior longitudinal ligament

Epidemiology

2:1 Male:Female

More common in Japanese and East Asian populations

 Articular process fracture

Natural history

Superior articular process fracture

- potentially unstable

Inferior articular process fracture

- thought to be more stable

CT scan

Definition

Loss of ligamentous stability between atlas and axis

Can cause impingement of the spinal cord

Etiology

Indications

RA 

OA 

AVN 

Contra-indications

Infection

Charcot

Paralysis of deltoid

Torn rotator cuff

Insufficient glenoid bone stock

Epidemiology

Usually after 50-60 years of age

Aetiology

Primary 90% of cases

Secondary

- AVN

- trauma

- instability

Pathology