MRI

Bipartite Patella

Ossification

 

Patella may develop from one or multiple ossification centres at 3 years

 

Failure of centres to fuse may produce bipartite or tripartite patella

- usually bilateral and painless

 

Classically superolateral

 

Classification Saupe

 

I   Inferior Pole 5%

II  Lateral 20%

Background

Intact PCL

Anatomy

 

Size

 

2 x as strong as ACL

About the same length as ACL 38 mm

 

Cross sectional area 150% of ACL

13 mm diameter (thicker) 

 

2 Bundles

 

1.  Anterolateral

- most important

- double the size of the posteromedial

- tight in flexion

- try to reconstruct this bundle

Abductor tendon tears

Trochanteric Bursitis

 

Mechanism

 

Repetitive friction of iliotibial tract over GT

 

Aetiology

 

Overuse in athletes

Common post THR

 

May be associated with gluteus medius tears

 

Symptoms

 

Pain over upper lateral thigh with activity

- often related to hip flexion

 

Examination

 

Transient Osteoporosis Hip

Definition

 

Self limiting syndrome of unknown aetiology

- hip pain associated with osteoporosis of proximal femur 

 

DDx

 

AVN

- AVN of the hip in pregnancy is rare but possible

- TOH tends to be diffuse on MRI, while AVN is localised

- extends to neck and metaphysis

- transient osteoporosis has normal bone scan

 

Incidence

 

Rare

- M: F 3:1

Background

Bilateral Hip AVN Xray

 

Definition

 

Non-traumatic or traumatic condition of femoral head with bone death

 

Epidemiology

 

20 - 50 yo (average 38)

- M: F 4:1

 

NHx  

 

70-80% with AVN will progress within 1 year

 

Posterior Instability

Definition

 

Patients usually complain of subluxation rather than dislocation

- rarely requires reduction

 

Different entity to acute posterior dislocation usually

 

Epidemiology

 

Rare

 

Aetiology

 

1.  Ligamentous laxity > 50%

- commonly associated with MDI

- posterior only 20%

- posterior & inferior 20%