MRI

Chordoma

Definition

 

Primary malignancy arising from remnants of the notochord

 

Epidemiology

 

Rare malignant tumour

 

Middle-aged adults (50-70)

 

M>F

 

Location

 

In midline in axial skeleton

 

Base of skull 35%

 

Vertebrae 15%

- especially cervical

 

Sacrum 50%

 

PVNS

Definition

 

Pigmented Villo-Nodular Synovitis

- benign inflammatory process that arises in synovial tissues

- contains significant amounts of hemosiderin

 

Epidemiology

 

Age: 20 - 50

Sex: M > F

 

Types

 

A.  Diffuse

- throughout joint synovium

- more difficult to treat / excise fully

 

Synovial Chondromatosis

DefinitionSynovial Chondromatosis Knee MRI

 

Chondroid Metaplasia of synovium affecting large joints

 

Nodules of hyaline cartilage

- formed in the subsynovial layer of joint capsules

 

Epidemiology

 

Rare lesion

Most common in 20's and 30's

Sex: M > F (2:1)

Monoarticular

 

Site

 

Multiple Hereditary Exostosis

AKA

 

Diaphyseal Aclasis / Multiple Osteochondromas

 

Definition

 

Heritable skeletal dysplasia

 

Epidemiology

 

AD with variable penetrance (96%)

 

Malignant Transformation

 

Incidence of malignant transformation much higher 

- 10% overall

- 1 % / year

 

Chondrosarcoma (CS) > Osteosarcoma (OS)

 

MRI

Creation of images

 

Placing patient into a strong magnetic field

- 30 000 x stronger than the earth's magnetic field

 

Stronger magnets, better images, shorter times

- 1.5 Tesla 

- 3 Telsa

 

The nuclei of elements with odd numbers of protons line up

- i.e. hydrogen atoms

- hydrogen is plentiful in fat and water

 

A radiofrequency is then applied, exciting the protons

Postoperative discitis

SymptomsT45 discitis

 

Period of pain relief after disc surgery

- followed by increasing back pain & occasional leg pain

 

Pain may be disproportionate to physical findings

 

Low grade fever common

 

SLR & femoral stretch tests elicit pain in some cases 

 

Bloods

 

Revison ACL Surgery

Graft selection

 

A.  Synthetic Grafts

 

Good initial results but unacceptably high failure rate with longer follow-up

 

Problems

 

1.   Too stiff (low ultimate strain) 

- poor resistance to abrasion

- ligament failure by attrition most common

 

2.  Recurrent synovitis, infection, loosening and osteolysis

 

B.  Autograft