2. MSK (Osteoporosis/Osteopenia and Complications)

Question 1

Osteopenia (definition)

Answer 1

Increased lucency of bones. Usually but not always caused by osteoporosis.

Question 2

Osteomalacia (7)

Answer 2

Soft bone due to excess uncalcified osteoid.
Usually due to vitamin D issues (renal, liver or other causes).
Looks like diffuse osteopenia.
Features include:
- Ill-defined trabeculae
- Ill-defined cortocomedullary junction
- Bowing
- Looser’s zones

Question 3

Looser zones (3)

Answer 3

Wide lucent bands that traverse bone at right angles to cortex.
Caused by osteomalacia and rickets, less commonly OI.
They are a type of insufficiency fracture.

Question 4

Osteoporosis (6)

Answer 4

Decreased bone density (bone density usually peaks at around 30).
Naturally decreases faster during menopause.
Imaging:
- Thin sharp cortex
- Prominent trabecular bars
- Lucent metaphyseal bands
- Spotty lucencies

Question 5

Osteoporosis (causes) (5)

Answer 5

Age (main cause)
Meds (Steroids, heparin, phenytoin)
Endocrine (cushings, hyperthyroidism)
Anorexia
Osteogenesis Imperfecta

Question 6

DEXA scores (3)

Answer 6

T score = density relative to young adult
T >-1.0 = normal. T -1 to -2.5 = Osteopenia. T<-2.5 = Osteoporosis
Z score = density relative to age matched control

Question 7

False positives/negatives on DEXA (5)

Answer 7

False positive
- Absent normal structures
- Status post laminectomy
False negative
- Including excessive osteophytes, dermal calcifications or metal
- Including too much femoral shaft when doing hip (shaft normally denser bone)
- Compression fracture in area measured.

Question 8

RSD - Reflex Sympathetic Dystrophy (5)

Answer 8

Unilateral RA with preserved joint space.
Causes severe osteopenia (like disuse osteopenia)
Commonly involved hand and shoulder.
May occur after trauma or infection, resulting in overactive sympathetic system.
Intra-articular uptake on bone scan (2ndary to increased synovial membrane vascularity) is somewhat characteristic.

Question 9

Transient osteoporosis - types (2)

Answer 9

Transient osteoporosis of the hip
Regional migratory osteoporosis

Question 10

Transient osteoporosis of the hip (6)

Answer 10

Classically 3rd trimester female with left hip involvement.
Actually more common in men and usually bilateral.
Normal joint space.
Self limiting and resolves in a few months.
XR shows osteopenia. MRI shows oedema.
Focally increased uptake on bone scan.

Question 11

Regional migratory osteoporosis (4)

Answer 11

Idiopathic.
Classic Hx of pain in a joint, which resolves, then shows up elsewhere.
Associated with osteoporosis.
More common in men.

Question 12

Osteoporotic compression fracture (3)

Answer 12

Common.
Band like fracture line, T1 dark, T2 variable.
Non-deformed portions of vertebral body have normal signal.

Question 13

Neoplastic compression fracture (3)

Answer 13

Vertebral mets don’t cause fractures until the whole vertebral body is replaced with tumour.
Abnormal marrow signal (not band like), involvement of posterior margin.
Look at rest of spine, mets are often multiple.

Question 14

Osteochondritis Dissecans (OCD) (4)

Answer 14

New terminology calls them OCLs (L for lesions)
Spectrum of aseptic separation of osteochondral fragment, which can lead to gradual fragmentation of articular surface and secondary OA.
Usually secondary to trauma, can be secondary to AVN.
Classically happens in femoral condyle, patella, talus and capitulum.

Question 15

OCD - staging (4)

Answer 15

Stage 1: Stable, covered by intact cartilage, intact with host bone
Stage 2: Stable on probing, partly not intact with host bone
Stage 3: Unstable on probing, complete disunity of lesion.
Stage 4: Dislocated fragment/

Question 16

OCD - Rx (4)

Answer 16

Unstable fragments can lead to secondary OA. Look for high T2 signal undercutting the fragment from the bone to call it unstable.
Absence of T2 signal at bone fragment interface suggests good osseous bridging and stability.
Granulation tissue at interface (enhances with Gd) doesn’t mean stable

Question 17

Osteochondroses (2)

Answer 17

Group of conditions, usually seen in childhood
Characterized by involvement of the epiphysis or apophysis with collapse, sclerosis and fragmentation, suggesting osteonecrosis

Question 18

Kohlers (3)

Answer 18

Osteochondrosis of Tarsal Navicular.
Affects 4-6YO males.
Rx: not surgical

Question 19

Freiberg infraction (2)

Answer 19

Osteochondrosis of 2nd metatarsal head.
Adolescent girls, can lead to secondary OA.

Question 20

Severs (2)

Answer 20

Calcaneal apophysis osteochondrosis.
Some call it normal growing pains in kids

Question 21

Panners (3)

Answer 21

Capitulum osteochondrosis.
5-10YO, thrower.
No loose bodies.

Question 22

Perthes (2)

Answer 22

Femoral head osteochondrosis.
Caucasian child, 4-8YO.

Question 23

Keinbock (2)

Answer 23

Carpal lunate osteochondrosis.
Age 20-40. Associated with negative ulnar variance.