Radiology

1. X rays; plain films

a. Fractures and associated clinical findings

- open fractures (i.e., those with broken skin) are an orthopedic emergency

Bone	Location	Nerve/vessel involvement	Clinical findings/presentation
Skull	Temporal or parietal bones	Middle meningeal artery	Epidural hematoma (requires emergency surgery to prevent uncal herniation)
	Base of skull: sphenoid, occipital or temporal bones	Know the structures transmitted through various foramina (p. 108 in First Aid)	Based on structure(s) affected
Humerus	Shaft	Radial nerve	Wrist drop Loss of triceps & brachioradialis reflexes
	Surgical neck	Axillary nerve	Loss of deltoid action
Rib	Anterior		May induce hypoventilation
	Posterior		Suspect child abuse
Vertebrae	C1 (Jefferson's fracture)		From axial load (fall on head)
	Lumbar spine (compression)		Most common pathologic fracture in osteoporosis
Radius	Distal (Colle's fracture)	Often involves ulna (styloid process)	Slip and fall accidents (attempt to break fall with hand)
Scaphoid		Radial artery	Most common fracture Easily missed on X rays Point tenderness in snuffbox May result in avascular necrosis (urgent)
Femur	Neck	Medial circumflex femoral artery	May result in avascular necrosis of femoral head; common in elderly (after a fall) due to osteoporosis
	Distal metaphysis (bucket handle)		Suspect child abuse

b. PA and lateral chest films

1. Important landmarks (see p. 36-37 of High Yield Gross Anatomy)

Landmark	PA	Lateral
Costodiaphragmatic recess	Space between lateral chest wall and diaphragm (outside of lung)
Major blood vessels	Aortic arch, pulmonary artery, SVC	Aortic arch, ascending aorta, descending aorta, SVC, IVC, R and L pulmonary arteries
Cardiac chambers	Right border = RA Left border = LV Superior border = LA Inferior border = RV	Anterior border = RV Lower posterior border = LV Upper posterior border = LA

2. Abnormalities seen with different diseases

Disease	Abnormality on chest films
Consolidation	White opacity in lung field due to solidification of lung mass (e.g., fluid exudate filling air spaces in pneumonia)
Pneumothorax	Partial or complete collapse of lung (based on location of border); overexpansion of rib cage and depression of diaphragm on affected side; sometimes, displacement of mediastinum away from the pneumothorax
Mitral stenosis	LA enlargement, pulmonary vascular redistribution, interstitial edema, Kerley B lines (due to edema in pulmonary septae); late = RV enlargement
Cardiomyopathy (dilated)	Enlarged cardiac silhouette; if in heart failure, also pulmonary vascular redistribution, interstitial edema and pleural effusions

c. Abdominal films, including vasculature and other important structures

-usually in combination with a barium enema, pyelogram or arteriogram (of celiac trunk, SMA or kidney) to view specific structures. See p. 62-66 in High Yield Gross Anatomy.

d. Joint films, including important injuries/diseases (other than fractures)

1. Shoulder

- separation (acromioclavicular joint) = clavicle displaced upward relative to acromion (shoulder steps down from clavicle to acromion)

- dislocation (glenohumeral joint) = head of humerus lies inferior to the coracoid process of the scapula and may damage the axillary nerve

2. Wrist/MCP

- rheumatoid arthritis: periarticular osteopenia, marginal bone erosions, symmetric narrowing of joint space (loss of cartilage)

3. Hip

- Paget's disease of bone (characteristic appearance)

4. Knee

-soft tissue swelling from traumatic injury; MRI better to visualize ligaments/menisci

5. Spine

- herniated disc, usually at L5-S1 (S1 nerve root compression --> loss of achilles reflex) or L4-L5 (L5 nerve root compression --> loss of dorsiflexion)

6. DIP

- osteoarthritis: subchondral sclerosis, subchondral cysts, marginal osteophytes, loss of joint space (loss of cartilage)