Lines in Orthoradiology

·         dens projects into base of skull

McGregor's line > 4.5 mm (line from posterior hard palate to base of occiput if dens is > 4.5 mm ==> basilar invagination)

Chamberlain's line > 3 mm (line from posterior hard palate to posterior lip of foramen magnum if dens > 3mm above line ==> basilar invagination )

McRaes line: connects ant + post margins of the foramen magnum ( Basion + Opisthion)

The odontoid should not project above this line

·         elbow fracture

anterior humeral line: should pass thru capitellum

radio-capitellar line: should bisect radius + capitellum

·         Reid's baseline: "anthropologic" baseline - from infraorbital point (inferiormost pt of bony orbit) to superior border of external auditory meatus

Note: "axial" CTs use "supraorbital-meatal" line (about 25 degrees to Reid's)

·         Blumensaats line: Line drawn on a lateral radiograph with the knee flexed 30o through the dome of the inter condylar notch which should intersect the lower pole of the patella

If the patella is above this line = patella alta

·         the convex outline of the prox carpal row (= the Shentons line of the wrist)

·         Normal calcification in growing cartilage produces dense transverse bands at the juxta-epiphysial zones (Frankels white line) in Scurvy

·         Hilgenreiners horizontal line through triradiate cartilage and Perkins vertical line from outer edge of acetabulum- should have head medial to vertical line and below horizontal line)

·         Von Rosen's line described in 1956 (with hips abducted 45o and 25o internally rotated line up the shaft of the femur should intersect acetabulum and not ilium above it)

Shentons line should be continuous

·         Trethowans sign - Line up superior margin of neck should intersect epiphysis (usually 20% of the femoral head lateral to this line)

Capeners sign -AP view in the normal hip the posterior acetabular margin cuts across the medial corner of the upper femoral metaphysis. With slipping the entire metaphysis is lateral to the posterior acetabular margin