Lines of Mensuration

Question 1

Landmarks: A line is drawn from the nasion to the center of the sella turcica. A line is drawn from the basion (anterior foramen magnum) to the center of the sella turcica.

What is the significance?

Answer 1

Basilar Angle

If this angle is > 152 degrees, it is indicative of Platybasia, which may be associated with
basilar impression.

Question 2

Landmarks: A line is drawn from the hard palate to the base of the occiput.

What is the significance?

This is the most accurate line to evaluate for basilar impression.

Answer 2

McGregor’s Line

If the odontoid is > 8mm above this line in males or

• *> 10mm** above this line in females, this indicates
• *Basilar Impression**

Question 3

Landmarks: The hard palate to the opishtion (posterior foramen magnum)

What is the significance?

Answer 3

Chamberlain’s Line

If the Odontoid is > 7mm above this line, it indicates
Basilar Impression

Question 4

Landmarks: Anterior Foramen magnum (basion) to the posterior foramen magnum (opisthion)

What is the significance?

Answer 4

Macrae’s Line

If the occipital bone is above this line, this indicates
Basilar Impression

Question 5

Landmarks: C1 anterior tubercle to the odontoid

What is the significance?

Answer 5

Atlantodental Interspace

If this space is > 3mm in adults or > 5mm in children,
this indicates Transverse Ligament Rupture or
instability due to trauma, Down’s Sydnrome or Inflammatory Arthritis.

Question 6

Landmarks: Posterior body margins are checked for alignment with what should be a smooth, continuous line.

Answer 6

George’s Line

Discontinuous line may indicate A-P vertebral malposition such as Antero/Retrolisthesis

Question 7

Landmarks: Lines drawn at each spinolaminar junction should form a smooth arc-like curve

Answer 7

Posterior Cervical Line

Discontinuous lines may indicate A-P vertebral malposition such as Antero/Retrolisthesis

Question 8

Landmarks: Lines drawn at the posterior bodies of C2 and C7

Where should flexion & extension intersect at?
If it doesn, what could be the possible reasons?

Answer 8

Stress Lines of Csp

Flexion should intersect at C5/C6
Extension should intersect at C4/C5
May be altered by muscle spasm, joint fixation
or disc degeneration

Question 9

Landmarks: Anterior Vertebral bodies to posterior margin of air shadow of the pharynx, larynx, and trachea.

What are the indications and measurements for the Retropharyngeal, Retrolaryngeal & Retrotracheal spaces?

Answer 9

Prevertebral Soft Tissues

Soft Tissue Mass
(tumor, infection or hematoma)

Retropharyngeal (C2-C4): > 7mm

Retrolaryngeal (C5): > 14mm

Retrotracheal (C6-C7): > 22mm

Question 10

Landmarks: Locate superior and inferior extremes of scoliosis. Draw a parallel line through the superior end plate of extreme superior vertebra and through inferior endplate of extreme inferior vertebra. Intersecting perpendicular lines are drawn and the angle is measured.

Significance: Scoliosis evaluation (Preferred Method)

Answer 10

Cobb’s Method

Question 11

Landmarks: Locate superior and inferior extremes of scoliosis and apical segment. Diagonal lines are drawn to locate the center of the vertebral bodies. Two lines are drawn connecting center of apical segment with each end vertebra and resultant angle measured.

How is this value different than Cobb’s Method?

Answer 11

Risser-Ferguson Method

Values are 25% below Cobb Method

Question 12

Landmarks: Tangential line is drawn parallel and through the posterior margin of S1 and a vertical line is drawn intersecting the sacral line

What should the measurements be?

Answer 12

Sacral Inclination

30-72 degrees

~ 46 degrees

Question 13

Landmarks: Oblique line drawn through and parallel to the sacral base; Horizontal line parallel to the bottom edge of the film.

Significance:

Normal Angle?
Average Angle?

Answer 13

Lumbosacral Angle

26-57 degrees

~ 41 degrees

Question 14

Meyerding’s Grading Method of Spondylolisthesis

Landmarks: The sacral base is divided into quarters and the relative position of the posterior inferior aspect of L5 is made.

Explain the significance & the grading?

Answer 14

Determines the degree of Spondylolisthesis

Grade 1 = 0-25%

Grade 2 = 26-50%

Grade 3 = 51-75%

Grade 4 = 76-100%

Question 15

Landmarks: Line drawn parallel and through the sacral base. Perpendicular line drawn from the sacral promontory.

What is the significance?

Answer 15

Ullmann’s Line

L5 beyond the perpendicular line indicates
Spondylolisthesis

Question 16

Einsenstein’s Method for Sagittal Canal Measurement

Landmarks: Line drawn to connect the tips of the superior and inferior articlar processes. The distance to posterior body margin at the midpoint is measured.

What is the significance?

Answer 16

Measurement of > 15mm indicates
Spinal Canal Stenosis

Question 17

Canal/Body Ratio

Landmarks are drawn as follows:
A. Interpedicular Distance
B. Sagittal Canal Dimension (Eisenstein’s method)
C. Transverse Body Dimension
D. Sagittal Body Dimension

What is the significant ratio?

Answer 17

Ratio should be 1x2 / 3x4

The higher the ratio, the smaller the canal
If > 1:6 at L3, L4 or > 1:6.5 at L5
Canal Stenosis is indicated

Question 18

Landmarks: Lines are drawn parallel and through the inferior end plate of L5 and the superior end plate of S1

What is the significance?

Answer 18

Lumbosacral Disc Angle

Normal Lumbosacral Disc Angle
10-15 degrees

Question 19

Landmarks: Vertical line is drawn through the center of the L3 vertebral body down to the sacrum

What is the significance?

Answer 19

Lumbar Gravity Line

If the line is anterior to sacrum = Hyperlordosis
If the line is posterior to sacrum = Hypolordosis

Question 20

Landmarks: A line is drawn parallel and through the inferior end plate

What is the significance?

Answer 20

Macnab’s Line

If the line intersects the superior articular process of the vertebra BELOW, it indicates
extension malposition or facet imbrication

Question 21

Hadley’s “S” Curve

Landmarks: A curvilinear line is drawn along the inferior aspect of the TVP, the inferior articular process, and through the joint space to the superior articular process of the vertebra below.

Indications?

Answer 21

Should be a smooth “S” shaped curve
An interruption in the S-curve indicates
subluxation or facet imbrication

Question 22

Landmarks: A line is drawn along the pelvic inlet to the outer aspet of the obturator foramen.

Indication?

Answer 22

Kohler’s Line

If the acetabular floor crosses the line, it indicates
Protrusio Acetabuli

Question 23

Landmark: A smooth curvilinear line is drawn along the inferior femoral neck to the superior aspect of the obturator foramen

Indication?

Answer 23

Shenton’s Line

An interrupted, discontinuous line indicates a
Dislocation, Neck Fracture or
Slipped Capital Femoral Epiphysis

Question 24

Landmarks: A smooth curvilinear line is drawn along the outer ilium, across the joint and onto the femoral neck

Indications?

Answer 24

Iliofemoral Line

Bilateral asymmetry indicates:
Slipped Femoral Capital Epiphysis
Dislocation
Fracture
Dysplasia

Question 25

Landmarks: Two lines are drawn through and parallel to the mid-axis of the femoral shaft and the femoral neck What is a normal angle? What is the indication if it is \> or \< ?

Answer 25

Femoral Angle aka Mikuliez's Angle Normal angle = 120-130 degrees Coxa Vara = \< 120 degrees Coxa Valga = \> 130 degrees

Question 26

Landmarks: A line is drawn through and parallel to the femoral shaft. A perpendicular line is drawn tangential to the tip of the greater trochanter. Indication?

Answer 26

Skinner's Line The fovea capitis should lie above or at the level of the trochanter line. If the fovea capitus falls below this line, it indicates Fracture or Coxa Vara

Question 27

Landmarks: A line drawn along the outer margin of the femoral neck Indications?

Answer 27

Klein's Line The femoral head should intersect the line. Failure to intersect the line indicates a Slipped Capital Femoral Epiphysis

Question 28

Patellar Position Landmarks: a line is drawn between the superior and inferior patellar pole. A line is drawn between the inferior patellar pole and the tibial tubercle. Indication?

Answer 28

Patellar length and patellar tendon length should be approximately equal. If the tendon length is 20% greater than patellar length = Patella Alta

Question 29

Heel Pad Measurement Landmarks: The shortest distance is measured between the plantar surface of the calcaneus and the external skin contour. Indication?

Answer 29

If the distance is \> 25mm is male or \> 23mm in female, this signifies increased thickness often associated with Acromegaly

Question 30

Landmarks: The three highest points on the superior aspect of hte calcaneus are connected with 2 lines. Indication?

Answer 30

Boehler's Angle If the resultant angle is \< 28 degrees, this indicates Calcaneal Fractue or Dysplastic Calcaneus