Lines of Mensuration Flashcards
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?
Basilar Angle
If this angle is > 152 degrees, it is indicative of Platybasia, which may be associated with
basilar impression.
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.
McGregor’s Line
If the odontoid is > 8mm above this line in males or
- *> 10mm** above this line in females, this indicates
- *Basilar Impression**
Landmarks: The hard palate to the opishtion (posterior foramen magnum)
What is the significance?
Chamberlain’s Line
If the Odontoid is > 7mm above this line, it indicates
Basilar Impression
Landmarks: Anterior Foramen magnum (basion) to the posterior foramen magnum (opisthion)
What is the significance?
Macrae’s Line
If the occipital bone is above this line, this indicates
Basilar Impression
Landmarks: C1 anterior tubercle to the odontoid
What is the significance?
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.
Landmarks: Posterior body margins are checked for alignment with what should be a smooth, continuous line.
George’s Line
Discontinuous line may indicate A-P vertebral malposition such as Antero/Retrolisthesis
Landmarks: Lines drawn at each spinolaminar junction should form a smooth arc-like curve
Posterior Cervical Line
Discontinuous lines may indicate A-P vertebral malposition such as Antero/Retrolisthesis
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?
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
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?
Prevertebral Soft Tissues
Soft Tissue Mass
(tumor, infection or hematoma)
Retropharyngeal (C2-C4): > 7mm
Retrolaryngeal (C5): > 14mm
Retrotracheal (C6-C7): > 22mm
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)
Cobb’s Method
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?
Risser-Ferguson Method
Values are 25% below Cobb Method
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?
Sacral Inclination
30-72 degrees
~ 46 degrees
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?
Lumbosacral Angle
26-57 degrees
~ 41 degrees
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?
Determines the degree of Spondylolisthesis
Grade 1 = 0-25%
Grade 2 = 26-50%
Grade 3 = 51-75%
Grade 4 = 76-100%
Landmarks: Line drawn parallel and through the sacral base. Perpendicular line drawn from the sacral promontory.
What is the significance?
Ullmann’s Line
L5 beyond the perpendicular line indicates
Spondylolisthesis
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?
Measurement of > 15mm indicates
Spinal Canal Stenosis
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?
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
Landmarks: Lines are drawn parallel and through the inferior end plate of L5 and the superior end plate of S1
What is the significance?
Lumbosacral Disc Angle
Normal Lumbosacral Disc Angle
10-15 degrees
Landmarks: Vertical line is drawn through the center of the L3 vertebral body down to the sacrum
What is the significance?
Lumbar Gravity Line
If the line is anterior to sacrum = Hyperlordosis
If the line is posterior to sacrum = Hypolordosis
Landmarks: A line is drawn parallel and through the inferior end plate
What is the significance?
Macnab’s Line
If the line intersects the superior articular process of the vertebra BELOW, it indicates
extension malposition or facet imbrication
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?
Should be a smooth “S” shaped curve
An interruption in the S-curve indicates
subluxation or facet imbrication
Landmarks: A line is drawn along the pelvic inlet to the outer aspet of the obturator foramen.
Indication?
Kohler’s Line
If the acetabular floor crosses the line, it indicates
Protrusio Acetabuli
Landmark: A smooth curvilinear line is drawn along the inferior femoral neck to the superior aspect of the obturator foramen
Indication?
Shenton’s Line
An interrupted, discontinuous line indicates a
Dislocation, Neck Fracture or
Slipped Capital Femoral Epiphysis
Landmarks: A smooth curvilinear line is drawn along the outer ilium, across the joint and onto the femoral neck
Indications?
Iliofemoral Line
Bilateral asymmetry indicates:
Slipped Femoral Capital Epiphysis
Dislocation
Fracture
Dysplasia
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 < ?
Femoral Angle aka Mikuliez’s Angle
Normal angle = 120-130 degrees
Coxa Vara = < 120 degrees
Coxa Valga = > 130 degrees
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?
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
Landmarks: A line drawn along the outer margin of the femoral neck
Indications?
Klein’s Line
The femoral head should intersect the line.
Failure to intersect the line indicates a
Slipped Capital Femoral Epiphysis
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?
Patellar length and patellar tendon length should be approximately equal. If the tendon length is
20% greater than patellar length = Patella Alta
Heel Pad Measurement
Landmarks: The shortest distance is measured between the plantar surface of the calcaneus and the external skin contour.
Indication?
If the distance is > 25mm is male or > 23mm in female, this signifies increased thickness often associated with Acromegaly
Landmarks: The three highest points on the superior aspect of hte calcaneus are connected with 2 lines.
Indication?
Boehler’s Angle
If the resultant angle is < 28 degrees, this indicates
Calcaneal Fractue or Dysplastic Calcaneus
