KNEE JOINT AP LATERAL

x ray knee joint AP and Lateral projection

x ray knee
AP PROJECTION

ANATOMIC STRUCTURES

Knee joint
Distal femur
Proximal tibia and fibula
FILM SIZE
8 x 10 in. (18 x 24 cm), lengthwise
PATIENT POSITION
Place patient supine (face up) on table withpillow under head
Place lead shield over patient to protect gonads
NOTE: In some departments, the AP projection is obtained in an upright position (weight bearing) using a horizontal beam.

PART POSITION

Extend leg, making certain that pelvis is not rotated.(When we do not keep our knees straight, we get an abnormal knee x ray)
NOTE: If the patient is unable to extend the leg fully, consider performing the alternative PA projection
Align long axis of affected leg with mid-line of table, making certain that opposite leg is abducted (away from midline) far enough to prevent superimposition
Rotate entire leg medially internally) about 5 to place an imaginary line between femoral epicondyles parallel to plane of table Supports may be placed on both sides of distal leg and ankle to aid in immobilization and maintaining position
Center cassette (in Bucky tray) to areas in (1cm) below apex (distal surface) of patella.
NOTE: This examination should be performed with a Bucky exposure or grid cassette unless the anteroposterior measurement of the knee is less than 10 cm

CENTRAL RAY

Direct central ray at a 5′ cephalic (toward head) angulation to enter in.(1 cm) below apex of patella
NOTE: A 5º cephalic angulation is needed to direct central ray perpendicular to tibial plateau and to open knee joint space

Best projection for patella  we should take skyline view knee

IMAGE CRITERIA

normal knee xray  joint should be seen without rotation(medial and lateral portions of joint space should be equal unless there is deterioration from pathology or trauma).
Distal femur should be seen.
Patella should superimpose femur.
best position of normal knee joint x ray Proximal tibia should partially superimpose head of fibula

knee lateral view
KNEE LATERAL VIEW PROJECTION

knee x ray views

Distal femur
Proximal tibia and fibula
Patella (in profile)
patellar knee effusion.

FILM SIZE
PATIENT POSITION
ANATOMIC STRUCTURES

NOTE: Best projection for evaluating supra
8 X 10 in. (18 x 24 cm), lengthwise
Place patient on table in lateral position(turned to side of affected extremity), making certain that opposite extremity does not
Adjust rotation of body and entire lower extremity until knee is in lateral position (plane of patella perpendicular to plane of table).
Center cassette (in Bucky tray) to areas in. (1 NOTE: This examination should be performed with a Bucky exposure or grid cassette unless tube lateral measurement of the knee is interfere with area being radio graphed.
Place pillow under patient’s head,
Place lead shield over patient to protect gonads.
NOTE: In some departments, the lateral projection is obtained in an upright position (weight bearing) using a horizontal beam x ray for knee pain. This can not be done in case of severe knee pain

PART POSITION

NOTE: If there is a recent or suspected fracture of the patella, do not flex knee (lest fracture fragments become  distracted).
Have patient partially extend leg, allowing knee to flex 45°
NOTE: It has been recommended that the knee should be flexed less than 150 in patients with possible knee effusion, since increased flexion tends to obscure the suprapatellar area and prevent radiographic demonstration of an effusion Align long axis of femur with mid line of table Center knee to midline of table.apex (distal surface of patella,) below less than 10 cm

CENTRAL RAY

Direct central ray at a 5 cephalic (toward head) angulation to enter knee at a level 1/2 in. (1 cm) below apex of patella
NOTE A 5° cephalic angulation is needed to compensate for the plane of the femur not being parallel to the table while the plane of the lower leg is parallel to the table. Occasionally, an angle greater than 5° is needed for patients with large legs. Always be certain that the central ray is perpendicular to the joint space.
IMAGE CRITERIA
Knee joint should be seen in lateral position (as evidenced by superimposition of femoral condyles).
Proximal tibia should slightly superimposehead of fibula.
Patella should be seen in profile with joint space between patella and femur well demonstrated

EXCEPTION

If the patient has sustained trauma fractured knee x ray or is unable to assume the lateral position , broken knee xray an alternative projection is the crosstable lateral, for which the patient is placed supine with the leg extended and the knee supported on sponges.
Place the cassette to either the lateral or medial side of the leg, and use a horizontal beam Make certain that the cassette is low enough to include the posterior surface of the knee.

This projection very important for x ray of knee replacement

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