140 knee and distal femur

AP oblique knee lateral rotation

10x12" IR lengthwise. CR directied .5" inferior to the patellar apex. angle is variable depending on measurement between ASIS and tabletop. <19 cm = 3 to 5 degrees caudad, 19-24 cm = 0 degrees, >24 cm = 3-5 degrees cephalad. patient supine, if necessary, elevate the hip of the unaffected side enough to rotate the affected limb. support the elevated hip and knee of unaffected side. center IR .5" below apex of the patella. externally rotate the limb 45 degrees. collimate to 10x12" on collimator.

AP proximal femur projection

7x17 IR or 14x17" IR CR perpendicular to the mid-femur and the center of the IR. Patient supine, pelvis not rotated. center the affected thigh to the midline of the IR when the patient is too tall to include the entire femur, include the joint closest to the area of interest on one image. proximal femur must include the hip joint, place the top of the IR at the level of the ASIS. rotate limb internally 10 to 15 degrees to place the femoral neck in profile. collimate 1" on the sides of the shadow of the femur and 17" in length.

AP oblique knee lateral rotation structures shown

AP oblique projection of laterally rotated femoral condyles, patella, tibial condyles, and head of the fibula

AP femur structures shown

AP projection of the femur, including the knee joint or hip or both.

Patella

Knee cap. largest and most constant sesamoid bone in the body. flat, triangular bone situated at the distal anterior surface of the femur. develops in the tendon of the quadriceps femoris muscle between 3 and 5 years of age.

Anterior cruciate ligament

Lateral condyle of femur to medial side of tibia

Fibular collateral ligament

Lateral side of femur to lateral side of fibula

Anterior crest

Sharp ridge that extends along the anterior surface of the tibial body, beginning at the tuberosity

Femur

The longest, strongest, and heaviest bone in the body. Consist of one body and two articular extremities.

Patellar apex

Tip, directed inferiorly, lies .5" above the joint space of the knee, and is attached to the tuberosity of the tibia by the patellar ligament. Superior border of the patella is called the base.

PA knees weight bearing method (rosenberg) structures shown

Useful for evaluating joint space narrowing and showing articualr cartilage disease. image is similar to images obtained when radiographing the intercondylar fossa

Adductor tubercle

a raised bony area that receives the tendon of the adductor muscle. It is important to identify on lateral knee radiographs because it assist in identifying over rotation or under rotation.

Superior femur

articulates with the acetabulum of the hip joint.

Medial condyle

contains the adductor tubercle, which is located on the posterolateral aspect.

AP knees weight bearing method evaluation criteria

evidence of proper collimation, no rotation of the knees, both knees, knee joint space centered to the exposure area, adequate IR size to show the longitudinal axis of the femoral and tibial bodies or shafts.

AP oblique knee medial rotation evaluation criteria

evidence of proper collimation, tibia and fibula separated at their proximal articulation, posterior tibia, lateral condyles of the femur and tibia, both tibial plateaus, open knee joint, margin of the patella projecting slightly beyond the medial side of the femoral condyle. soft tissue around the knee joint. bony detail on the distal femur and proximal tibia.

distal tibiofibular

fibrous syndesmosis slightly movable

Tibial plateaus

flatlike superior surfaces, slope posteriorly 10 to 20 degrees. smooth facets for articulation with the condyles of the femur.

PA knees weight bearing method (rosenberg) evaluation criteria

no rotation of knees both knees knee joint centered to exposure area

PA patella projection evaluation criteria

proper collimation. patella completely superimposed by the femur. adequate penetration for visualization of the patella clearly through the superimposing femur. no rotation.

Patella and patellofemoral joint (sunrise method) evaluation criteria

proper collimation. patella in profile. open patellofeoral articulation. surfaces of the femoral condyles. soft tissue of the patellofemoral articulation. bony detail on the patella and femoral condyles.

PA patella projection structures shown

provides sharper recorded detail than in the AP projection because of a closer OID

Fibula

slender compared with its length and consists of one body and two articular extremities. Proximal end of fibula is expanded into a head which articulates with the lateral condyle of the tibia. At lateroposterior aspect of the head is a conic projection called the apex. enlarged distal end of the fibula is the lateral malleolus.

proximal tibiofibular

synovial gliding, freely movable

Femorotibial

synovial hinge, freely movable

Intercondylar eminence

terminates in two peaklike processes called medial and lateral intercondylar tubercles. lateral condyle has a facet at its distal posterior surface for articulation with the head of the fibula

AP axial intercondylar fossa (beclere method) structures shown

the intercondylar fossa, intercondylar eminence, and knee joint.

Preventing fragment separation

to prevent fragment separation in new or unhealed patellar fractures, the knee should not be flexed more than 10 degrees

Trochlear groove

triangular area superior to the intercondylar fossa on the posterior femur. popliteal blood vessels and nerves pass

Lateral and medial meniscus

two fibrocartilage disks. Lie on the tibial plateau. The center of the plateau contains cartilage that articulates directly with the condyles of the knee. The menisci provide stability for the knee and act as a shock absorber. Are commonly torn during injury. either a knee arthogram or MRI scan must be performed to visualize a meniscus tear

AP knees weight bearing method

14x17" IR. CR horizontal and perpendicular to the center of the IR, entering at a point .5" below the apices of the patellae. Patient in upright position with the back toward a vertical bucky. adjust patient's position to center the knees to the IR. Place toes straight ahead, with feet separated for balance. ask patient to stand straight with knees fully extended and weight equally distributed on the feet. Center IR .5" below the apices of the patellae. collimate 14x17" on the collimator

AP distal femur projection

7x17 IR or 14x17" IR CR perpendicular to the mid-femur and the center of the IR. Patient supine, pelvis not rotated.center the affected thigh to the midline of the IR when the patient is too tall to include the entire femur, include the joint closest to the area of interest on one image. rotate the patient's limb internally to place it in true anatomic position. the limb is natually turned externally when laying on the table. ensure that the epicondyles are parallel with the IR. place bottom or IR 2" below the knee joint. collimate 1" on the sides of the sadow of the femur and 17" in length

AP oblique knee medial rotation structures shown

AP oblique projection of the medially rotated femoral condyles, patella, tibial condyles, proximal tibiofibular joint, and head of the fibula

Distal femur

Broadened and has two large eminences: the larger medial condyle and the smaller lateral condyle. Anteriorly, the condyles are separated by the patellar surface, a shallow, triangular depresseion. Posteriorly, the condyles are separated by a deep depression called the intercondylar fossa. A slight prominence above and within the curve of each condyle forms the medial and lateral epicondyles.

AP oblique knee lateral rotation evaluation criteria

proper collimation, medial femoral and tibial condyles, tibial plateaus, open knee joint, fibula superimposed over the lateral half of the tibia, margin of the patella projected slightly beyond the edge of the lateral femoral condyle. soft tissue around the knee joint, bony detail on the distal femur and proximal tibia.

Lateral femur evaluation criteria

proper collimation. most of the femur and the joint nearest to the pathologic condition or site of injury ( a second radiograph of the other end of teh femur is recommended). Any orthopedic appliance in its entirety. trabecular detail on the femoral body. With knee included: superimposed anterior surface of the femoral condyles. patella in profile. open patellofemoral space. inferior surface of the femoral condyles not superimposed because of divergent rays. With hip included: opposite thigh not over area of interest. Greater and lesser trochanters not prominent.

Patellofemoral joint

synovial gliding, freely movable

Patella and patellofemoral joint (sunrise method) structures shown

vertical fractures of bone and the articulating surfaces of the patellofemoral articulation

AP oblique knee medial rotation

10x12" IR lengthwise. CR directied .5" inferior to the patellar apex. angle is variable depending on measurement between ASIS and tabletop. <19 cm = 3 to 5 degrees caudad, 19-24 cm = 0 degrees, >24 cm = 3-5 degrees cephalad. patient supine, support the ankles. Medially rotate the limb and elevate the hip of the affected side enough to rotate the limb 45 degrees. place support under hip if needed. collimate to 10x12" on collimator.

PA knee projection

10x12" IR. CR directed at an angle of 5 to 7 degrees caudad to exit a point .5" inferior to the patellar apex. Because the tibia and fibula are slightly inclined, the central ray is parallel with the tibial plateau. A perpendicular CR may be needed for patients with large thighs or when the foot is dorsiflexed. Patient in prone position with toes resting on the radiographic table, or place sandbags under the ankle for support. Center a point .5" below the patellar apex to the center of the IR and adjust the patient's leg so that the femoral epicondyles are parallel with the tabletop. Because the knee is balanced on the medial side of the obliquely located patella, care must be used in adjusting the knee

Lateral knee projection mediolateral

10x12" IR. CR directed to the knee joint 1" distal to the medial epicondyle at an angle of 5 to 7 degrees cephalad. slight angulation prevents joint space from being obscured by the magnified image of the medial femoral condyle. In addition, in the lateral rucumbent position, the medial condyle is slightly inferior to the lateral condyle. Center IR to CR. patient on affected side, ensure pelvis is not rotated. For standard lateral have patient bring the affected knee forward and extend the other limb behind it. other limb may also be placed in front of the affected knee on a support block. flexion of 20 to 30 degrees is usually preferred to relax the muscles and show maximum volume of joint cavity. epicondyles perpendicular to the IR. collimate 10x12" on the collimator

PA knees weight bearing method (rosenberg)

14x17" IR. CR horizontal and perpendicular to the center of the IR, perpendicular to the tibia and fibula. 10 degree caudal angle is sometimes used. patient standing with anterior aspect of the knees centered to the vertical bucky. For direct PA have patient stand upright with knees in contact with the vertical grid device, center IR at a level .5" below the apices of the patellae. have patient grasp the edges of the grid device and flex the knees to place the femora at an angle of 45 degrees.

PA knee evaluation criteria

Open femorotibial joint space with interspaces of equal width on both sides if the knee is normal. Knee fully extended if the patient's condition permits. No rotation of femur if tibia is normal. slight superimposition of the fibular head with the tibia. Soft tissue around the knee joint. Bony detail surrounding the patella.

AP knee evaluation criteria

Evidence of proper collimation, open femorotibial joint space, with interspaces of equal width on both side if the knee is normal. Knee fully extended if patient's condition permits. Patella completely superimposed on the femur. No rotation of the femur (femoral condyles symmetric) and tibia (intercondylar eminence centered). Slight superimposition of the fibular head if the tibia is normal. Soft tissue around the knee joint. Bony detail surrounding the patella on the distal femur.

Leg

Two bones, tibia and fibula.

Femur body

cylindric, slightly convex anteriorly, and slants medially 5 to 15 degrees. Extent of medial inclination depends on the the breadth of the pelvic girdle. When femur is vertical, the medial condyle is lower than the lateral condyle. 5-7 degree difference between condyles. Because of this difference, on lateral radiographs of the knee the CR is angled 5 to 7 degrees cephalad to open the joint space of the knee.

Tibial tuberosity

On anterior surface of the tibia just below the condyles. ligamentum patellae attaches.

Knee joint

One of the most complex joints in the human body. Femur, tibia, fibula, and patella are held together by a complex group of ligaments that work together to provide stability for the knee joint.

Lateral surface of tibia

flattened and contains the triangular fibular notch for articulation with the fibula. surface under the distal tibia is smooth and shaped for articulation with the talus. Anterolateral surface contains the anterior tubercle , whcih overlays the fibula.

lateral malleolus

is pyramidal and marked by several depressions at its inferior and posterior surfaces. viewed axially, the lateral malleolus lies approximately 15 to 20 degrees more posterior than the medial malleolus.

Tibia

larger of two leg bones, weight bearing, medial side of leg.

Mediolateral knee structures shown

lateral image of the distal end of the femur, patella, knee joint, proximal ends of the tibia and fibula, and adjacent soft tissue.

Lateral femur structures shown

lateral projection of about three fourths of the femur and the adjacent joint. if needed, use tow IRs to show the entire length of the adult femur.

AP knees weight bearing method structures shown

the joint spaces of the knees. Varus and Calgus deformities can also be evaluated with this procedure

Mediolateral distal Femur

7x17" IR or 14x17" lengthwise. CR perpendicular to the mid-femur and the center of the IR. draw the patient's uppermost limb forward and support it at hip level on sandbags. adjust the pelvis in a true lateral postition. flex the affected knee about 45 degrees, place a sandbag under the ankle, and adjust the body rotation to place the epicondyles perpendicular to the tabletop. adjust position of the bucky tray so that the IR projects approximately 2" beyond the knee to be included. collimate 1" on the sides of the shadow of the femur and 17" in length.

Mediolateral proximal Femur

7x17" IR or 14x17" lengthwise. CR perpendicular to the mid-femur and the center of the IR. place top of the IR at the level of the ASIS draw the upper limb posteriorly, and support it. adjust the pelvis so that it is rolled posteriorly just enough to prevent superimpostion 10 to 15 degrees from the lateral position is sufficient. collimate 1" on the sides of the shadow of the femur and 17" in length.

PA patella projection

8x10" IR lengthwise. CR perpendicular to the mid-popliteal area exiting the patella. collimate closely to the patellar area. Patient in prone position. if knee is painful, place one sandbag under the thigh and another under the leg to relieve pressure on the patella. Center IR to patella, adjust the position of the leg to place the patella parallel with the plane of the IR. Usually requires that the heel be rotated 5 to 10 degrees laterally. collimate 6x6" on the collimator.

Patella and patellofemoral joint (sunrise method)

8x10" IR. CR perpendicular to the joint space between the patella and the femoral condyles when the joint is perpendicular when the joint is not perpendicular, the degree of central ray angulation depends on the degree of flexion of the knee. angulation typically 15 to 20 degrees. close collimation is recommended. patient supine or prone. latter is preferable because the knee can usually be flexed to a greater degree, and immobilization is easier. Place IR transversely under the knee, and center it to the joint space betwen the patella and the femoral condyles. collimate to 4x4" on the collimator for a single side image and 4x10" for a bilateral examination.

AP axial intercondylar fossa (beclere method)

8x10" IR. CR perpendicular to the long axis of the lower leg, entering knee joint .5" below the patellar apex. patient supine. flex the affected knee enough to place the long axis of teh femur at an angle of 60 degrees to the long axis of the tibia. support knee on sandbags. place the IR under the knee and position the IR so that the center point coincides with the central ray. Adjust the leg so that the femoral condyles are equidistant from the IR. immobilize foot with sandbags.

Medial malleolus

At distal end of the tibia. broad medial surface prolonged into a large process.

AP knee projection

CR directed to a point .5" inferior to the patellar apex, variable angle depending on measurement between ASIS and table top. <19 cm=3-5 degree caudad, 19-24 cm=0 degrees, >24 cm=3-5 degrees cephalad. Patient supine with IR under the patient's knee, flex joint slightly to locate apex of patella, and as patient extends the knee, center the IR about .5" below the patellar apex. this centers IR to the joint space. Adjust patient's leg by placing the femoral epicondyles parallel with the IR for a true AP projection. Patella lies slightly off center to the medial side, if knee cannot be fully extended, a curved IR may be used. 10x12" IR collimate to 10x12" size on collimator.

Posterior cruciate ligament

Medial condyle of femur to lateral side of tibia

Tibial collateral ligament

Medial side of femur to medial side of tibia

AP axial intercondylar fossa (beclere method) evaluation criteria

Open intercondylar fossa. posteroinferior surface of the femoral condyles. intercondylar eminence and knee joint space. no superimposition of the fossa by the apex of the patella. no rotation, evident by slight tibiofibular overlap. soft tissue in the fossa and interspaces. bony detail on the intercondylar eminence, distal femrl, and proximal tibia.

Ligaments of the knee

Posterior cruciate ligament Anterior cruciate ligament Tibial collateral ligament Fibular collateral ligament

Fabella

Posterior knee area between condyles, contains a sesamoid bone in 3% to 5% or people. Is seen only on the lateral projection of the knee

Mediolateral knee evaluation criteria

evidence of proper collimation. Femoral condyles superimposed (locate the adductor tubercle on the posterior surface of the medial condyle to identify the medial condyle and to determine whether the knee is over rotated or under rotated) Open joint space between femoral condyles and tibia. Patella in a lateral profile. Open patellofemoral joint space. Fibular head and tibia slightly superimposed (over rotation causes less superimposition, and under rotation causes more superimposition) Knee flexed 20 to 30 degrees. All soft tissue around the knee. Femoral condyles with proper density.

AP femur evaluation criteria

evidence of proper collimation. most of the femur and the joint nearest to the pathologic condition or site of injury (second projection of the other joint is recomemended) femoral neck not foreshortened on the proximal femur. lesser trochanter not seen beyond the medial border of the femur or only a very small portion seen on the proximal femur. No knee rotation on the distal femur. Gonad shielding when indicated, but without the shield covering proximal femur. Any orthopedic appliance in its entirety. Trabecular recorded detail on the femoral shaft.