Chapter 6: Tib/Fib, Knee, Patella Flashcards
Tibia is the weight bearing bone of
lower leg. Considered a long bone
Proximal tibia extremity contains a medial and lateral condyle
Intercondylar eminence includes
2 pointed prominences called medial and lateral intercondylar tubercles
Tibial tuberosity on anterior surface for attachment of
patellar tendon & attaches to quadriceps muscle
From anterior, the femur slopes 5-15º medially from proximal to distal. Distal femur anteriorly demonstrates
The patella. Distal portion of patella sits approx ½” superior to knee joint when leg is fully extended
With flexion of the knee, the patella moves
distally along the patellar surface
Separated by the intercondylar fossa. Medial condyle slopes
inferiorly and posteriorly 5-7 degrees
The distinguishing difference between the medial and lateral condyles is the adductor tubercle on the posterolateral aspect of the
Medial condyle for attachment of the adductor muscle.Best demonstrated on a slightly rotated lateral distal femur.
Medial epicondyle (w/ adductor tubercle) is more prominent than lateral
Patella is the largest sesamoid in body, forms between ages 3-5. Approximately 2” in diameter. Apex is inferior and base is superior.
Anterior (outer) surface is rough, posterior surface is smooth & oval shaped for articulation with the femur
Patella is embedded in the tendon of quadriceps femoris muscle. Articulates only with
Femur, loose with extension and locked into place with flexion.
Lateral shows relation of patellar surface of the distal femur and patella. Patella moves
Down and into intercondylar sulcus, more movement with more flexion (up to 90º)
Axial (end on view) patella demonstrates the relationship of the patella to the
Patellar surface (intercondylar sulcus), patellofemoral joint space is visualized on axial view.
Intercondylar fossa is visualized on axial, as well as
medial and lateral epicondyles most laterally
LCL-fibular or lateral collateral ligament; attaches to the fibula at the head where it articulates with the prox tibia.
Extends from femur to lateral proximal fibula. (fibula is not considered part of the knee joint)
MCL (tibial) or medial collateral ligament: The collateral ligament are strong bands on the sides of the
Knee, that prevent adduction and abduction movements of the knee
ACL (anterior cruciate ligament) & PCL (posterior cruciate ligament) are strong rounded cords that cross each other as they attach respectively to the
Intercondylar eminence of the tibia. They create stability for the knee by preventing anterior and posterior movements within the knee joint.
Patellar ligamant provides stability anteriorly, deep to the patellar ligament is the
Infrapatellar fat pad which protects the anterior aspect of the knee joint as well
Synovial Membrane/Cavity & Menisci
- Articular capsule (bursa)
- Suprapatellar bursa
- Infrapatellar fat pad
- Medial meniscus
- Lateral meniscus
Femorotibial knee joint (modified hinge joint): Bicondylar allowing for
Flexion extension & some gliding & rotational movement during flexion
Patellofemoral knee joint (gliding plane joint): Saddle (sellar) due to
Shape and relationship of patella to anterior, distal femur
Proximal tibiofibular joint
Plane (gliding), limited movement
Bone cysts- benign neoplastic bone lesions filled with clear fluid, most often occur
Near the knee joint in children & adolescents. Usually seen on radiograph if pathologic fx occurs
Chondromalacia patellae- softening of the cartilage under the
Patella, wearing away causing pain
Osteochondroma: benign neoplastic bone lesion caused by overproduction of bone at a
Joint with the tumor growing parallel to the bone & away from the joint
Osgood-Schlatter-: when the patellar tendon
detaches part of the tibial tuberosity. common in boys 10-15 yrs
AP Projection-Lower Leg(Tibia & Fibula)
- IR 14x17 portrait (or diagonally), 40”-48” SID, 70-75 kVp (use more technique for proximal pain, less for distal pain)
- Pt supine with leg extended fully, no rotation. Dorsiflex foot 90º. Ensure ankle and knee joints are 1-2” from either end of IR to prevent divergent rays from projecting anatomy off the image. If leg will not fit on IR, do 2 projections including anatomy of injured area, use smaller IR to include other joint.
- **CR perpendicular to midpoint of lower leg. Collimate to include as much of the knee and ankle joint as possible. **
- Anatomy: Entire tibia and fibula including ankle and knee joint.
- Position: No rotation evidenced by demonstration of femoral and tibial condyles in profile. Intercondylar eminence (tibia) centered within the intercondylar fossa (femur). Some overlap of the fibula & tibial both proximally & distally
- Nearer equal density at both ends of IR. No motion, sharp cortical margins, contrast & density, ST and bony trabecular detail at both ends of tibia
Lateral Tibia and Fibula (Mediolateral Projection)
- IR 14x17 portrait or diagonal, 40-48 SID, 70-75 kVp
- Pt in lateral recumbent position on affected side. Place unaffected leg behind (or across) affected leg. Ensure true lateral position by evaluating plane of patella & have it perpendicular with IR. Ensure 1”-2” of knee and ankle joint on IR for divergent rays.
- CR perpendicular to midpoint of tib/fib
- Anatomy: Entire tib/fib included with ankle and knee joint (unless f/u). True lateral of tibia and fibula without rotation demonstrates tibial tuberosity in profile
- Position: Portion of fibular head superimposed over prox tibia & outlines of distal fibula superimposed over distal posterior tibia. Posterior borders of femoral condyles should appear superimposed. Collimate on both sides to st margins & include maximum amount of knee and ankle joints.
- Near equal density at both ends of IR. No motion, sharp cortical edges, contrast and density, st and bony trabecular details
*Can be done x-table in trauma situations
AP Projection- Knee
- IR 10x12 portrait, 40 SID, 65-75 kVp (more for table bucky vs table top)
- Pt supine with no rotation of pelvis, leg fully extended. Align & center leg and knee to CR, and table or IR. Rotate leg internally 3-5º for true AP (interepicondylar line is parallel to IR). Align CR parallel to articular facets (tibial plateau). Average sized patient CR will be perpendicular (19-24 cm measured at ASIS to table top)
**- ASIS to TT <19 cm 3-5º caudal - ASIS to TT >25 cm3-5º cephalic***
- CR enters ½” distal to patellar apex (knee joint)
- Anatomy: Distal femur and prox tib/fib shown. Femorotibial joint space open with articular facets (tibial plateau) seen on end with only minimal surface area visulized.
- Position: No rotation evidenced by symmetric appearance of the femoral & tibial condyles & joint space. Approx. medial half of fibular head superimposed by tibia. Intercondylar emminence center of intercondylar fossa
- Optimal exposure demonstrates outline of patella through distal femur. No motion, trabecular markings of all bones should be visible and appear sharp, ST detail visible
AP Oblique Projection-Knee(Medial/Internal Rotation)
- IR 10x12 portrait, 40 SID, 65-75 kVp
- Pt supine or semi supine with entire body and leg rotated partially away from side of interest. Support under elevated hip. Align and center leg and knee to CR and midline of table or IR. Rotate entire leg internally 45º- interepicondylar line should be 45º to plane or IR.
- CR (most likely) 3-5º cephalic entering ½” distal to patellar apex at midpoint of knee. Collimate to ST margins with full collimation at ends to IR borders to include maximum femur and tib/fib.
- Anatomy: Distal femur and prox tib/fib with patella superimposing the medial femoral condyle. Latral condyles of femur and tibia are well demonstrated. Medial and lateral knee joint appears unequal.
- Position: Proper amount of obliquity demonstrates the prox tibiofubular joint open with lateral condyles of femur and tibia in profile. The and neck of fibula well visualized without superimposition. Approx half of patella free of superimposition of femur
- Optimal exposure and no motion. Do not overexpose head and neck of fibula
AP Oblique Projection-Knee(Lateral/External Rotation)
- IR 10x12 portrait, 40 SID, 65-75 kVp
- Align and center leg and knee to CR and midline of table or IR. Rotate leg laterally 45º. (interepicondylar line should form 45º angle to plane of IR)
- CR angle 0 to 3-5º cephalic. Direct CR to midpoint of knee ½” distal to apex of patella. Collimate on both sides to include ST, include maximum femur and tib/fib
- Anatomy: Distal femur and prox tib/fib. Patella superimposing lateral femoral condyle. Medial condyles of femur and tibia are in profile
- Position: Proper amount of obliquity demonstrates prox fibula superimposed by prox tibia. Approx half of patella free of superimposition of lateral condyle
- Optimal exposure visualizes ST & trabecular markings of all, bones sharp and clear, no motion. Technique includes fibula demonstrated through tibia
Lateral Knee(Mediolateral Projection)
- IR 10x12 portrait, 40 SID, 65-75 kVp
- Lateral recumbent position. Rotate pt onto affected side and support unaffected leg posterior to affected leg (or cross anterior to affected leg). Flex knee 20-30º. Adjust rotation of body until leg is in true lateral position-femoral epicondyles superimposed. Plane of patella perpendicular to IR. Align and center leg and knee to CR and table or IR
- CR 5-7º cephalic directed 1” below medial epicondyle. Use horizontal beam if patient is unable to flex knee 20-30º and is done lateromedially (x-table).
- Anatomy: Distal femur, prox tib/fib and patella shown in lateral profile. Patellofemoral and knee joints open.
- Position:mOver-rotation or under-rotation determined by identifying the adductor tubercle of medial condyle and by positon of fibular head over prox tibia. Over rotation-less superimposition of fibular head. Under roation- more superimposition of fibular head. True lateral is demonstrated by superimposition of posterior borders of femoral condyles. Patella visualized in profile with patellofemoral joint space open, knee joint centered.
- Optimal exposure with no motion, ST detail, fat pad region ant to knee joint & sharp trabecular markings
AP Weight-Bearing Projection-Knee(Bilateral)
- IR 14x17 crosswise upright bucky, 40 SID
- Patient erect standing on step stool if tube does not go down far enough. Positon feet straight ahead with weight evenly distributed on feet. Provide support handles if necessary. Align and center bilateral knees to CR and to midline of bucky, adjust bucky and CR to align. May be taken PA with cephalic angle, easier for patient who are unable to straighten knee. Knees flexed 20º, feet straight ahead 10º caudal angle.
- CR perpendicular for average patient entering midpoint between knee joints ½” below patellar apex (5-10º caudad for thin pt). Collimate to distal femur and prox tib/fib ST borders.
- Anatomy: Distal femur, prox tib/fib femorotibial joint spaces demonstrated bilaterally.
- Position: No rotation of both knees evident by symmetric appearance of femoral and tibial condyles. ½ of prox fibula superimposed over prox tibia.
- Optimal exposure-patella seen through femur ST visible, bony trabecular detail. No motion
PA Axial Projection-Knee(Holmblad Method)
- IR 8x10 portrait (14x17 landscape for bilat), 40 SID, 70-75 kVp
- Have pt kneel on table flex knees 60-70º.
- CR perpendicular to the lower leg; entering the superior aspect of the popliteal fossa and exiting at the level of the patellar apex
- Anatomy: Intercondylar fossa, articular facets(tibial plateau’s) and knee joint demonstrated clearly. Intercondylar fossa should appear in profile, open with superimposition of patella
- Position: No rotation is evidenced by symmetric appearance of distal posterior femoral condyles and superimposition of approx half of fibular head by tibia. Articular facets and intercondylar eminence of tibia visualized without superimposition.
- Optimal exposure, patella visualized through femur,trabecular markings of femoral condyles and prox tib appear sharp
PA Axial Projection-Knee(Holmblad Method-Modifications)
- TT versus bucky
- Pt partially standing with affected knee on TT (lower table). Have pt support weight primarily on unaffected side. Have patient lean forward 20-30º and hold position (forms 60- 70º angle of affected knee). Partially standing with affected leg on stool or chair
PA Axial Projection-Knee(Camp Coventry Method)
- Pt prone, flex knee 40-50º. Rest foot/ankle on support device
- CR 40-50º caudal to match degree of flexion
AP Axial Projection-Knee(Beclare Method)
- IR 8x10 landscape, 40 SID, 70-75 kVp
- Since AP, can cause distortion due to angle and OID. Pt supine, provide support under partially flexed knee, no rotation of leg. Flex knee 40-50º. Support IR firmly against posterior thigh and lower leg. Adjust IR to center at midknee joint.
- CR directed perpendicular to lower leg (40-45º cephalic) entering ½” distal to apex of patella.
- Anatomy: Intercondylar fossa, femoral condyles, tibial plateaus and intercondylar eminence visualized. Collimate to 4 sides of knee joint.
- Position: Intercondylar fossa should appear in profile without superimposition of patella. Intercondylar eminence and tibial plateaus and distal condyles of femur clearly visualized. No rotation visualized by symmetric appearance of distal posterior femoral condyles & superimposition of fibular head over tibia
PA Projection- Patella
- IR 8x 10 portrait, 40 SID, 70-75 kVp (table bucky)
- Pt prone legs extended support under ankle & lower leg
Align and center long axis of leg and knee to midline of table or IR. Interepicondylar line parallel to table or IR - CR perpendicular entering mid-popliteal area exiting mid-patella. Collimate to all 4 sides to include just patella and knee joint
- Anatomy: Knee joint and patella shown with decreased OID of patella. No rotation evidenced by symmetric condyles.
- Position: Patella centered to femur with correct slight internal rotation of ant knee. Patella in center of collimated field
- Optimal exposure, without motion
Lateral Patella (Mediolateral Projection)
- IR 8x10 portrait, 40 SID
- Pt in recumbent position with affected side down. Provide support for opposite knee, placed behind affected knee. Rotate patient so knee is in true lateral (femoral epicondyles superimposed and perpendicular to IR). Flex knee 5-10º. Align and center long axis of patella to CR and IR or table.
- CR perpendicular to IR entering mid-patellofemoral joint
- Anatomy: Profile image of patella, patellofemoral joint and femorotibial joint
- Positiom: Ant. and post. borders of medial and lateral femoral condyles should be superimposed, patellofemoral joint space should appear open
- ST bony trabecular detail and patella without over exposure.
Tangential Projection-Patella (Merchant Bilateral Method)
- IR 10-12 unilateral 14x17 bilateral landscape, 48-72 SID (to decrease magnification), 70-75 kVp
- Pt supine with knees flexed 40 over end of table resting on leg support. Make sure quadriceps are relaxed to prevent subluxation of patellae into intercondylar sulcus. Place support under knees to raise distal femurs to they are parallel to TT. Place knees and feet together to prevent rotation and allow for relaxation. Place IR on edge against legs about 12” below knees (perpendicular to CR)
- Angle CR caudal 30º from horizontal plane. Adjust CR angle if needed for true tangential projection of patellafemoral joint spaces entering midway between patellae. Close collimation to all sides of patellae
- Anatomy: Intercondylar sulcus (trochlear groove) and patella visualized in profile.
- Position: Open patellofemoral joint space. No rotation of knee evidenced by symmetric appearance of patella, ant femoral condyles and intercondylar sulcus. Correct CR entry evidenced by open patella femoral joints
- Optimal exposure, ST and joint space margins, bony trabecular detail.
Tangential-Axial or Sunrise: Patella (Inferosuperior projection)
- IR 14x17 bilateral crosswise or 8x10 portrait for unilateral, 40 SID
- Pt supine or sitting with legs together (for bilateral) unaffected leg extended for unilateral. Flex knees 40-45º (legs relaxed). Ensure no leg rotation- patients tend to lean their knees laterally. Place IR on edge of midthigh, tilted to be perpendicular to CR (position CR first then adjust IR). Use sandbags tape, or have patient hold IR in place.
- CR directed inferiosuperiorly at 10-15º angle from lower leg to be tangential to patellofemoral joint. Palpate borders of patella to determine specific CR angle required to pass through patellofemoral joint space. Make sure quadriceps are relaxed.
- Anatomy: Evidence of proper collimation.Patella in profile. Femoral condyles and intercondylar sulcus.
- Position: Open patellofemoral articulation. Soft tissue and bony trabecular detail. No superimposition of patellae or tibial tuberosity’s
Tangential-Axial or Sunrise: Patella (Hughston Method)
- IR 8x10 portrait, 40 SID
- Pt prone, flex affected leg so tib/fib forms a 50-60º angle from full extension. Support foot/ankle, or use gauze, Thera band, or sheet to have patient hold position.
- CR angle 45º cephalad entering tangential to patellofemoral joint
- Anatomy: Evidence of proper collimation. Patella in profile.
Femoral condyles and intercondylar sulcus. - Position: Open patellofemoral articulation. Soft tissue and bony trabecular detail. No superimposition of patellae or tibial tuberosity
Tangential-Axial or Sunrise: Patella (Settegast Method)
- IR 8x10 portrait, 40 SID
- PT prone/supine/ or sitting. Flex knee to a minimum of 90º.
- Direct CR tangential (15-20º from lower leg) to patellofemoral joint space. Collimation.
- Anatomy: Open patellofemoral joint space, intercondylar sulcus, patella well visualized
- Position: No rotation by symmetric appearance of patella, ant femoral condyles and intercondylar sulcus
- ST, joint space margins and trabecular markings of patella. Femoral condyles appear underexposed with only anterior margins clearly defined
What projection is this image
mediolateral-lateral
The following image is a PA or AP axial projection used to demonstrate the
intercondylar fossa and the tibial plateau
