Lower Limb

Tube angulation and CR for Calcaneus Axial:

40° cephalic, base of 3rd metatarsal

Foot: (AP, Obl, & Lat)

AP Axial: a 10 degree posterior angle is used, the central ray is perpendicular to the metatarsals, reducing foreshortening. AP Oblique: Rotate leg medially until the plantar surface of the foot forms an angle of 30 degrees to IR. Lateral: adjust plantar surface of the forefoot perpendicular to the IR. CR enters at base of third metatarsal. Collimate 1 inch on the sides and 1 inch beyond the calcaneus and distal tip of the bones.

Femur - Routine Projections

AP and Lateral.

Tib/Fib - Routine Projections

AP and Lateral.

Toes: (AP, Obl, and Lat)

AP axial projection 15 degrees cephalic to open the joint spaces and reduce foreshortening. AP oblique medially rotate 30-45 degrees. On the lateral position tape the toes above the one being examined into a flexed position. CR at third MTP joint. Collimate 1 inch on all sides of the toes, including 1 inch proximal to the MTP joint.

Foot - Routine Projections

AP, Oblique (30 degrees medial), and Lateral.

Ankle - Routine Projections

AP, Oblique (45 degrees medial), and Lateral.

Knee - Routine Projections

AP, Oblique (45 degrees medial), and Lateral.

Toes - Routine Projections

AP, Oblique, and Lateral.

Ankle: (AP, Obl, & Lat)

AP: Adjust the ankle joint in the anatomic position (foot pointing straight up) to obtain a true AP projection. AP: CR is perpendicular through the ankle joint midway between malleoli. Lateral: Dorsiflex the foot, and adjust it in the lateral position. Dorsiflexion is required to prevent lateral rotation of the ankle. Oblique: medially rotate 45 degrees. Mortise Joint: medially rotate 15-20 degrees. Collimate 1 inch on the sides of the ankle and 8 inches lengthwise to include heel.

Leg: (AP & Lat)

AP: Adjust the leg so that the femoral condyles are parallel with the IR and the foot is vertical. Lateral: place the patella perpendicular to the IR. Also flex knee to ensure lateral position. CR perpendicular to center of leg. Collimate 1 inch on the sides and 1 and one half inch beyond ankle and knee joints.

Tangential Projection - Settegast Method:

CR is perpendicular to the joint space between the patella and the femoral condyles when the joint is perpenducular. Degree of angulation depends on the degree of flexion of the knee. Usually 15-20 degrees. Collimate to 4 inches by 4 inches for single knee. Collimate 4 inches by 10 inches for bilateral knees.

Largest and strongest tarsal bone:

Calcaneus

Paget disease:

Chronic metabolic disease of bone marked by weakened, deformed, and thickened bone that fractures easily.

Dislocation:

Displacement of a bone from the joint space.

Fracture:

Disruption in the continuity of bone.

Bone cyst:

Fluid-filled cyst with a wall of fibrous tissue.

Osteoarthritis or degenerative joint disease:

Form of arthritis marked by progressive cartilage deterioration in synovial joints and vertebrae.

Gout:

Hereditary form of arthritis in which uric acid is deposited in joints.

Osgood-Schlatter disease:

Incomplete separation or avulsion of the tibial tuberosity.

Osteomyelitis:

Inflammation of bone due to a pyogenic infection.

The proximal end of the fibula is expanded into a head, which articulates with the:

Lateral condyle of the tibia.

The ankle joint (ankle mortise, or mortise joint) is formed by the articulations between the:

Lateral malleolus of the fibula and the inferior surface and medial malleolus of the tibia.

Osteoclastoma or giant cell tumor:

Lucent lesion in the metaphysis, usually at the distal femur.

Chondrosarcoma:

Malignant tumor arising from cartilage cells.

Ewing sarcoma:

Malignant tumor of bone arising in medullary tissue.

Osteosarcoma:

Malignant, primary tumor of bone with bone or cartilage formation.

Patella: (PA & Lateral)

PA: Place the patient in the prone position. PA: CR is perpendicular to midpopleteal area exiting the patella. Lateral: Flex affected knee 5-10 degrees. PA: Collimate closely to the patellar area. Lateral: Collimate to 4 inches by 4 inches.

Osteomalacia or rickets:

Softening of the bones due to vitamin D deficiency.

Leg - Structures and Eval:

Structures shown AP and Lateral: The resulting image shows the tibia, fibula, and adjacent joints. Evaluation Criteria AP: ▪ Ankle and knee joints on one or more images. ▪ Entire leg without rotation. □ Proximal and distal articulations of the tibia and fibula moderately overlapped. □ Fibular midshaft free of tibial superimposition. Lateral: ▪ Ankle and knee joints on one or more images. ▪ Entire leg in true lateral position. □ Distal fibula lying over the posterior half of the tibia. □ Slight overlap of the tibia on the proximal fibular head. □ Moderate separation of the tibial and fibular bodies or shafts (except at their articular ends). ▪ Possibly no superimposition of femoral condyles because of divergence of the beam.

Calcaneus - Structures and Eval:

Structures shown Axial: The resulting image shows an axial projection of the calcaneus. Lateral: the ankle joint and the calcaneus in lateral profile. Evaluation Criteria: Axial: ▪ Calcaneus and subtalar joint. ▪ No rotation of the calcaneus—the first or fifth metatarsals not projected to the sides of the foot. ▪ Anterior portion of the calcaneus with brightness similar to the posterior portion; otherwise, two images may be needed for the two regions of thickness. Lateral: ▪ Entire calcaneus, including ankle joint and adjacent tarsals. ▪ No rotation of the calcaneus □ Tuberosity in profile. □ Sinus tarsi open. □ Calcaneocuboid and talonavicular joints open.

Patella - Structures and Eval:

Structures shown PA: provides sharper recorded detail than the AP projection because of a closer object-to-IR distance (OID). Lateral: The resulting image shows a lateral projection of the patella and patellofemoral joint space. Evaluation Criteria ▪ Patella completely superimposed by the femur ▪ No rotation ▪ Adequate brightness and contrast for clear visualization of the patella through the superimposing femur Lateral: ▪ Knee flexed 5 to 10 degrees ▪ Patella in lateral profile ▪ Open patellofemoral joint space

Tangential Projection - Settegast Method - Structures and Eval:

Structures shown Shows vertical fractures of bone and the articulating surfaces of the patellofemoral articulation. Evaluation Criteria ▪ Patella in profile. ▪ Femoral condyles and intercondylar sulcus. ▪ Open patellofemoral articulation.

Second largest tarsal bone:

Talus

The Patella:

The knee cap, is the largest and most constant sesamoid bone in the body.

The Femur:

The longest and strongest bone in the body.

The proximal end of the tibia has two prominent processes:

The medial and lateral condyles.

The Leg: (two bones)

Tibia: Second largest bone in body and is weight bearing. Fibula: On lateral side and does not bear weight.

The distal tibiofibular joint:

a fibrous syndesmosis joint allowing slight movement.

The proximal tibiofibular joint:

a synovial gliding joint. The head of the fibula articulates with the posteroinferior surface of the lateral condyle of the tibia.

The superior portion of the femur articulates with the:

acetabulum of the hip joint (considered with the pelvic girdle).

The knee joint, or femorotibial joint:

is the largest joint in the body. It is called a synovial modified-hinge joint. In addition to flexion and extension, the knee joint allows slight medial and lateral rotation in the flexed position.

The apex (directed inferiorly), lies ______ above the joint space of the knee,

one half inch.

The patellofemoral joint

patella articulates with the patellar surface of the femur and protects the front of the knee joint.

The knee joint contains two fibrocartilage disks called:

the lateral meniscus and medial meniscus.

Intercondylar Fossa - Holmblad Method - Structures and Eval:

three positions: (1) standing with the knee of interest flexed and resting on a stool at the side of the radiographic table. (2) standing at the side of the radiographic table with the affected knee flexed and placed in contact with the front of the IR. (3) kneeling on the radiographic table. Flex the knee 70 degrees from full extension (20-degree difference from the central ray. CR is perpendicular to the lower leg, entering the superior aspect of the popliteal fossa.

The foot consists of 26 bones:

• 14 phalanges (bones of the toes). • 5 metatarsals (bones of the instep). • 7 tarsals (bones of the ankle).

The intertarsal articulations are as follows:

• Calcaneocuboid. • Cuneocuboid. • Intercuneiform (two). • Cuboidonavicular. • Naviculocuneiform. • Talocalcaneal. • Talocalcaneonavicular.

The proximal foot contains seven tarsals:

• Calcaneus. • Talus. • Navicular. • Cuboid. • Medial cuneiform. • Intermediate cuneiform. • Lateral cuneiform.

The group of complex ligaments that form the knee joint are called:

• Posterior cruciate ligament. • Anterior cruciate ligament. • Tibial collateral ligament. • Fibular collateral ligament.

Femur: (AP and Lateral)

AP: With the knee included: • distal femur, rotate the patient's limb internally to place it in true anatomic position. Ensure that the epicondyles are parallel with the IR. • Place the bottom of the IR 2 inches below the knee joint. AP: With the hip included • proximal femur, which must include the hip joint, place the top of the IR at the level of the ASIS. • Rotate the limb internally 10 to 15 degrees to place the femoral neck in profile. Lateral: With the knee included: • 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. CR is perpendicular to the midfemur and the center of the IR. Collimate 1 inch on the sides of the shadow of the thigh and 17 inches in length.

Knee:

AP:CR is directed to the point one half inch inferior to the patellar apex. Lateral: Flexion of 20-30 degrees is perferred to show joint space more clearly. Epicondyles should be perpendicular to IR. Collimate to 10 inches by 12 inches.

Abbreviations:

ASIS: Anterior superior iliac spine. DIP: Distal interphalangeal. IP: Interphalangeal. PIP: Proximal interphalangeal. MTP: Metatarsophalangeal. TMT: Tarsometatarsal.

Jones:

Avulsion fracture of the base of the fifth metatarsal.

Pott:

Avulsion fracture of the medial malleolus with loss of the ankle mortise.

Calcaneus: (Axial & Lateral)

Axial: hold the ankle in right-angle dorsiflexion. CR enters near the base of the third metarsal at a cephalic angle of 40 degrees. Axial: Collimate 1 inch on three sides of the shadow of the calcaneus. Lateral: Collimate to 1 inch past the posterior and inferior shadow of the heel. Include medial malleolus and the base of the fifth metatarsal.

Osteochondroma or exostosis:

Benign bone tumor projection with a cartilaginous cap.

Osteoid osteoma:

Benign lesion of cortical bone.

Enchondroma:

Benign tumor consisting of cartilage.

Femur - Structures and Eval:

Structures shown The resulting image shows an AP projection of the femur, including the knee joint or hip or both. Evaluation Criteria: AP: ▪ Most of the femur and the joint nearest to the pathologic condition or site of injury (a second projection of the other joint is recommended). ▪ 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 the proximal femur. ▪ Any orthopedic appliance in its entirety. Lateral: With the 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 the hip included: • Opposite thigh not over proximal femur and hip joint. • Greater trochanter superimposed over distal femoral neck. • Lesser trochanter visible on medial aspect of proximal femur.

Knee - Structures and Eval:

Structures shown The resulting image shows an AP projection of the knee structures (Fig. 6-121). Evaluation Criteria AP: ▪ Knee fully extended if patient's condition permits. ▪ Entire knee without rotation . □ Femoral condyles symmetric and tibia intercondylar eminence centered. □ Slight superimposition of the fibular head if the tibia is normal. □ Patella completely superimposed on the femur. ▪ Open femorotibial joint space, with interspaces of equal width on both sides if the knee is normal. Oblique: ▪ Tibia and fibula separated at their proximal articulation. ▪ Posterior tibia. ▪ Lateral condyles of the femur and tibia. ▪ Both tibial plateaus. ▪ Margin of the patella projecting slightly beyond the medial side of the femoral condyle. ▪ Open knee joint. Lateral: ▪ Knee flexed 20 to 30 degrees in true lateral position as demonstrated by femoral condyles superimposed. □ Anterior surface of medial condyle closer to patella results from overrotation toward the IR. □ Anterior surface of medial condyle farther from patella results from underrotation away from the IR. □ Inferior surface of medial condyle caudal to lateral condyle results from insufficient cephalad CR angle. □ Inferior surface of lateral condyle caudal to medial condyle results from too far cephalad CR angle. ▪ Fibular head and tibia slightly superimposed. ▪ Patella in a lateral profile. ▪ Open patellofemoral joint space. ▪ Open joint space between femoral condyles and tibia.

Toes - Structures and Eval:

Structures shown: AP: the 14 phalanges of the toes; the distal portions of the metatarsals; and, on the axial projections, the IP joints. Lateral: Lateral projection of the phalanges of the toe and the IP articulations projected free of the other toes. Evaluation Criteria: ▪ Entire toes, including distal ends of the metatarsals. ▪ Toes separated from each other. AP: ▪ No rotation of phalanges; soft tissue width and midshaft concavity equal on both sides. ▪ Open IP and MTP joint spaces on axial projections Oblique: ▪ Proper rotation of toes, as demonstrated by more soft tissue width and more midshaft concavity on elevated side. ▪ Open IP and second through fifth MTP joint spaces. ▪ First MTP joint (not always opened). Lateral: ▪ Entire toe, without superimposition of adjacent toes; when superimposition cannot be avoided, the proximal phalanx must be shown. ▪ Toe(s) in a true lateral position . □ Toenail in profile, if visualized and normal. □ Concave, plantar surfaces of the phalanges. □ No rotation of the phalanges. ▪ Open IP joint spaces; the MTP joints are overlapped but may be seen in some patients.

Foot - Structures and Eval:

Structures shown: AP: (dorsoplantar) projection of the tarsals anterior to the talus, metatarsals, and phalanges. Oblique: interspaces between the following: the cuboid and the calcaneus, the cuboid and the fourth and fifth metatarsals, the cuboid and the lateral cuneiform, and the talus and the navicular bone. Lateral: entire foot in profile. Evaluation Criteria: AP: ▪ No rotation of the foot, as demonstrated by equal amounts of space between the second through fourth metatarsals. ▪ Overlap of the second through fifth metatarsal bases. ▪ Axial projection resulting in improved demonstration of IP, MTP, and TMT joint spaces. ▪ Open joint space between medial and intermediate cuneiforms. Oblique: ▪ Entire foot, from toes to heel. ▪ Proper rotation of foot . □ Third through fifth metacarpals free of superimposition. □ Bases of the first and second metatarsals superimposed on medial and intermediate cuneiforms. □ Navicular, lateral cuneiform, and cuboid with less superimposition than in the AP projection. ▪ Tuberosity of the fifth metatarsal. ▪ Lateral TMT and intertarsal joints. ▪ Sinus tarsi. Lateral: ▪ Superimposed plantar surfaces of the metatarsal heads. ▪ Fibula overlapping the posterior portion of the tibia. ▪ Tibiotalar joint.

Ankle - Structures and Eval:

Structures shown: AP: shows a true AP projection of the ankle joint, the distal ends of the tibia and fibula, and the proximal portion of the talus. Lateral: a true lateral projection of the lower third of the tibia and fibula; the ankle joint; and the tarsals, including the base of the fifth metatarsal. Oblique: 45-degree medial oblique projection shows the distal ends of the tibia and fibula. Evaluation Criteria: AP: ▪ Ankle joint centered to exposure area. ▪ Medial and lateral malleoli. ▪ Talus with proper brightness. ▪ No rotation of the ankle. □ Normal overlapping of the tibiofibular articulation with the anterior tubercle slightly superimposed over the fibula. □ Talus slightly overlapping the distal fibula. □ No overlapping of the medial talomalleolar articulation. ▪ Tibiotalar joint space. Lateral: ▪ Ankle joint centered to exposure area. ▪ Distal tibia and fibula, talus, calcaneus, and adjacent tarsals. ▪ Ankle in true lateral position . □ Tibiotalar joint well visualized, with the medial and lateral talar domes superimposed. □ Fibula over the posterior half of the tibia. ▪ Fifth metatarsal base and tuberosity should be seen to check for Jones fracture. Oblique: ▪ Ankle joint centered to exposure area. ▪ Distal tibia, fibula, and talus. ▪ Proper 45-degree rotation of ankle. □ Tibiofibular articulation open. □ Distal tibia and fibula overlap some of the talus. Mortise Joint: No overlap of the anterior tubercle of the tibia and the superolateral portion of the talus with the fibula.

Intercondylar Fossa: Holmblad Method:

Structures shown: The intercondylar fossa and posteroinferior articular surfaces of the condyles of the femur, as well as the medial and lateral intercondylar tubercles of the intercondylar eminence and tibial plateaus in profile (Fig. 6-139). Holmblad1 stated that the degree of flexion used in this position widens the joint space between the femur and tibia and gives an improved image of the joint and the surfaces of the tibia and femur. Evaluation Criteria: ▪ Open intercondylar fossa. ▪ Posteroinferior surface of the femoral condyles. ▪ Knee joint space open, with one or both tibial plateaus in profile. ▪ Apex of the patella not superimposing the fossa. ▪ No rotation, demonstrated by slight tibiofibular overlap and centered intercondylar eminence.