Lower Limb Anatomy PDF

Lower limbs & pelvic Anatomy and positioning TA. NOURA DANNOUN  The lower extremities The lower extremities are divided into: 1. The foot. 2. The ankle joint. 3. The leg. 4. The knee joint. 5. The thigh (femur). 6. Hip joint. 7....

Lower limbs & pelvic Anatomy and positioning TA. NOURA DANNOUN  The lower extremities The lower extremities are divided into: 1. The foot. 2. The ankle joint. 3. The leg. 4. The knee joint. 5. The thigh (femur). 6. Hip joint. 7. Pelvis.  The Foot The foot is the terminal segment of the lower limb. It is composed of 26 bones; arranged in 3 groups: 1. The tarsal bones{7}. 2. The metatarsal bones{5}. 3. The phalanges {14}.  The tarsal bones They are 7 (irregular shaped) bones. (1) The talus bone. (2) The calcaneus bone. (3) The nivicular bone. (4) The cuboid bone. (5) The cuneiform bones {3 bones}.  1) The Talus Lies immediately below the tibia and between the calcaneus and navicular bones. The 2nd largest bone of the tarsal bones. It is formed of 3 part: 1. The body, between the lower end of the tibia and the upper surface of the calcaneus. 2. The neck, which is ill-defined constriction between the body and the head. 3. The head, is the anterior rounded part of the bone.  The talus articulates with the following bones: Tibia and fibula. Calcaneus. Navicular.  2) The Calcaneus The largest tarsal bones. Lies below the talus. The upper surface is divided into 3 areas: 1. Posterior area: is covered by a fatty tissue mass which lies between the ankle joint and the tendon calcaneus 2. Anterior area. Is grooved at its posterior end by sulcus ccalcaneus. 3. Middle area. is large, oval convex articular surface which articulates with the inferior surface of the taus. The calcaneus articulates with talus Superiorrly and cuboid bone anteriorly. 3) The Navicular Lies between the talus and the cuneiform bones. Has a boat shape. Articulates with the anterior end of the talus, cuboid laterally and the three cuneiforms anteriorly. 4)The Cuboid Lies in front of the calcaneus and behind the 4th and 5th metatarsals. At the lateral side of the tarsal bones. Articulates with: Calcaneus. Lateral cuneiform. 4th and 5th metatarsal bones.  5) The Cuneiform bones They are 3 bones: 1. Medial (interal). 2. Intermediate (middle). 3. Lateral (external). They have a wedge shape. Situated between the nivicular behind and the first 3rd metatarsal bones in front.  Metatarsal bones The metatarsals are located in the forefoot, between the tarsals and phalanges. They are numbered I-V(1-5) (medial to lateral). Each metatarsal has a similar structure. They are convex dorsally and consist of a head, neck, shaft, and base (distal to proximal).  The 1st metatarsal bone is the shortest and the most massive. The head is larger than the base. Articulate with the medial cuneiform. The 2nd metatarsal bone is the longest one, its articulates with the middle cuneiform at the base., at the sides with the other 2 cuneiform and 3rd metatarsal. The 3rd metatarsal, articulates at its base with the lateral cuneiform and its sides with the 2nd and 4th metatarsal. The 4th metatarsal, articulates at the base with the cuboid and at its sides with the 3 rd and 5th metatarsal. The 5th, articulates at the base with the cuboid and midially with the 4th metatarsal.  The 2nd,3rd and 4th metatarsal bones are similar : The base have wedge shape and wider above than below. The heads are narrower than the bases. The shafts are slightly curved being convex towardes the dorsum of the foot. They have three or four articulations: Proximally – tarsometatarsal joints – between the metatarsal bases and the tarsal bones. Laterally – intermetatarsal joint(s) – between the metatarsal and the adjacent metatarsals. Distally – metatarsophalangeal joint – between the metatarsal head and the proximal phalanx Phalanges The phalanges are the bones of the toes. The second to fifth toes all have proximal, middle, and distal phalanges. The great toe has only 2; proximal and distal phalanges. They are 14 bones. They are similar in structure to the metatarsals, each phalanx consists of a base, shaft, and head.  The 1st digit is also called halux, big toe and great toe. The proximal phalanx of the great toe is larger than the others. The middle and distal phalanges of the 5th toe are frequently fused and form one bone. The middle phalanges are shorter and thicker. The foot has a Superior surface (the dorsal) and the inferior surface (the sole or planter) The joint Metatarso-phalangeal joints: between the proximal phalanges and the metatarsal bone. Proximal Interphalangeal joints: between the proximal and middle phalanges. Distal Interphalangeal joints: between the middle and the distal phalanges. Sesamoid bones of the foot Two or three sesamoid bones at the metatarso- phalangeal joint of the big toe.. Occasionally, a sesamoid bone over the Interphalangeal joint of the big toe (halux). Occasionally, at the Metatarso-phalangeal joint of the 2nd and 5th toes. Toe: AP projection Clinical indication : Fractures and dislocations of the phalanges and digits. Pathologies such as osteoporosis and osteoarthritis (gout), especially in the first digit. Technical factors FFD/SID : 40" (100cm). Film size:18×24 cm, landscape. Nongrid. Focal spot : small. Shielding: shield radiosensitive tissues outside region of interest. Patient position :place pt Supine or seated on table; knee should be flexed with planter surface of foot resting on IR. Part position: Center and align long axis of digit to CR and long axis of portion of IR being exposed. Ensure that MTP joint of digit in question in centered to CR.  CR: Angle CR 10°-15° toward calcaneus (CR perpendicular to phalanges). If a 15° wedge is placed under the foot for parellel part film alignment, the CR is perpendicular to the IR. Center CR to MTP joint in question. Toes: lateral -mediolateral or Lateromedial projection Clinical indication : Fractures and dislocatios of the phalanges and digits. Pathologies such as osteoporosis and osteoarthritis (gout), especially in the first digit. Technical factors ' FfD/SID : 40" (100cm). Film size:18×24 cm, landscape. Nongrid. Focal spot : small. Shielding: shield radiosensitive tissues outside region of interest. Patient position and part position :  CR: CR perpendicular to IIR. CR directed to Interphalangealjoint for first digit and to proximal Interphalangeal joint for second to fifth digits. Foot:AP projection Clinical indication : Location and extent of fractures and fragment alignments, joint space abnormalities, soft tissue effusions Location of opaque foreign bodies Technical factors: SID(FFD) 40" (100cm). IR -24×30cm, portrait. Nongrid Shielding: shield radiosensitive tissues outside region of interest. Patient position: Place patient supine; provide a pillow for patient’s head; ex knee and place plantar surface (sole) of affected foot at on IR. Part position: Extend (plantar ex) foot but maintain plantar surface resting at and frmly on IR (Fig. 6.56). Align and center long axis of foot to CR and to long axis of Evaluation Criteria Anatomy Demonstrated: Entire foot should be demonstrated, including all phalanges and metatarsals and navicular, cuneiforms, and cuboids (Figs. 6.57 and 6.58). Position: Long axis of foot should be aligned to long axis of portion of IR being exposed. No rotation as evidenced by nearly equal distance between second through fifth metatarsals. Bases of first and second metatarsals generally are separated, but bases of second to fifth metatarsals appear to overlap. Intertarsal joint space between first and second cuneiforms should be demonstrated. Collimation to area of interest. Exposure : Optimal density (brightness) and contrast with no motion should visualize sharp borders and trabecular markings of distal phalanges and tarsals distal to talus. See higher kV technique for more uniform densities between phalanges and tarsals. Sesamoid bones (if present) should be seen through head of first metatarsal. Foot: AP oblique Clinical Indications Location and extent of fractures and fragment alignments, joint space abnormalities, soft tissue effusions Location of opaque foreign bodies Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 cm (10 × 12 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient supine or sitting; ex knee, with plantar surface of foot on table; turn body slightly away from side in question. Part Position Align and center long axis of foot to CR and to long axis of portion of IR being exposed. Rotate foot medially to place plantar surface 30° to 40° to plane of (see Note). The general plane of the dorsum of the foot should be parallel to IR and perpendicular to CR (Fig. 6.59). Use 45° radiolucent support block to prevent motion. Use sandbags if necessary to prevent IR from slipping on tabletop. CR CR perpendicular to IR, directed to base of third metatarsal Evaluation Criteria (Medial Oblique ) Anatomy Demonstrated: Entire foot should be demonstrated from distal phalanges to posterior calcaneus and proximal talus (Figs. 6.61 and 6.62). Position: Long axis of foot should be aligned to long axis of IR. Correct obliquity is demonstrated when third through fifth metatarsals are free of superimposition. First and second metatarsals also should be free of superimposition except for base area. Tuberosity at base of fifth metatarsal is seen in profile and is well visualized. Joint spaces around cuboid and the sinus tarsi are open and well demonstrated when foot is positioned obliquely correctly. Collimation to area of interest. Exposure : Optimal density (brightness) and contrast with no motion should visualize sharp borders and trabecular markings of phalanges, metatarsals, and tarsals. Foot: lateral-mediolateral or lateromedial Clinical Indications Location and degree of anterior or posterior displacement of fracture fragments, joint abnormalities, and soft tissue effusions Location of opaque foreign bodies Technical Factors Minimum SID—40 inches (102 cm) IR size—18 × 24 cm (8 × 10 inches), for smaller foot, or 24 × 30 cm (10 × 12 inches), for larger foot, portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in lateral recumbent position; provide pillow for patient’s head. Part Position (Mediolateral Projection) Flex knee of affected limb about 45°; place opposite leg behind the injured limb to prevent over-rotation of affected leg. Carefully dorsiFLex foot if possible to assist in positioning for a true lateral foot and ankle (Fig. 6.63). Place support under leg and knee as needed so that plantar surface is perpendicular to. Do not over-rotate foot. Align long axis of foot to long axis of IR (unless diagonal placement is needed to include entire foot). Center mid area of base of metatarsals to CR. CR CR perpendicular to IR, directed to medial cuneiform (at level of base of third metatarsal) Evaluation Criteria Anatomy Demonstrated: Entire foot should be demonstrated, with a minimum of 1 inch (2.5 cm) of distal tibia- fibula. Heads of metatarsals are superimposed with the tuberosity of the fifth metatarsal seen in pro le (Figs. 6.65and 6.66). Position: Long axis of the foot should be aligned to the long axis of IR. True lateral position is achieved when tibiotalar joint is open, distal fibula is superimposed by the posterior tibia, and distal metatarsals are superimposed. Collimation to area of interest. Exposure : Optimal density (brightness) and contrast should visualize borders of superimposed tarsals and metatarsals. No motion; cortical margins and trabecular markings of calcaneus and nonsuperimposed portions of other tarsals should appear sharply defined. CALCANEUS: PLANTODORSAL (AXIAL) PROJECTION Clinical Indications Pathologies or fractures with medial or lateral displacement Technical Factors Minimum SID—40 inches (102 cm) IR size—18 × 24 cm (8 × 10 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient supine or seated on table with leg fully extended. Part Position Center and align ankle joint to CR and to portion of IR being exposed. Dorsiflex foot so that plantar surface is near perpendicular to IR CR Direct CR to base of third metatarsal to emerge at a level just distal to lateral malleolus. Angle CR 40° cephalad from long axis of foot (which also would be 40° from vertical IR long axis of foot is perpendicular to IR). Evaluation Criteria Anatomy Demonstrated: Entire calcaneus should be visualized from tuberosity posteriorly to talocalcaneal joint anteriorly (Figs. 6.73 and 6.74). Position: No rotation; a portion of the sustentaculum tali should appear in profile medially. With the foot in proper 90° flexion, correct alignment and angulation of CR are evidenced by open talocalcaneal joint space, no distortion of the calcaneal tuberosity, and adequate elongation of the Calcaneus. Collimation to area of interest. Exposure : Optimal density (brightness) and contrast with no motion demonstrate sharp bony margins and trabecular markings and at least faintly visualize talocalcaneal joint without overexposing distal tuberosity area. CALCANEUS:LATERAL—MEDIOLATERAL P ROJECTION Clinical Indications Bony lesions involving calcaneus, talus, and talocalcaneal joint Demonstrate extent and alignment of fractures Technical Factors Minimum SID—40 inches (102 cm) IR size—18 × 24 cm (8 × 10 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in lateral recumbent position, affected side down. Provide a pillow for patient’s head. Flex knee of affected limb about 45°; place opposite leg behind injured limb. Part Position Center calcaneus to CR and to unmasked portion of IR, with long axis of foot parallel to plane of IR (Fig. 6.75). Place support under knee and leg as needed to place plantar surface perpendicular to IR. Position ankle and foot for a true lateral, which places the lateral malleolus about 1 cm posterior to the medial malleolus. Dorsiflex foot so that plantar surface is at right angle to leg. CR CR perpendicular to IR, directed to a point 1 inch (2.5 cm) inferior to medial malleolus Evaluation Criteria Anatomy Demonstrated: Calcaneus is demonstrated in profile with talus and distal tibia- fibula demonstrated superiorly and navicular and open joint space of the calcaneus and cuboid demonstrated distally (Figs. 6.76 and 6.77). Position: No rotation as evidenced by superimposed superior portions of the talus, open talocalcaneal joint, and lateral malleolus superimposed over posterior half of the tibia and talus. Tarsal sinus and calcaneocuboid joint space should appear open. Four-sided collimation should include ankle joint proximally and talonavicular joint and base of fifth metatarsal anteriorly. Exposure : Optimal exposure visualizes some soft tissue and more dense portions of calcaneus and talus. Outline of the distal fibula should be faintly visible through the talus. Trabecular markings appear clear and sharp, indicating no motion  The ankle joint In the formation of the ankle joint participate: 1. The articular surface (superior area) of the talus bone. 2. The articular surface of the tibial lower end. 3. The articular surface of the fibular lower end. 4. Ligaments and extensive synovial membrane.  The joint allows the foot to move freely in several directions. It is of considerable importance in traumatic medicine. The ankle joint is: A pair joint. Mobile. A synovial joint type Hinge joint, consists of: Hyaline cartilage. Capsular ligament. Synovial membrane. Synovial fluid. Muscles and tendons. ANKLE:AP PROJECTION Clinical Indications Bony lesions or diseases involving the ankle joint, distal tibia and Fibula, proximal talus, and proximal fifth metatarsal The lateral portion of the ankle joint space should not appear open on this projection—see AP Mortise Projection. Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 cm (10 × 12 inches),portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in the supine position; place pillow under patient’s head; legs should be fully extended. Part Position Center and align ankle joint to CR and to long axis of portion of IR being exposed. Do not force dorsifexion of the foot; allow it to remain in its natural position. Adjust the foot and ankle for a true AP projection. Ensure that the entire lower leg is not rotated. The intermalleolar line should not be parallel to IR. CR CR perpendicular to IR, directed to a point midway between malleoli Evaluation Criteria Anatomy Demonstrated: Distal one-third of tibia- fibula, lateral and medial malleoli, and talus and proximal half of metatarsals should be demonstrated (Figs. 6.79 and 6.80). Position: Long axis of the leg should be aligned to collimation field and to IR. No rotation if the medial mortise joint is open and the lateral mortise is closed. Some superimposition of the distal fibula by the distal tibia and talus exists. Four-sided collimation should include the distal one-third of the lower leg to the proximal half of the metatarsals. All surrounding soft tissue also should be included. Exposure : Optimal exposure with no motion demonstrates clear bony margins and trabecular markings. Talus must be penetrated enough to demonstrate the cortical margins and trabeculae of the bone. Soft tissue structures also must be visible. ANKLE: AP MORTISE P ROJECTION—15 ° TO 20 ° MEDIAL ROTATION Clinical Indications Evaluation of pathology involving the entire ankle mortise and the proximal fifth metatarsal, a common fracture site. This is a common projection taken during open reduction surgery of the ankle. Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 cm (10 × 12 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in the supine position; place pillow under patient’s head; legs should be fully extended. Part Position Center and align ankle joint to CR and to long axis of portion of IR being exposed. Do not dorsiflex foot; allow foot to remain in natural extended (plantarfexed) position (allows for visualization of base of fifth metatarsal, a common fracture site). Internally rotate entire leg and foot about 15° to 20° until intermalleolar line is parallel to. Place support against foot if needed to prevent motion. CR CR perpendicular to IR, directed midway between malleoli Evaluation Criteria Anatomy Demonstrated: Distal one-third of tibia and fibula,tibial plafond involving the epiphysis if present, lateral and medial malleoli, talus, and proximal half of the metatarsals should be demonstrated. Entire ankle mortise should be open and well visualized (3 to 4 mm space over entire talar surface is normal; an extra 2 mm widening is abnormal) (Figs. 6.82 and 6.83). Position: Proper obliquity for the mortise joint is evidenced by demonstration of open lateral and medial mortise joints with malleoli demonstrated in profile. Only minimal superimposition should exist at distal tibiofibular joint. Collimation to area of interest. Exposure : No motion as demonstrated by sharp bony outlines and trabecular markings. Optimal exposure should demonstrate soft tissue structures and sufficient density (brightness) for talus and distal tibia and fibula. ANKLE :LATERAL—MEDIOLATERAL (OR LATEROMEDIAL) PROJECTION Clinical Indications Projection is useful in the evaluation of fractures, dislocations, and joint effusions associated with other joint pathologies Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 cm (10 × 12 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in the lateral recumbent position, affected side down; provide a pillow for patient’s head; flex knee of affected limb about 45°; place opposite leg behind injured limb to prevent over-rotation. Part Position (Mediolateral Projection) Center and align ankle joint to CR and to long axis of portion of IR being exposed. Place support under knee as needed to place leg and foot in true lateral position. Dorsiflex foot so that plantar surface is at a right angle to leg or as far as patient can tolerate; do not force. (This helps maintain a true lateral position.) CR CR perpendicular to IR, directed to medial malleolus Evaluation Criteria Anatomy Demonstrated: Distal one-third of tibia and fibula with the distal fibula superimposed by the distal tibia, talus, and calcaneus appear in lateral profile. Tuberosity of fifth metatarsal, navicular, and cuboid also are visualized (Figs. 6.89 and 6.90). Position: No rotation is evidenced by distal fibula being superimposed over the posterior half of tibia. Tibiotalar joint is open with uniform joint space. Collimation field should include distal one-third of lower leg, calcaneus, tuberosity of fifth metatarsal, and surrounding soft tissue structures. Collimation to area of interest. Exposure : No motion, as evidenced by sharp bony margins and trabecular patterns. Lateral malleolus should be seen through the distal tibia and talus, and soft tissue must be demonstrated for evaluation of joint effusion. ANKLE : AP STRESS PROJECTIONS Clinical Indications Pathology involving ankle joint separation secondary to ligament tear or rupture Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 cm (10 × 12 inches), portrait Nongrid Shielding Shield radiosensitive tissues outside region of interest. Supply lead gloves and a lead apron for the individual who is applying stress if stress positions are handheld during exposures. Patient Position Place patient in supine position; place pillow under patient’s head; leg should be fully extended, with support under knee. Part Position Center and align ankle joint to CR and to long axis of portion of IR being exposed. Dorsiflex the foot as near the right angle to the lower leg as possible. Stress is applied with leg and ankle in position for a true AP with no rotation, wherein the entire plantar surface is turned medially for inversion and laterally for eversion. CR CR perpendicular to IR, directed to a point midway between malleoli Evaluation Criteria Anatomy Demonstrated and Position: Ankle joint for evaluation of joint separation and ligament tear or rupture is shown. Appearance of joint space may vary greatly depending on the severity of ligament damage. Collimation to area of interest (Figs. 6.93 and 6.94). Exposure : No motion, as evidenced by sharp bony margins and trabecular patterns. Optimal exposure should visualize soft tissue, lateral and medial malleoli, talus, and distal tibia and fibula. The leg ( tibia and fibula) The tibia The tibia is a long bone of Vertical direction, lying medial to fibula and larger than it, and it is composed of a shaft and 2 end. The tibia is the main bone of the lower leg. It expands at its proximal and distal ends; articulating at the knee and ankle joints respectively. The tibia is the second largest bone in the body and it is a key weight-bearing structure.  The upper end A massive bony mass, expanded transversely and consists from 2 condyles (lateral and medial) which have: 1. A circumference: 2 cm wide, on its: Anterior part, tibial tuberosity. Lateral side, an articular facet for fibular head Interrupted posteriorly by the intercondylar area. 2. A superior articular surface, separated in the midline by the intercondylar area, which shows a raised part called the intercondylar eminence (formed of two tubercles). The lower end The inferior surface articulates with the talus at the ankle joint. The medial extension of the lower end is called medial malleilus. The lateral surface of lower end is seen with fibular notch, the place in which fibula articulates with tibia. The shaft Has slight "S" shape: the upper part is convex medially and the lower part convex laterally. It is a triangular shape with 3 surfaces and 3 borders. Surfaces: Medial: smooth and palpable. Lateral : toward the fibula. Posterior : with rough line "soleal line" for soleus Borders: anterior: sharp, and also called tibial crest. The Fibula The Fibula is a long and thin bone of Vertical direction, lying at the lateral side of the leg, composed of a shaft and two end. The upper end It is also called the head of the tibula, it is the expanded position of the bone, and roughly in shape, there is a blunt process called the apex of the head. Thheadis is attached to the shaft by the neck. The lower end It forms the lateral malleolus which is lower than the medial one and it is palpable. It has a rounded depression called the malleolar fossa. The Shaft Is a triangular shape with: 3 surfaces : -lateral -medial (with medial crest). -posterior. 3 borders : -anterior. -posterior. -medial or interosseous. Ossification centers of the leg Each of tibia and fibula has 3 centers one for the shaft and one for each end. The upper tibial center appears before or shortly after birth and fused at the age of 18 years. The lower tibial center appears at a bout the age of 2 years and fused at 18 years old. Upper fibular center appears at 4 years old, and fused at the age of 25 years. Lower fibular center appears at 2 years age and fused at the age of 20 years. LOWER LEG (TIBIA AND FIBULA): AP PROJECTION Clinical Indications Pathologies involving fractures, foreign bodies, or lesions of the bone Technical Factors Minimum SID—40 inches (102 cm); may increase to 44 to 48 inches (112 to 123 cm) to reduce divergence of x-ray beam and to include more of body part IR size—35 × 43 cm (14 × 17 inches), portrait (or diagonal, which requires cc44 inches [112 cm] minimum SID) Nongrid (unless lower leg measures >10 cm) Shielding Shield radiosensitive tissues outside region of interest. Patient Position Place patient in the supine position; provide a pillow for patient’s head; entire leg should be fully extended. Part Position Adjust pelvis, knee, and leg into true AP with no rotation Place sandbag against foot if needed for stabilization, and dorsiflex foot to 90° to lower leg if possible. Ensure that both ankle and knee joints are 1 to 2 inches (3 to 5 cm) from ends of IR (so that divergent rays do not project either joint off IR). If limb is too long, place the lower leg diagonally (corner to corner) on one 35 × 43 cm (14 × 17 inches) IR to ensure that both joints are included. (Also, if needed, a second smaller IR may be taken of the joint farthest from the injury site.) CR CR perpendicular to IR, directed to midpoint of lower leg Evaluation Criteria Anatomy Demonstrated: Entire tibia and fibula must include ankle and knee joints on this projection (or two if needed). The exception is alternative routine on follow-up examinations (Figs. 6.96 and 6.97). Position: No rotation as evidenced by demonstration of femoral and tibial condyles in profile with intercondylar eminence centered within intercondylar fossa. Some overlap of the fibula and tibia is visible at both proximal and distal ends. Collimation to area of interest. Exposure : Correct use of anode heel effect results in an image with nearer equal density at both ends of IR. No motion is present, as evidenced by sharp cortical margins and trabecular patterns. Contrast and density (brightness) should be optimum to visualize soft tissue and bony trabecular markings at both ends of tibia. LOWER LEG (TIBIA AND FIBULA): LATERAL—MEDIOLATERAL PROJECTION: Clinical Indications Localization of lesions and foreign bodies and determination of extent Alignment of fractures demonstrated Technica l Factors Minimum SID—40 inches (100 cm); may increase to 44 to 48 inches (112 to 123 cm) to reduce divergence of x-ray beam and to include more of body part IR size—35 × 43 cm (14 × 17 inches), portrait (or diagonal, which requires 44 inches [112 cm] minimum SID) Nongrid (unless lower leg measures >10 cm) Shielding Shield all radiosensitive tissues outside region of interest. Patient Position Place patient in the lateral recumbent position, injured side down; the opposite leg may be placed behind the affected leg and supported with a pillow or sandbags. Part Position Ensure that leg is in true lateral position (plane of patella should be perpendicular to IR). Ensure that both ankle and knee joints are 1 to 2 inches (3 to5 cm) from ends of IR so that divergent rays do not project either joint off IR. If limb is too long, place the lower leg diagonally (corner to corner) on one 35 × 43 cm (14 × 17inches) IR to ensure that both joints are included. CR CR perpendicular to IR, directed to midpoint of lower leg Evaluation Criteria Anatomy Demonstrated: Entire tibia and fibula must include ankle and knee joints on this projection (or two if needed). Exception is alternative routine on follow-up examinations (Fig. 6.99). Position: True lateral of tibia and fibula without rotation demonstrates tibial tuberosity in profile, a portion of the proximal head of the fibula superimposed by the tibia, and outlines of the distal fibula seen through posterior half of the tibia. Posterior borders of femoral condyles should appear superimposed. Collimation to area of interest. Exposure : No motion is present, as evidenced by sharp cortical margins and trabecular patterns. Correct use of the anode heel effect results in near-equal density at both ends of the image. Contrast and density (brightness) should be optimum to visualize soft tissue and bony trabecular markings  The knee joint In formation of the knee joint, participate the following elements: 1. The articular surface of the femur condyles and trochlea. 2. The articular surfaces of the tibial condyles. 3. The patella. 4. The articular capsule with ligaments and synovial membrane. 5. Medial and lateral menisci (2 semilunar cartilage).  The medial meniscus is connected with the tibial collateral ligament, but the lateral meniscus is separate from the fibular collateral ligment by synovial tissue. The synovial membrane of the the knee joint is extensive, it extends upwards from the upper border of the patella to form a large pouch called ( the supra-patellar bursa), and at the sides it passes downwards, posteriorly is the reflected forwards to cover the cruciate ligaments. The central posterior portion of the fibrous capsula has no synovial covering.  Bursae of the knee joint Around the knee joint there are 3 bursae: 1. The suprapatellar bursa: lies between the lower end of the femur and quadriceps femoris. 2. The prepatellar bursa : lies between the anterior surface of patella and the skin. 3. The infrapatellar bursa : lies between the lower part of the tibial tuberosity and the skin. The knee joint is a mobile joint, type hinge joint. Patella (kneecap) The patella is a large sesamoid bone, situated in the tendon of the femural quadriceps muscle. It has a triangular shape, with a base, apex and 2 bordees and 2 surfaces (anterior and posterior or articular). The base is superior in position and the apex inferior. The borders (lateral and medial) are rounded and well defined.  The patellar base is thick The anterior surface is marked by quadriceps tendon. The posterior surface or the articular surface articulates eith the patellar surface in the lower end of the femur. Ossification of the patellar begins about the third year of life and is completed about the puberty(18 years).  Functions The patella has two main functions: Leg extension – Enhances the leverage that the quadriceps tendon can exert on the femur, increasing the efficiency of the muscle. Protection – Protects the anterior aspect of the knee joint from physical trauma. KNEE:AP PROJECTION Clinical Indications Fractures, lesions, or bony changes related to degenerative joint disease involving the distal femur, proximal tibia and fibula, patella, and knee joint Technical Factors Minimum SID—40 inches (102 cm) IR size—24 × 30 (10 × 12 inches), portrait Grid or Bucky, >10 cm Nongrid, tabletop, 10 cm Nongrid, tabletop,