Radiography of the lower limb

1. Part I
Radiography of Lower Limb

2. Lower Limb
 Foot
 Leg – tibia & fibula
 Femur (distal and mid)

3. Foot
 Divided into three groups
1. Phalanges (toes/or digits) 14
2. Metatarsals (instep) 5
3. Tarsals 7
Total 26

4. Phalanges – Toes (Digits) and
Metatarsals

5. Joints

6. Tarsals
1. Calcaneus (os calcis)
2. Talus (astragalus)
3. Cuboid
4. Navicular (scaphoid)
5. 1st, 2nd, and 3rd cuneiforms

7. Calcaneus (Os Calcis)
 The largest and strongest bone in the
foot
 The posterior portion often called the
heel bone
 Inferoposteriorly it has a rough striated
process called tuberosity
 Tuberosity has two small rounded
processes at its widest points called the
lateral process (smallest) and medial
process (largest)

8. Calcaneus (Os Calcis)
 Articulations
 Articulate with two bones
 The cuboid anteriorly
 The talus superiorly
 Forms the subtalar (talocalcaneal) joint
 Three articulation facets
o Posterior articular facet (largest)
o Middle articular facet: it is the upper
portion of the sustentaculum tali
o Anterior articulation facet
 Calncaneal sulcus: a deep depression
b/w posterior and middle articular facets
which forms the sinus tarsi (tarsal
sinus) when combined with similar
depression of the talus

9. Talus (Astragalus)
 2nd largest tarsal bone
 Articulations
 Articulates with four bones
 Tibia and fibula superiorly
 Calcaneus inferiorly
 Navicular anrteriorly

10. Navicular (Scaphoid)
 Flattened oval-shaped
 Articulations
 Articulates with four bones
 Talus posteriorly
 Three cuneiforms anteriorly

11. Cuneiforms
 Wedge-shaped
 Three bones
1. Medial: largest
2. Intermediate: smallest
3. Lateral
 Articulations
 Medial cuneiform
 Articulated with four bones: navicualr
proximally; 1st and 2nd metatarsals distally;
Intermediate cuneiform laterally
 Intermediate cuneiform
 Articulates with four bones: avicular
proximally; 2nd metatarsal distally; medial
and lateral cuneiforms on each side
 Lateral cuneiform
 Articulates with six bones: navicular
proximally; 2nd, 3rd, and 4th metatarsals
distally; intermediate cunefirom medially;
cuboid laterally

12. Cuboid
 Articulations
 Articulates with four bones
 Calcaneus proximally
 Lateral cuneiform and navicular
(occasionally) medially
 Fourth and fifth metatarsals distally

13. Arches
 Two arches to provide a strong,
shock-absorbing support for body
weight
1. Longitudinal arch
 Springy
 Composes
 Medial component: cal., tal., nav., 1st
cun., and 1st MT
 Lateral component: cal., tal., and
cub.
 Most of the arch on the medial and
midaspects of the foot
2. Transverse arch
 Located primarily along the plantar
surface of the distal tarsals and the

14. Ankle Joint
 Formed by three bones: tibia, fibula, and talus
 Frontal view
 The inferior portions of the tibia and fibula
form a deep “socket” or thee-sided opening
called a mortise into which the upper talus
fits
 The entire three-part joint space of the ankle
mortise is not seen in a true AP projection b/c
of the overlapping of portions of the distal
fibula and tibia by talus. This caused by the
more posterior position of the distal fibula
 A 15o internally rotated AP projection, called
mortise position, is used to visualize this
mortise joint that should have an even space
over the entire talar surface
 The distal tibial surface forming the roof of
the ankle mortise joint is called the tibial
plafond (ceiling) (potential site of fx)

15. Ankle Joint
 Lateral view
 True lateral view shows that
the lateral malleolus is ~1 cm
posterior in relationship to the
medial malleolus

16. Ankle Joint
Axial view

17. Exercise
A
B
C
D

18. Leg – Tibia and Fibula

19. Femur (Distal and Mid)
 Anterior view

20. Femur (Distal and Mid)
 Posterior view

21. Femur (Distal and Mid)
 Lateral view

22. Femur (Distal and Mid)
 Axial view

23. Patella

24. Knee Joint
 Major knee ligaments

25. Knee Joint
 Menisci (articular disks)

26. Exercise
A B
C D
E
F

27. Radiographic Positioning
 Positioning considerations
 Radiographic examinations of lower limb below the
knee are generally done on a tabletop
 Distance = 100 cm
 Gonadal shielding
 Use lead vinyl-covered shield
 Shift the unused Bucky tray away from the field of x-ray to avoid
scattering
 Collimation
 Collimation borders should be visible on all four sides if the IR is
large enough too allow this without cutting off essential anatomy

28. Positioning Considerations
 General positioning
 Always place the long axis of the part being
radiographed // to the long axis of the IR
 If more than on projection is taken on the same
IR, the part should be // to the long axis of the
part of the IR being used
 All body parts should be oriented in the same
direction
 Exception: for leg radiograph in adults, the limb
should be oriented diagonally to include knee
and ankle joints
 Correct centering
 In general, the par t being radiographed should
be // to the plane of the IR
o

29. Positioning Considerations
 Exposure factors
 Lower-to-medium kV (50-70)
 Short exposure time
 Small FS
 Adequate mAs for sufficient density
 Optional technique for foot: an increase to 70-75 kV with
accompanying decrease in mAs will decrease contrast to result in a
more uniform exposure density b/w the phalanges and the tarsals
 Imaging receptors
 Detail screen in used with or without grid depending on part
thickness

30. Positioning Considerations
 Pediatric patients
 Patient motion should be restricted
 Use immobilization device such as sponge, tape, or sand bags
 Ask family for help  ensure protection for help
 Speak to child in a soothing manner and with language the child can
readily understand to ensure maximal cooperation
 Geriatric patients
 Provide clear and complete instructions
 Routine examination might be altered to accommodate the older
patient’s physical condition
 Use adequate immobilization device
 Exposure factors may need to be reduced

31. Positioning Considerations
 Placing of markers and patient ID information
 Always place it in the location least likely to
superimpose anatomy of interest for that projection
 Increase exposure with cast
TYPE OF CAST INCREASE IN EXPOSURE
Small to medium plaster cast Increase mAs 50%-60% or +5-7 kV
Large plaster cast Increase mAs 100% or +8-10 kV
Fiberglass cast Increase mAs 25%-30% or +3-4 kV

32. Positioning Considerations
 Digital imaging considerations:
1. Collimation: insures optimal quality
2. 30% rule: at least 30% of the IP should be exposed to ensure accurate exposure
index (or “S” number)
3. Lead masking: for multiple projections
4. Accurate centering: as in the FSR
5. Grid use with DR: acceptable
6. Evaluation of exposure index value: to verify that the exposure factors used were
in the correct range to ensure an optimum quality image with the least possible
radiation dose to the patient
7. Exposure factors:
 Wide exposure latitude
 Consider the ALARA principle: use highest possible kVp with lowest possible mAs
 Generally 60 kVp is the lowest factor used for any CR or DR procedures

33. Pathologic Indications
1. Bone cyst
 Benign neoplastic bone lesion filled
with clear fluid
 Most often occur near the knee joint
in children and adolescents
 Generally not detected on
radiographs until a pathologic fx
occurs
 When detected on radiograph they
appear as lucent areas with a thin
cortex and sharp boundaries
 Most common radiographic exam: AP
& lateral of affected limb
 Possible radiographic appearance:
well-circumscribed lucency

34. Pathologic Indications – cont’d
2. Chondromalacia patellae (runner’s
knee)
 Softening of the cartilage under the
patella → wearing of cartilage, pain, and
tenderness
 Cyclists and runners are vulnerable to
this condition
 Most common radiographic exam: AP &
lateral knee, tangential (axial) of
femoropatellar joint
 Possible radiographic appearance:
pathology of femoropatellar joint space,
possible misalignment of patella

35. Pathologic Indications – cont’d
3. Chondrosarcomas
 Most common radiographic exam: AP & lateral of affected limb, CT, MRI
 Possible radiographic appearance: bone destruction with calcification in the cartilaginous
tumor
4. Encondromas:
 Most common radiographic exam: AP & lateral of affected limb
 Possible radiographic appearance: well-defined radiolucent tumor with thin cortex (often
result in pathologic fx with minimal trauma)
5. Ewing’s sarcoma
 Most common radiographic exam: AP & lateral of affected limb, CT, MRI
 Possible radiographic appearance: ill-defined are of bone destruction with surrounding
“onion peel” (layers of periosteal reaction)
6. Exostosis (osteochondroma)
 Most common radiographic exam: AP & lateral of affected limb
 Possible radiographic appearance: a projection of bone with cartilaginous cap; grows //
to shaft and away from nearest joint
7. Fractures

36. Pathologic Indications – cont’d
8. Gout
 Form of arthritis that my be hereditary
 Uric acid appears in excessive quantities in
the blood and may be deposited in the joints
and other tissues
 Common initial attacks occur in the 1st MTPJ
of the foot
 Later attacks may also occur in other joints
such as the 1st MCPJ of the hand, but
generally these are not seen
radiographically until more advanced
conditions develop
 Most cases occur in men, and first attacks
rarely occur before age 30
 Most common radiographic exam: AP (obl.)
& lateral of affected part (most common
initially in MTPJ of foot)
 Possible radiographic appearance: uric acid

37. Pathologic Indications – cont’d
9. Joint effusion
10. Multiple myeloma
 Most common radiographic exam: AP & lateral
of affected part
 Possible radiographic appearance: multiple
“punched-out” osteolyte lesions throughout
affected bone
11. Osgood Schlatter disease
 Inflammation of the bone and cartilage involving
the anterior proximal tibia
 Most common in boys ages 10-15
 Cause: an injury that occurs when the large
patellar tendon detaches part of the tibial
tuberosity to which it is attached
 Most common radiographic exam: AP & lateral

38. Pathologic Indications – cont’d
12. Osteoarthritis
 Most common radiographic exam: AP, obl. &
lateral of affected part
 Possible radiographic appearance:
narrowed, irregular joint spaces with
sclerotic articular surfaces and spurs
 Exposure factor adjustment: advanced stage
may require slight decrease (-)
13. Osteoclastomas (giant cell tumors)
 Benign bone lesions
 Occur in long bones of young adults
 Usually occur in the proximal tibia or distal
femur after epiphyseal closure
 Most common radiographic exam: AP &
lateral of affected part, CT, MRI
 Possible radiographic appearance: large

39. Pathologic Indications – cont’d
14. Osteogenic sarcomas (osteosracomas)
 Most common radiographic exam: AP & lateral
of affected part, CT, MRI
 Possible radiographic appearance: excessively
destructive lesion with irregular periosteal
reaction; classic appearance is sunburst pattern
that is diffuse periosteal reaction
15. Osteoid osteomas
 Benign bone lesions
 Usually occurs in teenagers or young adults
 Symptoms include localized pain that typically
worsens at knight but is relieved by over-the-
counter anti-inflammatory or pain medications
 The tibia and the femur are the most likely sites
of these lesions
 Most common radiographic exam: AP & lateral
of affected part
 Possible radiographic appearance: small,
round-oval density with lucent center

40. Pathologic Indications – cont’d
16. Osteomalacia (rickets)
 Means bone softening
 Caused by lack of bone mineralization b/c of the deficiency
in calcium, phosphorous, and/or vit. D in the diet or an
inability to absorb these minerals
 Bowing of the weight-bearing parts often results
 In children, this defect is known as rickets and more
commonly results in bowing of the tibia
 Most common radiographic exam: AP & lateral of affected
limb
 Possible radiographic appearance: decreased bone
density, bowing deformity in weight-bearing limbs
 Exposure factor adjustment: loss of bone matrix requires
decrease (-)
17. Paget’s disease (osteitis deformas)
 Most common radiographic exam: AP & lateral of affected
part/s
 Possible radiographic appearance: mixed areas of
sclerotic and cortical thickening and lytic or radiolucent

41. Pathologic Indications – cont’d
18. Reiter syndrome
 Affects the sacroiliac joint and lower
limbs of the young men
 Includes bilateral attack, arthritis,
urithritis, and conjunctivitis
 Caused by a previous infection of the
GIT, such as salmonella, or by a
sexually transmitted infection
 Most common radiographic exam: AP
& lateral of affected part
 Radiographic appearance: specific
area of bony erosion at the Achilles
tendon insertion on the
posterosupoerior margins of the