Radiology of the Foot

1. Radiology of the Foot Mark Wahba X-Ray rounds July 24th, 2003

2. Goals • Approach to radiography of the foot • Become familiar with a Lisfranc injury • Become familiar with a Jones fracture

3. Outline • Bones • Views • Important Points • Lisfranc Joint • Jones fracture • Films

4. The foot • 28 bones • 57 articulations

5. 3 anatomic and functional regions • Hindfoot: talus, calcaneus • Midfoot: navicular, cuboid, cuneiforms • Forefoot: metatarsals, phalanges, sesamoids

6. Bones

7. Bones

8. Accessory Ossification Centres • Normal • 30% of population • Smooth corticated surfaces

9. Adequate views • Anterior-Posterior • Oblique • Lateral

10. AP

11. AP view • Medial margin of the base of the 2nd metatarsal is in line with the medial margin of the middle cuneiform • Base of the 3rd metatarsal is obscured • View 1st and 2nd MT, medial and middle cuneiform

12. AP alignment

13. Oblique

14. Oblique view • Medial margin of the base of the 3rd metatarsal should be in line with the medial margin of the lateral cuneiform • Base of the 2nd metatarsal is obscured • View 3,4,5 MT, lateral cunieform, navicular, cuboid

15. Oblique alignment

16. Lateral

17. Lateral • Hindfoot • Soft tissues • View articulations: CalCub, TN, NCun

19. Bohler’s Angle • Draw a line from the posterior aspect of the calcaneum to its highest midpoint • Draw a line from the anterior aspect of the calcaneum to its highest midpoint • Measured angle is from 20-40 degrees

20. Bohler’s Angle

21. Jacques Lisfranc

22. Lisfranc Joint • named for Jacques Lisfranc (1790-1847), a field surgeon in Napoleon's army • “described an amputation performed through this joint because of gangrene that developed after an injury incurred when a soldier fell off a horse with his foot caught in the stirrup” • refers to the articulation involving the first and second metatarsals with the medial and middle cuneiforms

24. Any injury to this area, whether dislocation or fracture-dislocation, is termed a Lisfranc injury • Initially missed 20% of the time • high risk of chronic pain and functional disability if they go unrecognized

26. Presentation • Hx of Direct trauma • Hx of Indirect trauma: “force is transmitted to the stationary foot so that the weight of the body becomes a deforming force by torque, rotation or compression” • Pain in midfoot • Inability to weight bear, especially on toes • Lisfranc Injury of the Foot: A Commonly Missed Diagnosis, BURROUGHS et al., American Family Physician, July 1998, 58 no. 1 ,p.118

27. Why? • “While transverse ligaments connect the bases of the lateral four metatarsals, no ligament exists between the first and second metatarsal bases.  The joint capsule and dorsal ligaments form the only minimal support about the Lisfranc joint, creating a "weak link" that is prone to injury.” • http://emedhome.com/case-archivedata.cfm?ID=case120701

28. Almost invariably involve metatarsal fractures • Usually the 2nd metatarsal • # cuboid, cuneiform, navicular occur in 39% • Weight bearing views are useful

29. Signs of a Lisfranc injury • The medial shaft of the 2nd metatarsal should be aligned with the medial aspect of the middle cuneiform on the AP view. • The medial shaft of the 3rd metatarsal should be aligned with the medial aspect of the lateral cuneiform on the oblique view. • The first metatarsal cuneiform articulation should have no incongruency. • The presence of small avulsed fragments ("fleck sign")should be sought in the medial cuneiform-second metatarsal space. • The naviculocuneiform articulation should be evaluated for subluxation. • Should be no "step-off" as each metatarsal shaft should never be more dorsal than its respective tarsal bone • http://emedhome.com/case-archivedata.cfm?ID=case120701

30. AP

31. AP

32. Oblique view

33. Oblique view

34. lateral

35. lateral

36. Jones Fracture

37. Jones Fracture • “Sir Robert Jones described his own fracture of the fifth metatarsal in 1902, when he injured himself while dancing around a Maypole at a military garden party” • # at base of 5th metatarsal at metaphyseal-diaphyseal junction

39. w/in 1.5 cm distal to tuberosity of 5th metatarsal • Should not be confused w/ more common avulsion # of 5th metatarsal tuberosity • An oblique radiograph is essential to accurately assess this fracture

40. trauma site corresponds to the area between the insertion of the peroneus brevis and tertius tendons • peroneus tertius originates on anterior aspect of fibula • injury occurs when the ankle is plantar flexed and a strong adduction force is applied to the forefoot

42. Jones fracture

44. Ortho follow up • NWB cast 6-8 weeks • Notorious for nonunion and needing ORIF b/c of low vascularization and high stresses at this site

45. 5th metatarsal avulsion #

46. aka Dancer’s Fracture • Conservative treatment 4-6 wks • Cast, brace, crutches, wooden soled shoe

47. Thought to occur due to stress on the plantar aponeurosis causing an avulsion • Fractures of the Fifth Metatarsal Yu W. D. et al, THE PHYSICIAN AND SPORTSMEDICINE - VOL 26 - NO. 2 - FEBRUARY 98

48. Apophysis of 5th metatarsal • “bony outgrowth that has never been entirely separated from the bone of which it forms a part” • Found in the skeletally immature

49. Stress fracture • a stress phenomenon at the metaphyseal-diaphyseal junction • “severe intramedullary sclerosis, profound thickening of both the medial and lateral cortices, lucency in the lateral cortex”

50. Treat conservatively or operatively depending on activity level