1. Fractures and dislocations of the carpus
By Gatobu 6A

2. Scope Introduction Anatomy Imaging of carpal bones
Lunate fractures/lunate dislocation
Perilunate dislocation

3. Introduction
Carpus is a complex unit of bony articulations that transfers the forces of the hand to the supporting forearm and upper extremity
Allows wide range of motion in 2 planes
Carpal bones are 8 in number arranged in 2 rows
Main motions
Extension
Flexion
Radial and ulnar deviation
The primary axis of motion resides within the head of carpitate.

4. General, surgical and applied anatomy
Bones and joints
Composed of 8 bones in 2 rows
The 8 bones are influenced by
Shape of distal radius
The distal ulnar
Triangular fibrocartilage complex

5. Anatomy of the Wrist
Carpal bones tightly linked by capsular and interosseous ligaments.
Capsular (extrinsic) ligaments originate from the radius and insert onto the carpus.
Interosseous (intrinsic) ligaments traverse the carpal bones.
The lunate is the key to carpal stability.

6. Extrinsic ligaments
Extrinsic ligaments link the carpal bones to the radius, ulna, and metacarpals.

7. Intrinsic ligaments
The intra-articular intrinsic ligaments connect adjacent carpal bones.

8. Lunate
Connected to both scaphoid and triquetrum by strong interosseous ligaments.
Injury to the scapholunate or lunotriquetral ligaments leads to asynchronous motion of the lunate and leads to dissociative carpal instability.

9. Intercarpal Ligaments
Injury to these ligaments leads to abnormal motion between the two rows, and non-dissociative wrist instability patterns.

10. Neurovascular anatomy
Circulation of the wrist is obtained through the radial, ulnar, and anterior interosseous arteries and the deep palmar arch

11. Neurovascular anatomy
The scaphoid, capitate, and about 20% of all lunates are supplied by a single vessel and thus are at risk for avascular necrosis.
The trapezium, triquetrum, pisiform, and 80% of lunates receive nutrient arteries through two nonarticular surfaces and have consistent intraosseous anastomoses. AVN is therefore rare.
The trapezoid and hamate lack an intraosseous anastomosis and, after fracture, can have avascular fragments.

12. Mechanism of injury
Most common is an axial compression force applied with the wrist in hyperextension
Most common injury is a fall on the outstretched hand
Other mechanisms
Palmer flexion,twisting injuries

13. Mechanism of injury High energy forces
Results in carpal bone fractures or ligamentous disruption of both extrinsic and extrinsic ligaments and perilunate dislocation
Low energy forces results in minor injuries such as sprains

14. Imaging Plain radiographs: multiple views necessary: Anteroposterior
Lateral
Oblique
Clenched-fist AP
Radial and ulnar deviation

15. Imaging
Gilula's lines. A. AP views show three smooth Gilula arcs in a normal wrist. These arcs outline proximal and distal surfaces of the proximal carpal row and the proximal cortical margins of capitate and hamate. B. Arc I is broken, which indicates an abnormal lunotriquetral joint due to a perilunate dislocation. .

16. Imaging Standard scaphoid views detect most carpal injuries
PA x-ray with wrist neutral and in ulnar deviation
elongates scaphoid to better visualize
MRI scans are useful in detecting occult fractures, AVN of the carpal bones, and ligamentous injuries.
Perilunate dislocations are easily missed if the continuity of Gilula's line is not assessed.

17. General Principles of Treatment
Carefully evaluate x-rays for subtle fractures and/or evidence of carpal instability.
Reduce and immobilize scaphoid fractures or perilunate injuries pending definitive treatment.
Diagnose and appropriately treat ligament and bony injuries.

18. Lunate fractures Rare <1% of all carpal fractures
Isolated fractures of lunate often missed

19. Lunate anatomy Sits like a keystone in the proximal row
Well protected in concavity of the lunate fossa of the radius
Vascular supply-proximal carpal arcade dorsally,palmarly
7-26% of lunates have single volar or dorsal blood supply

20. Mechanism of injury Hyperextension injury Others:
repetitive stresses of the wrist
Strenuous push
Avulsion of the dorsal pole( S-L tension)

21. Classification of lunate fractures
Acute fractures are classified in 5 groups:
Frontal fracture of palmer pole
Osteochondral fractures of the proximal articular surface
Frontal fracture of the dorsal pole
Transverse fracture of the body
Trans articular fracture of the body

22. Imaging Plain radiographs Technetium 99m bone scan CT scan
Arthroscopic exam

23. Lunate fractures
MRI

24. Management of lunate fractures
Undisplaced-cast immobilization for 4wks
ORIF
Displaced fractures
Associated carpal instability
Non-union

25. Perilunate dislocation
Triquetral and scaphoid malrotation
Result of a fall on an outstretched, hyperextended hand
Relatively rare
Occurs when the lunate maintains normal position with respect to the distal radius while all other carpal bones are dislocated posteriorly

26. Perilunate dislocation
Very commonly associated with a scaphoid waist fracture
Sometimes ulnar styloid as well
Lunate appears triangular in shape on PA view
Lunate rotates forward slightly on lateral view
In lateral view, all other carpal bones are dislocated posterior with respect to lunate

27. Perilunate dislocation

28. Perilunate dislocation
Represents 2nd of the 4 stages of ligamentous injury around lunate bone resulting from forced hyperextension
They are referred to as lesser arc injuries
The 4 stages of injury are:
Scapholunate dissociation(stage I)
Perilunate dislocation(II)
Midcarpal dislocation(III)
Lunate dislocation(IV)
With increasing hyperextension perilunate dislocation may become a lunate dislocation

29. Mechanism of Injury
Load applied to hand forcing the wrist into extension and ulnar deviation
Severe ligament injury necessary to tear the distal row from the lunate to produce perilunate dislocation

30. Physical Exam Dorsal displacement of the carpus may be seen
Significant swelling common
Evaluate for compartment syndrome
If lunate is dislocated, median nerve symptoms may be present

31. Imaging

32. Imaging
Note lack of “colinearity” among the radius, lunate, and capitate on the lateral x-ray.

33. Imaging
Note loss of normal carpal “arcs” and abnormal widening of the scapholunate interval.
Look for associated fractures “trans-scaphoid” injuries

34. X-ray usually Obvious

35. X-ray may be subtle

36. Initial Treatment
Closed reduction is performed with adequate sedation.
Early surgical reconstruction if swelling allows.
Immediate surgery needed if there are signs of median nerve compromise.
Delayed reconstruction if early intervention is not necessary.

37. Technique of Closed Reduction
Longitudinal traction for minutes
For dorsal perilunate injuries: apply dorsal directed pressure to the lunate volarly while a reduction maneuver is applied to the hand and distal carpal row
Palmar flexion then reduces the capitate into the concavity of the lunate.

38. Closed Reduction and Pinning
Poor results with closed reduction and pinning alone
Very difficult to reduce adequately
wrist needs to be ulnarly deviated to correct scaphoid flexion
radial deviation needed to close S-L gap

39. ORIF with volar and dorsal approaches Procedure of Choice

40. Dorsal Approach
Repair S-L ligament

41. Volar Approach

42. Reduce lunate first- may need to temporary pin to radius

43. Pin Carpus: S-L, L-T and mid-carpal joints

44. Trans-scaphoid Perilunate Injuries
Require reduction and fixation of the fractured scaphoid.
Most of these injuries best treated
ORIF with volar and dorsal approaches
repair of injured structures.
Open repair supplemented by pin and screw fixation.

45. Fix scaphoid first: dorsal approach

46. Pin L-T and Mid-carpal joints

47. Make sure Radius-Lunate-Capitate are colinear and S-L angle restored

48. Perilunate Injuries Conclusion
Perilunate fracture dislocations are high-energy injuries
Must recognize different injury patterns
transcaphoid
pure ligamentous
trans radial-styloid
Early open and anatomic fixation with volar and dorsal approaches provides the best chance at a reasonable functional result

49. Perilunate dislocation conclusion
Median nerve dysfunction- 16% of the patients
16-25% of perilunate dislocations are missed initially

50. Lunate dislocation
Most severe of carpal instabilities Most frequently dislocated carpal bone
Most commonly associated with a trans-scaphoid fracture
Involves all the intercarpal joints and disruption of most of  the major carpal ligaments
Produces volar dislocation and forward rotation of lunate Concave distal surface of lunate comes to face anteriorly

51. Lunate dislocation Capitate drops into space vacated by lunate
Results in dislocation of other carpal bones
Capitate and all other carpal bones lie posterior to lunate on lateral radiograph
Triangular appearance of lunate on frontal projection  (piece of pie sign)
Spilled tea cup sign (lateral view)

52. Lunate dislocation

53. Lunate dislocation

54. Dislocated Lunate s/s tenderness Swelling ROM painful & limited
May compress median nerve

55. Lunate dislocation
Dislocation usually occurs in two steps – 1st the ligaments are torn and then the bone dislocates
+ Murphy’s sign
Murphy’s Sign – pt makes a fist.
Indication – lunate dislocation

56. Lunate dislocation-imaging

57. comparison

58. Other imaging modalities
CT scan
MRI

59. Treatment
Closed reduction at A/E
ORIF

60. Complications Wrist arthritis Persistent pain Joint instability
Recovery takes at least 6months

61. Thank you