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Imaging Anatomy of the Wrist

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1 Imaging Anatomy of the Wrist
25 May 2012 Dept. of Diagnostic Radiology UFS M. Pieters Imaging Anatomy of the Wrist

2 The wrist Osseous structures Ligaments Tendons
Neurovascular structures Anatomical variants

3 Osseous structures Trapezoid Hook of Hamate Trapezium Hamate Capitate
Pisiform Triquetrum Scaphoid Lunate Radius Ulna

4 Osseous structures

5 Osseous structures Lateral radiograph obtained in zero-rotation position. Note the position of the pisiform overlying the mid waist of the scaphoid indicates a properly positioned lateral



8 Carpal bone ossification
The capitate ossifies first and the pisiform last But the order and timing of the ossification of the other bones is variable Excluding the pisiform, they ossify in a clockwise direction from capitate to trapezoid as follows: Capitate Hamate Triquetral at 3 years Lunate bone at 5 years Scaphoid, trapezium and trapezoid at 6 years The pisiform ossifies at 11 years of age at 4 months

9 Supernumery bones Be sure not to confuse the lanula with a styloid process fracture


11 Compartments Important because these compartments can point to pathology on arthrography if the ligaments are disrupted. For example: contrast can be injected into the Radiocarpal compartmentand if it spreads into the midcarpal compartment, it can point to fractures etc.


13 Compartments, joints and ligaments
The midcarpal and radiocarpal joint are seperated by interosseous ligaments No communication Complex palmar and dorsal ligaments provide support Arthrogaphy – ideally conducted in 3 stages

14 Ligaments - dorsal

15 Ligaments - volar

16 Osseous structures - joints
• Distal (inferior) radioulnar joint: Pivot joint; ROM: Distal radius rotates around distal ulna • Radiocarpal joint: Ellipsoid joint created by proximal carpal row articulating with distal radius & ulna ROM: Flexion, extension, abduction, adduction, circumduction, no rotation

17 Osseous structures - joints
• Pisotriquetral: Gliding joint created by pisiform and triquetrum; Discretely separate from radiocarpal joint in 10-25%; ROM: Minimal • Midcarpal: Gliding joint created by articulation of proximal & distal carpal rows ROM: Some extension, abduction, minimal rotation

18 Osseous structures - joints
• Intercarpal: Gliding joints created by interface of individual carpal bones ROM: Complex • Carpometacarpal - First CMC (thumb base): Saddle joint, highly mobile; ROM: Flexion, extension, abduction, adduction, circumduction, rotation, opposition - Intermetacarpals 2nd-5th: Gliding joints; ROM: Limited mobility of 2nd & 3rd CMC, increasing mobility of 4th & 5th CMC

19 Arthrography Good evaluation for integrity of scapho-lunate, lunotriquetral ligaments & TFC Limited value for extrinsic ligaments Injections spaced to allow contrast resorption Radiocarpal joint injected first (most likely to document with single injection); If no tear, wait minutes & proceed sequentially with distal radio-ulnar and midcarpal injection Digital subtraction allows dynamic evaluation of ligament status and sequential compartment injection without delay Injectate: Iodinated contrast ( mg I/ml); Volumes: Midcarpal, 4-5 cc; radiocarpal, 2-3 cc; DRU, 1-2 cc; pisotriquetral, 1-2 cc

20 Arthrograms

21 Arthrograms Intact radiocarpal compartment - contrast filling pisotriquetral joint via prestyloid recess. Triangular fibrocartilage distal surface is outlined. Scapholunate & lunotriquetral ligaments are intact, with no evidence of spill into midcarpal joint.

22 Arthrograms

23 Radiographic measurements
Radial tilt The normal distal radius angulation Normal = 16-28’ Abn = fracture likely

24 Radiographic measurements
Lunate overhang: At least 50% of the lunate articular surface should articulate with the radial articular surface

25 Radiographic measurements
Ulnar variance refers to length of distal ulna relative to distal radius Ulnar minus: Ulna> 2 mm shorter than radius Ulnar plus: ulna longer than radius

26 tendons Talk about infection that can tack from the thumb along the flexor retinaculum.

27 Tendons - volar

28 Tendons - dorsal

29 Tendon sheaths - dorsal
Separate tendon sheaths enclose the extensor tendons in compartment 1 - 6

30 Tendon sheaths - volar Volar bursae: Ulnar and radial sheaths Common flexor tendon sheath encases – index, middle, ring and little finger tendons Flexor pollics longs has a separate sheath



33 Tendons - Carpal tunnel
Most important: Talk about what’s inside and what’s outside the carpal tunnel. ALSO adda few MRI Pics

34 Carpal tunnel - margins
Dorsal margin = carpals Volar margin = flexor retinaculum Medial margin = pisiform & hook of the hamate Lateral margin scaphoid & trapezium Proximal margin = radiocarpal joint Distal margin = MC base Contents: Flexor digitorum superficialis Flexor digitorum profundus Median nerve

35 Tendons - Carpal tunnel

36 Guyon canal

37 Guyon canal Margins: Ventral margin = Superficial flexor retinaculum Median margin = Pisiform and Flexor carpi ulnaris Dorsolateral margin = Deep flexor retinaculum Contents: Ulnar artery & vein, Ulnar nerve

38 Tendons – anatomical snuff box

39 Tendons – anatomical snuff box
Margins: Distal radius (proximal margin) Extensor pollicus longus (dorsal margin) Adductor pollicus longus & Extensor pollicus brevis (volar margin) APL & EPB converge just distal to 1st CMC (distal margin) scaphoid, trapezium, 1st CMC & radial styloid (deep margin) Contents: Cephalic vein radial nerve radial artery

40 Triangular fibro-cartiliginous complex
The term "triangular fibrocartilage complex of the wrist" was first coined by Palmer and Werner in 1981,1  Describes the cartilaginous and ligamentous structures that bridge the distal radius and ulna, Provides articulation with the adjacent lunate and triquetrum. Important stabilizer of the distal radioulnar joint Provides important shock absorption to the carpus.

41 TFCC The components of the TFCC include: The articular disc
The dorsal and volar radioulnar ligaments The meniscus homologue The extensor carpi ulnaris tendon sheath The ulnocarpal ligaments

42 TFCC It is the articular disc and the radioulnar ligaments that are the most important to evaluate. Characteristic triangular shape The articular disc may be only 1-2 millimeters thick within its central portion, but the TFC thickens considerably at its dorsal and volar aspects, as well as at the ulnar attachments. The thickened dorsal and volar components are what comprise the dorsal and volar radioulnar ligaments.

43 TFC A 3D depiction of the TFC (arrow) demonstrates its triangular shape and relatively thin central region. Viewed from above, the thickened peripheral components that represent the dorsal and volar radioulnar ligaments (arrows) are readily apparent.

44 Normal tfc A T1-weighted coronal image demonstrates a normal TFC. Normal intermediate signal intensity is evident at the ulnar attachment (arrow). The normal interface with articular cartilage at the radial side is also apparent (arrowhead), and should not be mistaken for a vertical tear.

45 TFCC – vertical tfcc tear

46 TFCC – mri Injuries to the TFCC are a frequent cause of ulnar sided wrist pain. MRI allows accurate pre-treatment evaluation of patients with suspected TFCC pathology Provides excellent characterization of TFCC tears and their associated wrist pathology. Such information is invaluable for the proper management of patients with TFCC tears.

47 Neurovascular structures

48 Neurovascular structures

49 Neurovascular structures

50 Neurovascular structures
Radial artery Origin: Terminal branch of brachial artery Course: Superficial to pronator quadratus Continues dorsally around radial styloid process Passes deep to APL & EPB Across anatomic snuffbox & deep to EPL

51 Neurovascular structures
Radial artery Branches: Palmar carpal branch Superficial palmar branch Main radial artery Dorsal carpal branch Deep palmar arch Small dorsal branch radiocarpal artery

52 Neurovascular structures
Ulnar artery: Course in wrist: Superficial to pronator quadratus Continues between FCU & FDS tendons Branches: Common interosseous Anterior interosseous Posterior interosseous artery Palmar carpal branch Dorsal carpal branch Deep palmar branch Superficial palmar branch

53 Neurovascular structures
Ulnar nerve: Origin: Brachial plexus-medial cord Course in wrist: Radial to FCU, close to ulnar artery At proximal pisiform: Nerve proximal to bifurcation; nerve deep to FCU, ulnar to ulnar artery & veins At distal pisiform: Nerve bifurcates into deep (motor) & superficial (sensory) branches At hook of hamate: Superficial branches volar to hook of hamate & ADM; nerve ulnar to ulnar artery & veins; deep branches are dorsal & ulnar to hook of hamate, deep to abductor digiti minimi, superficial to pisometacarpal ligament

54 Neurovascular structures
Radial nerve Origin: Brachial plexus-posterior cord Course in wrist: Branches into superficial & deep branches in distal forearm - Branches: • Superficial branch passes under brachioradialis tendon into dorsal wrist; divides into lateral branch (supplies radial wrist & thumb skin) & medial branch (supplies mid & ulnar wrist skin); divides to dorsal digital nerves supplying ulnar thumb, index, middle & radial ring fingers • Deep branch enters supinator volarly; exits distally & posteriorly as posterior interosseous nerve; supplies ECRB, supinator, ED, EDM, ECU, EPL, APL & El

55 Nutrient arteries of the scaphoid
In 13% of subjects these enter the scaphoid exclusively in its distal half. Fractures across scaphoid midportion - problematic The blood supply to the proximal portion is cut off Ischaemic necrosis Occurs in 50% of patients with displaced scaphoid fractures

56 Avascular necrosis

57 Vascular supply of the lunate
The large majority of the lunate is covered with articular cartilage, leaving only small areas accessible to nutrient vessels along the dorsal and volar poles. These "bare areas" correspond to ligamentous insertion sites, and thus trauma may result in avulsion injuries to the entering arteries. Internally, the lunate blood supply forms patterns resembling a Y (59%), an I (31%), or an X (10%).

58 Kienbock’s disease Diffusely decreased signal intensity is present within the lunate (arrow). Negative ulnar variance with compensatory thickening of the triangular fibrocartilage (arrowhead) is also present. Diagnosis Kienbock's Disease (avascular necrosis of the lunate).

59 Osteonecrosis of the lunate Negative ulnar variance Kienbock

60 Lateral – lunate osteonecrosis

61 A few anatomical variants
Examples from one study: Hypoplasia of the hook of the hamate bone Anomalous muscles inside the carpal tunnel Unusual location and double branching of the median nerve Aberrant median artery

62 A few anatomical variants
Accessory abductor digiti minimi

63 A few anatomical variants

64 A few anatomical variants

65 A few anatomical variants
Extensor digitorum brevis manus

66 A few anatomical variants

67 Bibliography Diagnostic and Surgical Imaging Anatomy – Muskuloskeletal – Manaster Applied Radiological Anatomy - Butler Anatomy for Diagnostic Imaging 3rd ed – Ryan Variations of the arterial pattern in the upper limb revisited: a morphological and statistical study, with a review of the literature – Rodrigues et al; J. Anat. (2001) 199, pp. 547±566 Accessory Muscles: Anatomy, Symptoms, and Radiologic Evaluation – Sookur et al - RadioGraphics 2008; 28:481–499

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