MSK Flashcards
LS
1
Q
What is the biceps anchor?
A
origin of the long head of the biceps tendon at the superior labrum
2
Q
What is the rotator interval?
A
space between the supraspinatus tendon and subscapularis tendon, seen well on sag oblique
3
Q
When does the magic angle phenomenon occur?
A
when collagen fibers are oriented at about 55 deg to the constant magnetic induction field (results in intermediate signal on short TE sequences such as T1, PD, and GR (T2*) images
4
Q
What and where is the critical zone?
A
hypovascular region of the tendon where magic angle phenomenon commonly occurs in the shoulder - about 1 cm proximal to the insertion of the supraspinatus tendon
5
Q
Where is the critical zone?
A
1-1.5 cm proximal to the tendon insertion. Tears at this location are not as common as previously believed.
6
Q
How do we differentiate magic angle from an abnormal tendon?
A
Use long TE sequences, such as T2. Signal changes in magic angle are not assoc w/ thinning, thickening, or irregularity of the tendon.
7
Q
Other causes of increased signal in normal supra tendon besides magic angle?
A
-connective tissue b/n tendon fascicles
8
Q
Causes of shoulder impingement syndrome
A
- abnormal config of the anterior acromion / acromial shape of type III: inferiorly projecting hook
9
Q
Causes of shoulder impingement syndrome
A
- anterior downsloping of the acromion (sag) - can be eval on sag and cor oblique - anterior acromion is more caudal than posterior acromion
10
Q
Causes of shoulder impingement syndrome
A
- low-lying acromion (coronal)
11
Q
Causes of shoulder impingement syndrome
A
- inferolateral tilt/slope of the acromion (coronal) - most lateral portion of acromion is tilted inferiorly relative to the clavicle
12
Q
Causes of shoulder impingement syndrome
A
- os acromiale
13
Q
Causes of shoulder impingement syndrome
A
- AC DJD
14
Q
Causes of shoulder impingement syndrome
A
- thick coracoacromial ligament - has never been shown to be related to impingement
15
Q
Causes of shoulder impingement syndrome
A
- post-traumatic osseous deformity
16
Q
Causes of shoulder impingement syndrome
A
- instability
17
Q
Causes of shoulder impingement syndrome
A
- muscle overdevelopment - weightlifters, swimmers, and other athlethes - deformity of superior surface of supraspinatus muscle caused by AC joint may be the only abnormality
18
Q
3 predominant shapes of the acromion based on scapular Y-view radiographs by Bigliani and colleagues
A
type I - flat undersurface
19
Q
Which acromion types were thought to have an increased incidence of cuff pathology?
A
type II and III (not borne out in practice -> acromion type no longer considered important in relation to cuff pathology)
20
Q
Up to what age does the os acromiale normally fuse?
A
25 yo
21
Q
On what view is the os acromiale best idenfitied?
A
axial
22
Q
On what MR images are biceps tendon subluxation and dislocation shown best?
A
axial
23
Q
Tears of the subscapularis tendon are best evaluated on what MR images?
A
axial or sag
24
Q
Where is Hill-Sachs defect seen best?
A
2 most superior axial images (below coracoid process, posterior flatting of humerus is normal)
25
Bankart fracture?
axial and sag
26
What is the sensi and speci for fill-thickness rotator cuff tears by MRI?
>90%
27
Acute tears of the long head of the biceps unrelated to impingement generally occur where?
distally, near the musculotendinous junction
28
What does GIRD mean?
glenohumeral internal rotational deficit aka posterosuperior impingement
29
What causes subcoracoid impingement?
narrowing of the space between tip of coracoid process and the humerus - may be congenital or due to coracoid fracture or surgery
30
Where is atrophy usually localized in the subscapularis, which may be an accessory sign for tear?
cranial aspect
31
What are the borders or margins of the rotator interval?
anterior: coracohumeral ligament, superior glenohumeral ligament, and capsule
32
What are the borders or margins of the rotator interval?
superior: supraspinatus tendon
33
What are the borders or margins of the rotator interval?
inferior: subscapularis tendon
34
What are the borders or margins of the rotator interval?
medial: coracoid process - base of the triangle
35
What are the borders or margins of the rotator interval?
lateral: transverse humeral ligament - apex - roof of bicipital groove
36
Causes of rotator interval tears?
anterior glenohumeral dislocations or glenohumeral instability, or surgical defect from arthro
37
What are the different types of instabilities?
1. anterior (nearly 95%)
38
What are the different types of instabilities?
2. posterior
39
What are the different types of instabilities?
3. multidirectional
40
What are the different types of instabilities?
4. superior - generally is assoc w/ multidirectional
41
Which of the types of instabilities account for most of the other 5%?
Posterior and multidirectional
42
What is glenoid dysplasia?
congenital deficiency of the depth and radius of curvature of the glenoid fossa - may predispose to instability; increased incidence of posterior labral tears or detachments because of absence of the bony posterior lip of inferior glenoid, w/c is replaced by labral tissue that is easily injured
43
Where does the joint capsule attach laterally? medially?
laterally on the anatomic neck of the humerus; medially, usually to the labrum or to the adjacent periosteum of the glenoid; *posterior capsule attaches directly on the posterior glenoid labrum
44
3 types of anterior capsule insertions
type I - medial attachment on or very near the labrum
45
3 glenohumeral ligaments
1. superior - level of the body of the coracoid process; prevents inferior displacement of humerus when abducted
46
4 glenohumeral ligaments
2. middle - lies deep to suscap tendon and adj to the anterior labrum (can mimic torn labral fragment); contributes to anterior stability
47
5 glenohumeral ligaments
3. inferior - main stabilizing ligament of the shoulder
48
What are the normal variants of the labrum?
-sublabral recess - presence of synovial recess/sulcus interposed between glenoid rim and labrum; undercutting of articular cartilage between the labrum and glenoid cortex; undercutting of the normal redundancy of the superior labrum (mimic superior labral tear)
49
What are the normal variants of the labrum?
-sublabral foramen - labral detachment from the glenoid / detached anterosuperior labrum; labrum attaches to the glenoid at the mid-portion (vs avulsed labrum - will not reattach at this point)
50
What are the normal variants of the labrum?
-Buford complex - congenital absence of the anterosuperior labrum; assoc w/ markedly thickened middle glenohumeral ligament
51
What are the normal variants of the labrum?
*Detachment of the labrum from the glenoid at any site other than the superior or anterosuperior glenoid is a true abnormality.
52
What are the glenoid labral tears w/ underlying instability?
Bankart and ALPSA
53
What are the noninstability labral lesions?
SLAP, labral cysts, and GLAD
54
4 types of SLAP lesions
type I - fraying of the free edge of the superior glenoid labrum
55
5 types of SLAP lesions
type II - detachment of superior labrum from the glenoid
56
6 types of SLAP lesions
type III - bucket-handle tear of the superior labrum w/o involvement of long head
57
7 types of SLAP lesions
type IV - bucket-handle tear of the labrum extending into the long head
58
Intermediate signal in the tendon after rotator cuff surgery may represent what?
degen, postop granulation tissue, or partial tear
59
When are rotator cuff tears massive?
when there are tears of >1 of the rotator cuff tendons
60
What is the superior and anterior border of the subcoracoid bursa?
coracoid process and the attached combined tendon of the short head of the biceps and the coracobrachialis
61
As the suprascapular nerve courses through the suprascapular notch, it provides motor innervation to what muscles?
supra and infra
62
As the suprascapular nerve extends distally into the spinoglenoid notch, it provides motor innervation to?
infra only
63
What nerve and artery run through the quadrilateral space?
axillary nerve (teres minor atrophy), posterior humeral circumflex artery
64
Borders of the quadrilateral space?
lateral: humerus
65
Borders of the quadrilateral space?
medial: long head of the triceps
66
Borders of the quadrilateral space?
superior: teres minor
67
Borders of the quadrilateral space?
inferior: teres major
68
Where are the pain and paresthesias felt in quadrilateral space syndrome?
lateral aspect of the shoulder and the posterosuperior region of the arm
69
What are the nerves that have been reported to be involved in Pasonage-Turner?
suprascapular - supra and infra
70
What are the nerves that have been reported to be involved in Pasonage-Turner?
axillary - teres minor and deltoid
71
What are the nerves that have been reported to be involved in Pasonage-Turner?
subscapular - subscapularis
72
What are the nerves that have been reported to be involved in Pasonage-Turner?
long thoracic - serratus anterior
73
What is post-traumatic osteolysis of the clavicle?
bone resorption of the distal end of the clavicle after a single episode of severe trauma, or it may occur from repetitive trauma
74
How are facet joints classified according to mobility?
diarthrodial / freely movable
75
How are cartilaginous articulations formed by the intervertebral disks classified according to mobility?
amphiarthrodial / minimally movable
76
What are the inner and outer portions of the annulus fibrosus made of?
inner - fibrocartilage; outer - concentrically oriented lamellae of collagen fibers
77
T/F? Distinction between the nucleus pulposus and inner annulus fibrosus is best done by MRI.
FALSE
78
T/F? Diffuse extension beyond the margins by 1-2 mm may occur in some histologically normal disks.
TRUE
79
T/F? Posterior margins of disks tend to be mildly concave in the upper lumbar spine, straight at the L4-L5 level, and slightly convex at the LS junction.
TRUE
80
Among the 3 types of annular tears, which is the only type of practical interest?
radial
81
What level do radial tears usually occur?
L4-5 and L5-S1
82
How do annular tears appear on contrast T1?
high signal
83
-mild?
anterior epidural fat is not obliterated
84
-moderate?
epidural fat is obliterated and thecal sac is displaced
85
-severe?
cord is being effaced or nerve roots displaced
86
What is a conjoined nerve?
2 nerve roots exiting the thecal sac at the same location. (They can be seen within dilated CSF space, and the lateral recess on the side of the conjoined nerve root is enlarged, indicating that this is a long-standing process)
87
What are the Modic types?
type 1 - inflammatory tissue --- low high enhance
88
What are the Modic types?
type 2 - focal conversion to fat --- high iso to high
89
What are the Modic types?
type 3 - sclerosis low ---- t1 low t2
90
Expected postop changes
-no marrow enhancement (unless Modic 1 changes are present)
91
Expected postop changes
-nerve roots - may enhance for 6 months
92
Expected postop changes
-epidural - peripheral enhancement of fibrosis (may mimic extrusion) in first 6 months; diffuse enhancement after 6 months; enhancement of fibrosis for years
93
Expected postop changes
-disks - enhancement of posterior annulus and increased T2 signal for years - as a result of curettage
94
Expected postop changes
-mass effect from scarring at the operated disk level may take months to resolve and may never resolve
95
What is a pseudomeningocele?
defect in the dura w/ a leak of spinal fluid
96
What are complications of spinal surgery?
a) spondylodiskitis and epidural abscess
97
What are complications of spinal surgery?
b) epidural hematoma
98
What are complications of spinal surgery?
c) failure of fusion of bone graft material
99
What are complications of spinal surgery?
d) arachnoiditis
100
What are complications of spinal surgery?
e) defect in the dural sac that creates a pseudomeningocele
101
Besides the enhancement, what are other signs that may hep distinguish epidural fibrosis from a disk abnormality?
may not be contiguous w/ the adjacent disk; instead of producing a mass effect on the dural sac, it may cause retraction
102
Infections of the spine generally occurs from?
hematogeneous spread of Staph aureus from a distant site
103
In adults, what is usually affected first in spondylodiskitis?
marrow in the region of a vertebral body end plate (osteomyelitis or spondylitis)
104
In children, what is usually affected first in spondylodiskitis?
disk - disks in children are more vascular
105
What consist the triad of MRI findings in spondylodiskitis?
1. low T1 in the marrow of adjacent vertebral bodies
106
What consist the triad of MRI findings in spondylodiskitis?
2. enhancement of marrow, and possibly of the disk if an abscess has not formed
107
What consist the triad of MRI findings in spondylodiskitis?
3. high T2 disk signal
