Shoulder Flashcards
(29 cards)
What is the main cause of RTC injuries in patients under 40yo?
What imaging is gold standard?
trauma injuries
MRI
What does the shoulder girdle consist of?
clavicle, scapula and humerus
What does 1/3 of the humeral head sit in that gives the joint its mobility?
the glenoid fossa
What are the RTC muscles?
Where do 3/4 of these muscles originate and insert?
supraspinatus, infraspinatus, teres minor, subscapularis
originates on posterior scapula, inserts on greater tubercle of humeral head (except subscap)
Why is the supraspinatus the most frequently injured shoulder tendon?
because it runs under the AC joint and under the humeral head (creates friction and pinch points)
The teres minor tendon almost never fails, but why would the muscle be evaluated?
the muscle can be scanned in comparison to the infra to look for evidence of long standing tears
How many muscles and tendons does the subscap have?
4 muscles and 4-6 tendons that insert on the lesser tuberosity of the humeral head
Which head of the biceps cannot be evaluated and why?
Which head is evaluated on every scan and where is it seen?
short head: inserts on coracoid process and isn’t seen
long head: sits in bicipital groove and inserts on the superior glenoid labrum
What is the RTC interval? why is it important to evaluate this area?
separation of subscap by supra by the biceps tendon
can be used to differentiate between pathology of the supra from the subscap
What is the glenoid labrum?
fibrocartilaginous ring lining outer glenoid fossa
- deepens the socket, posterior glenoid labrum is evaluated for fluid
What is another potential space for fluid accumulation in a supra tear?
AC joint
What are bursae?
What is the main bursa in the shoulder (largest in body)?
small thin sacs that contain small amounts of synovial fluid to reduce friction where tendons and muscles cross joint capsules
subacromial-subdeltoid bursa (essentially 2 but evaluated as 1)
What age will patients typically experience RTC failure?
which fail first etc?
over 40yo, incidence increases with age and can be asymptomatic (often incidental findings)
supra, then infra and subscap when the original tear extends
What causes acute tears?
trauma, falls, ruptures or dislocations
What causes chronic tears?
occur as a cumulative progression of an injury from overhead activities that cause microtraumas due to impingement
Where do partial thickness tears typically begin?
usually in the critical zone: found in anterolateral supra tendon, 1cm from insertion on greater tuberosity
may involve articular surface (most common) or bursal surface (2nd)
How does a partial thickness tear appear?
anechoic defect in tendon fibers (acute)
or hyperechoic area due to blood and bursal granulation tissue within the frayed tendon (chronic)
What are secondary indicators of partial thickness tears?
diffuse thickening and bone irregularities
Explain the difference in articular surface tears and bursal surface tears
(appearance and symptom)
1- typically presents as fluid in the biceps tendon sheath
2- tender to palpation
What is a complete tear?
involving full thickness and full width
retraction occurs with a separation of 2-4cm between torn tendon ends
What do full thickness tears demonstrate that partial tears dont?
communication between glenohumeral joint and subacromial bursa, leads to a large amount of fluid in SASD bursa
List the most common to rare tendon tears in the shoulder
supra, infra, subscap, teres
What are some signs that indicate a full thickness tear?
cartilage interface sign: echogenic line on anterior surface of humeral head cartilage
naked tuberosity sign: deltoid muscle in direct contain with humeral head
double effusion sign: fluid in SASD bursa and biceps tendon sheath
also deltoid muscle or SASD bursa herniation into RTC
Explain calcific tendinosis
process that can affect any RTC tendons
calcium aggregates can be solid, paste or liquid
