Shoulder Flashcards

Question

What muscles are involved in forward elevation?

Answer 1

Supraspinatus and deltoid

Answer 2

Infraspinatus, teres minor and subscapularis

Answer 3

Agonist: supraspinatus, trapezius Syngergist: deltoid

Answer 4

-Lat dorsi, pec major

Answer 5

Deltoid, pec major, biceps, pec major

Answer 6

-Lat dorsi, deltoid and pec major

Answer 7

- If shoulder becomes unstable, it can do so in several ways that are summarised by the Stanmore triangle - It defines 3 polar types of instability Type 1 (traumatic structural instability): - traumatic structural instability - this is where trauma damages the joint architecture, leading to excessive translation of humeral head within glenoid - a force pushes the humeral head in one direction (usually anteriorly) and the glenoid labrum is torn off - the humeral head then dislocates and knocks into the edge of the glenoid - Since humeral head is soft and glenoid is hard, it often results in a compression fracture of humeral head called a Hills-Sachs lesion - If you sustain traumatic dislocation once, it’s likely you will have a detached labrum because the avascular nature of cartilage nature means it’s bad at healing itself - There will be lack of congruency - On MRI we can see detached labrum which will affect ligaments and capsule - The overall result is that structures of the shoulder are now loose and less effective at keeping humeral head centred - This means that the next time the shoulder takes a hit, the proprioceptive information is sent to the brain but before the brain can send a signal back to the brain to re-centre the humeral head, it dislocates as there’s nothing passive to stop it popping out - This will keep occurring unless the labrum is reattached Type 2 (atraumatic structural): - atraumatic structural instability - This is hypermobility due to lax labrum and capsule - The humeral head can translate a lot more than normal, as a result, it can potentially dislocate - If it doesn’t dislocate, it will have a feeling of instability Type 3 (muscle patterning): - Proprioceptive issues and defective muscle patterning - These people are often known as voluntary dislocators - We rely on muscles (which act in force pairs) for shoulder stability - Proprioception and subsequent reflective muscle patterning usually mean agonist and antagonist produce equal and opposite forces keeping the humeral head centred in the glenoid - E.g pec major draws shoulder anteriorly whilst subscapularis draws head of humerus in the opposite direction, preventing anterior translation. As scapula retracts, pec major relaxes, otherwise it pulls the humeral head anteriorly. If pec major doesn’t relax, it pulls humeral head anteriorly whilst subscapularis retracts the scapula, pulling the glenoid posteriorly. This means the pec major essentially pulls the humeral head out of the glenoid - It leads to multiple dislocations without structural damage

Answer 8

Type 1 (traumatic structural instability): - traumatic structural instability - this is where trauma damages the joint architecture, leading to excessive translation of humeral head within glenoid - a force pushes the humeral head in one direction (usually anteriorly) and the glenoid labrum is torn off - the humeral head then dislocates and knocks into the edge of the glenoid - Since humeral head is soft and glenoid is hard, it often results in a compression fracture of humeral head called a Hills-Sachs lesion - If you sustain traumatic dislocation once, it’s likely you will have a detached labrum because the avascular nature of cartilage nature means it’s bad at healing itself - There will be lack of congruency - On MRI we can see detached labrum which will affect ligaments and capsule - The overall result is that structures of the shoulder are now loose and less effective at keeping humeral head centred - This means that the next time the shoulder takes a hit, the proprioceptive information is sent to the brain but before the brain can send a signal back to the brain to re-centre the humeral head, it dislocates as there’s nothing passive to stop it popping out - This will keep occurring unless the labrum is reattached

Answer 9

Type 2 (atraumatic structural): - atraumatic structural instability - This is hypermobility due to lax labrum and capsule - The humeral head can translate a lot more than normal, as a result, it can potentially dislocate - If it doesn’t dislocate, it will have a feeling of instability

Answer 10

Type 3 (muscle patterning): - Proprioceptive issues and defective muscle patterning - These people are often known as voluntary dislocators - We rely on muscles (which act in force pairs) for shoulder stability - Proprioception and subsequent reflective muscle patterning usually mean agonist and antagonist produce equal and opposite forces keeping the humeral head centred in the glenoid - E.g pec major draws shoulder anteriorly whilst subscapularis draws head of humerus in the opposite direction, preventing anterior translation. As scapula retracts, pec major relaxes, otherwise it pulls the humeral head anteriorly. If pec major doesn’t relax, it pulls humeral head anteriorly whilst subscapularis retracts the scapula, pulling the glenoid posteriorly. This means the pec major essentially pulls the humeral head out of the glenoid - It leads to multiple dislocations without structural damage

Answer 11

- Patients can move between different types of instability - If a patient starts off with a type 1 dislocation but it reoccurs, the joint capsule and ligaments will stretch out so they may become more of a type 2 - Patient may be aware of tendency for their shoulder to dislocate or proprioceptive pathways may become damaged, leading to type 3 - You can go from type 3 to type 1 as dislocations damage the joint architecture - You can go from type 3 to type 2 as dislocations and lack of muscle patterning cause joint capsule and ligaments to become lax over time - We need to diagnose which part is causing the most issues - this determines treatment approach

Answer 12

- Surgery can only treat abnormal anatomy such as type 1 and type 2. Surgery would make type 3 worse - Patient suffering from type 1 issue (labra tear or Hills-Sachs lesion), you can do labral repair and bony reconstruction of humeral head - Patient suffering from type 2 issue (lax and loose), you can do capsular shift to attempt to tighten up the joint capsule and ligaments - Patient suffering both type 1 and type 2, you can perform a labral repair and capsular shift - Patient with type 3, do physiotherapy to help coordinate correct muscle patterns Note: if you try and operate on a type 3, you will destroy normal anatomy so follow up physiotherapy will be useless - it will just result in more dislocations

Answer 13

- Labral tears in type 1 stability can be approached with a labral repair - This can be done arthroscopically - Firstly, where the bone was attached to labrum is cleaned up and irritated so that it bleeds - It needs to bleed because things stick to bleeding bone (remember bleeding is the first stage in tissue healing) - A Kevlar stitch is then passed through the labrum before a small hole is drilled into the bone - The stitch is then attached to an anchor which is subsequently driven into the hole of the bone - The loose ends of the stitch are then cut and another 2-3 stitches are done - This essentially pulls the detached labrum back down to the surface of the glenoid

Answer 14

-Function to centralise the axis of rotation whilst other muscles of the shoulder girdle act on the humerus - Deltoid attaches to acromium and deltoid tuberosity of humerus - as a result, it can only pull the humeral head superiorly until it hits the acromium - When it hits the acromium, it then has a fixed point to rotate around, although bone rubbing on bone is not pleasant - This is when the rotator cuffs come in - it pulls the humeral head medially into the glenoid which counteracts the upward pull of the deltoid - The result is that deltoid now pulls the arm into abduction as the action of the rotator cuffs fixes the point of rotation

Answer 15

- Clinical diagnosis where greater tuberosity catches on underside of acromium - This can happen due to e.g anatomy (overgrown acromium reduced the subcromial space), weak or uncoordinated rotator cuffs allowing humeral head to ride up towards acromium when deltoid contacts, weak scapula muscles allowing humerus to ride up Presentation: - patients are often 40+ - if they’re young, it’s more likely to be instability not impingement - complain of pain in lateral arm over deltoid area - clinical tests will point to impingement Treatment: - reduce pain using analgesics - steroid injections to reduce inflammation - physiotherapy - can help balance rotator cuffs and strengthen scapula muscles - if this fails , do surgery called subacromial decompression

Answer 16

- Usually done arthroscopically - Patient is anaesthetised - Arm in traction - Subacromial space is pumped with fluid - this distracts the space - A shaver is used to tidy up the overlying bone and detach the Coracoacromial ligament (which has no clear function) - The bone is exposed and a grinder is introduced from the posterior aspect - This is used to shave off small parts of the acromium to make it smoother and create some more space in the subacromial space

Answer 17

- Tears affecting rotator cuff tendon, but it’s normally the avascular supraspinatus tendon - As tears get bigger, they go into infraspinatus, though teres minor is rarely affected - Tears are detachment of muscle tendon from the bone - They start small and progress, peeling from bone Causes: - degenerative. Happens with age. Can be symptomatic or asymptomatic - traumatic. Affect younger patients. Can be caused by slipping on ice and landing on lateral aspect of arm which forces adduction. The rotator cuff pulls in the opposite direction and something fails in the middle. Always symptomatic Presentation: - 40+ years - anterosuperior muscular pain - clinical tests indicate tear as opposed to impingement Treatment: - similar to rotator cuff impingement - pain - this can be helped with analgesics - steroid injections to help with inflammation - physiotherapy

Answer 18

If a patient has a 2cm tear in the supraspinatus tendon, we operate as follows: - look at tear arthroscopically - we will not put the tendon back exactly where it came from as the muscle belly will retract the tendon - we will remove the separated distal end of the tendon - we then use a burr to make the bone bleed at the attachment site - kelvar stitches are then fired through the tendon and pulled tight reducing the tendon over the bone - a hole is then made in the bone and the stitch is anchored with a screw - the tails of the stitch are then cut and the repair is done - the weak point in this whole situation is the tendon - it is likely to re-tear if too much load is put through it - hence rehab involved 4 weeks in a sling is required and no load bearing for 8 weeks - Recovery takes 6-9 months

Answer 19

- a thorough history - expose the patient - inspect front and back e.g scars (open or arthroscopic), muscle wasting (deltoid or supraspinatus), deformity (clavicular fractures, ACJ dislocation) - Palpate the clavicle, ACJ, greater tuberosity, long head of biceps - Range of motion - flexion, extension, abduction, rotation Special tests: 1. Instability - laxity - sulcus sign (tests for inferior glenohumeral instability), anterior and posterior draw - anterior apprehension test - relocation test 2. Impingement - Neer’s sign - Hawkin’s test - Jobe’s test 3. Rotator cuffs - external rotation lag sign - hornblower’s sign (infraspinatus and teres minor) - internal rotation lag sign - liftoff test (subscapularis) - These tests have high sensitivity but poor specificity

Answer 20

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Shoulder Flashcards

(44 cards)