WEEK 3: 3.3 SHOULDER BIOMECHANICS Shoulder Mobility ● Osseous components of functional shoulder: ​ ○ AC joint: articular surface of clavicle is convex in all planes of motion ​ planejoint ○ SC joint: clavicle is convex frontal and concave sagittal plane ​ saddle ■ Very strong, stable joint joint ● Shoulder characteristics that benefit mobility: ​ ○ Healthy articular surface ○ Supple capsuloligamentous restraints ○ Glenoid fossa is flat ■ Helped by labrum ○ ⅓ to ¼ articulation with humeral head ■ Not a lot of joint congruency ○ Inferior capsule is lax ○ Recess in inferior capsule allows for more mobility ○ muscles Non-Contractile Stability Dynamic Stability Joint capsule Muscles of rotator cuff ligaments Ligamentous Muscle force couples Je Integrity of osseous articular structures Labrum ● Motions with significantly reduced contact between humerus and labrum: ​ ○ Max flexion, adduction, and IR ○ Max abduction and flexion ○ Adducted at the side, with the scapula rotated downward ○ *least amount of joint congruency Shoulder Osteology ● Scapular Structure: ​ ○ Scapula wide and thin structure ■ Easy gliding on thoracic wall ■ Multiple sites for muscle attachments ○ Overhanging acromion and coracoacromial ligament ■ Provides improved mechanical advantage of deltoid ○ Scaption plane: loose pack position → less impingement and stress ● Acromion types: ​ Mohehooked morechange forimpingement RTCtear ○ ○ Acromion type is a strong predictor of rotator cuff impingement OPEN ■ Type I: 3% incidence of rotator cuff tears ■ Type III: 70% incidence of rotator cuff tears ● Coracoid process: O ​ ○ Long lever → allows pec minor to provide scapular stability to ○ Site of attachment for coracobrachialis and short head of biceps ● Close/Open Packed Position: ​ ○ Close Pack: full abduction and ER I'll ○ Open Pack: 39 degrees of abduction in the scapular plane Ch08ED_ Shoulder Ligaments µ ● ● Glenohumeral ligaments: ​ ○ Distinct thickenings in the anterior capsule ○ Superior GH ligament: ​ ADD 1 guides ■ Torn SGHL allows inferior suIAPbluxation of humerus ■ Contracture limits ER and flexion ■ Taut: adduction, inferior and AP translations of humeral head ○ Middle GH ligament: ​ A ■ Blends with the subscapularis tendon ■ Taut: anterior translation of the humeral head, esp in ~45-60 degrees of abduction, ER ○ Inferior GH ligament: ​ 900Abd ■ Most important ligament for GH stability ■ Divided into anterior and posterior band with a axillary pouch in between that acts like a hammock to support the humerus during abduction and ER ■ Primary static stabilizer when the arm is abducted from 45-90 degrees S ■ Taut: M AB PB AP ● Anterior band: 90 degrees abduction and full ER, anterior a translation of humeral head ● Posterior band: 90 degrees abduction and full IR ● Axillary pouch: 90 degrees abduction, combined with AP and inferior translations ○ ● Coraco-humeral ligament: translation ​ AP ○ Has a similar restraMadd.intint to GH motion as the superior gleno-humeral ligament ○ Coraco-humeral ligament is taut with adduction providing significant restraint to inferior translation and ER of the humeral head ● Capsular Patterns: ​ ○ Adhesive capsulitis: ER limited > Abd > IR > Flex ○ Selected capsular hypomobility: IR > Abd > ER Coracoacromial Arch ● Structures under the arch: ○ Long head biceps ○ Superior JC odd ○ Supraspinatus, infraspinatus, subscapularis ○ Subdeltoid, subacromial bursa Subacromial Space ● Arm adducted suprahumeral space 10-11mm ● 60-120 degrees of scaption space is at its narrowest ● With overhead motion, supraspinatus tendon passes under the coracoacromial arch ○ With the addition of IR, the supraspinatus tendon passes under the igngaggann coracoacromial ligament ○ With the addition of ER, the supraspinatus tendon passes under the acromion ER acromion● Weak/injured RTC allows increased humeral head translation ○ Increased wear labrum ○ Overuse of static restraints ○ Overuse of dynamic restraints Muscle Functional Classification ● Scapular Pivoters: ​ movessoap ○ Traps, serratus anterior, levator scap, rhomboids major and minor ○ Functions at the scapulothoracic articulation ○ Serratus anterior: protracts, upwardly rotates scapula, and maintains scapula on thorax ■ Works in synergy with traps (force couple) ■ Active with all shoulder movements, esp flex and abd ■ Lower fibers draw inferior angle of the scapula forward upwardly rotating scapula ● Humeral Propellers: ​ moveshumerus ○ Lats, teres major, pec major, pec minor ○ IRs have larger mass than external rotators ● Humeral Positioners: ​ stabilizeshumerus ○ Deltoid: anterior, lateral, posterior ● Shoulder Protectors: ​ shoulderstability ○ Rotator cuff ■ Actively move and fine tune humeral head positioning during arm elevation ■ During abd, the greater tuberosity must pass under the coracoacromial arch ● Humerus must ER (infraspinatus, teres minor) ● Acromion must elevate ■ Contractile ligaments ■ Reinforces coracohumeral and glenohumeral ligaments ■ Controls GH arthrokinematics ● Horizontally oriented supraspinatus produces a compressive force into the glenoid fossa ● Holds humeral head in glenoid fossa during superior roll ● Provides: ○ Stability ○ Efficient fulcrum ○ Balances vertical force of deltoid avoiding impingement ○ In mid range arm elevation, passive restraints are lax ● Force Couples: ​ ○ Subscap co-contracts with infra and teres minor to depress and compress the Subscap infrag humeral head during overhead movements 1Min ○ Deltoid co-contracts with interior RTC muscles ■ Creates a compressive force and downward rotation force to Deltoid inf RTC counterbalance the deltoid ■ injury/weakness of the RTC allows deltoid to elevate humerus causing impingement of the RTC on the anterior acromion WEEK 5: SHOULDER PT. 2 Supraspinatus Tendonitis vs. Calcific Supraspinatus Tendonitis ● Supraspinatus tendon is susceptible to tendinous pathology: ​ ○ With the arm along the side of the body, the tendon is pulled down and over the greater tuberosity of the humerus → compressive force of the tendon into the tuberosity and creates a zone of avascularity ■ Decreased blood to tendon → pathology ■ Tensile stress + compressive force = flushes out blood and fluid = avascular ○ Shoulder tendinopathy: ​ ■ Reactive or degenerative: ABRALPATHOLOGY ​ immobilize ● Reactive: acute, just occurred youngerpeople ● Degenerative: chronic, takes time to happen/usually later in life controlparinginflammation olderpeopl ■ Etiology: activitymod ​ canbeunaccustomed dynamicstabilization ● Traumatic closedlopenchainax ● Overuse/repetitive (unaccustomed activity for that individual) ○ Is their body ready to handle the stresses? canhavesurgery ● Insidious debridement gradual ■ Presentation: ​ ANKARTISMPHUSAUTS ● Acute/subacute: signs of inflammation Bantam ● Pain with contraction/activity avulsion anteriorinferior ● Pain with passive stretch depending on tissue reactivity labrum ● Tenderness over tendon trauma ■ Treatment: ​ baidu.org laxity1spea'aliens ● PT surgery ● Reactive/Early Stage of Condition (acute/subacute) http ○ protect/reduce aggressive loading (frequency/duration) superiorlaterallesion ○ Encourage healing - STM, modalities anteriorposterior ● Degenerative/Late Stage of Condition (Chronic Condition) traumalmicrotrowma ○ Normalize load baidu.org laxity1spea'aliens ○ Transverse/Cross friction massage HillSachs ○ Exercise with heavy loading trauma dislocatesantlinf ○ Modalities ● Supraspinatus can be traditional tendonitis or calcific tendonitis: compression ​ fracture ○ But have same patient complaints and presentation ■ Difference: calcific tendonitis needs radiography to identify it Numeralhead ○ Calcific tendonitis: from local areas of necrosis within the tendon ​ onglenoid ■ Necrosis causes calcium to be deposited within the tendon ● But not as bone → has a toothpaste consistency ● Can be slow or fast ○ Fast → acute ○ Slow → chronic ■ Men > women menanestubborn ■ Same symptoms as non-calcific tendonitis ■ Radiograph to diagnose it toseecalcifiedpans ■ Positive exam findings: ​ ● Step 7: PFC → warmth and swelling over the supraspinatus MSTT ERAbd tendon inflammation to ● Step 8: AROM → painful arc 11 MLT IR Add ● Step 9: PROM → painful in IR and adfoppositeduction ISPET Wpmsp ● Step 10: MSTT → strong and painful with ER and abduction 17Imaging opaque ○ Good for diagnosing tendinopathy ○ Don’t move onto MMT because pain ● Step 11: MLT → decreased length and painful with IR and adduction st ● Step 15: PFT → painful over the supraspinatus tendon ● Step 17: Imaging → brightness (opaque area) noted within the supraspinatus tendon location ■ Treatment: ​ NO TREATMENT ● Anti-inflammPTatories or aspirate calcium deposit ● Maybe surgery if severe enough ○ Osteophytes forming on the underside of the acromion - tendon is squeezed every time patient raises arm ○ Keep GH joint slightly abducted after surgery ■ Increase blood supply and promote healing ● Lifestyle modification gina ○ Supraspinatus Tendonitis: arm at side of body causes a downward pull on ​ supraspinatus tendon over the greater tubercle ■ Compressive force causes zone of avascularity STEPS10111,15 ● Tensile stress + compressive force = flushes out blood/fluid → avascular ■ Examination: ​ www.ascakiticbrtw ogepn Tendinitislosis ● Step 7: PFC supraspinatus tendon → warmth and swelling ● Step 8: AROM: Painful arc → pain in mid range stronglypainful ● Step 9: PROM IR, Add = pain → lengthening tissues causes pain ● Step 10: MSTT ER and Abd = strong and painful → don’t do MMT ● Step 11: MLT IR and Add = Decreased length and painful ifeng.agai.hr ● Step 15: