Shoulder Trauma Normal anatomy Standard AP shoulder series

Shoulder Trauma

Normal anatomy • Standard AP shoulder series demonstrates most of the essential anatomy – Internal rotation, external rotation, abduction (baby arm) • Specialized views may be required to reduce overlap of certain structures • http: //eorif. com/Shoulderarm/Xray. Shoulder. html http: //www. ski-injury. com/specific-injuries/shoulder

Clavicle Fractures • 15% of all fractures; most common fracture during birth • Usually direct trauma • Males 2/3 of all clavicle fractures • More common in children and adolescents; incidence decreases with age

Clavicle fractures by location • Medial 1/3 - least common (5%) • Middle 1/3 - most common (75%) – If fracture is complete, medial fragment will be elevated by action of SCM and lateral fragment will be depressed by the weight of the upper extremity • Distal 1/3 - (20%) – Fracture may extend and become intra-articular http: //eorif. com/Shoulderarm/Clavicle%20 medial. html

Clavicle fracture complications • Child and adolescent heal without complication 95% of the time • Increased chance of complications in adults • Complications include: – Neurovascular damage – Non-union – Mal-union – Degenerative arthritis – Post-traumatic osteolysis

Neurovascular damage • Most commonly subclavian artery; less commonly subclavian vein; occasionally brachial plexus and sympathetic chain http: //bestpractice. bmj. com/best-practice/monograph/592/basics/aetiology. html

Non-union • 5% of cases • Lack of callous formation by 6 weeks post-injury signifies non-union • Radiographic signs: – Fracture margins become sclerotic and rounded with smooth contours over time • May require surgery http: //www. gentili. net/fracture. asp? ID=16

Malunion • If bones overlap and massive callus develops, cosmetic deformity and functional impairment results • May require surgery http: //www. sciencedirect. com/science/article/pii/S 1058274604002678

Degenerative Arthritis • Painful arthritis follows untreated intraarticular fractures • Radiographic signs are the usual findings in OA http: //www. drmaffet. com/shoulder-surgery-houston/ac-joint-arthosis-2/

Post-traumatic Osteolysis • Bone resorption of distal clavicle • First becomes radiographically visible 2 - 3 months after the injury – Distal cortex becomes hard to define and may become tapered over time • Injury may be trivial, not necessarily fracture or dislocation • Common in weightlifters http: //radiopaedia. org/images/631648

Scapular fractures • 80% have other fractures due to severity of trauma required to fracture scapula • May be seen on other shoulder views, but special projections may be required • 80% involve body and neck • Coracoid or acromion less often • Glenoid fractures occur with humeral dislocations (Bankhart and reverse Bankhart lesions) http: //www. feinberg. northwestern. edu/emergencymed/ residency/ortho-teaching/shoulder/case 42 answer. html

Humerus Fractures • Classified by anatomic location – Anatomic neck, greater tuberosity, lesser tuberosity, surgical neck, proximal shaft • Complications: – Non-union, malunion, DJD, AVN of humeral head, myositis ossificans, neurovascular damage http: //www. shoulderdoc. co. uk/article. asp? article=735

Anatomic Neck Fractures • Isolated neck fractures are rare – Usually associated fractures • High incidence of AVN • Hill-Sachs and reverse Hill-Sachs lesions – Impaction fractures of humeral head when it bangs against glenoid during dislocation http: //web. me. com/radrep/Radiographers_Reporting/The_Shoulder. . html

Greater Tuberosity Fracture • AKA Flap fracture • May occur by direct trauma or avulsion • Frequently fractured during anterior humeral dislocation • Best seen on external rotation view http: //en. wikipedia. org/wiki/File: Greatertrochaner. AP. png

Lesser Tuberosity Fracture • Can't be directly impacted, but may be associated with other fractures http: //www. medscape. com/viewarticle/420763 http: //www. internationalshoulderjournal. org/viewimage. asp? img=Int. JShoulder. Surg_2011_5_2_50_83198_u 3. jpg

Surgical Neck Fracture • Immediately distal to tuberosities • Most common of proximal humeral fractures • Axial artery and nerve prone to injury at this location http: //www 2. aofoundation. org http: //www. wheelessonline. com/ortho/proximal_humeral_fracture

Proximal Shaft Fracture • Mechanism is usually direct trauma • Fracture location in relation to muscular attachments determines deformity that is produced – Proximal to pec M, head abducts and rotates – Between pec M and delt, head will adduct - Distal to deltoid, head will abduct http: //radiopaedia. org/cases/proximal-humeral-fracture-in-child? fullscreen=true

Shoulder girdle dislocations • Most common joint in body to dislocate • Greater than 50% of all this locations • Four joints of the shoulder girdle – Glenohumeral joint 85%, acromioclavicular joint 12%, sternoclavicular joint 2% and scapula thoracic joint 1%

Glenohumeral Joint Dislocation • Classified by direction of displacement of humeral head – Anterior (most common), posterior, inferior or superior

Anterior GH Joint Dislocation • M. C. shoulder dislocation (95%) • Mechanism is forceful abduction and external rotation • Associated fractures during dislocation are common • Radiographic signs- interior medial head displacement, altered head shape and presence of Hill-Sachs or Bankart lesions • Humerus usually settles subcoracoid http: //www. feinberg. northwestern. edu/emergencymed/residency/ortho-teaching/shoulder/case 49/

Anterior GH Joint Dislocation • Hill-Sachs lesion (hatchet deformity) – Impaction fracture of posterior-superior aspect of head where it bangs into inferior glenoid • Bankart lesion – Fracture of inferior glenoid by humeral head impact complications recurrence http: //www. orthopaedia. com/display/Main/Hill-Sachs+Sign

Posterior GH Dislocation • Uncommon (2 -4%) • Fixes humeral head in internal rotation • Caused by epileptic convulsions, electric shock or extreme trauma, thus triple “e” syndrome • Reverse Hill-Sachs and reverse Bankart lesions – Impaction of anteromedial humeral head and posterior glenoid http: //www. radsource. us/clinic/0506

Posterior GH Dislocation • Radiographic signs: – – Rim sign- widening of glenohumeral joint space > 6 mm Trough line sign- appearance of double articular surface line Lack of humeral head/glenoid fossa overlap Vacant glenoid sign- lack of close contact at anterior joint margin – Tennis racquet appearancecystic appearance of humeral head in its malposition – Superior displacement of humeral head - Rare, but could have reverse Hill. Sachs (impaction fx. of anteromedial aspect of head) or reverse Bankart (posterior glenoid fx. ) http: //imageinterpretation. co. uk/images/shoulder/POSTERIOR%20 DISLOCATION 2%20 AP. jpg

Inferior GH Dislocation • AKA luxatio erecta • Mechanism is severe hyperabduction • In that motion, acromion acts as fulcrum on humeral neck, which levers humeral head inferiorly • Humerus gets stuck in abduction

Superior dislocation • Rare • Requires great force with elbow flexed and adducted • More likely to have superior displacement of head due to torn rotator cuff

Rotator cuff tears • Incidence increases with age • May be traumatic or degenerative • Radiographic sign is superior subluxation of humeral head (not dislocation) – Tear produces reduces holding power of infraspinatus tendon allowing unopposed elevation of humeral head by deltoid – Acromiohumeral measurement <7 mm signifies tear – Head may form pseudo-joint superiorly with clavicle and acromion

Rotator Cuff Tears • Arthrography- 85% sensitive – shows extravasation of contrast • Ultrasound- 60 to 85% sensitive • MRI up to 100% sensitive if tear is >2 cm http: //stemcelldoc. wordpress. com/tag/alternatives-to-rotator-cuff-surgery/

Glenoid Labral Tears • AKA SLAP lesion (Superior Labrum Anterior to Posterior • Occurs during dislocation • Associated with instability • MRI is modality of choice – Demonstrates labral avulsion, absence or a cleft http: //www. ericcressey. com/tag/slap-lesion

AC Joint Separation • Demonstrated with AP projection at 15°cephalic tube tilt (like clavicle view), but taken with and without weights – Needs to be bilateral for comparison measurements • Coracoclavicular Trapezoid ligament is actually 2 ligaments Conoid - Conoid and trapezoid ligaments http: //www. conquestchronicles. com/pages/The_Shoulder_Sprain

AC Joint Separation • Radiographic features – AC joint space normally 2 -4 mm – AC joint alignment- should be in good horizontal alignment – Coracoclavicular distance- normally 11 -13 mm; should be no more than 5 mm difference from side to side http: //www. emedx. com/emedx/diagnosis_information/shoulder_disorders/shoulder_separation_images. htm

Classification of AC Joint Injuries • Based on degree of injury – Type I- No tear; no radiographic signs – Type II- AC ligaments torn; coracoclavicular ligaments stretched, but intact • Radiograph shows increased AC joint space, but normal coracoclavicular distance – Type III- Next slide

Classification of AC Joint Injuries • Type III- AC ligaments AND coracoclavicular ligaments torn – Radiographic signs include widened AC joint space, elevation of distal clavicle above acromion and coracoclavicular distance >5 mm wider than the opposite side http: //velonews. competitor. com/2010/11/news/shoulder-separations-explained_150447

Sternoclavicular Joint Dislocation • Rare • Requires severe trauma • Posterior displacement of clavicle at SC joint is potentially life-threatening • CT is modality of choice

Scapulothoracic Joint Dislocation • AKA locked scapula • Rare • Severe trauma or post-thoracoplasty

References • Yochum, T. R. (2005) Yochum and Rowe’s Essentials of Skeletal Radiology, Third Edition. Lippincott, Williams and Wilkins: Baltimore.