Humerus Fractures

Published on 16/04/2015 by admin

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21 Humerus Fractures

Anatomy of the Humerus

image

Humerus and Pectoral Girdle

image

Shoulder Joint and Ligaments

Humerus

• Parts and landmarks: head, greater tubercle (tuberosity), lesser tubercle, intertubercular sulcus (bicipital groove), anatomical neck, surgical neck, deltoid tuberosity, radial groove, medial supracondylar ridge and epicondyle, lateral supracondylar ridge and epicondyle, trochlea, capitulum

Glenohumeral Joint

• Shallow, synovial ball-and-socket joint
• Supported by musculotendinous rotator cuff, composed of subscapularis, supraspinatus, infraspinatus, and teres minor fibers and tendons
• Fibrocartilaginous glenoid labrum effectively deepens glenoid fossa.
• Complex subdeltoid and subacromial bursae can communicate (pathologically) with joint cavity.
• Long tendon of biceps (long head) passes in a synovial tunnel through the superior joint capsule to a supraglenoid tubercle insertion.

Elbow Joint

• Distal humerus can be viewed as having diverging medial and lateral columns, with functionally independent joints.

image Trochlea

image Termination of medial column
image Articulates with ulna: flexion and extension

image Capitulum

image Termination of lateral column
image Articulates with radius: rotation

• See also “Elbow Joint” in Chapter 22, Forearm Fractures
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Arm: Serial Cross Sections

Compartments of the Arm

• Upper arm

image Lateral (deltoid, abductor): axillary nerve
image Anterior (biceps, flexor): musculocutaneous nerve
image Posterior (triceps, extensor): radial nerve

• Lower arm: anterior (biceps) and posterior (triceps)
• External investing brachial fascia is relatively tough.
• Brachial plexus and its nerves lie medially, between superior anterior and posterior compartments.

Vessels and Nerves

image

Arm: Brachial Artery and Anastomoses

Arterial Supply

• Subclavian artery provides numerous branches, forming anastomoses around scapula, glenohumeral joint, and proximal humerus.

image Dorsal scapular artery runs from base of neck along vertebral border of scapula.
image Suprascapular artery

image From mid-subclavian to scapula above transverse scapular ligament, above suprascapular notch
image Has supraspinous and infraspinous branches to respective fossae

image Axillary artery (continuation into axilla)

image Anterior humeral circumflex
image Posterior humeral circumflex
image Subscapular artery, circumflex scapular branches: anastomotic with dorsal scapular and suprascapular branches of subclavian
image Brachial artery: continuation of main vessel into the distal arm and cubital region; branches: deep brachial (profunda brachii), radial artery, ulnar artery, collaterals

Veins of the Arm

• Deep veins run parallel to axillary and brachial arteries and their major branches, often twin veins beside arterial branches.
• Valved: arterial counterpulsation effect pumps blood heartward
• Deep and superficial drainages connect.
• Superficial tributaries

image Cephalic vein: from lateral forearm, travels superficial to biceps to empty into axillary vein
image Basilic vein: from superficial forearm and distal arm; empties into axillary vein

• Deep tributaries: axillary vein, brachial vein
• Axillary vein continues into subclavian vein.
• Axillary vein lies superficial to axillary sheath and parts of brachial plexus.

Nerves of the Arm

• Hilton’s Law: nerves supplying a joint also innervate muscles acting across it, as well as skin over distal insertions of those muscles
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Arm: Brachial Plexus

Brachial Plexus

• Roots

image Anterior rami of C5, C6, C7, C8, T1
image Supraclavicular, in neck

• Trunks

image Superior (C5+C6), middle (C7), inferior (C7+T1)
image Supraclavicular, in neck

• Divisions

image Anterior (flexor) and posterior (extensor) from each trunk
image Clavicular level

• Cords: named by position around the axillary artery (2nd part)

image Lateral: anterior divisions of superior and middle trunks
image Medial: anterior divisions of inferior trunk
image Posterior: posterior divisions only of all 3 trunks

• Cords and terminal nerve branches of brachial plexus lie anteromedial to glenohumeral joint in axilla.
• Musculocutaneous nerve: leaves lateral cord immediately to enter coracobrachialis, then travel distally deep to biceps
• Lateral and medial pectoral nerves: from lateral and medial cords, respectively
• Radial nerve (posterior cord): tightly applied to posterior and lateral humerus in radial groove, deep to medial head of triceps
• Dislocation or proximal fractures can damage cords, axillary, or radial nerves.

Clinical Correlates

Compartment Syndrome

• Displaced supracondylar humeral fracture: most common cause of upper limb compartment syndrome
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Fractures of the Humerus

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Neer Classification of Proximal Humerus Fractures

Humerus Fractures

• Classified by location, 3 general types

Proximal Humerus Fractures

• Common injuries

image In elderly persons with osteoporosis, following a fall
image In younger persons, with high-energy impact

• May be associated with dislocations of humeral head
• Can involve humeral head, greater tuberosity, lesser tuberosity, and shaft
• Fracture patterns can be classified (Neer) by number of parts displaced >1 cm or angulated >45°
• Proximal fractures and dislocations risk injury to axillary nerve, passing through quadrangular space at surgical neck of humerus.
• Two-part fractures, involving anatomical neck above tuberosities, split head and risk avascular necrosis from disrupted supply.

Humeral Shaft Fractures

• Typically result from direct trauma, falls, penetrating wounds, vehicular accidents
• Neurovascular assessment necessary: radial nerve injury can result from primary injury or manipulation
• Compartment syndromes can easily occur.

Distal Humerus Fractures

• Supracondylar

image Extraarticular, through metaphysis
image Rare in adults
image Mechanism extension (>80%) or flexion
image Imaging should be studied for intercondylar extension.

• Transcondylar

image Primarily occur in elderly persons with osteopenia, with or without intercondylar extension
image Most common distal humerus fracture in adults
image May be displaced owing to muscle pulls

• Condylar; very rare in adults, more commonly lateral (involving capitulum)
• Supracondylar fracture treatment

image Open reduction with internal fixation preferred
image Closed reduction in children

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