-Fractures of the Radius and Ulna-Fractures of the head of the radius -Fractures of the neck of the radius-Fractures of the shafts of the radius-Fractures of the olecranon process-Olecranon Bursitis-The Metacarpals and Phalanges-

Fractures of the Radius and Ulna

Fractures of the head of the radius
can occur from falls on the outstretched hand. As the force is transmitted along the radius,

the head of the radius is driven sharply against the capitulum, splitting or splintering the head
.

Fractures of the neck of the radius
 occur in young children from falls on the outstretched hand.

Fractures of the shafts of the radius
 and ulna may or may not occur together. Displacement of the fragments is usually considerable and depends on the pull of the attached muscles. The proximal fragment of the radius is supinated by the supinator and the biceps brachii muscles. The distal fragment of the radius is pronated and pulled medially by the pronator quadratus muscle. The strength of the brachioradialis and extensor carpi radialis longus and brevis shortens and angulates the forearm. In fractures of the ulna, the ulna angulates posteriorly. To restore the normal movements of pronation and supination, the normal anatomic relationship of the radius, ulna, and interosseous membrane must be regained.

A fracture of one forearm bone may be associated with a dislocation of the other bone. In Monteggia’s fracture, for example, the shaft of the ulna is fractured by a force applied from behind.

There is a bowing forward of the ulnar shaft and an anterior dislocation of the radial head with rupture of the anular ligament. In Galeazzi’s fracture, the proximal third of the radius is fractured and the distal end of the ulna is dislocated at the distal radioulnar joint.

Fractures of the olecranon process

can result from a fall on the flexed elbow or from a direct blow. Depending on the location of the fracture line, the bony fragment may be displaced by the pull of the triceps muscle, which is inserted on the olecranon process. Avulsion fractures of part of the olecranon process can be produced by the pull of the triceps muscle. Good functional return after any of these fractures depends on the accurate anatomic reduction of the fragment.

Colles’ fracture is a fracture of the distal end of the radius resulting from a fall on the outstretched hand. It commonly occurs in patients older than 50 years. The force drives the distal fragment posteriorly and superiorly, and the distal articular

surface is inclined posteriorly. This posterior displacement produces a posterior bump, sometimes referred to as the “dinner-fork deformity” because the forearm and wrist resemble the shape of that eating utensil. Failure to restore the distal articular surface to its normal position will severely limit the range of flexion of the wrist joint.

Smith’s fracture is a fracture of the distal end of the radius and occurs from a fall on the back of the hand. It is a reversed Colles’ fracture because the distal fragment is displaced anteriorly

Olecranon Bursitis

A small subcutaneous bursa is present over the olecranon process of the ulna, and repeated trauma often produces chronic bursitis.

The Metacarpals and Phalanges

There are five metacarpal bones, each of which has a base, a shaft, and a head

The first metacarpal bone of the thumb is the shortest and most mobile. It does not lie in the same plane as the others but occupies a more anterior position. It is also rotated medially through a right angle so that its extensor surface is directed laterally and not backward.

The bases of the metacarpal bones articulate with the distal row of the carpal bones; the heads, which form the knuckles, articulate with the proximal phalanges.

 The shaft of each metacarpal bone is slightly concave forward and is triangular in transverse section. Its surfaces are posterior, lateral, and medial.

There are three phalanges for each of the fingers but only two for the thumb.

 

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Humerus-Fractures of the Proximal End of the Humerus-Humeral Head Fractures-Greater Tuberosity Fractures-Lesser Tuberosity Fractures-Surgical Neck Fractures-Fractures of the Shaft of the Humerus-Fractures of the Distal End of the Humerus-

Humerus

The humerus articulates with the scapula at the shoulder joint and with the radius and ulna at the elbow joint. The upper end of the humerus has a head, which forms about one third of a sphere and articulates with the glenoid cavity of the scapula. Immediately below the head is the anatomic neck. Below the neck are the greater and lesser tuberosities, separated from each other by the bicipital groove. Where the upper end of the humerus joins the shaft is a narrow surgical neck. About halfway down the lateral aspect of the shaft is a roughened elevation called the deltoid tuberosity. Behind and below the tuberosity is a spiral groove, which accommodates the radial nerve The lower end of the humerus possesses the medial and lateral epicondyles for the attachment of muscles and ligaments, the rounded capitulum for articulation with the head of the radius, and the pulley-shaped trochlea for articulation with the trochlear notch of the ulna. Above the capitulum is the radial fossa, which receives the head of the radius when the elbow is flexed. Above the trochlea anteriorly is the coronoid fossa, which during the same movement receives the coronoid process of the ulna. Above the trochlea posteriorly is the olecranon fossa, which receives the olecranon process of the ulna when the elbow joint is extended

Fractures of the Proximal End of the Humerus

Humeral Head Fractures

Fractures of the humeral head can occur during the process of anterior and posterior dislocations of the shoulder joint. The fibrocartilaginous glenoid labrum of the scapula produces the fracture, and the labrum can become jammed in the defect, making reduction of the shoulder joint difficult

Greater Tuberosity Fractures

The greater tuberosity of the humerus can be fractured by direct trauma, displaced by the glenoid labrum during dislocation of the shoulder joint, or avulsed by violent contractions of the supraspinatus muscle. The bone fragment will have the attachments of the supraspinatus, teres minor, and infraspinatus muscles, whose tendons form part of the rotator cuff. When associated with a shoulder dislocation, severe tearing of the cuff with the fracture can result in the greater tuberosity remaining displaced posteriorly after the shoulder joint has been reduced. In this situation, open reduction of the fracture is necessary to attach the rotator cuff back into place.

Lesser Tuberosity Fractures

Occasionally, a lesser tuberosity fracture accompanies posterior dislocation of the shoulder joint. The bone fragment receives the insertion of the subscapularis tendon, a part of the rotator cuff.

Surgical Neck Fractures

The surgical neck of the humerus , which lies immediately distal to the lesser tuberosity, can be fractured by a direct blow on the lateral aspect of the shoulder or in an indirect manner by falling on the outstretched hand.

Fractures of the Shaft of the Humerus

Fractures of the humeral shaft are common; displacement of the fragments depends on the relation of the site of fracture to the insertion of the deltoid muscle. When the fracture line is proximal to the deltoid insertion, the proximal fragment is adducted by the pectoralis major, latissimus dorsi, and teres major muscles; the distal fragment is pulled proximally by the deltoid, biceps, and triceps. When the fracture is distal to the deltoid insertion, the proximal fragment is abducted by the deltoid, and the distal fragment is pulled proximally by the biceps and triceps. The radial nerve can be damaged where it lies in the spiral groove on the posterior surface of the humerus under cover of the triceps muscle.

Fractures of the Distal End of the Humerus

Supracondylar fractures are common in children and occur when the child falls on the outstretched hand with the elbow partially flexed. Injuries to the median, radial, and ulnar nerves are not uncommon, although function usually quickly returns after reduction of the fracture. Damage to or pressure on the brachial artery can occur at the time of the fracture or from swelling of the surrounding tissues; the circulation to the forearm may be interfered with, leading to Volkmann’s ischemic contractureThe medial epicondyle (Fig. 9.10) can be avulsed by themedial collateral ligament of the elbow joint if the forearm is forcibly abducted. The ulnar nerve can be injured at the time of the fracture, can become involved later in the repair process of the fracture (in the callus), or can undergo irritation

on the irregular bony surface after the bone fragments are

reunited

.

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