-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.

 

ش