Practice Essentials
The forearm plays an important role in flexion and extension of the elbow and wrist, as well as pronation and supination. Forearm fractures of the radius and ulna can be described according to their location, pattern, displacement, and associated soft-tissue injury. No single classification takes all of these variables into account, but in most instances, forearm fractures can be classified according to location (proximal third, middle third, or distal third). (See also Forearm Fractures, Distal-Third Forearm Fractures, and Forearm Fractures in Emergency Medicine, as well as Galeazzi Fracture and Monteggia Fracture.)
Unlike middle-third forearm fractures in infants and children, these fractures in adults are unstable and result in significant dysfunction if treated inadequately. Nonanatomic alignment of the radial or the ulnar shaft can significantly impede forearm rotation. Therefore, nonunions and malunions of forearm fractures are functionally as well as cosmetically limiting. [1]
The independent but coordinated function of the wrist, forearm, and elbow is necessary to position and orient the hand in space. Injury to any of these components can result in significant functional deficit. Therefore, the main goal of treatment of middle-third forearm fractures is to restore anatomic length, alignment, and rotation in order to recover painless range of motion (ROM) of the elbow, forearm, and wrist. Adults with middle-third forearm fractures are typically treated surgically with open reduction and internal fixation (ORIF).
For patient education resources, see the First Aid and Injuries Center, as well as Broken Arm.
Anatomy
The forearm has a complex anatomy. From an osseous standpoint, the forearm is made up of the radius, the ulna, and the interosseous membrane.
The radius is composed of the radial head, the radial neck, and the biceps tuberosity proximally. The radial shaft extends distal to the biceps tuberosity and is located on the lateral aspect of the forearm when it is supinated. The radial shaft has a radial bow that extends from the bicipital tuberosity to the ulnar aspect of the distal radius at the wrist. Distally, the radius articulates with the carpal bones in the wrist.
The ulna serves as the axis around which the radius rotates during pronation and supination. Proximally, the ulna is composed of the olecranon and the coronoid, which articulate with the distal humerus at the elbow. The ulnar shaft is located on the medial aspect of the forearm. Distally, the ulnar shaft broadens to form the ulnar head and the styloid process.
The space between the radius and the ulna is primarily occupied by the interosseous membrane, which separates the anterior and posterior compartments of the forearm.
Etiology
The majority of middle-third forearm fractures occur from high-energy trauma (eg, motor vehicle accidents [MVAs] or sports injuries). Direct injury to the forearm can result from gunshot injuries or from blunt trauma to the forearm. Indirect injury to the forearm can also occur from either bending or torsional forces.
Epidemiology
The average annual incidence of forearm shaft fractures has been reported to be 1.35 per 10,000 population, with a range of 0-4 per 10,000 population, depending on age and gender. [2] Such fractures are relatively uncommon, compared with fractures of the humeral shaft, femur, and tibia. Forearm fractures predominantly occur in males, and the vast majority occur during the first four decades of life. [2] More than half of all forearm shaft fractures occur in males between the ages of 15 and 39 years. [2]
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Anteroposterior radiograph of displaced midshaft both-bone forearm fracture in adolescent with transitional growth plate. This fracture should be treated as adult injury.
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Lateral radiograph of displaced midshaft both-bone forearm fracture in adolescent. Note that alignment in this view appears to be adequate; however, radius is short.
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Anteroposterior radiograph of completed open reduction and internal fixation (ORIF) of middle-third forearm fracture.
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Lateral radiograph of open middle-third fracture of radius and ulna. Note proximity of bones to soft tissue.
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Anteroposterior radiograph of open middle-third fracture of radius and ulna. Joints above and below fracture are visible.
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Anteroposterior radiograph of completed fixation of middle-third forearm fracture.
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Lateral radiograph of completed open reduction and internal fixation (ORIF) of middle-third forearm fracture.
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Middle-third forearm fracture.
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Middle-third forearm fracture.
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Middle-third forearm fracture.
