Radius and Ulna Shaft



Radius and Ulna Shaft





EPIDEMIOLOGY



  • Forearm fractures are more common in men than women, secondary to the higher incidence in men of motor vehicle collisions (MVC) and motorcycle accidents (MCA), contact athletic participation, altercations, and falls from a height.


  • The ratio of open fractures to closed fractures is higher for the forearm than for any other anatomic area except the tibia.


ANATOMY



  • The forearm acts as a ring; a fracture that shortens either the radius or the ulna results either in a fracture or a dislocation of the other forearm bone at the proximal or distal radioulnar joint. Direct injuries (“nightstick”) are an exception.


  • The ulna, which is relatively straight, acts as an axis around which the laterally bowed radius rotates in supination and pronation. A loss of supination and pronation may result from radial shaft fractures in which the lateral curvature (“radial bow”) has not been restored.


  • The interosseous membrane occupies the space between the radius and ulna. The central band is approximately 3.5-cm wide running obliquely from its proximal origin on the radius to its distal insertion on the ulna. Sectioning of the central band alone reduces stability by 71% (Fig. 21.1).


  • Fracture location dictates deforming forces:



    • Radial fractures distal to the supinator muscle insertion but proximal to the pronator teres insertion tend to result in supination of the proximal fragment owing to unopposed pull of the supinator and biceps brachii muscles.


    • Radial fractures distal to the supinator and pronator teres muscles tend to result in neutral rotational alignment of the proximal fragment.







FIGURE 21.1 Line diagram showing the soft tissue connections of the radius and the ulna to each other. The proximal radioulnar joint is stabilized by the annular ligament. The distal radioulnar joint is stabilized by the dorsal and volar radioulnar ligaments and the triangular fibrocartilage complex. (From Richards RR. Chronic disorders of the forearm. J Bone Joint Surg 1996;78A:916-930.)


FRACTURES OF BOTH THE RADIUS AND ULNA SHAFTS


Mechanism of Injury



  • These fractures are most commonly associated with high-energy (MVC, MCA) accidents, although they are also commonly caused by direct trauma (while protecting one’s head), gunshot wounds, and falls either from a height or during athletic competition.


  • Pathologic fractures in this area are uncommon.



Clinical Evaluation



  • Patients typically present with gross deformity of the involved forearm, pain, swelling, and loss of hand and forearm function.


  • A careful neurovascular examination is essential, with assessment of radial and ulnar pulses, as well as median, radial, and ulnar nerve function.


  • One must carefully assess open wounds because the ulna border is subcutaneous, and even superficial wounds can expose the bone.


  • Excruciating or unremitting pain, tense forearm compartments, or pain on passive stretch of the fingers should raise suspicions of impending or present compartment syndrome. Compartment pressure monitoring should be performed, with urgent fasciotomy indicated for diagnosed compartment syndrome.


Radiographic Evaluation



  • Anteroposterior (AP) and lateral views of the forearm should be obtained, with oblique views obtained as necessary for further fracture definition.


  • Radiographic evaluation should include the ipsilateral wrist and elbow to rule out the presence of associated fracture or dislocation (e.g., Monteggia, Galeazzi).


  • The radial head must be aligned with the capitellum on all views.


Classification


Descriptive



  • Closed versus open


  • Location


  • Comminuted, segmental, multifragmented


  • Displacement


  • Angulation


  • Rotational alignment


Orthopaedic Trauma Association Classification of Fractures of the Radial and Ulna Shaft

See Fracture and Dislocation Compendium at http://ota.org/compendium/index.htm.



Jun 17, 2016 | Posted by in ORTHOPEDIC | Comments Off on Radius and Ulna Shaft

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