Disjointed – The Elbow

     The elbow is a hinge joint that connects the humerus bone to the radius and ulnar bones.  The humerus extends from the shoulder to the elbow.  The radius extends from the elbow to the wrist on the thumb side of the arm.  The ulnar bone extends from the elbow to the wrist on the little finger side of the arm.  The architecture of the radius allows it to rotate part way around the ulnar.  There are numerous other structures in the elbow that may be damaged with a dislocation.  They include major ligamentous structures, nerves, and arteries.  The ligamentous structures are the interosseous membrane, the radial collateral ligament, the ulnar collateral ligament, and the annular ligament.  There are three major nerves called the ulnar, medial, and radial nerves.  The brachial artery is a large artery the provides oxygen rich blood to the arm.  Around the area of the elbow, the brachial artery forks and becomes the radial and ulnar arteries.

     The basic classifications of the elbow dislocation are posterior, anterior, medial, lateral, divergent, and nursemaid’s elbow.  Classifications describe the position of the radius and ulnar bones in relation to the humerus.  The most common elbow dislocation seen in the emergency room is the posterior dislocation.  This is where the radius and ulnar bones are located behind the humerous.  It typically is caused by falling on an outstretched arm.  An anterior dislocation is when the radius and ulnar bones are positioned in front of the humerus bone.  Anterior dislocations can occur with an armbar that has enough traction on the extremity to seperate the elbow joint.  Then pressure is placed on the back of the elbow to  hyperextend the arm, thereby dislocating the elbow joint.  Medial and lateral dislocations may accompany posterior dislocations.  They have a poor prognosis due to the possible injury to ligaments, nerves and arteries.  Divergent dislocation describes a postion where the ulnar and radial bones seperate.  This may cause damage to the annular ligament and the interosseous membrane, which hold the two bones together.  Nursemaid’s elbow is typically seen in young children.  The radial head seperates from the humerus junction and gets “tangled” in the annular ligament.  It is caused by a sudden traction to the child’s arm.

     Elbow dislocations may have complications that require surgery.  Those complications include, but are not limited to fractures, damage to arteries, nerves, ligaments, or a delay in care.  After the joint is reset, a patient may develop weakness, numbness, blue fingers, stiffness, or joint instability.  A physician should be notified if these complications are noticed.

Disjointed series:

• Disjointed – The Shoulder

Disclaimer:

     If you have any concerns about your health and or well-being, please seek the counsel of a trained professional.  Don’t depend on the ramblings of a crazy little blogger nobody, such as myself.

Reference:

Reichmann, Eric F., Simon, Robert R., Campen, Angelique S. Kelly, “Chapter 68, Elbow Dislocation Reduction.”  Emergency Medicine Procedures. McGraw-Hill Professional, 2004.  614-620.