Monteggia fracture is the fracture of the proximal third of the ulna with dislocation of the radial head. The fracture is more common in children and rare in adults. Treatment will depend on the age of the patient.The normal position of the radial head and shaft should line up with the capitellum in any position. Dislocation of the radial head may be missed.
Type I Monteggia fractures occur in the middle or proximal third of the ulna with anterior dislocation of the radial head and characteristic apex anterior angulation of the ulna. This is the most common type and occurs in about 60% of cases. In children, you will immobilize the fracture in flexion and supination. Flex the elbow more than 90 degrees to relax the biceps.
Only 15% of Monteggia fractures are Type II. This fracture occurs in the middle or proximal third of the ulna with posterior dislocation of the radial head and characteristic apex posterior angulation of the ulna. You will need to immobilize this fracture in extension.
20% of Monteggia fractures are type III. These fractures occur at the ulna just distal of the coronoid process with lateral dislocation of the radial head.
Type IV only occur 5% of the time and is classified as the fracture of the proximal or middle third of the ulna with anterior dislocation of the radial head, and a fracture of the proximal third of the radius below the bicipital tuberosity. This fracture will require surgery, even in children.
With Monteggia Fracture Dislocations, it is important to perform a neurovascular exam. Nerve injury, especially involving the posterior interosseous nerve, is not uncommon. Additionally, you will want to watch the patient for compartment syndrome.
Treatment in adults consists of ORIF of the ulna—when the ulna is properly aligned and fixed, the radial head will reduce by itself. Radial head instability may usually be caused by nonanatomic reduction of the ulna or by interposition of the annular ligament. Fracture of the ulna may need a bone graft for healing.
When treating pediatric patients, it is important to note that the radial head ossifies around age 4. For Type I-III fractures, you will perform a closed reduction of the ulna to restore the length of the ulna and reduce the radial head. Remember to immobilize in flexion and supination. Type IV fractures or cases where you are unable to reduce the radial head or the length of the ulna in pediatrics will require surgery. Fixation will be done with an IM rod or a plate.
When treating old cases, you will perform an osteotomy of the ulna and an open reduction of the radial head, followed by plating of the ulna.