In Monteggia lesions, reduction and stable fixation of the ulna are required to ensure stable reduction of the radial head. The most important factor is restoration of the length of the ulna.
The radial head usually spontaneously reduces once the ulna is out to length.
If, after assessment of the fixation, the radial head is not accurately centered to the center of the capitellum in AP and lateral views, consider overcorrection of the ulna (see illustration).
Reduction of radial head
The radial head will usually reduce closed and remain stable once the ulna has been aligned.
Rotational movements of the forearm may be necessary to complete the reduction of the radial head.
After fixation of the ulna, use an image intensifier to carefully evaluate the position of the radial head relative to the capitellum.
This must be confirmed through a full range of flexion, extension, pronation and supination.
An arthrogram may be helpful, particularly in younger children with an unossified proximal radius.
Revision of ulnar reduction and fixation
At this stage the ulnar reduction can be revised if required, often to an overcorrected position, which usually results in a stable and anatomic reduction of the radial head.
This can be achieved by overbending and reinserting the ulnar nail. An external fixator or a plate can produce further overcorrection if needed.
Ulnar osteotomy for plastic deformity
There is a strong tendency for the radial head to redislocate in a Monteggia fracture with plastic deformity of the ulna.
This is due to rebound of the ulna. Correction of the ulnar deformity with a precontoured elastic nail is recommended. If this is not successful, an osteotomy of the ulna should be considered.
Both of these maneuvers should be performed before considering open reduction of the radial head.
Complete reduction with the nail may not be possible in the following cases:
- Severe bowing
- Bowing unresponsive to intraoperative correction
- Narrow nail in a small medullary canal
In this situation, a small osteotome can be used to divide the bone through a small incision over the apex of the bowing.
If there is residual subluxation or instability in any position after optimization of the ulnar correction, there may be interposed tissue (usually annular ligament) in the radiocapitellar joint and an open reduction should be performed.
Approach to radial head
Perform a lateral approach and manually reduce the radial head.
Removal of blocks to reduction
The annular ligament is the most common intraarticular block to reduction. In rare cases the ligament can be gently repositioned around the radial head.
More often the ligament must be incised or excised to allow reduction of the radial head.
Reassessment of radial head position
Reassess the position and stability of the radial head by direct visual inspection and image intensification.
Check the completed osteosynthesis with image intensification. These images should be retained for documentation or alternatively an x-ray should be obtained before discharge.
Make sure that the desired reduction has been achieved, the nail is of appropriate length and the radial head remains in the appropriate position.