1 Preliminary remarks top
Anatomical reduction and stable fixation of both fractures are desirable for 21-A3 fractures. Begin by exposing both fractures.
Usually, the ulnar fracture will be fixed first. Malreduction of the first of the fractures will usually impede reduction of the other. The specific fracture fixation is determined by the character of each fracture and is discussed below.
Rare type IV Monteggia fractures (complete dislocation of the radial head relative to capitellum) must be recognized, because both dislocation and fracture must be reduced.
In transverse or short oblique fractures of the radial neck, fixation of the radial head to the diaphysis is achieved by plating.
2 Reduction and preliminary fixation topenlarge
Expose the fracture ends with minimal soft tissue dissection off the bone.
Remove hematoma and irrigate.
Reduce the fracture with the help of small pointed reduction forceps and provisionally fix it with one or two 1.0 mm K-wires or reduction clamps. Difficulty with reduction may be due to the ulna’s being malreduced, or because the radial head is dislocated from the capitellum, perhaps with interposed annular ligament.
3 Plate positioning topenlarge
The radial head is completely covered by articular cartilage. The implant is applied to the radial head in a location that causes the least compromise of full pronation and supination.
Safe zone for plate and screw insertion
To determine the location of the "safe zone“, reference marks are made along the radial head and neck, to mark the midpoint of the visible bone surface. Three such marks are made with the forearm in neutral rotation, full pronation, and full supination as shown in the illustration.
The posterior limit of the safe zone lies halfway between the reference marks made with the forearm in neutral rotation and full pronation. The anterior limit lies nearly two thirds of the distance between the neutral mark and the mark made in full supination.
The nonarticulating portion of the safe zone for the application of implants to the radial head (or safe zone for prominent fixation) consistently encompasses a 90 degrees angle localized by palpation of the radial styloid and Lister's tubercle.
4 Choice of implant topenlarge
As the radial head is a small fragment, a mini fragment 1.5 or 2.0 T-plate, or a locking proximal radius plate is used to allow purchase of two or three screws in the proximal fragment.
The plate should be long enough to allow insertion of three screws in the distal fragment.
Prebend the plate according to the surface anatomy of the proximal radius. A slight convex bend at the fracture site may improve compression of the opposite cortex.
5 Creating compression topenlarge
Insert two or three screws (1.5 mm or 2.0 mm) through the plate into the proximal fragment. These are parallel to the proximal surface and entirely within the bone.
Attach a small bone hook in the distal hole of the plate and apply distal traction to the plate creating compression at the fracture site. At the time of application of compression, the temporary K-wires could be removed to enhance the compression effect. In this case use a small clamp to stabilize the fracture.
Distal plate fixation
With the fracture site compressed, attach the plate distally with two or three bicortical screws (1.5 or 2 mm). Eccentric screw holes (distally) may aid compression.
Check fracture reduction, stability and hardware prominence.
6 Final assessment top
Finally, assess the range of motion in pronation, supination, flexion and extension. Fixation should be stable and crepitus or restricted motion should be absent. Radiocapitellar and ulnohumeral joints should remain located through a full range of motion.
Check fractures and implants with image intensifier or x-ray.