1 Preliminary remark on 21-A3 fractures 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.
2 Bridge plating principles topenlarge
In multifragmentary fractures of the radial neck, fixation of the radial head to the diaphysis is achieved by bridge plating.
Bridge plating uses the plate as an extramedullary splint, fixed to the two main fragments, while the intermediate fracture zone is left untouched.
Anatomical reduction of the intermediate fragments is not necessary but alignment, rotation and length of the radius must be restored.
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 length depends on the fracture fragmentation. With a larger fracture zone, a longer plate has to be chosen.
Prebend the plate according to the surface anatomy of the proximal radius.
5 Reduction and fixation topenlarge
In multifragmentary radial neck fractures, indirect reduction is performed.
Apply the prebent plate with two or three screws to the radial head.
With the help of reduction forceps, adjust the plate to the diaphysis correcting length, rotation, and alignment.
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.
Fix the plate with two or three bicortical 1.5 or 2.0 mm screws to the distal fragment.
6 Final assessment top
Following repair of fractures and ligaments, elbow stability should be assessed through a full range of flexion-extension. Radiocapitellar and ulnohumeral joints should remain located.
Also check supination and pronation. Fixation should be stable. Crepitus or restricted motion should be absent.
Check fractures and fixation with image intensifier or x-ray.