1 General considerations 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.
Compression plate principles
In simple oblique fractures, compression can be achieved by combining axial compression with interfragmentary compression using a plate and a lag screw.
Sequence of screw insertion
There is a risk of shortening in oblique fractures if the plate is not first attached to the correct fragment. The first screw (in neutral position) should attach the plate to the fragment which forms an angle >90 degrees beneath the plate. The next screw (in eccentric position) is inserted into the opposite fragment, after this fragment has been reduced into the axilla.
A third screw is inserted as a lag screw through the plate, creating more interfragmentary compression.
2 Reduction and preliminary fixation top
Cleaning the fracture site
Expose the fracture ends with minimal soft tissue dissection off the bone.
Remove hematoma and irrigate.
Reduction can be achieved by direct or indirect reduction techniques.
Reduce the fracture with the help of small pointed reduction forceps and provisonally fix it with pointed reduction forceps. These may be repositioned or replaced to aid plate contouring.
Reduction with a plate
Fix the contoured and prebent plate with one screw to the appropriate fragment. Then reduce the distal fragment against plate and proximal fragment by manipulation of the distal ulna, possibly aided by a clamp outside the fracture site. Final adjustment of the screw may affect reduction, and may be delayed until a screw is placed in the opposite fragment.
In minimally displaced fractures this reduction might be achieved indirectly.
3 Plate preparation topenlarge
Use a seven hole plate. The plate may be a small fragment (3.5 mm) dynamic compression plate (DCP), or limited contact dynamic compression plate (LC-DCP), or locking plate (LCP) with conventional screws.
In osteoporotic bone there is an indication for the use of a an LCP in combination with locking head screws.
Contouring the plate
Contour the plate according to the surface anatomy of the ulna. Place a
slight convex bend over the fracture to ensure compression of the opposite
Contour the plate with bending irons or bending press.
4 Creating compression with the plate topenlarge
Apply a 3.5 mm cortical screw in neutral position next to the fracture into the proximal fragment. Insert a second 3.5 mm cortical screw in eccentric position next to the fracture into the opposite fragment, creating compression across the fracture.
To avoid the risk of shortening the plate has to be attached to the correct fragment first: The first screw should attach the plate to the fragment which forms an angle >90 degrees beneath the plate. The next screw is inserted into the opposite fragment (see also description of correct sequence of screw insertion in step 1b).
5 Insertion of a lag screw topenlarge
Further compression can then be achieved by inserting a lag screw through the plate as perpendicularly as possible to the fracture plane, or through the center of the fracture line.
6 Finish plate fixation topenlarge
Insert the rest of the screws in neutral position.
An interim assessment of alignment, stability and range of motion is advisable after fixation of the ulna. Check results with image intensifier or x-ray.
7 Final assessment top
Finally, after fixing both radius and ulna, 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 results with image intensifier or x-ray.