Monteggia equivalent, oblique fracture of ulna: open reduction, plate and screw fixation
Plating is the standard technique for treating forearm fractures in adults and is therefore best considered for skeletally mature or nearly mature children.
Children with open physes have thick active periosteum favoring stability and rapid healing with the ESIN method. Where such techniques are unavailable plating may be used in younger children.
If technically possible, ESIN is biologically favored. If plating is used, soft-tissue and periosteal stripping should be minimized.
Plating of oblique or spiral forearm shaft fractures
Plating of pediatric forearm shaft fractures follows the technique for plate fixation in adults.
For oblique or spiral forearm shaft fractures, interfragmentary compression can be achieved by one of the following techniques:
Lag screw outside the plate
Lag screw through the plate
Compression plate with consecutive lag screw through the plate
This results in absolute fracture stability.
Large wedge fragments may be fixed to one of the main segments before plate fixation with a lag screw, placed through or outside the plate.
For unstable multifragmentary forearm shaft fractures, bridge plating may be applied. This results in relative fracture stability.
Instruments and implants
A small fragment set consists of:
2.7 or 3.5 mm plates and screws
2.7 or 3.5 mm insertion set
Compression by lag screw
For interfragmentary compression a lag screw can be inserted either through a plate hole (1) or separate from the plate (2).
Axial compression results from eccentric screw (load screw) insertion with compression plates.
The ulnar plate can be positioned under the extensor carpi ulnaris (A), under the flexor carpi ulnaris (B), or in the interval between extensor and flexor carpi ulnaris (C).
With a more proximal fracture it can be more difficult to place the plate underneath the extensor muscle.
With more distal fractures, plates should be placed in the interval between the extensor and flexor carpi ulnaris (C).
Plating the tensile (subcutaneous) aspect of the ulna (C) is biomechanically preferable, but plate prominence can cause irritation.
Plates in positions A or B are covered by the muscle compartment and avoids this complication.
In the following procedure, the plate positioned on the subcutaneous border of the ulna (C) is illustrated.
The ulna is exposed by the direct approach between the flexor and extensor muscle compartments.
Reduction and fracture stability in children
Children’s periosteum is thick, tough tissue and is often intact on the concave (compression) side of a fracture.
Reduction maneuvers should be gentle to take advantage of the stability of the intact periosteum.
Exaggeration of the fracture deformity may be required to loosen the periosteum and allow for gentle reduction.
In pediatric fractures there is often a combination of patterns of bone failure. Residual plastic deformity may prevent anatomical reduction of some of the fracture edges. Provided the alignment of the bone is anatomical and overall reduction is stable it is not necessary to perfectly reduce the entire fracture.
Reduce the fracture anatomically, using a reduction forceps on each main fragment.
The use of blunt, as opposed to pointed, reduction forceps can be helpful, particularly if greater forces are required.
Pearl: twisting a reduction forceps
Reduction of overlapping oblique fractures can be achieved by twisting a reduction forceps, thereby lengthening the fracture.
Maintaining fracture reduction
Maintain the fracture reduction with pointed reduction forceps.
Place the forceps such that it will not interfere with the planned plate position.
4. Plate length and number of screws
In the forearm, in addition to any lag screw, three bicortical plate screws are suggested in each main fracture fragment due to the high torsional stresses.
Not every plate hole needs to be occupied by a screw.
In oblique or spiral forearm shaft fractures an empty plate hole may be necessary at the level of the fracture to introduce a lag screw.
5. Fixation – lag screw as primary fixation device outside plate
If the fracture morphology dictates that the interfragmentary lag screw be positioned separate from the plate, the plate then acts as a neutralization plate and axial compression should not be applied.
Insertion of lag screw
Insert a lag screw of appropriate length as perpendicular to the fracture plane as possible.
Maintain the reduction by leaving the pointed reduction forceps in situ.