1 Principles topenlarge
B2-type fractures are intraarticular, therefore they need anatomical reduction.
The plate in this procedure acts as a buttress to neutralize the axial forces on the tibial plateau and protects the weakened or fenestrated (windowed) medial cortex from failing.
The operative procedures for lateral condylar fractures (B2.1- and B2.2-type fractures) and medial condylar fractures (B2.3- type fractures) are comparable. A lateral condylar fracture treatment (B2.1- and B2.2-type fracture) is shown here.
2 Reduction topenlarge
Reduction of the impacted fragment(s)
Make a window in the anterolateral cortex of the tibial condyle lateral to the tibial tuberosity and about 5 cm distal to the joint line.
Introduce a curved impactor and elevate the impacted bone until the articular fragments are reduced and the joint is congruent again. Slight overcorrection will compensate for a slight loss in height of the reduced articular fragment(s) which may occur following surgery.
The articular surface may be inspected directly through a standard submeniscal articular exposure or by means of an arthroscope inserted through a medial portal.
Temporary fixation of the elevated articular fragments with K-wires may be helpful.
Filling of defect
The defect which is created once the impacted articular fragments are reduced must be filled with an autologous cancellous autograft or a corticocancellous block graft to support the elevated fragments. Alternatively the use of bone substitutes may be considered.
3 Fixation topenlarge
K-wire fixation is useful in maintaining the articular fragments reduced until the metaphyseal defect is bone grafted.
Positioning of the knee is important for correct reduction and fixation. If the knee has a valgus injury, then the knee should be held with more varus positioning to ensure a good reduction. If the knee has a varus injury (medial condyle) then valgus positioning during reduction is important.
In the purely depressed B2-type fracture, the plate acts as protection for the weakened fenestrated lateral cortex.
A raft plate is both stronger and more efficient in supporting the articular surface. Especially in comminuted and osteoporotic cases.
The plate and screws are placed perpendicular to the longitudinal and axial force in the tibial plateau fracture, resisting the displacement forces.
4 Fixation topenlarge
This case represents a B2.2 fracture with a nondisplaced split in the cortex as seen on the CT transverse cuts.
It has been reduced and fixed with both a buttress plate with raft screws and raft function (to protect the cortical window) and subchondral raft screws immediately below the joint to supplement the fixation as well. This construct of hardware is thought to be the best to maintain reduction in these pure impaction injuries.