Bony Anatomy
- The tibial plateau is the proximal weight-bearing surface of the tibia and articulates with the medial and lateral distal femoral condyles.
- The intercondylar eminence is positioned between the medial and lateral plateau and does not articulate directly with the femur.
- The lateral plateau is convex in both the coronal and sagittal plane.
- The medial plateau is concave in both the coronal and sagittal plane.
- The articular surface of the lateral plateau is proximal to the medial plateau; an approximate 3-degree varus angle exists between the shaft of the tibia and a line drawn across the articular surface in the nonarthritic knee.
- A posterior slope exists to the proximal tibial plateau that measures approximately 8 degrees.1
Radiographic Anatomy
Anterior-Posterior (AP) View
- On the standard AP view of the knee, the patella is centered between the medial and lateral femoral condyles; there is approximately one-third to one-half overlap of the fibular head with the lateral edge of the proximal tibia on this view (Fig. 23-1A and B).
- Excessive external rotation: the patella overlies the lateral distal femoral condyle, and there is increased overlap of the proximal tibia and fibula.
- Excessive internal rotation: the patella overlies the medial distal femoral condyle, and there is little to no overlap of the proximal tibia and fibula.
- Excessive external rotation: the patella overlies the lateral distal femoral condyle, and there is increased overlap of the proximal tibia and fibula.
Figure 23-1 A. Standard AP view of lateral split depression lateral plateau fracture. B. Standard C-arm position for true AP of the tibial plateau.
AP with 10-Degree Caudal Tilt
- An AP view of the proximal tibia with 10 degrees of caudal tilt provides an image parallel to the joint surface; this can be particularly useful fluoroscopically in assessment of articular reduction (Fig. 23-2A and B).
Figure 23-2 A. AP view with 10 degrees of caudal tilt; beam is nearly parallel to tibial plateaus. B. Caudal tilt C-arm position used to efface the true articular joint line view of the tibial plateau.
Lateral View
- On the standard lateral view of the knee, the posterior aspect of the femoral condyles is perfectly superimposed. The uninjured lateral plateau is seen proximal to the medial plateau (Fig. 23-3).
Figure 23-3 Standard lateral view of lateral split depression lateral plateau fracture. In this image, lateral plateau is depressed (yellow arrow) and is lower than the uninjured medial plateau (blue arrow).
Modified Lateral Views
- On the lateral view, the leg can be brought into adduction (toward the midline/away from the x-ray source) to elevate the medial plateau into view (Fig. 23-4A and B).
- Similarly, the leg can be brought into abduction (away from the midline/toward the x-ray source) to elevate the lateral plateau into view (Figs. 23-5A and B and 23-6).
Figure 23-4 A. Bicondylar plateau fracture; leg is adducted toward image intensifier, elevating medial plateau into view. B. Depiction of leg adduction relative to the true C-arm lateral which is used to profile the medial tibial plateau fracture/reduction.
Figure 23-5 A. Bicondylar plateau fracture; leg is abducted away from image intensifier, elevating lateral plateau into view. B. Depiction of leg abduction relative to the true C-arm lateral which is used to profile the lateral tibial plateau fracture/reduction.
Figure 23-6 Posterior view of a typical bicondylar tibial plateau fracture pattern. The lateral split depression results in widening of the lateral tibial joint line and an increased posterior slope. The normal gentle convex shape of the lateral tibial articular surface is lost due to the joint depression. The posteromedial coronal shear fragment demonstrates an unstable fragment prone to articular step-off and may be of varying size with tibial eminence or posterior lateral joint extension.
Preoperative Imaging
- Standard AP and lateral radiographs should be obtained prior to any advanced imaging (Figs. 23-7 and 23-8).
- Following evaluation of the plain injury radiographs, a determination should be made as to whether an external fixator will be placed for fracture or soft tissue reasons.
- A computed tomography (CT) scan is commonly obtained following plain radiographs and should be obtained after external fixation, if applicable.
- Axial, coronal, and sagittal CT reconstructions are useful to for fracture classification and preoperative planning2 (Figs. 23-9–23-11).
- If an external fixator is applied, connecting clamps should be placed so they do not impede AP or lateral fluoroscopy of the knee and proximal tibia. Schanz pins should also be placed away from the joint surface and intended location of fixation hardware (Figs. 23-12 and 23-13).
Figure 23-7 Standard AP (7) and lateral (8) plain radiographs of a split depression lateral plateau fracture.
Figure 23-8 Standard AP (7) and lateral (8) plain radiographs of a split depression lateral plateau fracture.
Figure 23-9 Axial (9), coronal (10), sagittal (11) CT scan images of patient with split depression lateral plateau fracture.
Figure 23-10 Axial (9), coronal (10), sagittal (11) CT scan images of patient with split depression lateral plateau fracture.
Figure 23-11 Axial (9), coronal (10), sagittal (11) CT scan images of patient with split depression lateral plateau fracture.
Figure 23-12 AP (12) view of knee showing bar-to-bar clamp away from visualization of joint line. AP (13) view of the tibia demonstrating Schanz pin placement away from fracture and future implants.
Figure 23-13 AP (12) view of knee showing bar-to-bar clamp away from visualization of joint line. AP (13) view of the tibia demonstrating Schanz pin placement away from fracture and future implants.
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