Bony Anatomy
- The tibia is a long bone with a neutral coronal and sagittal axis but occasionally prone to variations in the tibial bow (where extreme variants of bow may prevent the use of an intramedullary nail).
- Triangular in shape, the anterior tibial crest is useful in determining alignment/rotation.
- There are wide proximal and distal metaphyseal regions where associated fractures require diligent reduction sequences to prevent malunion (especially with intramedullary nailing). In contrast, the tibial diaphysis is more consistently tubular with thick cortices and an isthmus (located within the distal third) that limits nail diameter.
- Adequate AP and lateral views of the tibial plateau must be obtained to achieve proper nailing start points (medial to the lateral tibial spine on AP view and just at the anterior edge of the articular surface on the lateral view).
Radiographic Anatomy
AP View of the Proximal Tibia
- Proper rotation must be obtained by demonstrating the patella centered over the femoral condyles, one-third fibula overlap at the proximal tibiofibular joint, and well-visualized tibial spines and plateau.1
- Correction of apex anterior and valgus deformity in proximal tibia fractures may be necessary with closed or percutaneous methods to assist in adequate imaging and fracture reduction (Fig. 24-1).
Figure 24-1 Post-reduction AP and lateral imaging of a proximal third tibial shaft fracture.
Lateral View of the Proximal Tibia
- Proper rotation is confirmed by overlap of the femoral condyles and tibial plateau cortices (Fig. 24-2).
- It is important to ensure that the tibial tubercle and anterior articular margin are well visualized when intramedullary fixation is chosen as the optimal start point is just at the anterior articular edge.
Figure 24-2 Overlap of tibial articular surfaces and femoral condyles is key to a proper lateral knee image.
AP View of the Distal Tibia/Fibula
- This image is utilized for proper guidewire placement (centered in the tibia at physeal scar), assessment of rotation, implant placement, and assessment of interlock screw length and ankle alignment (Fig. 24-3).
- The mortise view of the ankle has 15-degree internal rotation from an AP image of the knee. This can be useful to assist in rotational assessment. If syndesmosis is intact, tibiofibular overlap, the incisura, and fibular length (using dime sign) can all be used as markers to aide in fracture reduction. Syndesmotic stress exams should be performed in distal third tibial fractures (Fig. 24-4).
Figure 24-3
Figure 24-4 Baseline (left) and stress (right) mortise ankle films after fixation of tibia and fibula fractures.
Lateral View of the Distal Tibia
- A proper lateral of the ankle should demonstrate a perfect “dome” lateral projection of the talus, which depicts a lateral of the tibial physeal scar and about 50% tib/fib overlap. This is important for the perfect circle distal interlock technique and to ensure adequate reduction, rotation, and ankle alignment (Fig. 24-5).
Figure 24-5 Note that post-fixation hardware can occasionally obscure visualization. In these instances, obliques may be utilized for confirmation of screw length and anatomic reduction.
Preoperative Imaging
- AP and lateral imaging of the entire tibia and fibula is critical for assessing the overall deformity, comminution, and fracture pattern. These images are the mainstay for preoperative planning (Figs. 24-6 and 24-7).
- Dedicated XR imaging of the knee and ankle is important to determine intra-articular extension, isolated posterior malleolus fractures (oblique or spiral distal tibia fractures),2 or other associated pathology (Figs. 24-8 and 24-9).
- Consider CT imaging to assess for occult articular fractures, or limited cuts to determine alignment and rotation. CT imaging may also assist in preoperative planning (reduction and fixation techniques) (Figs. 24-10 and 24-11A and B).
- Consider AP and lateral imaging of contralateral leg with measurement device to assess length, alignment, and rotation for comminuted or length unstable injuries.
- Calibrated diameter measurements of orthogonal views of the isthmus can aid preoperative planning nail diameter.
- Consider CT imaging to assess for occult articular fractures, or limited cuts to determine alignment and rotation. CT imaging may also assist in preoperative planning (reduction and fixation techniques) (Figs. 24-10 and 24-11A and B).
Figure 24-6 Note that implants above or below may influence surgical planning and implant selection. In this case, the tibial arthroplasty component prevented optimal access for tibial nail insertion in this osteoporotic fracture, thereby necessitating open reduction internal fixation and a neutralization plate protecting the remainder of the tibia.
Figure 24-7 Full length tibia XR’s demonstrating total knee arthroplasty hardware limiting the approach for a intramedullary nail. In these instances, minimally invasive reduction and plate fixation may be more easily applied.
Figure 24-8 Note the comminution to this proximal tibia fracture having both a plateau and shaft component. This was amenable to compression and plate fixation of the plateau with nail stabilization of the diaphysis.
Figure 24-9 Note the sequence of fixation of the articular surface, followed by independent treatment of the tibial shaft fracture with an intramedullary implant.
Figure 24-10 Despite a distal tibial fracture component, careful assessment of this CT scan demonstrated insight for the proper clamp vectors for reduction and fixation with distal lag screws and intramedullary nail stabilization.
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