How to Use Full-Length Standing Radiographs to Measure Posterior Tibial Slope and Anterior Tibial Translation.

Background: Increased posterior tibial slope (PTS) and anterior tibial translation (ATT) result in a higher risk of anterior cruciate ligament reconstruction failure. Accurate measurement of PTS and ATT is essential to guide surgical planning in these patients. Full-length weightbearing lateral tibial radiographs yield the most accurate measurement of PTS and ATT compared with short-film tibial radiographs, computed tomography scans, and magnetic resonance imaging. Indications: We aim to demonstrate a validated, reproducible technique in a stepwise fashion to accurately measure PTS and ATT using full-length weightbearing lateral tibial radiographs. This presentation adds to the field by offering a precise measurement technique for surgical planning purposes. Technique Description: To precisely measure PTS using a full-length weightbearing lateral tibial radiograph, first, perpendicular lines are drawn 5 cm proximal to the ankle joint and 5 cm distal to the knee joint. A line is then extended proximally from the center of the perpendicular line near the ankle through the center of the perpendicular line near the knee, and then extended up to the tibial articular surface. Next, a line is drawn along the medial tibial plateau. The angle measured between these 2 lines is subtracted from 90° to yield the PTS.To precisely measure ATT, a line is drawn along the diaphysis of the tibia and approximated to the posterior aspect of the proximal tibia. Then, another parallel line is drawn and approximated to the posterior aspect of the distal femur. The distance between these lines is measured to yield anterior tibial translation. Results: We measured a PTS of 14.2° and an ATT of 12.6 mm using the technique described in this presentation. Discussion/Conclusion: This technique demonstrates an accurate and reproducible method to precisely measure PTS and ATT using full-length weightbearing lateral tibial radiographs. This technique yields greater accuracy in PTS and ATT than other imaging modalities. As a result, there is a direct benefit for surgical planning when using this technique. Patient Consent Disclosure Statement: The author(s) attests that consent has been obtained from any patient(s) appearing in this publication. If the individual may be identifiable, the author(s) has included a statement of release or other written form of approval from the patient(s) with this submission for publication.