Objectives: We hypothesized that a constant radiographic relationship exists between the lateral tibial and femoral condyles and that no side-to-side variation exists.
Methods: We reviewed anteroposterior x-rays of 217 uninjured adults ages 18-65, Included 109 unilateral and 108 bilateral radiographs with no or minimal osteoarthrosis (Kellgren-Lawrence grades 0-1). The perpendicular distance between the lateral-most margins of the tibial plateau articular surface (A) and the lateral femoral epicondyle (B) and the lateral femoral condyle articular surface (C) was measured in millimeters (mm). Medial and lateral measurements to point (A) were recorded as (-) and (+), respectively. First, the average of measured distances in all unilateral knees and randomly selected either right or left knees from the bilateral group (n = 217) was calculated. Comparison was made between both sexes. Next, A-B and A-C distances were compared between right and left knees in the bilateral group (n = 108) to find any significant difference (2-tailed t test, alpha = 0.05).
Results: The average A-B distance was 0.60 ± 2.40 mm (-4.82 to +6.49 mm). The mean A-C distance was -3.96 ± 2.07 mm (-8.51 to +3.98 mm). No significant difference was found between A-B and A-C distances between males (0.40 ± 2.62 mm and -3.91 ± 2.05 mm) and females (0.70 ± 2.28 mm and -3.99 ± 2.09 mm). Similarly, no significant difference was found between A-B and A-C distances between right (1.08 ± 2.31 mm and -3.90 ± 1.73 mm) and left knees (0.90 ± 2.38 mm and -4.31 ± 1.7 mm). Concordance coefficient for interobserver and intraobserver reliability showed substantial agreement.
Conclusion: In conclusion, this study provided a "normal" range for the relationship of the proximal lateral tibial plateau relative to the lateral femoral condyle. The lateral femoral epicondyle is generally aligned with the lateral tibial articular margin. The relationship between the lateral tibial plateau, lateral femoral epicondylar surface, and lateral femoral articular surface is constant from side to side. This technique is reproducible in the setting of fracture, and templating off of the contralateral uninjured knee may be beneficial in tibial plateau fracture surgery.