Purpose: To compare locking and non-locking single and dual plating constructs in maintaining posteromedial fragment reduction in a bicondylar tibial plateau fracture model. We hypothesized that posteromedial fragment fixation with medial and lateral non-locked constructs would tolerate higher loads than lateral locked constructs alone.

Method: Thirty adult-sized composite tibiae were identically fractured into an AO 41-C1.3 pattern. Six plate constructs were tested:

lateral 8-hole 3.5 mm conventional non-locking proximal tibial plate [CP];

CP + posteromedial 6 hole 3.5 mm limited contact dynamic compression plate [CP + LCDCP];

CP + postero-medial 6 hole 1/3 tubular plate [CP + 1/3 tubular];

8-hole 3.5mm Proximal Tibial Locking plate [PTLP];

8-hole 3.5 mm LCP (locking compression plate) proximal tibia plate [LCP];

9-hole Less Invasive Stabilization System [LISS] plate.

Specimens were cyclically loaded to failure or a maximum load of 4000N. Load at posteromedial fragment failure was recorded.

Results: Fragment failure occurred at the posteromedial fragment first. The CP + 1/3 tubular construct had the highest average load to failure (3040 N). In two instances, the CP + 1/3 tubular construct did not fail under the highest loads applied and was the only construct to have specimens that did not fail by 4000 N. The CP + 1/3 tubular plating construct demonstrated significantly higher load at failure compared with the PTLP (p=0.036), the LCP (p=0.004), and the LISS (p=0.012). The CP + 1/3 tubular group did not demonstrate a significant difference in load at failure when compared with the CP (p=0.093) or the CP + LCDCP (p=0.108). The LISS demonstrated a significantly higher load at failure compared to the LCP (p=0.046) but not to the PTLP (p=0.800).

Conclusion: The posteromedial fragment tolerated higher loads with the CP + 1/3 tubular plate construct. The superiority of the dual plate construct may in part be due to the unreliable penetrance of the posteromedial fragment by the laterally applied locking screws.