Biomechanical analysis of dual versus lateral locked plating in elderly bicondylar tibial plateau fractures: Does medial comminution matter?

OBJECTIVE

To assess dual plating versus lateral locked plate fixation of bicondylar tibial plateau fractures in an elderly cadaveric model with and without medial bone loss

PARTICIPANTS

10 pairs of elderly (range 78-93 years of age) fresh frozen tibias.

INTERVENTION: Bicondylar tibial plateau fractures were created reproducing AO/OTA 41 C1 (without medial bone loss) and C2 fractures (with medial bone loss). Cadavers were randomized to 4 different groups. Groups 1 and 2 were 41 C1 fractures and fixated with either dual or lateral plating, respectively. Groups 3 and 4 were fixated in a similar fashion with medial metaphyseal bone loss (41 C2 fracture) with dual plating Group 3 and lateral plating group 4. Lateral plating consisted of a 3.5 mm 5-hole lateral plate (ALPS, ZimmerBiomet) with 6 bicortical locking screws proximally and two diaphyseal screws. Dual plating groups underwent lateral plating and additional 3.5 mm 5-hole posteromedial 1/3 tubular plate (ZimmerBiomet) placed at the apex of the fracture with two shaft screws and one unicortical screw proximally. Specimens were tested in a Mechanical Testing System (MTS) machine loading both condyles.

OUTCOME MEASUREMENTS: Specimens were loaded to 300 N and coronal alignment obtained. Specimens were then cycled from 100 N to 700 N for 5000 cycles at 2 Hz. Average axial displacement, maximal displacement, average force and coronal alignment after 5000 cycles were recorded. Lastly, force to failure was recorded at 100 N/sec.

RESULTS

Mean axial displacement was 4.21 mm ranging from 3.12 mm in group 1 to 5.92 mm in group 4 (P = 0.51). Failure force averaged 3340 N ranging from 4342 N in group 1 to 2433 N in group 4 (P = 0.36). Maximal displacement ranged from 3.69 mm in group 1 to 7.37 mm in group 4 (P = 0.21). Change in coronal alignment ranged from 0.98° in group 1 to 1.97° in group 4 (P = 0.45). No statistically significant difference was noted between all four groups for all data points.

CONCLUSION

The results of this study demonstrate that a lateral locked plate may offer an alternative means of fixation in AO/OTA 41 C1 and C2 fractures.