Minimally invasive reconstruction of lateral tibial plateau fractures using the jail technique: a biomechanical study

Abstract

Background: This study described a novel, minimally invasive reconstruction technique of lateral tibial plateau fractures using a three-screw jail technique and compared it to a conventional two-screw osteosynthesis technique. The benefit of an additional screw implanted in the proximal tibia from the anterior at an angle of 90° below the conventional two-screw reconstruction after lateral tibial plateau fracture was evaluated. This new method was called the jail technique.

Methods: The two reconstruction techniques were tested using a porcine model (n = 40). Fracture was simulated using a defined osteotomy of the lateral tibial plateau. Load-to-failure and multiple cyclic loading tests were conducted using a material testing machine. Twenty tibias were used for each reconstruction technique, ten of which were loaded in a load-to-failure protocol and ten cyclically loaded (5000 times) between 200 and 1000 N using a ramp protocol. Displacement, stiffness and yield load were determined from the resulting load displacement curve. Failure was macroscopically documented.

Results: In the load-to-failure testing, the jail technique showed a significantly higher mean maximum load (2275.9 N) in comparison to the conventional reconstruction (1796.5 N, p < 0.001). The trend for better outcomes for the novel technique in terms of stiffness and yield load did not reach statistical significance (p > 0.05). In cyclic testing, the jail technique also showed better trends in displacement that were not statistically significant. Failure modes showed a tendency of screws cutting through the bone (cut-out) in the conventional reconstruction. No cut-out but a bending of the lag screws at the site of the additional third screw was observed in the jail technique.

Conclusions: The results of this study indicate that the jail and the conventional technique have seemingly similar biomechanical properties. This suggests that the jail technique may be a feasible alternative to conventional screw osteosynthesis in the minimally invasive reconstruction of lateral tibial plateau fractures. A potential advantage of the jail technique is the prevention of screw cut-outs through the cancellous bone.

Figure 1

The two different reconstruction techniques used in this study. The schematic drawing shows the two techniques used in this study; a) conventional reconstruction using a lateral two-screw osteosynthesis; b) jail technique.

Figure 2

The experimental setup. The figure shows the porcine model with osteotomy of the lateral tibial plateau set up in the material testing machine Palacos® - spacer.

Figure 3

The load displacement curve. This figure shows the load displacement from the recorded data during the testing protocols. The ordinate (y-axis) is the measured displacement recorded in mm. The abscissa (x-axis) shows the expressed load as force in newtons (N).

Figure 4

The failure modes. The figures show the failure mode in the two reconstructions; a) conventional reconstruction using a lateral two-screw osteosynthesis; b) jail technique using two lateral screws plus a jail screw. In Figure 4a, a screw was displaced as it cut through the bone. In Figure 4b, the lag screws were bent but no cut-out was observed.