Conservative techniques of treating fractures of the tibial plateau were common in the past but many of these techniques resulted in poor outcomes and even caused lifelong disability in many cases . A revolution in the operative treatments of these injuries was introduced by the AO Foundation [12, 13], which led to the development of different reconstruction techniques [9, 14], including minimally invasive options through arthroscopy. Because of these new developments, the number of reconstructions of tibial plateau fractures has increased significantly in recent years [9, 13, 14].
A minimally invasive technique using two parallel tension screws was first introduced by Schatzker et al. in 1979 . Since then, minimally invasive arthroscopically-assisted procedures have become the norm in treating fractures like Schatzker Type I and AO Type B1 [16–19] similar to the fractures simulated and evaluated in this study.
This study evaluated 2 minimally invasive reconstruction techniques of lateral tibial plateau fractures, the conventional two-screw osteosynthesis vs. the novel three-screw jail technique.
The results of the present study could not confirm our hypothesis that fixation with a third additional screw as inserted in a jail technique could strengthen structural properties in the reconstruction of lateral tibial plateau fractures better than the conventional technique. However, there are some indications that the jail technique may be a feasible alternative to the conventional osteosynthesis fixation method.
In the single cycle loading tests, significant differences in maximal load were documented. Additionally the jail technique showed a trend for better outcomes in terms yield load, stiffness and displacement though the differences did not reach statistical significance.
In most of the variables measured during the two testing protocols, no statistically significant differences were observed between the two reconstruction techniques.
All reconstructions survived the cyclic loading tests regardless of fixation technique used. This lack of measurable differences suggests that the two reconstructions have similar biomechanical characteristics.
Despite the similarities between the two techniques, the different failure modes in the two reconstructions suggest that the jail technique may hinder the upper lag screws from cutting through the cancellous bone during loading. A possible explanation may be that the lag screws did not absorb the entire axial load force and transmit it to the cancellous bone. Instead, the additional abutment of the jail screw transmitted parts of the axial load into the cortical bone .
This study had several limitations. First, the bone mineral density of the porcine tibia is higher than that of the human tibia [10, 21]. A high bone mineral density could theoretically lead to better biomechanical results. However, cadaver materials from donors who underwent tibial plateau reconstructions are hard to obtain and the low bone mineral density of older donors could lead to weaker biomechanical results.
Second, the experimental set up did not correlate to the physiological conditions in the clinical setting. The tibia was fixed statically and did not allow any movement. The load was applied axially in a worst-case scenario over the reconstructed tibial plateau. Structures such as the menisci were not considered. However, the experimental set up is a well-accepted procedure in orthopedic research [7, 8, 22, 23].
Third, we investigated the material properties of the reconstructions under cyclic loading only at time of surgery. Fracture healing undergoes substantial remodeling during the postoperative period. Therefore, we only investigated the primary stability of the reconstruction techniques.
Fourth, we used a three-screw reconstruction for the jail technique and compared it to a two-screw osteosynthesis in the conventional technique. This was done because a conventional technique using three parallel screws is often not possible in matters of space on the lateral tibial plateau.