gms | German Medical Science

Objectives: A novel technique called Dynamic Intraligamentary Stabilization (DIS) for treatment of acute anterior cruciate ligament (ACL) tears by using the Ligamys^® implant system creates immediate joint stability close to the preinjury level. The aim of this study was to biomechanically investigate the course of anteroposterior (AP) translational knee stability during the early post-operative phase. It is hypothesized that AP translational knee stability is fully maintained over a simulated rehabilitation period of 50'000 gait cycles.

Methods: Eight fresh-frozen human cadaveric knee joints were subjected to 50'000 cycles of 0°-70° flexion-extension movements in a custom-made test setup using a MTS 858 Bionix mechanical testing system (Figure 1 [Fig. 1]).

AP translational knee stability was assessed with simulated Lachman/KT-1000 testing in 0°, 15°, 30°, 60° and 90° of flexion in knee joints treated with DIS at cycle numbers 0, 100, 500, 2500, 10'000, 25'000, 50'000 and after explantation of the DIS device. Statistical analysis was performed using the Wilcoxon Signed-Rank Test with Bonferroni correction for multiple comparisons. The level of significance was set at p=0.05.

Results and Conclusion: AP translation increased non-significantly for all degrees of flexion over the whole cyclic test. The highest increase between cycle numbers 0 and 50'000 - 1.4 mm on average - was observed with a trend towards significance (p=0.078) in 30° flexion. For all flexion angles the AP translation after 50'000 cycles remained lower compared to the state after explantation of the DIS device (Table 1 [Tab. 1]).

The dynamic intraligamentary stabilization provides AP translational knee stability close to the immediate post-operative level over a simulated rehabilitation period of 50'000 gait cycles and therefore supports the ACL during biologic healing.