Abstract
Background:
Posterolateral tibial fractures (PLTFs) are common concomitant injuries of an anterior cruciate ligament (ACL) rupture resulting in a loss of osseous support of the posterior horn of the lateral meniscus. It is unknown if the additional treatment of the PLTF brings a benefit in the treatment of symptomatic ACL-deficient knees.
Purpose:
To evaluate the kinematic effects of various reconstruction states in an ACL-deficient knee with PLTF, compared to the native knee.
Study Design:
Controlled laboratory study.
Methods:
Eight unpaired knees were tested using a 6 degrees of freedom robotic system equipped with a force-torque sensor in the following states: intact, ACL-deficient, ACL-deficient with PLTF, ACL reconstruction (ACLR) with PLTF, ACLR with lateral extra-articular tenodesis (LET) and PLTF, and ACLR with reconstructed PLTF states. Simulated laxity tests were performed at 0°, 30°, 60°, and 90° of flexion under constant loading: anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER). The simulated pivot-shift (PS) test was performed at 0°, 15°, 30°, and 45° of flexion. A linear mixed model with post hoc Bonferroni corrections for multiple comparisons was performed for statistical analysis.
Results:
Compared with the native state for ATT in 0° to 90°, no ACLR state showed any significant differences. ACLR with reconstructed PLTF compared to the native state presented a significant increase in IR at 60°. ACLR with LET presented a significant reduction of IR at 30° and 90° compared to the native state. In the simulated PS test, the ACLR with reconstructed PLTF showed a significantly higher ATT compared with the native state at 15° to 45°. In comparison, the ACLR with LET showed no significant differences to the native state at 0° to 45°. In line with clinical and biomechanical literature, differences in ATT ≥3 mm and rotational changes ≥3° were considered clinically meaningful thresholds.
Conclusion:
ACLR combined with LET provides superior restoration of anterior translational and rotational stability compared to ACLR alone or ACLR with PLTF repair, particularly in the PS test. Based on this biomechanical study, adding PLTF repair to ACLR for PLTFs ≤3 mm does not improve knee stability compared to standard ACLR alone.
Clinical Relevance:
From a biomechanical point of view, there is no indication that PLTF fragments ≤3 mm should be repaired when performing ACLR.
