Summary

Dynamic radiostereometry evaluation of Lateral Plasty addition to ACL Reconstruction

Abstract

Background

Lateral extra-articular tenodesis (LET) in the context of Anterior Cruciate Ligament (ACL) reconstruction are adopted to better control anterolateral knee instability in patients with high-grade pre-operative pivot-shift. However, several authors believe these procedures are harmful to knee cartilage since they cause lateral compartment over-constraint in daily life motion.
Hypothesis/Purpose: The first aim of the present study was to identify kinematical differences between ACL-reconstructed knees with anatomic SB and SB plus lateral plasty (SBLP) techniques during the execution of an active under weight-bearing activity. The secondary aim was to compare these post-surgery kinematical data to the ones of the same knees before ACL reconstruction and of healthy contralateral knees, in order to investigate if ACL surgery was able to restore physiological knee biomechanics during squat execution. The hypotheses were that I) SBLP technique allows a better restoration of internal-external knee rotation than SB and that II) ACL reconstruction does not fully restore physiological knee biomechanics regardless of the technique.

Methods

Thirty-two patients (42 knees) were included in the study and divided in ACL-injured (n=32), anatomical SB (n=9), SBLP (n=18), and healthy knee (n=10) groups. Patients were asked to perform a single leg squat before surgery and at minimum 18 months of follow up. Knee motion was determined using a validated model-based tracking process that matched subject-specific MRI bone models to dynamic biplane radiographic images, under the principles of Roentgen Stereophotogrammetric Analysis (RSA). Data processing was performed in a specific software developed in Matlab. Internal-External (IE), Varus-Valgus (VV) rotations, and Anterior-Posterior (AP) and Medio-Lateral (ML) translations were compared among the groups.

Results

No kinematical differences were found between SB and SBLP groups (p>0.05). A more tibial medial position (p<0.05) of the ACL-injured group was during the entire motor task and also persisted after ACL when compared to the healthy group. Differences in IE and VV were found between Injured ACL and healthy groups.

Conclusion

The absence of rotational differences between techniques excluded the existence of knee over-constraint in the presence of an SBLP procedure during the execution of a single leg squat. Nonetheless, ACL reconstruction failed in restoring knee biomechanics regardless of the surgical technique.