Summary

This study confirms that ITB and Kaplan Fibers are stabilizer of tibial IR in an ACL deficient knee

Abstract

Introduction

The contribution of the proximal (PFK) and distal (DFK) Kaplan fibers, distal extensions of the ilio-tibial band (ITB), is poorly evaluated. The objective was to investigate the involvement of the ITB, PFK and DFK in the control of the rotational stability in ACL deficient knees.

Material & Methods
This was a biomechanical study including 11 cadaveric knees. Using a 3D optoelectronic system (Motion Analysis®), full knee kinematics (0 to 90°, in Internal Rotation (IR) set at 5 Nm) as well as antero-posterior translatios at 30 and 90° of flexion (AP30, AP90) were analysed. Sequential sections were performed. After the analysis of the kinematics of the intact knee, sections of the ACL, the Kaplan Fibers and the ITB were performed successively. The sections of PKF and DKF were randomised.

Results

The combined section of PFK and DFK resulted in a significant increase in IR (p<0.05), starting at 30° of flexion. DKF section resulted in a greater increase in IR than PFK section (p<0.05). There was a significant increase in IR laxity after the ITB section over the entire kinematic profile (p<0.05). The respective or combined PFK and DFK sections had no influence on AP30 and AP90 translation (p>0.05), while the ITB section increased the AP laxity at 30 and 90° of flexion (p<0.05).

Conclusion

This study confirms that ITB is a major stabilizer of tibial IR in an ACL deficient knee. KF, especially DKF, reinforces this anti-rotational action. By establishing a connection with the distal femur, they appear to reinforce the action of the ITB. This additional rotational laxity associated with combined ACL, ITB and/or KF injuries suggests that their diagnosis should be included in the treatment algorithm by combining an extra-articular procedure with intra-articular reconstruction.