Linda Bühl (Basel / CH), Dr. Sebastian Müller (Basel / CH), Dr. Corina Nüesch (Basel / CH), PD Dr. Christian Egloff (Basel / CH), Prof. Annegret Mündermann (Basel / CH)
Abstract-Text (inkl. Referenzen und Bildunterschriften)
Introduction
Leg mechanics are altered after anterior cruciate ligament reconstruction (ACL-R)1. Although proponents of ACL-preserving InternalBrace-augmented repair (ACL-IB) believe that knee mechanics can be restored with this technique2, there is currently no evidence.
Aim
To compare landing mechanics between the legs in ACL-IB and ACL-R, and between patients (involved) and controls (non-dominant leg).
Method
Twenty-nine ACL-IB (sex 13m; age 36.8 years; BMI 24.7kg/m²; 25 months post surgery), 27 ACL-R (hamstring autograft; 13m; 37.0 years; 25.0 kg/m²; 24 months post surgery) and 29 controls (13m; 37.0 years; 23.4 kg/m²) completed single-leg hops for maximum forward distance. Maximum sagittal joint angles, moments and vertical ground reaction forces, and joint work contributions during landing (initial contact to peak knee flexion) were analyzed using motion capture. Leg differences within patients and between groups were tested using t-tests and analysis of variance (Tukey post hoc; p=.05, respectively). Only significant differences with a 95% confidence interval (CI) not overlapping with the 95%CI of the leg difference within controls (i.e., greater than expected in healthy subjects) were deemed meaningful and reported.
Results
Only in ACL-IB the operated knee had a meaningful lower maximum flexion angle (-8.3°; P=.001) and moment (-0.6 Nm/kg; P<.001) than the uninvolved knee, and a meaningful lower maximum knee flexion moment than controls (-0.5 Nm/kg; p=.020; Tab.1). There were no differences in the involved legs between ACL groups (Tab.1).
Conclusion
The lack of meaningful differences between ACL patients does not preclude that some patients have abnormal landing mechanics in the involved leg. In addition, ACL-IB does not appear to achieve normal landing mechanics. It is still unclear how the observed differences after ACL-IB relate to the risk of (re)injury or joint disease.
1Kotsifaki et al. Br J Sports Med 2020
2Rilk et al. Arthrosc Tech 2023