Summary
Patients with ACL rerupture feature significantly higher internal rotation laxity of the knee compared to primary ACL rupture. The extend of rotational laxity can be quantified by instrumented measurements.
Abstract
Background
There is a lack of precise measurement methods to determine the indication for reconstruction of the anterior lateral ligament (ALL).
Purpose
The aim of the current study was to objectify the rotational laxity after primary anterior cruciate ligament (ACL) rupture and ACL re-rupture after ACL reconstruction by instrumented measurement. It is hypothesized that knees with recurrent instability feature a higher internal rotation laxity compared to knees with a primary rupture of the native ACL.
Study Design: cross sectional study, Level of evidence III
Methods
In a clinical comparative study of successive patients with primary ACL rupture and ACL re-rupture were evaluated clinically and by instrumented measurement of the rotational and antero-posterior laxity with the Laxitester® and the KT1000®, respectively. Clinical examination comprised IKDC 2000, Lysholm Score, and Tegner Activity Scale. Power calculation and statistical analysis were performed (p-value <0.05).
Results
Twenty-four patients with primary ACL rupture and 23 patients with ACL Re-rupture were included. There was no significant side-to-side difference in anterior translation. In contrast, a significant side-to-side difference of the internal rotation laxity was found with a mean of 8.7±8.6° in patients with ACL re-rupture compared to 3.6±4.5° in patients with primary ACL rupture (p=0.014). A side-to side difference of internal rotational laxity =10° was found significantly more frequent in re-ruptures (53.6%) compared to primary ruptures (19.4%; p?0.001). A highly significant relationship between the extent of the pivot-shift phenomenon and side-to-side difference of internal rotation laxity was demonstrated (p<0.001). IKDC 2000 subjective (56.4±7.8 vs. 50.8±6.2; p=0.01) and Tegner Activity Scale (p=0.02) revealed significantly better scores in patients with primary ACL tear compared to patients with ACL re-rupture. No significant differences were seen in the Lysholm Score (p=0.78).
Conclusions
Patients with ACL re-rupture feature significantly higher internal rotation laxity of the knee compared to primary ACL rupture. The extend of rotational laxity can precisely be quantified by instrumented measurements. This can be an aid for the indication of an anterolateral ligament graft in revision surgery of the ACL.