Summary

Failed ACL reconstruction patients had nearly double the magnitude of rotatory knee instability as patients with primary ACL injury.

Abstract

Introduction

Rotatory knee stability is emerging as an important indicator to predict positive outcomes after anterior cruciate ligament (ACL) reconstruction. The aim of this study was to perform a comparative analysis of quantitative rotatory knee instability between patient cohorts undergoing revision ACL reconstruction and primary ACL reconstruction.

Methods

Seventeen patients undergoing revision ACL reconstruction between 2014-2015 were prospectively enrolled in this study (27.6 ±10.4 years, 5 female). They were matched with 17 primary ACL reconstruction patients (27±7.18 years, 9 female) based on associated injury pattern (9 medial meniscus (MM) tears, 1 lateral meniscus (LM) tear, 6 with tears of both menisci, and 1 with no meniscus tear in each group). Using validated methods, quantitative measurements of knee instability were performed while patients were under general anesthesia. A Rolimeter was used to quantify Lachman test results. Image analysis technique and inertial sensors were used to quantify anterior translation of the lateral compartment and acceleration of the tibia during the pivot shift test, respectively. A two-tailed paired t-test was used to analyze the difference between means of continuous variables, a chi-square test was used to analyze the difference between frequencies of categorical variables, and statistical significance was set at p<0.05.

Results

Concomitant procedures performed in the revision group were as follows: 9 meniscal repairs (6 MM, 1 LM and 2 both), 4 partial meniscectomies, 3 meniscal transplants (2 MM and 1 LM), 1 extra-articular tenodesis, and 1 high tibial osteotomy. In the primary group, there were ten meniscal repairs (8 MM, 2 both) and 5 partial meniscectomies (2 MM, 1 LM, and 2 both). There were no significant differences in concomitant procedures between groups. Preoperative examination under anesthesia demonstrated no significant differences in Lachman testing between the two groups (p=0.237). However, subjects undergoing revision reconstruction surgery had nearly twice the magnitude of both lateral compartment translation (5.1±3.1 vs. 2.9 ±1.8mm, p=0.04) and tibial acceleration (16.8±8.7 vs. 8.7 ±3.8mm/s2, p=0.01) with pivot shift testing compared to the primary ACL reconstruction group.

Discussion And Conclusion

Based on the findings of this study, rotatory knee instability in failed ACL reconstruction is almost double that of primary ACL injury. Hence, in revision ACL reconstruction additional soft tissue procedures may need to be considered to fully restore normal joint stability. Based on this data, surgeons should consider individualizing revision ACL reconstruction, and consideration should be given to additional procedures such as meniscal repair, meniscal transplant, high tibial osteotomy and extra-articular tenodesis, which may be required to completely restore knee stability in patients with failed ACL reconstruction.