Summary

The findings of this study indicate that the Marx Activity Rating Scale is a significant predictor of preoperative ACL-RSI, which is not associated with knee instability, suggesting that ACL-RSI may be an independent psychological state assessment.

Abstract

Objective.
The ACL-return to sport after injury scale (ACL-RSI) has attracted attention as an evaluation of psychological readiness for return to sport in patients with anterior cruciate ligament (ACL) reconstruction. However, few reports have investigated preoperative-related factors. Psychological readiness could be improved if possible intervention factors could be identified. This study aimed to investigate preoperative ACL-RSI and identify the factors that influence it.

Methods.
Out of the patients enrolled in the ACL reconstruction multicenter study (Chiba LEAF study) between December 2022 and July 2024, patients having a preoperative ACL-RSI evaluation were included. The cases with concomitant posterior cruciate ligament were excluded. Furthermore, we excluded cases with missing data from the waiting period, arthroscopic findings, Lachman test (Lachman), pivot shift test (PS), or preoperative Marx Activity Rating scale (Marx) were excluded. A total of 121 patients (55 women, mean age 28.7 ± 13.3 years, mean BMI 23.4 ± 3.6kg/m2) were finally analyzed.
As a primary analysis, a multiple regression was performed with preoperative ACL-RSI as the dependent variable and with age, gender, body mass index (BMI), waiting period, Marx, Lachman, PS, and cartilage injury as the independent variables. The evaluation of cartilage injuries was conducted using the ICRS grade in three regions: the medial and lateral tibiofemoral joints and the patellofemoral joint. The presence of a grade 2 or higher injury in at least one region was defined as a positive cartilage injury. Lachman and PS were assessed with IKDC grading, and the grade C or D was defined as unstable.
As explorational analyses, univariate analyses were performed. Age, BMI, Marx, Tegner Activity score (TAS), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Lysholm score were assessed in Spearman’s rank correlation coefficient. Preoperative ACL-RSI were compared in gender, Lachman, PS, cartilage injuries, medial meniscus injury, and lateral meniscus injury using Mann-Whitney U test or Kruskal-Wallis test. Meniscus injury involved vertical tear, radial tear, horizontal tear, flap tear, and root tear in this study. Statistical significance was set at P < 0.05.

Results.
The mean preoperative ACL-RSI was 50.23± 21.2. In multiple regression analysis, only Marx (p=0.001) was extracted as a significant predictor. In univariate analysis, significant differences were found in age (r= -0.21, p=0.03), Marx (r=0.35, p<0.001), TAS (r=0.27, p=0.01), KOOS-Sport (r=0.20, p=0.03), KOOS-QOL (r=0.25, p=0.006). There was no significant difference in cartilage injury and meniscus injury.

Discussion.
This study detected only the Marx Activity Rating Scale as a predictor of ACL-RSI and found that preoperative knee instabilities and other factors had no effect on preoperative ACL-RSI. Recent studies reported that higher postoperative ACL-RSI was associated with a higher re-tear rate. This study can support those reports and suggest that knee joint instability is not linked to psychological readiness.

Conclusion.
Preoperative knee instability and the other factors had no impact on ACL-RSI, and only the Marx Activity Rating Scale was a significant predictor of preoperative ACL-RSI.