Summary

In a retrospective study of more than 700 patients undergoing ACL reconstruction (ACLR), posterior tibial slope (PTS) ≥ 12° and static anterior tibial translation (SATT) ≥ 4mm appeared to be major intrinsic risk factors for ACLR rupture.

Abstract

Background

Historically, malpositioning of anterior cruciate ligament reconstruction (ACLR) tunnels has been the primary cause of ACLR rupture. However, this risk factor appears to be diminishing, allowing other intrinsic risk factors to become more prominent.

Hypothesis/Purpose:
This study aimed to analyze specific risk factors, namely posterior tibial slope (PTS) and static anterior tibial translation (SATT), and their respective thresholds concerning ACLR failure. It was hypothesized that a PTS ≥ 12° and SATT ≥ 5 mm are major risk factors for ACLR rupture.

Methods

In this single-center, single-surgeon study, a retrospective analysis of prospectively collected data was performed on patients who underwent ACLR between 2014 and 2017 to identify risk factors associated with ACLR rupture. Variables such as age, sex, laterality, graft type, associated surgeries, time to ACLR rupture, Tegner score, and International Knee Documentation Committee (IKDC) score were evaluated. Preoperative radiographs were used to measure PTS, SATT, and dynamic anterior tibial translation. Univariate and multivariate analyses were conducted to identify risk factors for ACLR rupture.

Results

A total of 851 patients were eligible. A minimum 6-year follow-up was obtained on 83.7% of the cohort. 717 ACLRs (mean age, 30.6 ± 11.3 years; 62% male) were analyzed, with a mean follow-up of 98.30 ± 19.54 months. Forty-one re-ruptures (5.7%) were identified. The risk of graft failure was significantly associated with a PTS ≥ 12° (odds ratio, 3; 95% CI, 1.4-6.1; p = 0.003), SATT ≥ 4 mm (odds ratio, 2.7; 95% CI, 1.3-5.6; p = 0.008), age < 20 years (odds ratio, 2.6; 95% CI, 1.3-5.5; p = 0.007), and lateral meniscus tears (odds ratio, 2.6; 95% CI, 1.1-5; p = 0.033). PTS was strongly associated with SATT (p < 0.001), and for every 1° increase in PTS, SATT increased by 0.5 mm. The re-rupture rate among patients with ACLR + lateral extra-articular tenodesis (LET) (5.8%) was not significantly different (p = 0.997) from those with ACLR alone (5.7%).

Conclusion

PTS ≥ 12°, SATT ≥ 4 mm, age < 20 years, and lateral meniscus tears are significant risk factors for ACLR failure. Deflexion osteotomy can reduce PTS and consequently affect SATT, making it a potential consideration in primary ACLR for young patients. LET does not appear to be a protective factor against ACLR rupture in this series.

Study Design: Cohort study
Level of evidence: III.