Lateral Femoral Notch Sign Presence, Location, and Depth Are Not Associated With Primary Anterior Cruciate Ligament Reconstruction Failure: A Retrospective Case-Control Study

Abstract

Purpose

To assess the relationship between the presence, depth, and location of the lateral femoral notch sign (LFNS) on preoperative magnetic resonance imaging (MRI) and the risk of anterior cruciate ligament reconstruction (ACLR) graft failure, as well as secondary return to sport (RTS) endpoints.

Methods

Patients with primary ACLR failure between 2012 and 2021 were identified and matched to patients without primary ACLR failure by sex, age, and body mass index. Patients with incomplete medical records, inadequate follow-up, or concomitant lateral extra-articular tenodesis or anterolateral ligament reconstruction were excluded. The presence, depth, and location of the LFNS were recorded from patients' preoperative MRI. Intraoperative data, concomitant injuries, ACLR failure, and RTS were collected.

Results

Of the 253 included patients, 158 (62.5%) were male, the mean age was 22 ± 9.1 years old, and the mean body mass index was 25.7 ± 5.7. 87(34.4%) had a LFNS on preoperative MRI. There was no difference in the prevalence of the LFNS between patients with primary ACLR failure (42 [32.1%]) and without primary ACLR failure (45 [36.9%]) (odds ratio 1.24, 95% confidence interval 0.74-2.08; P = .42). Among patients with the LFNS, there was no difference in mean depth between those with and without primary ACLR failure, or when stratifying depth by 1.0-1.5 mm, 1.5-2.0 mm, and >2.0 mm. The mean location of the LFNS from Blumensaat line did not differ between patients with or without primary ACLR failure, and RTS rate, level, and time were comparable between patients with and without the LFNS.

Conclusions

There was no significant difference in the presence, depth or location of the LFNS in patients with and without primary ACLR failure. Presence of the LFNS is not associated with additional risk of primary ACLR failure, and clinical outcomes were comparable in patients with and without the LFNS.

Level of Evidence

Level IV, retrospective case-control study.