2017 ISAKOS Biennial Congress ePoster #1021

 

Postoperative Change of Anterior Tibial Subluxation at Maximum Extension Position after Anterior Cruciate Ligament Reconstruction

Daisuke Araki, MD, PhD, Kobe, Hyogo JAPAN
Takehiko Matsushita, MD, Kobe, Hyogo JAPAN
Kyohei Nishida, MD, Pittsburgh, pennsylvania UNITED STATES
Toshikazu Tanaka, MD, Kobe JAPAN
Nobuaki Miyaji, MD, Kobe, Hyogo JAPAN
Toshiyuki Kanzaki, MD, PhD, Kobe, Hyogo JAPAN
Kazuyuki Ibaragi, MD, Kobe JAPAN
Ryosuke Kuroda, MD, PhD, Kobe, Hyogo JAPAN

Kobe University Graduate School of Medicine, Kobe, JAPAN

FDA Status Not Applicable

Summary

Anterior tibial subluxations (ATS) to the femur were assessed at pre-, post-anterior cruciate ligament (ACL) reconstruction and 1-year after surgery. A positive correlation was observed between ATS and the injury-surgery period It is suggested that ACL reconstruction should be performed within 6 months after an injury.

Abstract

Introduction

It has been reported that anterior cruciate ligament (ACL) deficiency causes anterior tibial subluxation (ATS) to the femur. However, the factor underlying ATS is still unknown. Therefore, this study aimed to investigate the changes of ATS before and after ACL reconstruction over time and the factors affecting ATS.

Methods

Seventy-two unilateral ACL-injured patients were enrolled in this study. ACL-injured, ACL-reconstructed and contralateral normal knees were evaluated under general anesthesia at three different time points; pre-ACL reconstruction, post-ACL reconstruction, and 1-year after surgery. ATS to the femur was measured during maximum extension using fluoroscopy. The true lateral view of the knee was obtained for measurement. First, a line was drawn from the peak anterior point (A) to the posterior point (B) of the medial tibial plateau. Next, a line was drawn perpendicular to the first line (A-B) from the anterior point of the Blumensaat’s line. The intersection of the two lines was defined as the point (C). A-C / A-B × 100 % was defined as the ratio of ATS to the femur, and the side-to-side difference was evaluated. The patients were divided by injury-surgery periods into four groups; (1) 0-3 months (17 patients), (2) 3-6 months (26 patients), (3) 6-12 months (17 patients), (2) more than 12 months (12 patients). To assess the changes of ATS over time and the factors affecting ATS, statistical analysis was performed between the side-to-side difference of the ratio of ATS to the femur and injury-surgery period, the medial meniscal tears, and the tibial posterior slope angles. One-way analysis of variance was used for the comparison of the side-to-side difference of the ratio of ATS among 4 groups. The multiple comparison of the Fisher’s protected least significant difference was used to assess the data considered significant by the analysis of variance.

Results

The side-to-side differences in the ratio of ATS to the femur in (3) and (4) were significantly larger at pre-ACL reconstruction than those in (1) and (2) (p < 0.05). However, no significant differences were observed among 4 groups at post-ACL reconstruction. At 1-year after surgery, the side-to-side differences in the ratio of ATS to the femur in (3) and (4) were significantly larger than those in (1) and (2) again (p < 0.05). In addition, a positive correlation was detected between ATS at pre-ACL reconstruction and those at 1-year after surgery (r = 0.62). The ratio of ATS with medial meniscus injury was significantly higher than those with medial meniscus repaired or without injury. But, there was no correlation between ATS and the tibial posterior slope (r = -0.013).

Conclusions

ATS to the femur in maximum extension increases over time in ACL-deficient knees and these trend was also observed at 1-year after surgery. Medial meniscus injury may be one of the factor affecting ATS. There is no relationship between ATS and tibial posterior slope. From the result of this study, it is suggested that ACL reconstruction should be performed within 6 months after ACL injury.