Summary

Few studies have reported the ligamentization of autografts after ACL reconstruction in a pediatric population.

Abstract

Background

Few studies have reported the ligamentization of autografts after ACL reconstruction in a pediatric population.

Purpose

The aim of this study was to compare the MRI aspect between the autografts and the healthy ACL in an open physis population and to assess if the MRI signal at 6 months postoperative was predictive of rerupture.

Methods

We prospectively enrolled 100 patients (7-16 years) who had undergone ACL reconstruction (quadriceps tendon, hamstring tendon, fascia lata). 65 patients had postoperative MRI (at 6 months, one and 2 years), 7 patients had postoperative MRI before a rerupture of the graft, and 28 patients didn’t have postoperative MRI. 20 teenagers (15-18 years) with a healthy ACL were assessed for comparison.
Using the sagittal images, the signal/noise quotient (SNQ) from 3 different areas of the ACL (proximal, middle and distal region) and the Howell graft score were measured. Using the axial images in the tibia the Howell score was evaluated. Chi2 test, Mantel Haenszel test, Wilcoxon signed rank test and Student test were used.

Results

- For the healthy ACLs, we found a significant difference between the SNQ of the 3 different areas and a majority (55%) of Howell 3, 25% of Howell 2 and 20 % of Howell 1.
- For healthy autografts, we found a significantly lower SNQ between 6 and 12 months (mean SNQ = 32 ± 6,7 vs 9,3 ± 2,67.) and between 6 and 24 months (mean SNQ = 32 ± 6,7 vs 9.17 ± 2,13). We did not find any difference between the 3 areas regardless of the MRI delay. We found a significant improvement of the intra-articular Howell score between 6 and 24 months and between 12 and 24 months; and for the intratibial Howell score only between 12 and 24 months.
- We did not find any difference between the healthy grafts and the reruptures at 6 months postoperatively, nor between the different graft types used for the surgery.

Conclusion

- This study showed a significant inhomogeneity of SNQ and intra-articular Howell scores in the healthy ACL.
- SNQ and Howell scores improved until 2 years postoperatively but the ligamentization does not restore the inhomogeneity of the healthy ACL. The grafts were more homogeneous.

The MRI images were very different between ACL graft and healthy ACL and the MRI signal at 6 months was not predictive of rerupture.