Description
Objectives: This study investigated the association between preoperative knee instability and graft maturation, as observed on MRI two years after
anterior cruciate ligament (ACL) reconstruction. Graft maturity is pivotal to postoperative outcomes, with immature grafts at an elevated risk of re-injury.
This research focused on whether preoperative knee instability influenced graft maturity, as depicted by the signal/noise quotient (SNQ) on MRI.
Methods: One hundred six patients (48 male, 58 female; average age 27.2 ± 12.2 years) who underwent primary double-bundle ACL reconstruction using
autograft hamstring tendon from October 2016 to April 2021 were analyzed retrospectively. Patients were categorized based on preoperative pivot shift
grades:77 patients (grades 0, 1, and 2) were in group L, whereas 29 patients (grade 3) were in group H. Group H was divided into two subgroups: Subgroup
A comprising 17 patients with isolated ACL reconstruction, and Subgroup L, comprising 12 patients with ACL and concomitant anterolateral ligament (ALL)
reconstruction. A 1.5-T MRI was used to evaluate the knees two years post-surgery. The signal/noise quotient (SNQ) was assessed for the anteromedial
bundle (AMB) and posterolateral bundle (PLB) of the ACL graft and further segmented into proximal, middle, and distal sections (Image A). Statistical tests
were employed, including the Student’s t-test, Mann–Whitney U test, and chi-squared test, with significance set at p < .05.
Results: For the AMB, group L demonstrated significantly lower SNQ values than group H: P section (4.2 ± 4.5 vs. 6.8 ± 5.4 [P = .015]); M section (6.9 ±
6.3 vs 10.3 ± 8.2 [P = .023]); and D section (7.4 ± 6.9 vs 10.6 ± 8.1 [P = .044]). Group L had significantly lower SNQ values for the PLB in one of its three
sections: D section (8.0 ± 7.2 vs 11.6 ± 10.1 [P = .039]). However, there were no significant differences in the SNQ values for the P and M sections of the
PLB between the groups. The residual pivot shift rates were 22.8% and 36.4% in groups L and H, respectively (P = .26). Patient-reported outcomes, such as
KOOS (96.0 ± 5.0 vs 96.4 ± 4.0 [P = .74]) and Lysholm scores (96.3 ± 6.1 vs 96.0 ± 5.9 [P = .86]), showed no significant difference between the groups
(Table 1). Furthermore, between subgroups A and L, no significant differences in the SNQ were observed across all sections of the AMB and PLB (Table 2).
Conclusions:
Patients with a preoperative pivot shift grade of 3, irrespective of whether they underwent combined ALL reconstruction, exhibited reduced ACL graft
maturation on MRI two years after surgery. For patients with significant preoperative knee instability in ACL-injured knees, close observation is crucial to
prevent further re-injury and achieve good clinical results.
