Preserved anterolateral ligament graft continuity on MRI and lower knee laxity after ACL graft failure than before index combined ACL-ALL reconstruction: A retrospective case series.

Abstract

To evaluate magnetic resonance imaging (MRI)-based continuity and signal characteristics of reconstructed anterolateral ligament (ALL) grafts and compare anteroposterior and rotational knee laxity after anterior cruciate ligament (ACL) graft failure with values recorded before the index combined ACL-ALL reconstruction. This retrospective case series included 15 patients who experienced ACL graft failure after combined ACL-ALL reconstruction; the index combined procedure was primary in 12 patients and a revision in 3. MRI was reviewed to assess ALL graft continuity, intrinsic signal changes and periligamentous edema. Side-to-side anterior tibial translation (ATT) measured with the KT-1000 arthrometer and pivot-shift grade were compared between the preindex reconstruction assessment and the assessment after ACL graft failure using Wilcoxon signed-rank tests. ACL graft failure occurred at a mean of 22 ± 1.5 months (range, 18-24 months) after the index reconstruction. The ALL graft showed preserved continuity on MRI in all 15 patients (100%), and mild signal changes were observed in 9 (60%). Median ATT was lower after ACL graft failure than before the index reconstruction (5 vs. 7 mm; median paired reduction, 2 mm [IQR, 1-3]; p = 0.001). Median pivot-shift grade was also lower (1 vs. 2; median paired reduction, 1 grade [IQR, 1-1.5]; p = 0.001). ATT and pivot-shift grade improved in 12 of 15 patients (80%), and no patient demonstrated a high-grade pivot shift after ACL graft failure. Following ACL graft failure after combined ACL-ALL reconstruction, MRI showed preserved ALL graft continuity in all cases, and knee laxity was lower than before the index reconstruction. In this setting, physical examination findings should be interpreted cautiously because anteroposterior and rotational laxity may be lower than expected. The retrospective design and small, heterogeneous sample preclude causal attribution to the ALL graft and any conclusion that anterolateral revision can be omitted. Level IV.