Eccentrically widened bone tunnels after all-inside anterior cruciate ligament reconstruction: a computed tomography and three-dimensional model-based analysis

Abstract

Purpose To evaluate the extent of tunnel widening after anterior cruciate ligament reconstruction (ACLR) using the all-inside technique and to establish its correlation with patient-reported clinical outcomes and femoral graft bending angle (GBA). Methods Tunnel widening was evaluated using computed tomography (CT)-based three-dimensional (3D) models, and the femoral GBA was directly measured on CT images using the Picture Archiving and Communication System (PACS) software. Clinical follow-up was routine procedure, and patient-reported clinical outcomes mainly included International Knee Documentation Committee (IKDC), Lysholm, and Knee Injury and Osteoarthritis Outcome Scores (KOOS) scores, and subjective knee stability assessment. Results Fifty-two patients received standard all-inside ACLR, with a median follow-up of 6 months. Reconstructed anterior cruciate ligaments (ACLs) were scanned during the first 3 days and 6 months after surgery. On both the femoral and tibial sides, bone tunnels were most significantly enlarged at the articular aperture segment; the femoral tunnel was 9.2 ± 1.3 mm postoperatively and was significantly enlarged by 32% to a mean tunnel diameter of 12.1 ± 2.0 mm at 6 months after surgery. Moreover, the extent of tunnel enlargement gradually decreased as the measured levels approached those of the bone cortex. The femoral tunnel center was shifted into the anterior and distal direction, and the tibial tunnel center was shifted into the posterior and lateral direction. Additionally, the mean femoral GBA was 105.9° ± 8.1° at the 6-month follow-up. Tunnel enlargement and GBA were not significantly correlated with patient-reported outcomes. Conclusions Femoral and tibial tunnels were significantly greater and eccentrically shifted at the 6-month follow-up after all-side ACLR. However, the extent of tunnel widening does not markedly affect the short-term clinical outcomes. Meanwhile, the femoral GBA was not significantly correlated with femoral tunnel widening or patient-reported outcomes. Although the tunnel widening following all-inside ACLR was not associated with clinical outcomes, it potentially caused difficulties in revision ACLR. Level of evidence Level IV.

Anterior Screw Insertion Results in Greater Tibial Tunnel Enlargement Rates after Single-Bundle Anterior Cruciate Ligament Reconstruction than Posterior Insertion: A Retrospective Study

“…However, the clinical outcomes were comparable between the two groups. Both groups showed significant improvement in IKDC scores and KOOS scores, which is in accordance with previous literature [ 24 , 53 , 54 , 55 ]. Our data also demonstrated no correlation between TER and clinical outcome scores, which may be attributed to the relatively short follow-up period.…”

“…TE of the femur and tibia have been extensively documented after ACLR [ 24 , 25 , 26 ]. Tunnel widening usually occurs in the first 6 months after surgery and becomes stable within a year, and the most significant widening occurs within the first 6 weeks and reportedly progresses until two years [ 10 , 27 ].…”

Anterior cruciate ligament femoral side retained stump technique reduces enlargement of the femoral bone tunnel after anterior cruciate ligament reconstruction

“…Tunnel enlargement results in an eccentric shift of the femoral tunnel position in the anterior and distal directions. As a result, the mechanical traction of the ACL graft constantly generates eccentric stresses on the tunnel wall, leading to tunnel widening [ 43 ]. Moreover, it has been shown that there is an increase in case changes in the meniscus after ACL revision surgery [ 44 ], which may lead to more severe osteoarthritis.…”

Outcomes of RigidFix Cross Pin Fixation in Femoral and Tibial Tunnel for Anterior Cruciate Ligament Reconstruction

“…A study showed that the ultimate failure load of graft was reduced by approximately 25% due to graft laceration by the interference screw 28 . Suspensory fixation allows for circumferential tendon‐bone contact, but its fixation point far away from the joint line can produce a “bungee effect” and a “windshield wiper effect” with cyclic loading 29–31 . Trans‐tunnel (i.e., RigidFix cross pins) could avoid eccentric fixation and graft injury caused by interference screws, also avoiding the “bungee effect” and “windshield wiper effect” caused by suspensory fixation, which is conducive to graft‐bone incorporation.…”

“…28 Suspensory fixation allows for circumferential tendon-bone contact, but its fixation point far away from the joint line can produce a "bungee effect" and a "windshield wiper effect" with cyclic loading. [29][30][31] Transtunnel (i.e., RigidFix cross pins) could avoid eccentric fixation and graft injury caused by interference screws, also avoiding the "bungee effect" and "windshield wiper effect" caused by suspensory fixation, which is conducive to graftbone incorporation. Thus, the trans-tunnel method seems to have advantages over the other two in theory.…”