Background and Objectives: The aim of this study is to investigate the femoral tunnel geometry (femoral tunsnel location, femoral graft bending angle, and femoral tunnel length) on three-dimensional (3D) computed tomography (CT) and graft inclination on magnetic resonance imaging (MRI) after anatomic anterior cruciate ligament (ACL) reconstruction using a flexible reamer system. Materials and Methods: A total of 60 patients who underwent anatomical ACL reconstruction (ACLR) using a flexible reamer system were retrospectively reviewed. One day after the ACLR procedure was performed, all patients underwent three-dimensional computed tomography (3D-CT) and magnetic resonance imaging (MRI). The femoral tunnel location, femoral graft bending angle, femoral tunnel length, and graft inclination were assessed. Results: In the 3D-CTs, the femoral tunnel was located at 29.7 ± 4.4% in the posterior to anterior (deep to shallow) direction and at 24.1 ± 5.9% in the proximal to distal (high to low) direction. The mean femoral graft bending angle was 113.9 ± 5.7°, and the mean femoral tunnel length was 35.2 ± 3.1 mm. Posterior wall breakage was observed in five patients (8.3%). In the MRIs, the mean coronal graft inclination was 69.2 ± 4.7°, and the mean sagittal graft inclination was 52.4 ± 4.6°. The results of this study demonstrated that a comparable femoral graft bending angle and longer femoral tunnel length were observed compared with the reported outcomes from previous studies that used the rigid reamer system. Conclusions: ACLR using a flexible reamer system allowed for an anatomic femoral tunnel location and a comparable graft inclination to that of the native ACL. In addition, it achieved a tolerable femoral graft bending angle and femoral tunnel length.

Positioning of the femoral tunnel during anterior cruciate ligament (ACL) reconstruction is the most crucial factor for successful procedure. Owing to the inter-individual variability in the intra-articular anatomy, it can be challenging to obtain precise tunnel placement and ensure consistent results. Currently, the three-dimensional (3D) reconstruction of computed tomography (CT) scans is considered the best method for determining whether femoral tunnels are positioned correctly. Postoperative 3D-CT feedback can improve the accuracy of femoral tunnel placement. Precise tunnel formation obtained through feedback has a positive effect on graft maturation, graft failure, and clinical outcomes after surgery. However, even if femoral tunnel placement on 3D CT is appropriate, we should recognize that acute graft bending negatively affects surgical results. This review aimed to discuss the implementation of 3D-CT evaluation for predicting postoperative outcomes following ACL re-construction. Reviewing research that has performed 3D CT evaluations after ACL reconstruction can provide clinically significant evidence of the formation of ideal tunnels following anatomic ACL reconstruction.

Background and Objectives: Revision anterior cruciate ligament reconstruction (ACLR) is demanding and yields inferior outcomes compared with primary procedures. The quadriceps tendon (QT) autograft with bone block has biomechanical and biological advantages though clinical evidence in revision remains limited. This study evaluated the clinical and radiological outcomes of revision ACLR using bone-block QT autograft in young, active patients. Materials and Methods: A case series with a level of evidence of 4. Thirty-four patients (28 men, 6 women; mean age, 27.2 ± 5.8 years) who underwent revision ACLR with a bone-block QT autograft between 2021 and 2023 were retrospectively reviewed. The mean follow-up was 37.4 ± 3.2 months. Clinical assessments included the Lysholm, International Knee Documentation Committee (IKDC) subjective, and Tegner activity scores, along with isokinetic strength testing. Objective stability was evaluated using pivot shift grading and Telos stress radiography. Radiological analyses included 3D computed tomography for tunnel positioning and magnetic resonance imaging for tunnel widening. Perioperative and postoperative complications were recorded. Results: All clinical outcomes improved significantly from baseline to 2-year follow-up: Lysholm (62.7 ± 9.6 to 87.1 ± 10.3), IKDC (59.0 ± 10.8 to 79.5 ± 11.1), and Tegner (3.5 ± 1.2 to 5.6 ± 1.3; all p < 0.001). However, the Tegner score remained lower than the pre-injury level (6.1 ± 1.4; p = 0.035). At the final follow-up, 91.2% of the patients had returned to sports, with 59% resuming sports at their pre-injury level or higher. Side-to-side anterior laxity decreased from 8.5 ± 1.7 mm to 1.4 ± 1.1 mm on Telos stress radiography (p < 0.001). Preoperatively, 82% of patients demonstrated high grade pivot shift (≥grade 2), which improved to 91% graded as negative or grade 1 at final follow-up (p < 0.001). Isokinetic evaluation showed improvements in quadriceps (28.7% ± 12.5% to 12.4% ± 8.1%) and hamstring (18.3% ± 9.7% to 8.9% ± 6.5%) deficit (both p < 0.001). MRI demonstrated minimal tunnel widening (tibia, +1.3 ± 0.9 mm, p = 0.012; femur, +0.3 ± 0.6 mm, p = 0.148). Three complications (8.8%) were observed: one cyclops lesion, one transient extension deficit, and one graft rupture. No patellar fractures, septic arthritis, or revision procedures occurred during the follow-up period. Conclusions: Bone-block QT autografts provide a reliable option for revision ACLR, yielding functional improvement, restored stability, and minimal donor-site morbidity, with low complications. These findings support their consideration as the preferred graft choice for young active patients needing revision reconstruction.

This study aimed to characterize the Magnetic Resonance Imaging (MRI) features of the Anterolateral Ligament (ALL) in young adults without Anterior Cruciate Ligament (ACL) injury and evaluate its visibility using MRI. In this retrospective analysis, MRI scans of 66 young adults without ACL injuries were assessed by two radiologists. The ALL was examined from its bone-to-bone attachment between the lateral femoral epicondyle and the lateral tibia. The visibility of the ALL was classified as normal, probably normal, abnormal, or non-visualized, based on ligament continuity and thickness relative to the Meniscotibial Ligament (MTL). A continuous structure with thickness equal to or greater than the MTL was considered normal; continuous but wavy and thin features were categorized as probably normal; discontinuity and angulation were deemed abnormal. The proximal attachment of the ALL was categorized as anterior, central, or posterior to the Fibular Collateral Ligament (FCL), while the distal attachment was noted as either at the same location or distal to the MTL. The ALL was identified in 87.9–95.5% of knees and was non-visualized in 4.5–12.1% of cases. Continuous ligamentous structures were observed in 63.7–71.2% of knees (normal in 30.3–37.9%; probably normal in 27.3–40.9%), whereas 19.7–30.3% exhibited abnormal features. Inter-observer agreement was moderate to substantial (κ = 0.66, 0.56), and intra-observer agreement was substantial to excellent (κ = 0.82, 0.66). Among the 58 visible ALLs, proximal attachments were predominantly anterior (63.8%) or central (32.8%) to the FCL, with a minority posterior (1.7%). In total, 4 of the 19 central insertions were incorporated into the FCL mid-substance, and one case was blended into the meniscofemoral ligament. Distal attachments were equally distributed between the same location (50%) and distal to the MTL (50%) (mean 3.7 mm distal). In conclusion, MRI was feasible for detecting the ALL in most young adults without ACL injury, revealing continuous ligament structures in about two-thirds of cases. Approximately 40% of cases exhibited a thickness equal to or greater than the MTL, with the majority of proximal attachments located anterior to the FCL and distal attachments evenly divided between the same insertion and distal to the MTL.