Femoral Tunnel Widening Via Transcondylar Cross-Pin Fixation Versus Extracortical Suspensory Fixation After Single-Bundle ACLR: A Systematic Review and Meta-analysis

Anterior Cruciate Ligament Reconstruction Utilizing Double Adjustable-Loop Suspensory Fixation Devices Provides Good Clinical Outcomes in Patients under the Age of 40 Years at Two-Year Follow-Up

Background: Anterior cruciate ligament reconstruction (ACLR) using double adjustable fixation gained popularity in the last decade due to its minimally invasive technique. However, suspensory fixation devices could be related to recurrent instability, poor clinical outcomes, and patient dissatisfaction. The present study aims to evaluate the clinical outcomes following ACLR using double adjustable-loop suspensory fixation devices in the demanding population of young patients. Methods: Between 2019 and 2022, 95 patients with knee post-traumatic anterior cruciate ligament insufficiency were treated with primary ACLR using semitendinosus quadrupled graft and double adjustable-loop suspensory fixation devices and followed for at least two years. Concomitant lesions were also treated at the same surgical time. The knee examination form of the International Knee Documentation Committee (IKDC) was used to assess clinical evaluation, and the return to physical activities using the Tegner Activity Scale was recorded. Patient-reported objective measures (PROMs) were also evaluated, including the IKDC subjective and Lysholm scores. Results: Sixty-six males and twenty-nine females with a mean age of 23.8 (range 18-37) and a mean BMI of 24.9 (SD ± 2.42) kg/m2 were included in this study. All patients were evaluated clinically as normal or nearly normal at the final follow-up. PROMs also significantly improved postoperatively (p < 0.05) compared to the preoperative values. The Tegner Activity Scale increased from 2 to 7, the IKDC mean score improved from 43.9 (±8.9) to 93.3 (±12.3), and the modified Lysholm from 47.3 (±11.1) to 92.9 (±16.6). No complications or adverse events were recorded. Conclusions: Anterior cruciate ligament reconstruction utilizing double adjustable-loop suspensory fixation devices provides good clinical and functional outcomes in young patients at a two-year follow-up.

Increased Bone Plug Depth From the Joint Increases Tunnel Enlargement in Anterior Cruciate Ligament Reconstruction Using Bone-Patellar Tendon-Bone Autograft With Suspensory Femoral Fixation

Purpose

To determine a safe bone plug depth fixation zone based on early tunnel enlargement rates in anterior cruciate ligament (ACL) reconstruction using bone-patellar tendon-bone (BPTB) autograft with suspensory femoral fixation.

Methods

Patients who had undergone rectangular tunnel ACL reconstruction using BPTB autograft with suspensory femoral fixation were retrospectively identified. Femoral and tibial tunnel aperture areas were measured on computed tomography 2 weeks and 6 months after surgery to calculate rates of femoral and tibial tunnel enlargement (FTE and TTE), respectively. Femoral bone plug depth (FBPD) and tibial bone plug depth (TBPD) were defined as the distance of the tip of the plug from the respective joint lines. Optimal FBPD and TBPD cutoff values were calculated for the following rates of FTE and TTE, respectively: 0%, 15%, 30%, and 50%.

Results

Sixty-four patients (19 females, 45 males; mean age, 29.5 ± 12.3 years) were included in the study. The femoral and tibial tunnel apertures significantly enlarged over time. FBPD (P < .001; r = 0.607) and TBPD (P = .013; r = 0.308) were positively correlated with FTE and TTE, respectively. The optimal FBPD cutoff value was 2.8 mm for FTE rates of 0% and 15%, 3.6 mm for 30%, and 6.0 mm for 50%. The optimal TBPD cutoff value was 1.48 mm for a 0% TTE rate and 5.1 mm for those higher. The cutoff value specificities were lower for the tibial tunnel than the femoral tunnel for each tunnel enlargement rate.

Conclusion

Early tunnel enlargement and bone plug depth were significantly correlated in bone the femoral and tibial tunnels. The degree of correlation was higher in the femoral tunnel. To minimize bone tunnel enlargement, the distal end of the femoral bone plug should be placed less than 2.8 mm from the tunnel aperture.

Level of Evidence

Level IV, therapeutic case series.

ACL graft with extra-cortical fixation rotates around the femoral tunnel aperture during knee flexion

PURPOSE

An understanding of the behavior of a new ACL graft in the femoral tunnel during knee motion and external loading can provide information pertinent to graft healing, tunnel enlargement, and graft failure. The purpose of the study was to measure the percentage of the tunnel filled by the graft and determine the amount and location of the graft-tunnel contact with knee motion and under external knee loads.

METHODS

Single bundle anatomical ACL reconstruction was performed on six cadaveric knees. Specimens were positioned with a robotic testing system under: (1) passive flexion-extension, (2) 89-N anterior and posterior tibial loads, (3) 5-N m internal and external torques, and (4) 7-N m valgus moment. The knees were then dissected, repositioned by the robot and the geometry of the femoral tunnel and graft were digitized by laser scanning. The percentage of tunnel filled and the contact region between graft and tunnel at the femoral tunnel aperture were calculated.

RESULTS

The graft occupies approximately 70% of the femoral tunnel aperture and anterior tibial loading tended to reduce this value. The graft contacted about 60% of the tunnel circumference and the location of the graft-tunnel contact changed significantly with knee flexion.

CONCLUSION

This study found that the graft tends to rotate around the tunnel circumference during knee flexion-extension and contract under knee loading. The "windshield-wiper" and "bungee cord" effect may contribute to femoral tunnel enlargement, affect graft healing, and lead to graft failure. There can be a considerable motion of the graft in the tunnel after surgery and appropriate rehabilitation time should be allowed for graft-tunnel healing to occur. To reduce graft motion, consideration should be given to interference screw fixation or a graft with bone blocks, which may allow an earlier return to activity.