Effect of Percentage of Femoral Anterior Cruciate Ligament Insertion Site Reconstructed With Hamstring Tendon on Knee Kinematics and Graft Force

High anteromedial insertion reduced anteroposterior and rotational knee laxity on mid-term follow-up after anatomic anterior cruciate ligament reconstruction

Background

The position of the femoral insertion has a great influence on the laxity of the knee joint after ACLR, especially for rotational laxity.

Purpose

To compare the effects of different femoral tunnel positions on knee stability after arthroscopic anterior cruciate ligament reconstruction (ACLR).

Methods

The clinical outcomes of 165 patients after autograft ACLR were analyzed retrospectively. The patients were separated into three groups according to the position of the femoral tunnel, as follows: low center (LC) group, 53 patients; high center (HC) group, 45 patients; and high anteromedial (HAM) group, 67 patients. The side-to-side differences (SSDs) in anteroposterior knee laxity measured using a KT-2000 arthrometer and the pivot shift test (PST) pre- and postoperatively were compared among the three groups and analyzed.

Results

After 5 years postoperatively, the SSD in the anteroposterior knee laxity in the three groups was significantly decreased postoperatively compared with preoperatively in knees; meanwhile, the negative PST rate was significantly increased in the three groups. The postoperative SSD in anteroposterior knee laxity was significantly increased in the HC group compared with the LC and HAM groups (1.5 ± 1.3 VS 1.0 ± 1.1 VS 1.0 ± 1.0, P<0.05). The negative postoperative PST rate was higher in both the LC and HAM groups than in the HC group (84.9% VS 91.0% VS 71.1%, P<0.05), and there was no significant difference in the negative PST rate between the LC and HAM groups (84.9% VS 91.0%, P>0.05). The negative postoperative PST rate was significantly higher in the HAM group than in the LC and HC groups for patients with a high degree of laxity preoperatively (31.3% VS 3.3% VS 14.4%, P>0.05).

Conclusion

Patients in HAM group showed better control over anteroposterior laxity, rotational laxity, and subjective knee function compared to other groups post operation. Therefore, the HAM point is the closest to the I.D.E.A.L point concept, and is recommended as the preferred location for the femoral tunnel in ACLR.

Augmenting ACL Repair With Suture Tape Improves Knee Laxity: A Biomechanical Study

Background

Anterior cruciate ligament (ACL) repair is an alternative to reconstruction; however, suture tape support may be necessary to achieve adequate outcomes.

Purposes

To investigate the influence of suture tape augmentation (STA) of proximal ACL repair on knee kinematics and to evaluate the effect of the 2 flexion angles of suture tape fixation.

Study Design

Controlled laboratory study.

Methods

Fourteen cadaveric knees were tested using a 6 degrees of freedom robotic testing system under anterior tibial (AT) load, simulated pivot-shift (PS) load, and internal rotation (IR) and external rotation loads. Kinematics and in situ tissue forces were evaluated. Knee states tested were (1) ACL intact, (2) ACL cut, (3) ACL repair with suture only, (4) ACL repair with STA fixed at 0° of knee flexion, and (5) ACL repair with STA fixed at 20° of knee flexion.

Results

ACL repair alone did not restore the intact ACL AT translation at 0°, 15°, 30°, or 60° of flexion. Adding suture tape to the repair significantly decreased AT translation at 0°, 15°, and 30° of knee flexion but not to the level of the intact ACL. With PS and IR loadings, only ACL repair with STA fixed at 20° of flexion was not significantly different from the intact state at all knee flexion angles. ACL suture repair had significantly lower in situ forces than the intact ACL with AT, PS, and IR loadings. With AT, PS, and IR loadings, adding suture tape significantly increased the in situ force in the repaired ACL at all knee flexion angles to become closer to that of the intact ACL state.

Conclusion

For complete proximal ACL tears, suture repair alone did not restore normal knee laxity or normal ACL in situ force. However, adding suture tape to augment the repair resulted in knee laxity closer to that of the intact ACL. STA with fixation at 20° of knee flexion was superior to fixation with the knee in full extension.

Clinical Relevance

The study findings suggest that ACL repair with STA fixed at 20° could be considered in the treatment of femoral sided ACL tears in the appropriate patient population.

Arthroscopic centralization reduces extrusion of the medial meniscus with posterior root defect in the ACL reconstructed knee

PURPOSE

The purpose of this study was to evaluate the effects of arthroscopic meniscal centralization reinforcement for a medial meniscus (MM) posterior root defect on knee kinematics and meniscal extrusion in the anterior cruciate ligament reconstructed (ACLR) knee. The hypothesis was that the medial meniscus centralization would reduce extrusion and anterior laxity in ACLR knee with a medical meniscal defect.

METHODS

Fourteen fresh-frozen human cadaveric knees were tested using a six-degrees-of-freedom robotic system under the following loading conditions: (a) an 89.0 N anterior tibial load, (b) 5.0 Nm internal and external rotational torques, (c) a 10.0 Nm valgus and varus loadings, and (d) a combined 7.0 Nm valgus moment and then a 5.0 Nm internal rotation torque as a static simulated pivot shift. The tested knee states included: (1) anatomic single-bundle cruciate ligament reconstruction with intact medial meniscus (MM Intact), (2) anatomic single-bundle cruciate ligament reconstruction with medial meniscus posterior root defect (MM Defect), (3) Anatomic single-bundle cruciate ligament reconstruction with medial meniscus arthroscopic centralization (MM Centralization). Medial meniscus arthroscopic centralization was performed using 1.4 mm anchors with #2 suture. The MM extrusion (MME) was measured using ultrasound under unloaded and varus loading conditions at 0° and 30° of flexion.

RESULTS

Anterior tibial translation (ATT) increased significantly with MM posterior root defect compared to MM intact at all flexion angles. With MM centralization, ATT was not significantly different from the intact meniscus at 15° and 30° of flexion. Meniscus extrusion increased significantly with the root defect compared to intact meniscus and decreased significantly with meniscal centralization compared to the root defect at both flexion angles.

CONCLUSIONS

In ACL reconstruction, cases involving irreparable medial meniscal posterior root tears, applying arthroscopic centralization for avoiding the meniscal extrusion should be considered. Clinically, in ACL reconstruction cases with irreparable medial meniscal posterior root tears, applying arthroscopic meniscal centralization for avoiding the meniscal extrusion should be considered. Meniscal centralization decreases the extrusion of the MM and offers improvements in knee laxity.

Arthroscopic Anterior Cruciate Ligament Repair With Single-Bundle Hamstring Tendon Augmentation Providing Complete Femoral Footprint Restoration for Sherman Type One Tears: A Technique Guide

There is renewed interest in performing arthroscopic anterior cruciate ligament (ACL) repairs in appropriate patients who have Sherman type 1 ACL tears. However, ACL repairs are associated with unacceptably high failure rates, which may be partly improved with suture augmentation. Our technique uses a hamstring autograft tendon to reconstruct a bundle through a femoral tunnel while inserting the native ACL tissue into the other bundle's femoral footprint. The tear pattern dictates whether the native ACL tissue is inserted into the anteromedial or posterolateral lateral femoral origin. The improved cellular and biomechanical milieu for healing of both the repair and reconstruction may translate to earlier return to sport and reduced failure rates. In addition, by restoring the entire femoral footprint with a single femoral tunnel, improved rotational control is achieved without the bone stock loss observed in traditional ACL double-bundle reconstruction.

The proximal posterior cartilage of the lateral femoral condyle can be used as a reference for positioning the femoral tunnel in ACL reconstruction

PURPOSE

To describe the femoral insertion of the ACL using the posterior proximal cartilage of the lateral femoral condyle as the anatomical reference.

METHODS

Twenty knees were dissected. The X-axis (deep-shallow) and Y-axis (high-low) were determined using the femoral diaphysis and the proximal cartilage of the lateral femoral condyle (point C) as a reference, which were easily identified by direct visualization through the anteromedial portal. The distances to the center of the anteromedial and posterolateral bands and to the center of the ACL were measured.

RESULTS

The mean distances were 7.2 mm (SD: 0.7) between the center of the anteromedial bundle and the Y-axis (AM-Y), 9 mm (SD: 1.1) between the center of the ACL and the Y-axis (M-Y), and 12.7 mm (SD: 0.9) between the center of the posterolateral bundle and the Y-axis (PL-Y). Regarding the distance (from point C to the distal cartilage along the X-axis), the center of the anteromedial bundle (AM) was 35% (SD: 4.9%), the center of the posterolateral bundle was 62% (SD: 3.7%), and the center of the ACL (M) was 44% (SD: 7%) of the CD distance on average.

CONCLUSION

Given the similarity among the specimens in terms of the height of the ACL on the Y-axis in relation to the proximal posterior cartilage of the femoral lateral condyle (point C), this point can be used as an arthroscopic intraoperative parameter to define the position of the femoral tunnel in ACL reconstruction for single- or double-bundle techniques.

Graft Diameter Should Reflect the Size of the Native Anterior Cruciate Ligament (ACL) to Improve the Outcome of ACL Reconstruction: A Finite Element Analysis

The size of the anterior cruciate ligament (ACL) often varies between individuals, but such variation is not typically considered during ACL reconstruction (ACLR). This study aimed to explore how the size of the ACL affects the selection of a suitable graft diameter. A finite element model of a human knee was implanted with intact ACLs of different dimensions (0.95, 1 and 1.05 times the size of the original ACL) and with grafts of different diameters, to simulate ACLR (diameter 7.5–12 mm in 0.5 mm increments). The knee models were flexed to 30° and loaded with an anterior tibial load of 103 N, internal tibial moment of 7.5 Nm, and valgus tibial moment of 6.9 Nm. Knee kinematics (anterior tibial translation (ATT), internal tibial rotation (ITR) and valgus tibial rotation (VTR)) and ligament forces were recorded and compared among the different groups. The results showed that, compared with the intact knee, a graft diameter of 7.5 mm was found to increase the ATT and VTR, but reduce the graft force. Increasing the graft diameter reduced knee laxity and increased the graft force. A 10% increase in the size of the ACL corresponded to a 3 mm larger graft diameter required to restore knee stability and graft force after ACLR. It was concluded that the graft diameter should be selected according to the dimensions of the native ACL, for better restoration of knee functionality. This study may help to improve the clinical treatment of ACL ruptures.