Optimal Combination of Femoral Tunnel Orientation in Anterior Cruciate Ligament Reconstruction Using an Inside-out Femoral Technique Combined With an Anterolateral Extra-articular Reconstruction

Optimal Anterolateral Ligament Tibial Tunnel Orientation to Prevent ACL Tunnel Collision and Saphenous Nerve Injury

Background

Collision risks between femoral tunnels during combined anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction have been reported. However, studies on collision risks between tibial tunnels and optimal ALL tibial tunnel orientation are lacking.

Purpose

To analyze the optimal orientation of the ALL tibial tunnel to minimize collisions with the ACL tibial tunnel while preventing injury to the saphenous nerve in combined reconstruction.

Study Design

Descriptive laboratory study.

Methods

Preoperative magnetic resonance imaging (MRI) and postoperative computed tomography (CT) images of patients who underwent primary ACL reconstruction using the anteromedial portal technique were analyzed. Only patients with preoperative MRI scans including thin-cut images (<1 mm) were included for 3-dimensional (3D) reconstruction. Patients who underwent ALL reconstruction or had poorly 3D-reconstructed essential structures were excluded to ensure accurate reproduction of bony attachments and landmarks associated with ALL. Bony structures of the knee joint, including the proximal tibia with the actual ACL tibial tunnel, were reconstructed from the postoperative CT scans. The greater saphenous vein (GSV), which runs together with the saphenous nerve, was reconstructed from the preoperative MRI and subsequently transferred to the CT model, maintaining the appropriate positional relationship. Twelve orientations of the ALL tunnel (at 10° intervals, ranging from 0° to 20° anteriorly and from 0° to 30° distally) were simulated with the final 3D model, starting from the ALL tibial footprint (midpoint between the Gerdy tubercle and the fibular head, 10 mm distal to the joint line), to measure the distances between the ALL tunnel trajectory and other structures (ACL tibial tunnel, GSV) by each orientation.

Results

A total of 35 out of 304 patients were included in this study. An anteriorly oriented ALL tunnel decreased the minimum distance to the ACL tibial tunnel (MD-ACL) and increased minimum distance to the GSV (MD-GSV) (all P < .001). A distally oriented ALL tunnel increased MD-ACL and decreased MD-GSV (all P < .001). Optimal ALL tunnel orientation was 10° anterior to 30° distal (MD-ACL, 14.6 ± 4.0 mm; MD-GSV, 27.8 ± 12.4 mm) and 20° anterior to 30° distal (MD-ACL, 11.5 ± 3.6 mm; MD-GSV 43.6 ± 12.9 mm), considering both collisions with the ACL tunnel and the potential risk of injury to the saphenous nerve.

Conclusion

The optimal orientations of the ALL tibial tunnel to avoid collision with the ACL tibial tunnel and prevent saphenous nerve injury are 10° anterior to 30° distal and 20° anterior to 30° distal for far-cortex drilling techniques, starting from the midpoint between the Gerdy tubercle and the fibular head, 10 mm distal to the joint line.

3D printing technology is a more accurate tool than an experienced surgeon in performing femoral bone tunnels in multi-ligament knee injuries

Purpose

Current surgical methods for multi-ligament knee reconstruction involve the creation of several reconstruction tunnels in the distal femur. However, the limited bone mass in the knee increases the risk of tunnel convergence. Increasing the accuracy of tunnel direction can minimize tunnel collision during anatomical reconstruction. 3D-printed patient-specific instrumentation (PSI) has gained prominence in orthopaedic surgery due to its precision. This study aims to compare the accuracy of PSI with that of the 'freehand' approach by an experienced surgeon for drilling the medial and lateral femoral tunnels while adhering to the recommended angulations for multi-ligament knee injuries.

Methods

Ten cadaveric knees underwent computerized tomography (CT) scans to identify anatomical femoral attachments of the lateral collateral ligament (LCL), popliteal tendon (PT), medial collateral ligament (MCL) and posterior oblique ligament (POL). Using Materialise Mimics Medical v25.0 software, virtual planning of a bone tunnel for each ligament was performed, and a total of four tunnels per knee were obtained. Ten PSIs were designed for five knees: five for the medial side and five for the lateral side. The first five knees were operated on via PSI, and the other five knees were operated on by an experienced surgeon using freehand drilling based on preoperative plans. The angular deviation and entry point were assessed by overlaying post-operative CT images onto preoperative CT images.

Results

In the freehand group, the median angular deviation was 22.3°, with an interquartile range (IQR) of 17.6-25.2°. The PSI group presented a significantly greater accuracy in angular deviation for femoral tunnels of 5.7°, with an IQR of 4-8.2° (p < 0.001). Compared with that in the preoperative planning group, the median entry point distance in the freehand group was 5.5 mm, with an IQR of 2.6-8.8 mm. The PSI group had a median entry point distance of 4.2 mm, with an IQR of 3.6-5.7 mm (p = n.s).

Conclusions

Compared with the freehand technique performed by an experienced surgeon, PSI demonstrated significantly greater accuracy in terms of the mean angular deviation.

Level of Evidence

Level V.

Editorial Commentary: Preferred Strategies to Avoid Collision Between Tunnels for Lateral Extra-articular Procedures and Anterior Cruciate Ligament Reconstruction Include Outside-In Drilling, Cortical Fixation, and Use of a Single Femoral Tunnel

When performing lateral extra-articular procedures (LEAPs) at the time of anterior cruciate ligament (ACL) reconstruction, it is essential to be aware of the possibility of tunnel collision and understand strategies to avoid it. The risk of tunnel collision is high, especially if an anteromedial portal ACL femoral tunnel is drilled. Tunnel collision can be avoided by using a single femoral tunnel for both procedures, outside-in femoral tunnel drilling to place the ACL tunnel a safe distance away from the LEAP, and cortical fixation techniques. Other strategies that have been explored have included anteromedial portal drilling in low degrees of flexion, anterior angulation of LEAP tunnels, and the use of an "anterior Lemaire" position. These alternative strategies are not preferred because they are associated with an increased risk of iatrogenic injuries to important posterolateral structures, penetration of trochlea articular cartilage, and overconstraint, respectively.

Overconstraint Associated With a Modified Lemaire Lateral Extra-Articular Tenodesis Is Decreased by Using an Anterior Femoral Insertion Point in a Cadaveric Model

PURPOSE

To investigate tibiofemoral knee kinematics when shifting the femoral insertion point of the modified Lemaire lateral extra-articular tenodesis (LET) anterior to the lateral epicondyle.

METHODS

Six fresh-frozen human knee joints were tested on a test bench in the following states: (1) native, (2) anterolateral insufficient, (3) original Lemaire (oLET; insertion point: 4 mm posterior and 8 mm proximal to the epicondyle), (4) anterior Lemaire (aLET; insertion point: 5 mm anterior and 5 mm proximal to the epicondyle). Internal tibial rotation was statically investigated under an internal tibial torque of 5 Nm in 0°, 30°, 60°, and 90° of flexion. Anterior translation was statically investigated during a simulated Lachman test with an anterior translational force of 98 N. Additionally, the range of internal tibial rotation and anterior translation were dynamically investigated by a simulated pivot-shift test. Tibiofemoral kinematics were measured using an optical 3D motion analysis system.

RESULTS

The aLET showed an internal tibial rotation comparable to the native state for all tested flexion angles except 90° (0°: P = .201; 30°: P = .118; 60°: P = .126; 90°: P = .026). The oLET showed an internal tibial rotation below the values of the native state for all tested flexion angles indicating an overconstraint (0°: P = .003; 30°: P = .009; 60°: P = .029; 90°: P = .029). Direct comparisons between aLET and oLET showed a significantly decreased overconstraint at 0° and 30° of flexion (P = .001 and P = .003, respectively) when using the aLET. No differences in anterior translation and internal tibial rotation were found between the oLET and aLET during simulated Lachman and pivot-shift test (P > .05), approximating the native state.

CONCLUSIONS

An anteriorly shifted LET insertion point restored internal tibial rotation after anterolateral insufficiency to the native state while decreasing the overconstraint of internal tibial rotation induced by an LET using the originally described insertion point for small flexion angles ≤30°.

CLINICAL RELEVANCE

Using an LET insertion point anterior to the epicondyle was recently reported to lower the risk of tunnel interference and has now been shown to restore internal tibial rotation effectively in vitro in the course of the present study. Concerns of overconstraining internal tibial rotation are not diminished by this technique, but using an anterior insertion point helps to decrease overconstraint.

Lateral Extra-articular Tenodesis With Cortical Suspensory Femoral Fixation and Suture Tape Augmentation

This article aims to provide a new surgical technique for rotational instability in the setting of anterior cruciate ligament rupture. Two main groups of surgical procedures can be identified in the treatment of anterolateral knee instability: lateral extra-articular tenodesis and anterolateral ligament reconstruction. Although the importance of anterior cruciate ligament reconstruction in anterolateral complex injuries is well known, the superiority of lateral extra-articular tenodesis over anterolateral ligament reconstruction or vice versa has not yet been shown. Both techniques show improved outcomes and reduced graft failure rates. The presented procedure can be considered a modification of the technique first described by Lemaire. Better tensioning can be achieved through cortical suspension by identifying the anisometric point on the lateral femur and performing a medial pullout on the femoral side. The advantages of this technique are better fine-tuning and tensioning, less invasiveness, and adjustable cortical fixation, which allows for a precise, incremental tensioning of the graft, ensuring circumferential healing of the graft within the socket and reducing the risk of graft laceration, which may happen with interference screws. Internal bracing provides excellent contact pressure between the femoral button and femoral cortex, ensuring that adequate tensioning is applied to the graft.

Four-Stranded Semitendinosus Tendon Anterior Cruciate Ligament Reconstruction With Mini-invasive Anterolateral Ligament Reconstruction

Anterior cruciate ligament reconstruction (ACLR) is presently acknowledged as a prevalent procedure within the field of sports medicine surgery. Among the various graft options available, autograft hamstring tendons have emerged as one of the frequently used choices. This selection is primarily driven by the advantages it offers, such as reduced postoperative knee pain and a comparatively smoother surgical recovery process, when compared with the use of bone-patellar tendon-bone autografts. Quadrupled (4-stranded) semitendinosus tendon grafts have gained substantial popularity in recent years. This graft option offers the advantage of preserving the gracilis tendon while simultaneously exhibiting exceptional biomechanical strength. Furthermore, clinical studies have shown that the combination of ACLR and anterolateral ligament reconstruction yields superior outcomes, circumventing the application of nonanatomic extra-articular procedures involving the use of the fascia lata. The objective of this technical note is to outline a meticulous approach for ACLR using a 4-stranded semitendinosus tendon graft, applying a double-suspensory fixation method, and incorporating a minimally invasive procedure for anterolateral ligament reconstruction.

Lateral augmentation procedures in anatomic anterior cruciate ligament reconstruction. How to avoid tunnel collision with intraoperative tunnel visualization: A technical note

Lateral extra-articular tenodesis (LET) or anterolateral ligament (ALL) reconstruction can be used as an augmentation procedure in anatomic anterior cruciate ligament (ACL) reconstruction and are thought to minimize rotational instability, lower re-rupture rates of the ACL graft and improve functional outcomes after surgery. Young patients with high-grade pivot shift or generalized laxity participating in high demand/pivoting sports are considered as the ideal candidates for such a procedure. Both in LET and in ALL reconstruction, femoral fixation of the graft using an interference screw remains a challenge due to the possibility of tunnel convergence of the two tunnels created in the femur, namely the ACL femoral tunnel and the tunnel created in the lateral femur for the LET or ALL procedure. With this technical note, we aim to describe a safe approach for femoral tunnel creation by providing the surgeon not only with instructions for a safe orientation but also with the possibility to check for a possible tunnel collision by using the arthroscope through the anteromedial portal. Although instructions can be used both for LET and ALL reconstruction (same femoral tunnel), a modified Lemaire LET is extensively described since this procedure is the authors' preference for augmenting anatomic ACL reconstruction.

The Digital Twin: A Potential Solution for the Personalized Diagnosis and Treatment of Musculoskeletal System Diseases

Due to the high prevalence and rates of disability associated with musculoskeletal system diseases, more thorough research into diagnosis, pathogenesis, and treatments is required. One of the key contributors to the emergence of diseases of the musculoskeletal system is thought to be changes in the biomechanics of the human musculoskeletal system. However, there are some defects concerning personal analysis or dynamic responses in current biomechanical research methodologies. Digital twin (DT) was initially an engineering concept that reflected the mirror image of a physical entity. With the application of medical image analysis and artificial intelligence (AI), it entered our lives and showed its potential to be further applied in the medical field. Consequently, we believe that DT can take a step towards personalized healthcare by guiding the design of industrial personalized healthcare systems. In this perspective article, we discuss the limitations of traditional biomechanical methods and the initial exploration of DT in musculoskeletal system diseases. We provide a new opinion that DT could be an effective solution for musculoskeletal system diseases in the future, which will help us analyze the real-time biomechanical properties of the musculoskeletal system and achieve personalized medicine.

Three-dimensional-printed patient-specific instrumentation is an accurate tool to reproduce femoral bone tunnels in multiple-ligament knee injuries

PURPOSE

Multiple-ligament knee reconstruction techniques often involve the creation of several bone tunnels for various reconstruction grafts. A critical step in this procedure is to avoid short tunnels or convergences among them. Currently, no specific template guide to reproduce these angulations has been reported in the literature, and the success of the technique still depends on the experience of the surgeon. The aim of this study is to analyze the accuracy and reliability of 3D-printed patient-specific instrumentation (PSI) for lateral and medial anatomical knee reconstructions.

METHODS

Ten cadaveric knees were scanned by computed tomography (CT). Using specific computer software, anatomical femoral attachments were identified: (1) on the lateral side the lateral collateral ligament (LCL) and the popliteal tendon (PT) and (2) on the medial side the medial collateral ligament (MCL) and the posterior oblique ligament (POL). Four bone tunnels were planned for each knee, and PSI with different directions were designed as templates to reproduce the planned tunnels during surgery. Twenty 3D-printed PSI were used: ten were tailored to the medial side for reconstructing MCL and POL tunnels, and the other ten were tailored to the lateral side for reconstructing LCL and PT tunnels. Postoperative CT scans were made for each cadaveric knee. The accuracy of the use of 3D-printed PSI was assessed by superimposing post-operative CT images onto pre-operative images and analyzing the deviation of tunnels performed based on the planning, specifically the entry point and the angular deviations.

RESULTS

The median entry point deviations for the tunnels were as follows: LCL tunnel, 1.88 mm (interquartile range (IQR) 2.2 mm); PT tunnel, 2.93 mm (IQR 1.17 mm); MCL tunnel, 1.93 mm (IQR 4.26 mm); and POL tunnel, 2.16 mm (IQR 2.39). The median angular deviations for the tunnels were as follows: LCL tunnel, 2.42° (IQR 6.49°); PT tunnel, 4.15° (IQR 6.68); MCL tunnel, 4.50° (IQR 6.34°); and POL tunnel, 4.69° (IQR 3.1°). No statistically significant differences were found in either the entry point or the angular deviation among the different bone tunnels.

CONCLUSION

The use of 3D-printed PSI for lateral and medial anatomical knee reconstructions provides accurate and reproducible results and may be a promising tool for use in clinical practice.

Anatomy, Biomechanics, and Reconstruction of the Anterolateral Ligament of the Knee Joint

Despite remarkable advances in the clinical outcomes after anterior cruciate ligament reconstructions (ACLRs), residual rotational instability of the knee joint remains a major concern. Since the anterolateral ligament (ALL) on the knee joint has been “rediscovered”, the role of anterolateral structures, including ALL and deep iliotibial band, as secondary stabilizers of anterolateral rotatory instability has gained interest. This interest has led to the resurgence of anterolateral procedures combined with ACLRs to restore rotational stability in patients with anterior cruciate ligament (ACL) deficiencies. However, the difference in concepts between anterolateral ligament reconstructions (ALLRs) as anatomical reconstruction and lateral extra-articular tenodesis (LETs) as non-anatomical reinforcement has been conflicting in present literature. This study aimed to review the anatomy and biomechanics of anterolateral structures, surgical techniques, and the clinical outcomes of anterolateral procedures, including LET and ALLR, in patients with ACL deficiencies.