Multiple ligament anatomic-based reconstructions of the knee: State- of-the-art

Multiple knee ligament injuries are defined as a disruption of any combination of the four main ligament complexes; the cruciate ligaments, posterolateral corner, and posteromedial corner. Evaluation requires consideration of the entire clinical picture, including injury to associated structures, directions and degree of instability, neurovascular compromise and appropriate imaging, and physical examination. Reconstruction is favored over repair and anatomic- based reconstruction techniques have been validated to restore the native biomechanics of the knee and lead to successful patient-reported and objective outcomes. Anatomic-based reconstruction of many knee ligaments simultaneously requires precise knowledge of the relevant anatomical landmarks, careful planning of reconstruction tunnel positions, and orientations to avoid tunnel convergence, and employment of immediate early motion in the post-operative rehabilitation regimen to provide the patient the best chance for relatively normal use of the affected limb.

Rate of Tibial Tunnel Malposition Is Not Changed by Drilling Entirely Within the Stump of Preserved Remnants During ACL Reconstruction: A Prospective Comparative 3D-CT Study

Background: Remnant preservation during anterior cruciate ligament (ACL) reconstruction (ACLR) is controversial, and it is unclear whether the stump aids or obscures tibial tunnel positioning. Purpose/Hypothesis: The aim of this study was to determine whether the rate of tibial tunnel malposition is influenced by remnant preservation. The hypothesis was that using a remnant-preserving technique to drill entirely within the tibial stump would result in a significant reduction in tibial tunnel malposition as determined by postoperative 3-dimensional computed tomography (3D-CT). Study Design: Cohort study; Level of evidence, 2. Methods: Patients undergoing ACLR between October 2018 and December 2019 underwent surgery with a remnant-preserving technique (RP group) if they had a large stump present (>50% of the native ACL length) or if there was no remnant or if it was <50% of the native length of the ACL, they underwent remnant ablation (RA group) and use of standard landmarks for tunnel positioning. The postoperative tunnel location was reported as a percentage of the overall anteroposterior (AP) and mediolateral (ML) dimensions of the tibia on axial 3D-CT. The tunnel was classified as anatomically placed if the center lay between 30% and 55% of the AP length and between 40% and 51% of the ML length. Results: Overall, 52 patients were included in the study (26 in each group). The mean tunnel positions were 36.8% ± 5.5% AP and 46.7% ± 2.9% ML in the RP group and 35.6% ± 4.8% AP and 47.3% ± 2.3% ML in the RA group. There were no significant differences in the mean AP ( P = .134) and ML ( P = .098) tunnel positions between the groups. Inter- and intraobserver reliability varied between fair to excellent and good to excellent, respectively. There was no significant difference in the rate of malposition between groups (RP group, 7.7%; RA group, 11.5%; P ≥ .999). Conclusion: Drilling entirely within the ACL tibial stump using a remnant-preserving reconstruction technique did not significantly change the rate of tunnel malposition when compared with stump ablation and utilization of standard landmarks.

Evaluation of Tibial Tunnel Location with the Femoral Tunnel Created Behind the Resident's Ridge in Transtibial Anterior Cruciate Ligament Reconstruction

Few studies have determined whether a femoral bone tunnel could be created behind the resident's ridge by using a transtibial (TT) technique-single bundle (SB)-anterior cruciate ligament (ACL) reconstruction. The aim of this study was to clarify (1) whether it is possible to create a femoral bone tunnel behind the resident's ridge by using the TT technique with SB ACL reconstruction, (2) to define the mean tibial and femoral tunnel angles during anatomic SB ACL reconstruction, and (3) to clarify the tibial tunnel inlet location when the femoral tunnel is created behind resident's ridge. Arthroscopic TT-SB ACL reconstruction was performed on 36 patients with ACL injuries. The point where 2.4-mm guide pin was inserted was confirmed, via anteromedial portal, to consider a location behind the resident's ridge. Then, an 8-mm diameter femoral tunnel with a 4.5-mm socket was created. Tunnel positions were evaluated by using three-dimensional computed tomography (3D-CT) 1 week postoperatively. Quadrant method and the resident's ridge on 3D-CT were evaluated to determine whether femoral tunnel position was anatomical. Radiological evaluations of tunnel positions yielded mean ( ± standard deviation) X- and Y-axis values for the tunnel centers: femoral tunnel, 25.2% ± 5.1% and 41.6% ± 10.2%; tibial tunnel, 49.2% ± 3.5%, and 31.5% ± 7.7%. The bone tunnels were anatomically positioned in all cases. The femoral tunnel angle relative to femoral axis was 29.4 ± 5.5 degrees in the coronal view and 43.5 ± 8.0 degrees in the sagittal view. The tibial tunnel angle relative to tibial axis was 25.5 ± 5.3 degrees in the coronal view and 52.3 ± 4.6 degrees in the sagittal view. The created tibial bone tunnel inlet had an average distance of 13.4 ± 2.7 mm from the medial tibial joint line and 9.7 ± 1.7 mm medial from the axis of the tibia. Femoral bone tunnel could be created behind the resident's ridge with TT-SB ACL reconstruction. The tibial bone tunnel inlet averaged 13.4 mm from the medial tibial joint line and 9.7 mm medial from the tibia axis.

Anterior Cruciate Ligament Femoral Tunnel Placement: An Analysis of the Intended Versus Achieved Position for 221 International High-Volume ACL Surgeons

Background: Femoral tunnels that are not anatomically placed within the native anterior cruciate ligament (ACL) footprint during ACL reconstruction are associated with residual instability, graft rupture, and poor clinical outcomes. Although surgeons may intend to place their femoral tunnels within the native ACL attachment, this is not always achieved. This study assesses the variation between intended and achieved femoral tunnel positions in a large cohort of experienced ACL surgeons. Hypothesis: The accuracy with which experienced ACL surgeons achieve their intended femoral tunnel position is dependent on viewing portal, localization strategy, and drilling technique. Study Design: Controlled laboratory study. Methods: A total of 221 surgeons indicated their intended femoral tunnel location on a true lateral radiograph of a cadaveric knee specimen and a scaled photograph. Each surgeon then arthroscopically demonstrated the femoral tunnel on the specimen. The position was captured using fluoroscopy. The Euclidean distance (the straight-line distance between 2 points) between the intended and achieved tunnel positions, referenced to a grid applied to the lateral femoral condyle, was compared. Data were analyzed according to surgeons’ viewing portal (anteromedial [AM] or anterolateral [AL]), tunnel localization strategy (offset aimer, estimation from landmarks, ACL ruler, or C-arm fluoroscopy), and stated drilling technique (transtibial, AM portal, or outside-in). Results: Surgeons who viewed the lateral intercondylar notch wall through the AM portal were closer (mean distance, 9.5) to their intended position than those who viewed through the AL portal (mean distance, 15.1; P < .0001). By localization strategy, the mean distance between achieved and intended tunnel positions was greater for surgeons who used an offset aimer (14.5) and estimated the femoral tunnel position (12.9) than for those using a malleable ACL ruler (8.1; P < .0001) and fluoroscopy (4.3; P < .0001). Surgeons’ preferred drilling technique (AM portal, transtibial, or outside-in) had no effect on distance between intended and achieved positions. However, the mean achieved position was higher in the intercondylar notch for those using transtibial drilling ( P < .042). Conclusion: Surgeons using the AM portal to view the femoral attachment site were closer to their intended tunnel position than those who viewed it with the arthroscope in the AL portal. Surgeons who used fluoroscopy to localize femoral tunnel position were the closest to their intended position. Those who used estimation or an offset aimer had the farthest distance between achieved and intended tunnel positions. Clinical Relevance: Although accurate tunnel placement can be achieved using any method, given the disparity between intended and achieved tunnel positions, it may be advisable, even for high-volume surgeons, to verify the placement of their tunnels using either fluoroscopy or a malleable ACL ruler to ensure that they achieve their intended position. Fluoroscopy may be particularly useful for cases where the native femoral stump is no longer visible and for revisions. Viewing through the AM portal is recommended to aid accuracy of tunnel placement.

Effects of Remnant Tissue Preservation on Tunnel Enlargement After Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Hamstring Tendon

Background: The effects of remnant tissue preservation on tunnel enlargement after anatomic double-bundle anterior cruciate ligament (ACL) reconstruction have not yet been established. Hypothesis: The preservation of ACL remnant tissue may significantly reduce the degree and incidence of tunnel enlargement after anatomic double-bundle ACL reconstruction, while the remnant-preserving procedure may not significantly increase the incidence of tunnel coalition after surgery. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 79 patients underwent anatomic double-bundle ACL reconstruction. Based on the Crain classification of ACL remnant tissue, 40 patients underwent the remnant-preserving procedure (group P), and the remaining 39 patients underwent the remnant-resecting procedure (group R). There were no differences between the 2 groups concerning all background factors, including preoperative knee instability and intraoperative tunnel positions. All patients were examined using computed tomography and a standard physical examination at 2 weeks and 1 year after surgery. Results: During surgery, the femoral and tibial anteromedial (AM) tunnel sizes in both groups averaged 6.6 and 6.5 mm, respectively. The femoral and tibial posterolateral (PL) tunnel sizes in both groups averaged 6 and 6 mm, respectively. There were no differences in the intraoperative tunnel positions and tunnel sizes between groups. Concerning the femoral AM tunnel, the degree of tunnel enlargement in the oblique coronal and oblique axial views in group P was significantly less than that in group R ( P = .0068 and .0323, respectively). Regarding the femoral AM tunnel cross-sectional area, the degree and incidence of tunnel enlargement in group P were significantly less than those in group R ( P = .0086 and .0278, respectively). There were no significant differences in tunnel coalition between groups. In each group, there were no significant relationships between tunnel enlargement and each clinical outcome. Conclusion: Remnant preservation in anatomic double-bundle ACL reconstruction reduced enlargement of the femoral AM tunnel and did not increase the incidence of tunnel coalition. This is one of the advantages of remnant-preserving ACL reconstruction.

The Effect of Humeral and Ulnar Tunnel Placement on Achieving UCL Graft Isometry

Objectives: The elbow medial ulnar collateral ligament (UCL) is frequently injured in throwing athletes, most commonly baseball pitchers. When conservative management fails, surgical intervention can allow the athlete to return to sport. While extensive research has been devoted to UCL graft incorporation and outcomes based on varying surgical techniques, there is a paucity of literature available addressing optimal bone tunnel placement in achieving medial UCL graft isometry. The purpose of this study is to assess the effect of humeral and ulnar bone tunnel placement on achieving UCL graft isometry through elbow range-of-motion. Methods: Ten fresh-frozen cadaveric upper extremities were dissected to expose the native UCL in its entirety. Three equidistant humeral and ulnar tunnels were created at each UCL footprint. Suture was passed between nine possible tunnel combinations for each elbow affixed to an isometry guage. Each elbow was moved through a 120-degree arc of motion for each tunnel combination at 0, 30, 60, 90, and 120 degrees. Measured changes in isometry gauge tension were recorded and analyzed using one-way analysis of variance (ANOVA) with Tukey’s HSD for pairwise comparisons. A p-value of 0.05 was used to determine significance for all tests. Results: There was an overall significant effect (p < 0.0001) of tunnel placement at all degrees of flexion measured. Pairwise comparisons revealed increases in displacement between the central and posterior tunnel positions of the medial epicondyle, with significant differences (p=0.0009) occurring when paired with both the central and posterior aspect of the sublime tubercle. Profound differences (p < 0.0001) were noted between the anterior and posterior humeral tunnel positions. No significant differences noted between ulnar tunnel locations at any humeral location. Figure 1: Tunnel placement in the central part of the medial epicondyle (Centralepi) was generally the most isometric grouping, with Centralepi - Anteriortub being the most isometric combination of all. Data are represented as mean +/- SEM. Conclusion: Isometric graft placement of the medial elbow UCL is undoubtedly dependent upon optimal tunnel placement and even slight deviations from the native centroid at either the medial epicondyle or sublime tubercle can possibly lead to early graft failure or abnormal joint kinematics. This information can aid surgeons in performing isometric single bone tunnel UCL reconstruction or repair procedures in the future.