The Subscapularis-Sparing "Flipped Latarjet" Procedure.

The Latarjet procedure is a proven and effective operation to treat anterior shoulder instability. Especially in cases with anterior glenoid bone loss, the Latarjet operation is the most popular procedure to restore glenoid anatomy and avoid further dislocations. Next to the re-creation of the missing glenoid bone, the sling effect of the conjoint tendon transferred between a split in the subscapularis muscle is an important "soft tissue stabilizer" of the humeral head. However, it has been shown that the inferior part of the subscapularis muscle tends to degenerate, leading to fatty infiltration of the muscle itself. Also, exposure through the subscapularis split is technically demanding, and there is a risk of nerve damage due to the pulling forces of the retractors during open surgery. When performing the procedure arthroscopically, extremely low and medial portals are necessary to find a correct angle for the glenoid drilling when approaching from anterior. Neurovascular structures may be at risk during these surgical steps. The aim of the flipped Latarjet procedure is to facilitate a safe and reliable arthroscopic operation to anteriorly stabilize the shoulder by transferring the coracoid to the deficient glenoid without splitting the subscapularis muscle while keeping the benefits of a sling effect of the conjoined tendon.

Preoperative 3-dimensional computed tomography bone density measures provide objective bone quality classifications for stemless anatomic total shoulder arthroplasty.

BACKGROUND: Reproducible methods for determining adequate bone densities for stemless anatomic total shoulder arthroplasty (aTSA) are currently lacking. The purpose of this study was to evaluate the utility of preoperative computed tomography (CT) imaging for assessing the bone density of the proximal humerus for supportive differentiation in the decision making for stemless humeral component implantation. It was hypothesized that preoperative 3-dimensional (3-D) CT bone density measures provide objective classifications of the bone quality for stemless aTSA. METHODS: A 3-part study was performed that included the analysis of cadaveric humerus CT scans followed by retrospective application to a clinical cohort and classification with a machine learning model. Thirty cadaveric humeri were evaluated with clinical CT and micro-CT (µCT) imaging. Phantom-calibrated CT data were used to extract 3-D regions of interest and defined radiographic scores. The final image processing script was applied retrospectively to a clinical cohort (n = 150) that had a preoperative CT and intraoperative bone density assessment using the "thumb test," followed by placement of an anatomic stemmed or stemless humeral component. Postscan patient-specific calibration was used to improve the functionality and accuracy of the density analysis. A machine learning model (Support vector machine [SVM]) was utilized to improve the classification of bone densities for a stemless humeral component. RESULTS: The image processing of clinical CT images demonstrated good to excellent accuracy for cylindrical cancellous bone densities (metaphysis [ICC = 0.986] and epiphysis [ICC = 0.883]). Patient-specific internal calibration significantly reduced biases and unwanted variance compared with standard HU CT scans (P < .0001). The SVM showed optimized prediction accuracy compared with conventional statistics with an accuracy of 73.9% and an AUC of 0.83 based on the intraoperative decision of the surgeon. The SVM model based on density clusters increased the accuracy of the bone quality classification to 87.3% with an AUC of 0.93. CONCLUSIONS: Preoperative CT imaging allows accurate evaluation of the bone densities in the proximal humerus. Three-dimensional regions of interest, rescaling using patient-specific calibration, and a machine learning model resulted in good to excellent prediction for objective bone quality classification. This approach may provide an objective tool extending preoperative selection criteria for stemless humeral component implantation.

Primary Stability and Bone Contact Loading Evaluation of Suture and Screw based Coracoid Graft Fixation for Anterior Glenoid Bone Loss.

BACKGROUND: Reconstruction techniques for anterior glenoid bone loss have seen a trend from screws to suture-based fixations. However, comparative biomechanical data, including primary fixation and glenoid-graft contact pressure mapping, are limited. HYPOTHESIS: Suture-based bone block cerclage (BBC) and suspensory suture button (SB) techniques provide similar primary fixation and cyclic stability to double-screw fixation but with higher contact loading at the bony interface. STUDY DESIGN: Controlled laboratory study. METHODS: In total, 60 cadaveric scapulae were prepared to simulate anterior glenoid bone loss with coracoid autograft reconstruction. Graft fixation was performed with 3 different techniques: (1) an interconnected all-suture BBC, (2) 2 SB suspensions, and (3) 2 screws. Initial compression was analyzed during primary fixation. Cyclic peak loading with 50 N and 100 N over 250 cycles at 1 Hz was performed with a constant valley load of 25 N. Optical recording and pressure foils allowed for spatial bone block tracking and contact pressure mapping at the glenoid-graft interface. Load-to-failure testing was performed at a rate of 1.5 mm/s with ultimate load and stiffness measured. RESULTS: Initial graft compression was higher with screw fixation (141 ± 5 N) compared with suture-based fixations (P < .001), with BBC fixation providing significantly higher compression than SB fixation (116 ± 7 N vs. 91 ± 5 N; P < .001). Spatial bone block migration and ultimate failure load were similar between the BBC and screw groups. The SB group showed significantly increased bone block translation (3.1 ± 1.0 mm; P≤ .014) and rotation (2.5°± 1.4°; P≤ .025) and significantly lower ultimate failure load (180 ± 53 N) compared with the BBC (P = .046) and screw (P = .002) groups. Both suture-based fixations provided significantly increased graft-glenoid contact loading with higher pressure amplitudes (P≤ .032) and contact pressure after cyclic loading (+13%; SB: P = .007; BBC: P = .004) compared with screw fixation. CONCLUSION: Both SB and interconnected cerclage fixation improved dynamic contact loading compared with screw fixation in a biomechanical glenoid bone loss model. Cerclage fixation was biomechanically comparable with screw fixation but with a greater variability. SB fixation showed significantly lower primary fixation strength and greater bone block rotation and migration. CLINICAL RELEVANCE: Suture-based bone block fixations improved graft-glenoid contact loading, but the overall clinical consequence on healing remains unclear.

Biomechanical Stability of Lateral Ulnar Collateral Ligament Reconstruction and Repair of the Elbow: The Role of Ligament Bracing on Gap Formation and Stabilization.

BACKGROUND: Augmented (internal braced) lateral ulnar collateral ligament (LUCL) repair has been biomechanically compared with reconstruction techniques in the elbow. However, LUCL repair alone has not yet been compared with augmented repair and reconstruction techniques. HYPOTHESIS: Internal bracing of LUCL repair would improve time-zero stabilization regarding gap formation, stiffness, and residual torque as compared with repair alone and reconstruction techniques to restore native elbow stability. STUDY DESIGN: Controlled laboratory study. METHODS: Overall, 24 cadaveric elbows were used for either internal braced LUCL repair (Repair-IB) or single- and double-strand ligament reconstruction with triceps (Recon-TR) and palmaris longus tendon graft (Recon-PL), respectively. Laxity testing in external rotation was consecutively performed at 90° of elbow flexion on the intact, dissected, and repaired conditions and with the previously assigned techniques. First, intact elbows were loaded to 7.0-N·m external torque to evaluate time-zero ligament rotations at 2.5, 4.0, 5.5, and 7.0 N·m. Rotation-controlled cycling was performed (total of 1000 cycles) for each surgical condition. Gapping, stiffness, and residual torque were analyzed. Finally, these and 8 additional intact elbows underwent torque-to-failure testing (30 deg/min). RESULTS: The dissected state showed the highest gap formation and lowest peak torques (P < .001). While gap formation of Repair-IB (P < .021) was significantly lower than that of repair without internal bracing at all rotation levels, gaps of Recon-PL were similar to and Recon-TR were significantly higher than those of Repair-IB except for the highest torsion level. Residual peak torques at specific rotation angles between native state and Recon-TR (α2.5), Recon-PL (α4.0), and Repair-IB (α5.5) were similar; all other comparisons were significantly different (P < .027). Torsional stiffness of Repair-IB was significantly higher at all rotation angles measured. Analysis of covariance showed significantly less gap formation over residual peak torques for Repair-IB (P < .001) as compared with all other groups. The native state failure load was significantly higher than Recon-PL and Recon-TR failure loads, with similar stiffness to all other groups. CONCLUSION: Repair-IB and Recon-PL of the LUCL showed increased rotational stiffness relative to the intact elbow for restoring posterolateral stability to the native state in a cadaveric model. Recon-TR demonstrated lower residual peak torques but provided near-native rotational stiffness. CLINICAL RELEVANCE: Internal bracing of LUCL repair may reduce suture-tearing effects through tissue and provide sufficient stabilization for healing throughout accelerated and reliable recovery without the need for a tendon graft.

Primary Fixation and Cyclic Performance of Single-Stitch All-Inside and Inside-Out Meniscal Devices for Repairing Vertical Longitudinal Meniscal Tears.

BACKGROUND: Primary device fixation and the resistance against gap formation during repetitive loading influence the quality of meniscal repair. There are limited biomechanical data comparing primary tensioning and cyclic behavior of all-inside versus inside-out repair. HYPOTHESIS: All-inside devices provide higher initial load on the meniscal repair than inside-out fixation, and stiffer constructs show higher resistance against gap formation during cyclic loading. STUDY DESIGN: Controlled laboratory study. METHODS: In total, 60 longitudinal bucket-handle tears in human cadaveric menisci were created and repaired with a single stitch and randomly assigned to 4 all-inside groups (TrueSpan, FastFix 360, Stryker AIR, FiberStich) and 2 inside-out groups (suture repair [IO-S], suture tape [IO-ST]). Residual load after repair tensioning (50 N) and relief displacement were measured. Constructs underwent cyclic loading between 2 and 20 N over 500 cycles (0.75 Hz) with cyclic stiffness, gap formation, and final peak elongation measured. Ultimate load and stiffness were analyzed during pull to failure (3.15 mm/s). RESULTS: All-inside repair demonstrated significantly higher primary fixation strength than inside-out repair. The significantly highest load (mean ± SD; 20.1 ± 0.9 N; P < .037) and relief displacement (-2.40 ± 0.32 mm; P < .03) were for the knotless soft anchoring FiberStich group. The lowest initial load (9.0 ± 1.5 N; P < .001) and relief displacement (-1.39 ± 0.26 mm; P < .045) were for the IO-S repair group. The final gap formation (500th cycle) of FiberStich (0.75 ± 0.37 mm; P < .02) was significantly smaller than others and that of the IO-S (1.47 ± 0.33 mm; P < .045) significantly larger. The construct stiffness of the FiberStich and IO-ST groups was significantly greater at the end of cyclic testing (16.7 ± 0.80 and 15.5 ± 1.42 N/mm; P < .042, respectively) and ultimate failure testing (23.4 ± 3.6 and 20.6 ± 2.3 N/mm; P < .005). The FastFix 360 (86.4 ± 4.8 N) and Stryker AIR (84.4 ± 4.6 N) groups failed at a significantly lower load than the IO-S group (P < .02) with loss of anchor support. The FiberStich (146.8 ± 23.4 N), TrueSpan (142.0 ± 17.8 N), and IO-ST (139.4 ± 7.3 N) groups failed at significantly higher loads (P < .02) due to suture tearing. CONCLUSION: Overall, primary fixation strength of inside-out meniscal repair was significantly lower than all-inside repair in this cadaveric tissue model. Although absolute differences among groups were small, meniscal repairs with higher construct stiffness (IO-ST, FiberStich) demonstrated increased resistance against gap formation and failure load. CLINICAL RELEVANCE: Knotless single-stitch all-inside meniscal repair with a soft anchor resulted in less gapping, but the overall clinical significance on healing rates remains unclear.

Independent Suture Augmentation With All-Inside Anterior Cruciate Ligament Reconstruction Reduces Peak Loads on Soft-Tissue Graft. A Biomechanical Full-Construct Study.

PURPOSE: To evaluate the effect of suture augmentation (SA) of 7-mm and 9-mm diameter graft on load sharing, elongation, stiffness, and load to failure for all-inside anterior cruciate ligament reconstruction (ACLR) in a biomechanical Study was funded by Arthrex ID: EMEA-16020. full-construct porcine model. METHODS: Bovine tendon grafts, 7-mm and 9-mm diameter, with and without SA were tested using suspensory fixation (n = 8). The independent SA was looped over a femoral button and knotted on a tibial button. Preconditioned constructs were incrementally increased loaded (100N/1,000 cycles) from 100N to 400N for 4,000 cycles (0.75 Hz) with final pull to failure (50 mm/min). Isolated mechanical and optical measurements during construct loading of the SA allowed to quantify the load and elongation range during load sharing. Construct elongation, stiffness and ultimate strength were further assessed. RESULTS: Load sharing in 7-mm grafts started earlier (200N) with a significant greater content than 9-mm grafts (300N) to transfer 31% (125N) and 20% (80N) of the final load (400N) over the SA. Peak load sharing with SA reduced total elongation for 7-mm (1.90 ± 0.27 mm vs 4.77 ± 1.08 mm, P < .001) and 9-mm grafts (1.50 ± 0.33 mm vs 3.57 ± 0.54 mm, P < .001) and adequately increased stiffness of 7-mm (113.4 ± 9.3 N/mm vs 195.9 ± 9.8 N/mm, P < .001) to the level of augmented 9-mm grafts (208.9 ± 13.7N/mm). Augmentation of 7-mm (835 ± 92N vs 1,435 ± 228N, P < .001) and 9-mm grafts (1,044 ± 49N vs 1,806 ± 157N, P < .001) significantly increased failure loads. CONCLUSIONS: Load sharing with SA occurred earlier (200N vs 300N) in lower stiffness 7-mm grafts to carry 31% (7-mm) and 20% (9-mm) of the final load (400N). Loads until peak load sharing were transferred over the graft. Augmented constructs showed significantly lower construct elongation and increased stiffness without significance between variable grafts. Failure load of augmented grafts were significantly increased. CLINICAL RELEVANCE: Suture tape ligament augmentation may potentially protect biological grafts from excessive peak loading and elongation, thus reducing the risk of graft tears.

Biomechanical Functional Elbow Restoration of Acute Ulnar Collateral Ligament Tears: The Role of Internal Bracing on Gap Formation and Repair Stabilization.

BACKGROUND: Biomechanical studies have compared augmented primary repair with internal bracing versus reconstruction techniques of the anterior ulnar collateral ligament (aUCL) in the elbow. However, aUCL repair alone has not been compared with augmented repair or reconstruction techniques. HYPOTHESIS: Internal bracing of aUCL repair provides improved time-zero stabilization in terms of gap formation, torsional stiffness, and residual torque compared with both repair alone and the modified docking technique, with enhanced valgus stability restoration to that of the native ligament. STUDY DESIGN: Controlled laboratory study. METHODS: We randomized 8 matched pairs of cadaveric elbows to undergo either augmented aUCL repair or a modified docking technique through use of the palmaris longus tendon. Valgus laxity testing was consecutively performed at 90° of flexion on the intact, torn, and repaired conditions as well as the previously assigned techniques. First, intact elbows were loaded up to 10 N·m valgus torque to evaluate time-zero ligament rotations at valgus moments of 2.5, 5.0, 7.5, and 10 N·m. Rotation controlled cycling was performed (total 1000 cycles) for each surgical condition. Gap formation, stiffness, and residual torque were analyzed. Finally, these elbows and 8 additional intact elbows underwent torque to failure testing (30 deg/min). RESULTS: Repair alone revealed low torsional resistance and gapping, similar to the torn state. The augmented repair technique showed significantly higher torsional stiffness (P < .001) and residual torque (P < .001) compared with all other conditions and restored native function. Although reconstruction revealed similar initial stiffness and residual torque compared with an intact ligament, a steady decrease of torsional resistance led to a completely loose state at higher valgus rotations. Analysis of covariance between all groups showed significantly less gap formation for augmented repair (P < .001). The native failure load and stiffness were significantly higher and were similar to those of augmented repair (P = .766). CONCLUSION: Internal bracing of aUCL repair restored valgus stability to the native state with statistically improved torsional resistance, loading capability, and gap formation compared with reconstruction, especially at the upper load range of native aUCL function in the elbow. CLINICAL RELEVANCE: We found that aUCL repair with an internal brace effectively improves time-zero mechanical characteristics and may provide stabilized healing with accelerated and reliable recovery without the need for a tendon graft.

Independent Suture Tape Reinforcement of Tripled Smaller-Diameter and Quadrupled Grafts for Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation: A Biomechanical Full Construct Model.

PURPOSE: To compare the effect of independent suture tape reinforcement on the dynamic elongation and stiffness behavior as well as ultimate strength of tripled smaller-diameter and quadrupled soft-tissue grafts for anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Tripled smaller-diameter (8 mm) and quadrupled (9 mm) bovine tendon grafts with and without suture tape reinforcement (n = 8 in each group) were tested using femoral suspensory and tibial interference screw fixation. The suture tape was femoral sided and fixed independent from the graft by passing it through the suspensory button and securing the 2 open tibial strands with a secondary interference screw. Dynamic testing was performed in position and force control at 250 N and 400 N, followed by pull to failure with the mode of failure noted. Dynamic elongation, stiffness, and ultimate strength were analyzed. RESULTS: Tripled constructs showed a significantly worse structural performance than quadrupled constructs at higher loads. Reinforcement of tripled and quadrupled grafts substantially decreased total elongation by 56% (4.54 ± 0.75 mm vs 2.01 ± 0.50 mm, P < .001) and 39% (3.25 ± 0.49 mm vs 1.98 ± 0.51 mm, P < .001), respectively, by significantly increasing dynamic stiffness. No statistical significance was found between the reinforced groups. Failure loads of reinforced tripled (1,074 ± 148 N vs 829 ± 100 N, P = .003) and quadrupled (1,125 ± 157 N vs 939 ± 76 N, P = .023) grafts were also significantly improved. CONCLUSIONS: Independent reinforcement of soft-tissue grafts with suture tape strengthened the performance especially of tripled smaller-diameter grafts for ACLR with tibial screw fixation by significantly improving dynamic elongation at increased stiffness and ultimate strength. Quadrupled reinforced grafts showed no over-constraining and structurally behaved similarly to tripled grafts with reinforcement. CLINICAL RELEVANCE: Independent reinforcement for ACLR may provide an option for protecting autografts or allografts against irreversible lengthening during the maturation and remodeling phases of healing.

Intraoperative Preconditioning of Fixed and Adjustable Loop Suspensory Anterior Cruciate Ligament Reconstruction With Tibial Screw Fixation-An In Vitro Biomechanical Evaluation Using a Porcine Model.

PURPOSE: To evaluate the effect of preconditioning according to intraoperative workflow on initial tension and elongation behavior for femoral adjustable loop devices (ALDs) and closed loop devices (CLDs) in suspensory anterior cruciate ligament reconstruction (ACLR) with tibial screw fixation in a biomechanical in vitro study. METHODS: Three ACLR groups with tibial screw fixation were biomechanically tested in a full-construct setup using porcine tibias. Groups (n = 8 per group) varied by femoral fixation method and consisted of a CLD (group 3) and ALD fixation with (group 2) and without simulated intraoperative preconditioning (group 1). The change in tension after screw insertion and the displacement to restore the initial loading situation were measured. Grafts underwent dynamic cycling (1,000 cycles at 0.75 Hz) using both a position and a force control mode. RESULTS: Data are presented as mean [standard deviation]. Placement of an interference screw induced a graft tension loss of 62% (49.4 [0.4] N vs 19.0 [10.0] N, P < .001) by introducing a laxity of 0.53 [0.26] mm. Intraoperative preconditioning led to a higher initial load level (228.3 [19.8] N) compared with unconditioned ALD (156.1 [25.5] N, P < .001) and CLD groups (156.6 [12.8] N, P < .001) with less force decrease over position-controlled cyclic loading. Furthermore, initial (-0.22 [0.16] mm) and dynamic elongation (0.88 [0.23] mm) were reduced compared with the unconditioned ALD (0.65 [0.35] mm, P < .001; and 1.56 [0.19] mm, P < .001) and CLD groups (0.16 [0.26] mm, P < .001; and 1.64 [0.24] mm, P < .001). CONCLUSIONS: ACLR with femoral ALD fixation and intraoperative preconditioning allows for restoration of time-zero screw-imparted slack and leads to significantly reduced cyclic elongation in accordance with native ACL function. Both ALD and CLD control groups behaved similarly, with total elongation less than 3 mm including time-zero slack. CLINICAL RELEVANCE: Although the clinical relevance of time-zero graft tension loss is uncertain, the use of an ALD in concert with tibial screw fixation may be favorable to allow for tension optimization.

Independent Suture Tape Reinforcement of Small and Standard Diameter Grafts for Anterior Cruciate Ligament Reconstruction: A Biomechanical Full Construct Model.

PURPOSE: To compare the dynamic elongation, stiffness behavior, and ultimate failure load of standard with small diameter soft tissue grafts for anterior cruciate ligament (ACL) reconstruction with and without high-strength suture tape reinforcement. METHODS: Both a tripled "small" diameter and a "standard" quadrupled tendon graft with and without suture tape reinforcement were tested using suspensory fixation (n = 8 each group). The suture tape was passed through the suspensory fixation button on the femur and tibia to ensure independent (safety belt) fixation from the graft in vitro. The testing of the constructs included position-controlled cyclic loading, force-controlled cyclic loading at 250 N and 400 N as well as pull to failure (50 mm/min). RESULTS: Reinforcement of a small diameter graft significantly reduced dynamic elongation of 38% (1.46 ± 0.28 mm vs 2.34 ± 0.44 mm, P < .001) and 50% (2.55 ± 0.44 mm vs 5.06 ± 0.67 mm, P < .001) after the 250 N and 400 N load protocol, respectively. Reinforcement of a standard diameter tendon graft decreased dynamic elongation of 15% (1.59 ± 0.34 mm vs 1.86 ± 0.17 mm, P = .066) and 26% (2.62 ± 0.44 mm vs 3.55 ± 0.44 mm, P < .001). No significant difference was found between both reinforced models. The ultimate failure loads of small and standard diameter reinforced grafts were 1592 ± 105 N and 1585 ± 265 N, resulting in a 64% (P < .001) and 40% (P < .001) increase compared with their respective controls. CONCLUSIONS: Independent suture tape reinforcement of soft tissue grafts for ACL reconstruction leads to significantly reduced elongation and higher ultimate failure load according to in vivo native ACL function data without stress-shielding the soft tissue graft. CLINICAL RELEVANCE: If in vitro results are translational to human knees in vivo, the suture tape reinforcement technique for ACL reconstruction may decrease the risk of graft tears, particularly in the case of small diameter soft tissue grafts.

Intraoperative Workflow for All-Inside Anterior Cruciate Ligament Reconstruction: An In Vitro Biomechanical Evaluation of Preconditioning and Knot Tying.

PURPOSE: To evaluate and compare the effect of preconditioning according to intraoperative workflow on the elongation behavior of single-side and fully knotted all-inside anterior cruciate ligament (ACL) reconstruction configurations in a biomechanical in vitro study. METHODS: Four full construct all-inside ACL reconstruction groups (n = 8 per group) were tested using porcine tibias and bovine tendons. Groups included both an all-inside configuration with one- (group 1) and both-side knotted adjustable loop-length devices (group 2), without and with performing intraoperative preconditioning (group 1-intraoperative preconditioned [IPC], group 2-IPC). Adjustable loop-length devices for control groups were knotted according to test configurations. Intraoperative preconditioning specimens were further precycled for 10 times at 0.5 Hz and manually retensioned before knotting. All groups underwent dynamic cycling in position and force control mode each for 1,000 cycles at 0.75 Hz according to in vitro loading parameters replicating the in vivo ACL environment. Finally, a load-to-failure test at 50 mm/min was performed. RESULTS: Intraoperative preconditioning increases initial graft tension for single- (242 ± 22 N vs 174 ± 13 N; P < .0001) and both-side knotted configurations (225 ± 15 N vs 159 ± 10 N; P < .0001) compared with controls and allows maintained graft tension at higher levels until reaching the end of position-controlled cyclic loading. Furthermore, dynamic elongation is reduced for one- (1.93 ± 0.28 vs 0.76 ± 0.12; P < .0001) and both-side knotted (1.84 ± 0.20 vs 0.96 ± 0.32; P < .0001) configurations by 61% and 47%, respectively. No intergroup (group 1 vs group 2 and group 1-IPC vs group 2-IPC) statistically significant differences could be found between one- and both-side knotted configurations. CONCLUSIONS: All-inside ACL reconstruction with preconditioning according to intraoperative workflow leads to a statistically significant improved mechanical behavior and may allow for optimizing initial graft tension and elongation for all-inside ACL reconstruction to reduce knee laxity. A single-side knotted configuration achieves similar stabilization strength to fully knotted constructs. CLINICAL RELEVANCE: Graft insertion until tunnel docking increases the intratunnel graft portion that may optimize graft incorporation. Eliminating a suture knot stack may improve intraoperative workflow and reduce postoperative knot irritation.