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Purpose: Displaced tibial eminence fractures require surgical fixation in order to obtain a stable knee joint. Suture fixation with FiberWire(®) seems to be the most favorable therapeutic option. Biomechanical studies show failure of this technique most commonly due to a suture cutout with subsequent fracture of the tibial eminence fragment. The goal of this study is to compare the biomechanical properties of three different techniques of suture fixation using FiberWire(®)., Methods: Bone mineral density was evaluated in 18 human knee specimens by pqCT, and three similar groups were formed. A standardized anterior tibial eminence fracture was created, and suture fixation was performed using one of three different techniques in 6 specimens each. Cyclic and destructive testing was conducted., Results: Significant differences between the three techniques could be shown neither in the cycles needed to achieve a steady state nor in a failure load or initial stiffness. Almost all specimens failed by suture cutout., Conclusion: The presented modification of the existing technique for suture fixation of tibial eminence fractures did not lead to an increased initial stability nor did it lower the rate of suture cutout. All tested suture techniques showed comparable initial stiffness and failure load.

Purpose: This study investigates the influence of various femoral anterior cruciate ligament graft fixation methods on the amount of tension degradation and the initial fixation strength after cyclic flexion-extension loading in a porcine knee model., Methods: One hundred twenty porcine digital extensor tendons, used as 4-stranded free tendon grafts, were fixated within porcine femoral bone tunnels by use of extracortical button, cross-pin, or interference screw fixation. One hundred twenty porcine patellar tendon-bone grafts were fixated by use of cross-pin, interference screw, or press-fit fixation. Each femur-graft complex was submitted to cyclic flexion-extension loading for 1,000 cycles throughout different loading ranges, and the total loss of tension was determined. After cyclic testing, the grafts were loaded to failure, and the data were compared with a pullout series without cyclic loading., Results: Tension degradation after 1,000 cycles of flexion-extension loading averaged 62.6% +/- 10.0% in free tendon grafts and 48.9% +/- 13.35% in patellar tendon-bone grafts. There was no influence of the loading range on the total amount of tension degradation. The total amount of tension degradation was the highest with interference screw fixation of free tendon and patellar tendon-bone grafts. Despite excessive loss of tension, the initial fixation strength of the femur-graft complex was not reduced., Conclusions: The method of femoral graft fixation significantly influenced tension degradation during dynamic flexion-extension loading. Femoral graft fixation methods that secure the graft close to the tunnel entrance and that displace the graft substance from the center of the bone tunnel show the largest amount of tension degradation during cyclic flexion-extension loading. The graft substance, not the fixation site, was the weakest link of the graft complex within this investigation., Clinical Relevance: We believe that the graft fixation method should be considered when aiming to improve the precision of femoral graft placement in anterior cruciate ligament reconstruction.

Correct placement of the tibial and femoral bone tunnel is prerequisite to a successful anterior cruciate ligament (ACL) reconstruction. This study compares the resulting radiographic femoral bone tunnel position of two commonly used techniques for arthroscopically assisted drilling of the femoral bone tunnel: the transtibial approach or drilling through the anteromedial arthroscopy portal. The resulting bone tunnel position was assessed in postoperative knee radiographs of 70 patients after ACL reconstruction. Three independent observers identified the femoral bone tunnel and determined its position in the lateral and A-P view. Differences in femoral tunnel position between transtibial and anteromedial drilling were evaluated. In the sagittal plane, significantly more femoral bone tunnels were positioned close to the reference value using an anteromedial drilling technique (86%) when compared to transtibial drilling (57%). Drilling through the transtibial tunnel resulted in a significantly more anterior position of the femoral tunnel. In the frontal plane, femoral bone tunnels which were placed through the anteromedial arthroscopy portal displayed a significantly greater angulation towards the lateral condylar cortex (50.92 degrees ) when compared to transtibial drilling (58.82 degrees ). In conclusion, drilling the femoral tunnel through the anteromedial arthroscopy portal results in a radiographic femoral bone tunnel position which is suggested to allow stabilization of both anterior tibial translation and rotational instability when using a single bundle reconstruction technique. Further studies may evaluate if there are any clinical advantages using the anteromedial portal technique.

Introduction: Press-fit fixation of bone-patellar tendon–bone (BPTB) grafts in anterior cruciate ligament (ACL) reconstruction has been analyzed biomechanically in previous studies; however, the use of quadriceps tendon–patellar bone (QTPB) grafts has not been studied so far. It is hypothesized that QTPB grafts provide primary fixation strength comparable to BPTB grafts in press-fit ACL reconstruction with respect to bone plug length and loading angle. Materials and methods: Fifty-two QTPB grafts were harvested from fresh human cadaver knees (mean age 73.3 years) with the length of the patellar bone plug being either 15 mm (Group I) or 25 mm (Group II). The grafts were anchored within fresh porcine femora (mean age 12 months) using a press-fit fixation technique. Forty-eight specimens were loaded to failure at 10 mm/s with varying loading angles of 0°, 30°, and 60° until failure. A microradiographic pre–post-implantation analysis was conducted on four grafts. Results: The biomechanical testing showed a significant difference in the ultimate failure loads comparing Group I (mean 224±79.3 N) to Group II (mean 339±61.4 N), both showing mean ultimate failure loads to increase with rising loading angle. The predominant mode of failure was graft pullout at axial loading and tendon rupture at 60° loading angle. The microradiographic analysis revealed an iatrogenic damage of the bone–tendon junction on the cancellous aspect of the bone plug in all trials, corresponding with the site of impactor placement during implantation. Conclusion: QTPB grafts provide a loading capability comparable to BPTB grafts in press-fit ACL reconstruction. The broad and profound area of quadriceps tendon attachment to the patellar bone plug makes graft implantation demanding. [ABSTRACT FROM AUTHOR]