High flexion femoral side remnant preservation positioning technique: a new method for positioning the femoral tunnel in anterior cruciate ligament reconstruction.

Purpose: The aim of this study is to find a new method for femoral side preservation positioning in anterior cruciate ligament (ACL) reconstruction and test the accuracy and precision of this method.

Method: Fifty patients with isolated ACL rupture (42 males and 8 females) who underwent single-bundle ACL reconstruction in our hospital between July 2022 and July 2023 were included. The lowest point of the cartilage margin of the lateral wall of the intercontinental fossa and the tibial plateau plumb line at 120° of knee flexion were used as the anatomical landmarks for positioning of the femoral tunnel for ACL reconstruction surgery. Femoral side remnant preservation was performed in all cases. Three-dimensional CT was performed 3 days postoperatively to collect the data, which were analyzed using Mimics 21.0 software. We measured the posterior cortical distance of the femoral condyle at 90° of knee flexion and the vertical distance from the center of the bone tunnel to the cortical extension line behind the femur. All femoral tunnel positions were marked on a 4 × 4 grid and visualized using the quadrant method.

Results: Using the new positioning method in 50 knees, the average distance of x was 25.26 ± 2.76% of t and the average distance of y was 23.69 ± 6.19% of h. This is close to the results of previous studies, where x was 24.2 ± 4.0% of t and the average distance of y was 21.6 ± 5.2% of h. Most femoral tunnel positions were located in the same area. The D values were distributed as follows: 60% in the range of 0 to 2 mm, 24% in the range of 2 to 4 mm, and 16% more than 4 mm. The E values were distributed as follows: 80% in the range of 0 to 4 mm and 20% more than 4 mm.

Conclusion: In arthroscopic ACL reconstruction, the knee was flexed at 120° and the lowest point of the cartilage edge of the lateral wall of the intercondylar fossa and the tibial plateau plumb line were used as anatomical landmarks for the positioning of the femoral bone tunnel, which resulted in more accurate femoral bone tunnel positioning, better reproducibility, and better preservation of the femoral stump compared to traditional positioning methods.