[Arthroscopic reconstruction of the anterior cruciate ligament with paired semitendinosus tendon. Experimental results of a new fixation method].

Problem: The major problem of reconstructing the anterior cruciate ligament (ACL) with the semitendinosus tendon (STT) is the low primary stability of the STT graft fixation techniques.
Methods: On 10 cadaver knees a surgical procedure for arthroscopic reconstruction of the ACL with the double looped STT was performed. The femoral attachment was achieved with an "U-formed" tendon wrapped around a bone-plug, which then was blocked in a single-staged femoral bone tunnel. The tibial fixation was attained using a bone-plug and an interference-screw. Anatomic studies were performed on the STT of the cadaver knees. Isometrical determinations were performed intraoperatively for precise anatomical placement of the tendon. We compared these measurements with the postoperative position of the STT-transplant. The tibial and the femoral attachment was tested separately for primary stability and stiffness. The mode of failure of the fixation methods was determined.
Results: The average length of the STT was 29.4 cm (SD +/- 3.6 cm, 24-33). With comparing the measured intraoperative and postoperative isometrical values we found a high correlation. The primary stability of the attaching methods in the pullout-testing amounted for the femoral attachment to 448.2 N (SD +/- 76.5 N, 322-560 N) and for the tibial attachment to 440.0 N (SD +/- 72.5 N, 316-538 N). The average stiffness of the femoral fixation was 29.23 N/mm (SD +/- 1.64 N/mm; 26.6-32.1 N/mm). The average stiffness of the tibial fixation measured 28.31 N/mm (SD +/- 1.55 N/mm, 25.1-30.4 N/mm).
Conclusion: The presented method provides an economical and easy to perform autologous STT-fixation technique with a high level of primary stability.