[Anatomic and clinical study on 4-bone-tunnel double-bundle anterior cruciate ligament]

To conduct a primary clinical analysis on 411 cases of arthroscopic 4 bone-tunnel double-bundle anterior cruciate ligament (ACL) reconstruction done by one operator on the basis of anatomic measurements of cadaver knees.

Twenty-two adult male Chinese cadaver knees of 25-45 years old were dissected. The sizes, distributions and positions of femoral and tibia footprints of anterior medial bundle (AMB) and posterior lateral bundle (PLB) of ACL and their fiber's orientations were measured and recorded. The anatomy and measurement results were used by one operator in 413 double-bundle ACL reconstruction knees of 411 cases with arthroscopic 4 bone-tunnel technique. Among them, 297 males and 114 females, there were 222 left knees and 191 right knees. The average age was 27.61 +/- 7.23 years old.

The anatomy results showed the locations and sizes of AMB and PLB footprints in both femoral and tibia sides were different for different individuals. It was suggested to locate AMB femoral tunnel 7.95 +/- 1.40 mm inferior to 12:00 o'clock position on the posterior edge of the lateral wall of intercondylar fossa with 1 mm thick of the posterior wall of finished AMB femoral tunnel. With the knee flexed to 90 degrees, the PLB tunnel was 5.05 +/- 0.76 mm superior to the lower cartilage edge of the lateral wall of intercondylar fossa, 8.60 +/- 1.52 mm away from the anterior cartilage edge and 8.65 +/- 1.54 mm from the posterior edge. The anatomic orientations of tibia and femoral tunnels were also measured. The study results were used in arthroscopic double-bundle ACL reconstructions of 413 knees. In double-bundle ACL reconstruction operations, the grafts were used in the way from 2-strip double-bundle to 9-strip double-bundle. For most cases, Endo-Button was used for femoral fixation and bio-absorbable interference screw and staple were used for tibia fixation. For the patients adopting autologous semitendinosus and gracilis tendons (STG), the diameter of PLB bone tunnels was 5-6 mm in 95.9% cases, while that of AMB bone tunnel 5-7 mm in 72.4% cases. After a 28-month follow-up in 75 cases, the results showed that double-bundle ACL reconstruction could better reconstruct the stability of knees.

In 4-bone-tunnel double-bundle arthroscopic ACL reconstruction, both bone tunnel positions and their orientations should be determined according to the anatomic measurement results. Since the PLB diameters of 95.9% cases were 5-6mm, considering the operative outcome of ACL revision, the double bundle ACL reconstruction technique was safe. A better knee stability could be reconstructed by this technique.