In vivo graft tension in anatomic double-bundle anterior cruciate ligament reconstruction during active leg-raising motion with the knee splinted.

PURPOSE: The purpose of this study was to measure the in vivo graft tension in anatomic 2-bundle anterior cruciate ligament (ACL) reconstruction during active leg-raising exercise with the knee immobilized.

METHODS

Anatomic double-bundle ACL reconstruction was performed with autogenous semitendinosus tendons in 7 patients while under general anesthesia. Two grafts were fixed with 2 EndoButton-CL devices (Smith & Nephew Endoscopy, Andover, MA) on the femur and were temporarily fixed to 2 tension-adjustable force gauges on the anterior tibial cortex. Then, a knee brace in semi-flexion was put around the knee, and 10 N of initial tension was applied to each graft at 20° of flexion. The tension on the anteromedial (AM) and posterolateral (PL) grafts was continuously measured during active leg-raising motion with the knee immobilized after patients had awoken from anesthesia. Then, the tension measurement was repeated during active leg-raising motion with the knee immobilized while a 2-kg weight was fitted around the ankle.

RESULTS

In situ graft tension during active leg-raising motion with a knee brace was 10.9 ± 4.0 N for the AM graft and 8.6 ± 5.1 N for the PL graft, whereas the tension with a 2-kg weight around the ankle was 10.9 ± 3.4 N for the AM graft and 9.9 ± 3.6 N for the PL graft. There was no significant difference between each graft in the 2 motions with a paired t test.

CONCLUSIONS

Graft tension with the knee immobilized with a semi-flexed knee brace during active leg-raising motion was 19.5 N with no weight and 20.8 N with additional weight, both of which were almost equal to the initial graft tension at the time of fixation at 20°. Thus the leg-raising exercise can be recommended as safe when a semi-flexed knee brace is worn after ACL reconstruction.

CLINICAL RELEVANCE: These findings will help to plan postoperative rehabilitation programs with security.