The causes of failure of anterior cruciate ligament (ACL) reconstruction mainly involve incorrect tunnel positioning. There is no intraoperative tool allowing the surgeon to test graft biomechanics and to confirm that the new graft is in an optimal position.

Control is improved with computer assisted navigation.

In this retrospective study, revision ACL reconstruction was performed with a new autologous graft in a continuous series of 52 failed ACL reconstructions. A computer assisted navigation system was used intraoperatively in all knees. Evaluation with this system confirmed the position of old and new tunnels as well as intraoperative laxity.

Evaluation of tunnel position based on traditional radiological criteria found in the literature significantly underestimated graft biomechanics: 69% of the cases presented with unfavorable graft ansiometry (mean: 13±2.2mm) while the correct position of the tibial tunnel was identified in 64% of cases on radiography and the femoral tunnel in 48%. All new grafts were optimally positioned by the computer assisted navigation system with a mean isometery of 3.2 (±0.7) mm. Comparative pre- and postoperative evaluation of laxity showed a statistically significant improvement (P<0.001): preoperative and postoperative Lachman test: 10.5±2mm and 3±0.5, respectively; global rotational laxity: 24±5° and 37±7° respectively.

The use of a computer assisted navigation system allows optimal positioning of the graft as well as a predictive assessment of laxity.

Level IV, retrospective cohort study.