ACL repair with a single or double tunnel: a comparative laboratory study of knee stability using computer navigation

The purpose of the study was to investigate the biomechanical differences between single bundle (SB), single tunnel-twisted hamstring graft (ST-TG) and double bundle (DB) reconstruction of the anterior cruciate ligament (ACL), using computer navigation for data acquisition. Anterior translation in the medial compartment was corrected to near normal levels at 30 degrees and 90 degrees with all techniques. Anterior translation in the lateral compartment was corrected to near normal levels at 30 degrees and 90 degrees. However, the ST-TG and the DB were overcorrected to below-preoperative levels. The DB significantly overconstrained internal rotation at different angles. Anterior translation in the lateral compartment on maximum internal rotation was significantly overconstrained using a DB. We conclude that ACL reconstruction restores near normal knee kinematics. Our data suggest that the ST-TG and the DB better control anterior translation in the lateral compartment. It also suggests that DB caries a risk of overcorrection. This study has a small sample size and should be considered as a pilot study.