The biomechanical effectiveness of the Müller anterolateral femorotibial ligament (ALFTL) iliotibial band tenodesis on anterior stability and internal rotational stability of the ACL deficient knee was investigated in six cadaver knees. Anterior drawer and internal rotation of the tibia were measured at 15 degrees increments from 0 degrees to 90 degrees in response to 50 N of anteriorly applied tibial force and 3 Nm of internally applied internal torque, respectively, in the intact knee, the ACL excised knee, and following the ALFTL reconstruction. A strain gage was used to measure the resting graft tension and to measure strain in the graft during the load-displacement tests. The Müller ALFTL tenodesis failed to return normal anterior stability to the ACL deficient knee (P less than 0.05). The tenodesis did, however, reduce the anterior laxity of the ACL deficient knee from 30 degrees to 90 degrees of knee flexion (P less than 0.05). The tenodesis overconstrained internal tibial rotation of the ACL excised knee from 30 degrees to 90 degrees (P less than 0.05). Measurements of strain in the tenodesis supported the load-displacement findings that the tenodesis was most effective in constraining anterior drawer and internal tibial rotation from 30 degrees to 90 degrees of knee flexion.