Anterior Cruciate Ligament Reconstruction Revision

Preoperative Evaluation for ACL Revision The surgeon should have an understanding of the etiology of ACL reconstruction failure. In order to have accurate information, the medical history, current symptoms, type of graft, method of fixation, surgical approach, previous surgical notes, etc., should be obtained. The surgeon should also be aware of the patient’s activity level, functional goals, and expectations. Finally, to achieve a successful revision, the surgeon should know the etiology of the reconstruction failure. The physical examination should begin by inspecting the affected knee to look for effusion, signs of infection, and previous surgical incisions. Stance and gait should be assessed to identify any possible malalignment of the limb. The varus or valgus thrust gait should be further assessed. Specific maneuvers should be performed to evaluate the posterolateral or posteromedial corners. The valgus and varus stress tests at 0* and 30*, the position of the knee, and the range of motion should be compared to the normal side. The major cause of ACL reconstruction failure is technical error. Tunnel malposition, hardware malposition or failure, and unrecognized limb malalignment are the most common errors. A malpositioned graft will have a non-physiologic load, and if it is loaded beyond its yield point, the graft will be a failure. The most common type of tunnel malposition is an anterior (anatomically distal) femoral tunnel. This position results in reduced knee flexion due to increased graft tension, or if physiologic knee flexion is achieved, graft attenuation and/or failure. Vertical placement of the femoral tunnel will provide adequate anterior-posterior restraint but will compromise the rotational stability of the knee, e.g., negative Lachman test but positive pivot shift test. Malpositioning of the tibial tunnel also affects the graft. If the tibial tunnel is placed too anteriorly, the graft will hit the notch when the knee is extended. Posterior placement causes graft laxity in flexion and PCL impingement. Graft fixation is critical to maintain proper graft placement and tension, especially at approximately 2 weeks postoperatively when the graft is at its weakest. The risk of ACL reconstruction failure has been shown to be influenced by unrecognized bony malalignment and missed comorbidities, such as MCL laxity, LCL laxity, or neglected posteromedial, posterolateral rotatory insufficiency. The risk of graft failure may also be increased by untreated injuries to the posterolateral or posteromedial structures and the medial meniscus at the time of initial ACL reconstruction. Posteroanterior tibia slope and varus malalignment place increased stress on the graft, and a posteroanterior tibia slope of 12* or more has been shown to be the strongest predictor of recurrent ACL injury (Salmon et al). Preoperative evaluation for ACL revision.