Which of the following indicates a loss of flexion range of motion post ACL reconstruction?

• A. Posterior placement of the tibial tunnel
• B. Correct placement of femoral tunnel
• C. Anterior placement of the femoral tunnel
• D. Lateral meniscus tear

Answer: (C)

A loss of flexion range of motion after ACL reconstruction can be significantly influenced by the placement of the femoral tunnel. The anterior placement of the femoral tunnel can lead to anatomical and biomechanical deficits that restrict knee motion. Specifically, if the tunnel is placed too anteriorly, it may create tension in the graft that limits flexion, causing the patient to experience difficulties in achieving full knee range of motion. This positioning can also lead to impingement against surrounding structures, further exacerbating the loss of flexion.

In contrast, proper placement of the femoral tunnel, or a posterior placement of the tibial tunnel, is generally associated with more favorable outcomes regarding range of motion, as these positions help restore the natural biomechanics of the knee. A lateral meniscus tear typically affects stability and can lead to pain or swelling, but it is not directly tied to a loss of flexion range of motion in the same way that a poor tunnel placement would be. Therefore, the anterior placement of the femoral tunnel is the correct answer, as it most directly correlates with a loss of flexion following ACL reconstruction.