What is the most likely cause of limited range of motion at 6 weeks post ACL reconstruction?

• A. Posterior placement of the femoral tunnel
• B. Anterior placement of the femoral tunnel
• C. Tibial tunnel malpositioning
• D. Patellar tendon irritation

Answer: (B)

Limited range of motion six weeks after anterior cruciate ligament (ACL) reconstruction is often attributed to the positioning of the femoral tunnel. Anterior placement of the femoral tunnel can lead to functional limitations for several reasons.

When the femoral tunnel is placed too anteriorly, it can affect the tension and biomechanics of the reconstructed ligament. This improper positioning may increase the stress on surrounding tissues, leading to irritation and potentially influencing the healing process. As a result, patients may experience symptoms like joint stiffness, which limits their ability to fully extend or flex the knee.

Furthermore, in addition to biomechanical effects, improper tunnel placement can alter the natural kinematics of the knee joint, contributing to an inflammatory response or scarring around the joint that further restricts movement. Understanding these factors is crucial for rehabilitation, as it guides clinicians on what to address therapeutically when dealing with post-operative range of motion limitations.

Other factors that might contribute to limited motion include tunnel malpositioning or irritation from the patellar tendon, but the anterior placement of the femoral tunnel specifically stands out in clinical scenarios when assessing early post-operative complications.