Can I Bend My Knee After ACL Surgery?
Regaining the ability to bend the knee fully after Anterior Cruciate Ligament (ACL) surgery is a common concern for many patients. Restoring knee mobility is a central component of the overall recovery process. A structured approach to rehabilitation progressively addresses knee bending, aiming to safely restore the knee’s natural range of motion over time, allowing for a return to daily activities and sports.
Initial Knee Bending Expectations
In the immediate aftermath of ACL surgery, typically the first few days to weeks, patients can expect some limitations in knee bending. Swelling and inflammation are common due to surgical trauma, causing stiffness and discomfort. During this early phase, a physical therapist may guide passive range of motion, where the knee is moved by an external force. Active range of motion, where the patient uses their own muscles, is gradually introduced. Initial restrictions, such as limited weight-bearing or specific brace settings, protect the healing graft and manage swelling.
Gradual Progression of Range of Motion
Knee bending, or flexion, is expected to improve gradually over the rehabilitation period. Achieving full knee extension (straightening) is often prioritized early in recovery, typically within the first two weeks, as difficulties with extension can lead to long-term issues. For flexion, a common goal is to reach approximately 90 degrees of bending by the end of the first week, and 120 degrees by the end of week four. Full knee bending, typically around 135 to 140 degrees, is often aimed for between 4 to 12 weeks post-surgery. This gradual progression protects the newly reconstructed ligament as it heals, preventing excessive stress while steadily improving flexibility.
Key Strategies for Regaining Full Bending
Physical therapy plays a central role in restoring knee bending after ACL surgery, providing a structured program of exercises and techniques. Specific exercises are introduced progressively to improve flexion, such as heel slides and wall slides. Stationary cycling is also incorporated to promote knee flexion and increase blood flow. Manual therapy techniques, performed by a physical therapist, can help improve patellar mobility and reduce stiffness. While continuous passive motion (CPM) machines were historically used, their overall benefit in improving long-term range of motion after ACL reconstruction remains a subject of ongoing discussion.
Addressing Challenges with Knee Bending
Patients may encounter difficulties bending their knee, including persistent pain, swelling, or stiffness. An abnormal formation of scar tissue, known as arthrofibrosis, can occur, leading to a persistent inability to fully bend or straighten the knee and causing pain. This condition might manifest as a slow increase in range of motion after six weeks post-surgery. If severe or persistent pain, significant swelling, or a lack of progress in regaining motion is experienced, communicate these concerns with the surgeon or physical therapist. Early identification and management optimize recovery outcomes.
Individual Factors Affecting Recovery
The recovery timeline and the ease of regaining knee bending can vary considerably among individuals due to several influencing factors. The type of graft used for the ACL reconstruction (e.g., patellar tendon, hamstring, quadriceps tendon autograft, or an allograft) can influence the rehabilitation protocol and healing process. The presence of other knee injuries, such as meniscus tears or cartilage damage, can also affect the recovery timeline and may necessitate additional restrictions. Patient adherence to the prescribed rehabilitation program, including consistent effort with exercises and attendance at therapy sessions, is strongly associated with better outcomes. Age and pre-existing medical conditions can also play a role in the overall pace and success of rehabilitation.