Many parts of the body are involved in balance, including the eyes, inner ear, neck, trunk, and legs. Balance depends on the reflexes of each of these parts and the communication between them. An injury anywhere in this system can impact balance.
As a major stabilizer of the knee joint, the anterior cruciate ligament (ACL) is crucial to balance. If you tear your ACL, standing on one foot may be difficult. This is because the ligament loses its ability to steady the joint, and the tiny sensors in the knee ligaments, joints, and muscles have difficulty sending information about the joint’s position. Balancing becomes a challenge. But what if you have ACL surgery? Will your balance return to normal?
This study involved 25 patients with mainly sports-related ACL injuries. Eight of the patients were women; 17 were men. Their average age was 27. All of the patients had ACL reconstruction surgery. After surgery, half of them wore casts, and the other half wore braces and started exercises right away to improve knee movement. They all had six to eight months of rehabilitation training to restore the reflexes in their injured legs.
About three years after surgery, patients did a series of balance tests. First, they balanced on one or both feet with their eyes open and then with their eyes closed. Special sensors detected how much patients swayed back and forth in these positions. Next, the patients stood on one foot on a moving surface with their eyes open. Sensors recorded patients’ reaction times and how long it took for them to correct their balance. As a comparison, a group of people the same age with uninjured knees did these same tests.
Since one goal of ACL surgery is to restore the stability of the injured knee, the patients’ knees were also tested for looseness. Their injured knees were still looser three years after surgery than their uninjured knees or the knees of the comparison group.
Even though the operated knees were looser, balance was nearly the same between patients who had ACL injuries and the comparison group–with two exceptions. Patients who had ACL surgery had slower reaction times when the surface beneath them moved. But compared to the other group, they regained their balance faster. This may be because the ACL patients had learned to compensate for their injury.
The results of this study suggest that balance can be restored after ACL surgery. This goal is maximized with a rehabilitation program that focuses on retraining balance in the knee.