Anterior Cruciate Ligament (ACL) tears can occur in people of all ages and athletic abilities. This type of injury is a sidelining experience, which limits your ability to practice your sport, as well as your activities of daily living. This injury usually involves surgery, physiotherapy or a combination of the two. The results of several studies indicate that impaired proprioception is one of the consequences of ACL injury. What is proprioception? To understand the full meaning of the word, let’s talk about knee stability.
Stabilizing Your Knee
Four main ligaments stabilize your knee joint. Your anterior cruciate ligament stabilizes your knee during the rotational movements that occur during cutting and pivoting activities. Your ACL also prevents knee hyperextension, or locking of your knee.
ACL Modus Operandi
Your ACL bridges the connection between your tibia, your shin bone, and the femur, your thigh bone. It stabilizes this connection in two ways:
1. It maintains correct tibia-femur alignment, by preventing excessive movement.
2. It uses its mechanically sensitive nerve receptors, called proprioceptors, to sense the position of your knee joint. If your knee exceeds its normal range or speed of movement, the proprioceptors send a message to your brain. Your brain responds by stimulating the muscles that stabilize the knee joint.
Muscle Imbalances = Crossed Signals
If your proprioceptors sense that your knee was about to lock, your brain would signal your hamstrings to flex your knee. However, if your quads are significantly stronger than your hamstrings, your brain could send the wrong message. Instead of telling your hamstring to flex and protect your knee, it tell your quads to extend your leg. Extreme hyperextention will result in a torn ACL.
Consequences of an ACL Tear
Here’s the problem. If you tear your ACL, it’s not just your knee ligaments that suffer the damage. The proprioception within your knee gets damaged, too. This will trigger a significant loss in knee proprioception. Without proprioception, your nervous system cannot determine your knee’s position in space, its rate of motion, and its direction of movement. Some researchers have even found proprioceptive impairment in the non-injured knee!
What the Studies Tell Us
A 2013 study published in the Bone Joint Journal evaluated proprioception in both the injured and the uninjured limb in 25 patients with ACL injury and in 25 healthy controls. The research team used a force plate to assess:
• Joint position sense
• Detection of passive movement
• Postural sway
The researchers reported significant proprioceptive deficits in both ACL-deficient and uninjured knees compared with control knees. They noted that “based on these findings, the effect of proprioceptive training of the uninjured knee should be explored.”
Proprioceptive training is part of the physiotherapy process at iphysioperth. Talk to out staff. We can help!
Consult one of our physiotherapists and call i Physio Perth on (08) 9444 8729 now!