Are you taking your patients who have anterior cruciate ligament (ACL) injuries in the water? If you are treating a partially torn ACL — or a reconstructed ACL — you will want to follow some restrictions.
For instance, you will need to avoid open chain terminal knee resisted extension. In other words, you need to avoid resisted knee extension for the last 30 degrees of extension.
So, what does this mean for treatment? Do not put your patient in a resistance boot (or a flipper or fin) and then have the person rapidly flex and extend against the resistance of the water.
Why would this be a concern? The flexion component of the exercise would not be. In fact, resisted hamstring work is ideal for ACL rehab. Your hamstrings need to be “supertrained” in order to take on the role as a “supplemental ACL”.
It is the resisted extension that will get you into trouble. During the last 30 degrees or so of knee extension, the tibia will start to translate anteriorly on the femur.
Why? The insufficient or newly constructed ACL will be inadequate to hold in into position. This stretches the ACL and is contraindicated immediately after surgery or during conservative management of a partial ACL tear.