“At 13 months post ACLR (Anterior Cruciate Ligament Reconstruction), individuals exhibited average knee extensor moments that were 17% smaller in the surgical limb during a bilateral squat against body-weight resistance”
ACL injuries tend to be noted in some non-contact sports such as soccer and basketball. Contact sports, such as football, also have ACL tears noted during contact, such as a tackle that makes the knee buckle inwards.
The patient with an ACL tear will typically opt for surgery if he/she plans on returning to some type of sporting activity. There is a debate as to whether or not to have the surgery if there will be no return to sporting activity.
After the ACL surgery, the research above notes that patients are less likely to use the surgical side during a squatting activity (think getting up from the toilet) and will push more with the non-surgical side.
This makes sense to me. After the surgery, the patient is in a locked long leg brace and is unable to move fluidly on the affected leg. The patient will not spend as much time on the surgical leg because of this and will transfer the weight to the non-surgical side. It becomes a learned habit to transfer the weight to the non-surgical side, but this is just my opinion.
“The persistence of under-loading is concerning, as asymmetrical limb loading during landing tasks has been linked to increased risk for anterior cruciate ligament (ACL) reinjury”
This is important! If we never get the patient to load the leg in order to improve strength and motor control (ability move in the way that the brain dictates), then the patient is at a higher risk of future injuries.
Let me clarify: if you squat and allow your legs to go wet noodle during the squat, it will look like a knocked-kneed version of a squat. This is not inherently horrible, but when asking the body to absorb a large load in this positon, when not trained to absorb this load, may lead to an injury. It all comes down to progressively loading specific positions in order to learn how to hold this position.
This is a major component of Olympic weightling compared to powerlifting. In the performance of the snatch (the most explosive movement in sports), maintaining proper position is extremely important for completing the lift. In powerlifting, the position may be able to be off a little and the athlete can overcome the small error in position.
With regards to ACL rehabilitation, it is important that we ensure that the patient is able to have enough strength to maintain positions without the load (bodyweight jumps, external weight, etc) dictating positional changes.
“…the bilateral multijoint nature of a squat allows for compensations that can shift the task demands to the nonsurgical limb (interlimb compensation) or to adjacent joints within the surgical limb (intralimb compensation) to reduce knee extensor moments.”
The bodyweight squat can be performed differently and switches the load from either the hip to the knee.
If you watch someone squat (recommended for all people that will attempt to squat), the person should both watch the knee and the hip. If you look at opening and closing, this will be much easier.
- Watch the knee to see how much the knee “closes” or how much the angle changes from the calf to the hamstring
- Watch the hip to see how much the hip “closes” or how much the angle changes from the trunk to the thigh
Which joint moves more?
This will help the reader to understand whether the knee joint muscles or hip joint muscles will be the dominant movers during the squat. Those that have knee issues will tend to move the hip joint muscles more than knee joint muscles.
I’ll make a video on this at a later date.
“…individuals 1 month post ACLR performed bilateral sit-to-stand tasks with a 38% reduction in vertical ground reaction forces (vGRFs) in the surgical limb”
This very simply means that the person is pushing less with the surgical leg than the non-surgical leg.
This means that the surgical leg is taking less force through it and will not be able to generate the same amount of power. Also, it is typical to see the patient weight shifting towards the non-surgical leg.
“reduced knee extensor moments have been found along with increased hip extensor moments…may rely on interlimb compensations to unload the knee during early rehabilitation but adopt intralimb compensations as they progress through rehabilitation.”
This goes back to the differences in a powerlifting based squat and an Olympic weightlifting based squat. The more upright the torso, the more that the knee takes a load and the less upright the torso, the more the back and hips will take the load.
I am having this exact conversation with a patient currently following an ACLR, attempting to get the patient to increase the load on the knee.
“During early rehabilitation, strategies for restoring symmetrical weight bearing during bilateral tasks should be emphasized and reinforced even during submaximal tasks…efforts should be made to continue to focus on sagittal plane knee loading and avoid compensation with the hip extensors.”
I tend to use a mirror for visual feedback in order to allow the patient to see the weight shift between the legs. This tends to fix the problems for weight shifting. We then progress to doing the squatting motion away from a mirror in order to build in positional awareness without the need for visual cues.
In order to improve the knee to hip ratio regarding which joint moves more, the cues will switch from sitting back on a chair (similar to a box squat which is hip hinge emphasizd) to emphasizing sitting between the feet (similar to an overhead squat) which is more knee joint driven.
If you don’t have a PT that understands how to squat, this may be a difficult movement to restore with physical therapy alone.
It may be prudent to ask your PT to describe a squat prior to starting therapy in order to ensure that your therapist has at least a baseline knowledge of squatting.
If the therapist doesn’t start describing multiple techniques for squatting based on body shape, then the therapist may not be well versed in the movement.
If you have any questions about squatting or ACLR rehabilitation…comment below.
You can find me at Primarycarejoliet.com and wherever you subscribe to podcasts at A physio’s perspective: movementthinker.