ACL Injury: What's the best way to prevent and rehabilitate this?

The anterior cruciate ligament (ACL) is one of the four main ligaments within the knee joint that provides stability to the joint. Anterior - front

Cruciate - cross

The primary job of the ACL is to prevent the tibia (shin bone) translating excessively anterior along the femur (thigh bone). This is a classic injury in footballers and skiers.

ACL ruptures (full tears) usually end up in surgical repair, primarily due to the requirement of the sufferer to regain their knee stability. ie: They want to return to football and skiing and lacking that stability, vastly reduces that likelihood.

Full rehabilitation following surgery can take months! With excessive forces still putting an increased strain on the ACL, particularly with increased squats.

Is there an effective way to prevent ACL ruptures and rehabilitate them?

Dedinsky et al (2017) set out to answer just that. They acknowledged the reason for this excessive movement is due to an difference in quadriceps and hamstring activation. Ie: The quadriceps work harder that the hamstrings.

(positive testing for an ACL rupture)

The researchers stated that exercises that only work the quadriceps more than the hamstrings, typically occur in non weight bearing. For example: leg extension machines place an increased strain on the ACL

(leg extension)

Conversely, weight bearing exercises, for example: squats and leg press see a more balanced activation of the quadriceps and hamstrings. However, the authors identified that squatting too deep or with poor technique could still have a detrimental effect of the quadriceps / hamstrings co-activation and therefore a potential for an increased strain on the ACL

(squats with good and bad technique)

Therefore, the authors set out to find an exercise that produces similar quadriceps / hamstrings co-activation. We as physiotherapists are already aware that squatting without allowing the knee to travel forwards puts less strain (and pain for you) on the knee. The authors utilised this knowledge and assessed how effective a single leg squat, double leg squat, step ups and knee extensions are for hamstrings and quadriceps co-activation

Their results identified that a single leg squat is the most effective exercise for quadriceps / hamstrings co-activation. However

Deep squats switch off the hamstrings! They established performing a small knee bend is far more effective for quadriceps / hamstring co-activation. In consideration

Small knee bends that activate the hamstrings have a tendency to de-activate the gluteals. By doing this, you can potentially lead to other issues, particularly found in endurance athletes. Yet, for an exercise that minimalises the harm and is effective for an ACL rehabilitation, then look no further that the humble small knee bend. If you would like access to the original article, then please click below