What is an ACL injury?
An ACL injury occurs when the anterior cruciate ligament in the knee is (partially or completely) overstretched or torn.
The anterior cruciate ligament plays the important role in the knee by attaching the femur (upper leg) to the tibia (lower leg).
Common Causes of ACL injuries
Almost 75% of ACL (anterior cruciate ligament) injuries are caused without contact, and instead are self-induced by muscle placement.
This includes, but is not limited to, impingement on the intercondylar notch, quadriceps contraction, the quadriceps-hamstring force balance, and the axial compressive forces on the lateral aspect of the joint.
Interestingly, women are two to eight times more likely to sustain an ACL injury than men.
Some suggestions as for why this is, include:
- increased knee valgus (commonly known as “knock knees”)
- abduction moments,
- ACL size
- hormonal effects of oestrogen on the ACL
- foot position
Regardless, of the likelihood of demographics, it appears that particular movements of the feet and legs can contribute to a stronger likelihood of ACL injury overall.
However, the best solution is to target movements that increase the risk an injury.
Foot positioning is a particularly important connection to an injury occurrence, with the impact of whole-body dynamics.
This originates in movements in the hip, knee, ankle and foot, which absorb impact during normal landing and deceleration.
Ground Force Reaction to Foot Landing
A recent video-based analysis by Boden et al. revealed some key dynamic elements that can be correlated with a non-contact ACL injury during intensive sports.
- Subjects who landed on the ground and subsequently experienced ACL rupture came into contact using the hindfoot or with a flat foot, whereas those who did not rupture their ACL landed on their forefoot.
- Those with an ACL rupture reached a flatfooted stature 50% sooner than the latter group.
- The shorter time span, although minimal when comparing the footage, severely reduces the ability of the calf muscle to absorb the landing force, therefore sending the impact straight upward to the ACL.
A shorter stopping time can also be linked to a higher impactful force, increasing the likelihood of injury.
This analysis clearly revealed that by having a plantarflexed
ankle in the ideal position, or landing with the forefoot, protects the ACL by giving the impact time to dissipate.
Landing on one foot, substantially increases the chance of ACL injury, with the
threshold easily reached if the calf does not absorb a large amount of force.
Our legs naturally move inward in motion as the foot flattens, placing added tension and when stopped suddenly can lead to severe ACL injuries.
As with injury comes future complications
and the weakening of muscles, prevention is the best way to go, especially for athletes reliant on mobility.
How to help prevent your risk of an ACL injury
Even though ACL injury is a knee-related issue, custom orthotics for adequate foot positioning are an effective solution in reducing risks. Often the existence of a collapsed arch or hyper-
pronation (commonly known as “flat feet”) leads to a conversation informing a patient of the increased risk of ACL rupture, then a recommendation for the frequent use of custom-made
orthotics during all intensive sports activities.
Orthotics have also been linked to helping other knee
related conditions such as runners’ knee and knee arthritis.
A cross-sectional study into the effect of orthotics on basketball players revealed positive
effects. 150 female players over a 13-year period were assigned to either a control group (which did not receive orthotics) or a group that did receive orthotics.
The control group had an ACL
injury rate of 0.5 out of every 1000 exposures to activity, whereas the group with orthotics had
injury rates of 0.07 per 1000 exposures, decreasing the likelihood of injuries substantially.
The Correct Foot Form Will Help Your Knees
This is the best solution in prevention, as the additional shock absorption with a correctly formed foot, with support for all three arches of the foot, moisture resistance, and extra weight can
encourage landing on the forefoot, rather than the problematic angle of the hindfoot.
In combination, these characteristics limit foot pronation as much as possible, also known as a
It is essential that the orthotic must be rigid enough to prevent the tibial rotation associated with an ACL rupture.
This is particularly
important for athletes participating in high-impact sports on the ankles, feet and knees, such as
basketball, netball or soccer.
By using orthotics, we can allow athletes to become empowered to continue their physically
demanding careers, and the lifestyles of competitive sports players in our communities.
Especially with women having such high rates of ACL injury, keeping individuals in a physically
active routine is important for health and wellbeing.