Senchyna: ACL – the three dreaded letters in sports injuries

We’ve all heard about professional or Olympic athletes having suffered an ACL injury in the news or on TV.

We’ve all heard about professional or Olympic athletes having suffered an ACL injury in the news or on TV.

Kara Lang, Lindsey Vonn, Adrian Peterson and Derrick Rose are just a few of the high profile athletes who have sustained this kind of knee injury.

You may know someone who has had, or may yourself have had this injury and probably know how devastating it can be to recover from.

ACL injury has an annual incidence of more than 200,000 cases, with about 100,000 of these knees requiring surgery each year.

In fact, ACL injuries account for more than 30 per cent of all sports-related surgery.

The majority of ACL injuries occur while playing agility sports, and the most often reported sports are basketball, soccer, skiing, and football.

There a couple of basic ways you can injure your ACL.

One way is by an external force or blow applied to the knee, such as being hit at the outside of the knee with your foot planted in football, or from a fall while downhill skiing when the body and ski twist in opposite directions.

The other way to injure the ACL is from no contact at all – it just happens from simple actions like changing directions, landing from a jump, decelerating or planting your foot and throwing.

But if you thought it’s more common to tear your ACL from  contact, you’d be wrong.

Just over 70 per cent of all ACL injuries occur from non-contact events, while the remaining 30 per cent result from direct contact.

The knee contains four ligaments, of which the ACL (anterior cruciate ligament) is one. However, the ACL alone is responsible for the majority of the ligamentous stability in that joint, so if it gets stretched or torn, the knee becomes much less stable. And if, for example, the athlete sustains a more severe force or a blow to the outside of the knee, causing it to buckle inward, there can be three areas injured.

This ‘terrible triad’ injury consists of tearing the ACL, MCL and medial cartilage (meniscus).

A fact that many may not be aware of is that females are three to nine times more likely to tear their ACL than males involved in the same sport. This may due to multiple factors.

Because the females have a wider pelvis, that means that the position of the hip joint is wider and this creates more of an inward angle at the knee (called valgus position) than males – which is one of the prime predisposing factors for ACL tears.

Some of the other reasons are due to proposed neuro-motor factors, such as females landing with the knees too far forward compared to males who sit back more when landing from a jump. The front thigh (quadriceps) muscles appear to be stronger relative to the hamstrings in females, which also can add a shear force on the ACL.

The good news is that these issues can be addressed by preventative exercises that prepare the athlete for game situations that can potentially stress the leg and cause injury.

The exact cause of the injury is still being researched and more recently there has been more emphasis on the combination of anterior shear, rotation and inward buckling having roughly equal importance, though inward stress on the knee seems to be more influential. It’s very hard to protect one’s self from a contact injury, especially when you don’t see it coming, but you can help to reduce non-contact ACL injuries with awareness, practicing good biomechanics when jumping, landing, cutting and decelerating, and by spending time strengthening the hips and legs. With ACL’s, a little prevention goes a long, long way.


Kerry Senchyna is the founder, owner and president of West Coast Kinesiology and is a provincially registered kinesiologist.