Ask the physio: ACL injuries


The Anterior Cruciate Ligament (ACL) is undoubtedly the most important structure of the knee. It is certainly one of the most dreaded injuries for many athletes.

The ACL runs through the middle of the knee and plays an important role in keeping the knee stable, preventing the shin bone sliding out in front of the thigh bone. It also provides rotational stability to the knee during pivoting and twisting.

Unfortunately the ACL is also commonly injured in the sporting population and once injured can be very disabling and force you to sit out the rest of the season on the sidelines and usually go under the knife for a surgical repair.

When can the ACL be injured?

Injury to the ACL often occurs when landing, especially when landing in an awkward manner or on an uneven surface (such as another player’s foot). It can also occur when:

  • rapidly changing of direction
  • stopping suddenly
  • slowing down quickly while running
  • colliding or other direct contact with another player
  • landing badly for another reason, such as a slippery surface.

As you can see, the ACL can be injured doing things that most volleyball players will do multiple times during any season. How many of us have made it through a whole volleyball game (much less a season or our volleyball lives) without stopping suddenly, landing awkwardly or rapidly changing direction.

So how can you tell if your ACL is injured?

The most common presentation of an ACL injury is the feeling of a ‘pop’ in the knee at the time of injury followed by swelling with a few minutes to a couple of hours. The injury is usually quite painful initially but can settle quite quickly leaving only a feeling of instability in the knee with the occasional ‘giving way’ of the knee. These rules are not foolproof as some ACL injuries can occur with none of the above but usually the mechanism of injury with gives it away.

Unfortunately, female athletes are much more likely to injure their ACL when compared to male athletes male athletes in certain sports. The reason for this is blamed on differences in physical conditioning, muscular strength, and neuromuscular control. Other reasons include differences in pelvis and leg alignment, increased looseness in ligaments, and the effects of oestrogen on ligament properties (yep, the time of month has been shown to have a correlation with ACL injuries).


Your physiotherapist is usually the person who would diagnose an injury to your ACL. Commonly, they will start with a number of physical tests designed to put stress on the ACL. These tests are quite good but are not indestructible and some ACL injuries can be missed (Ivy has done both ACLs now and both times, it took 3 physios to diagnose).

For this reason, an MRI is the gold standard for ACL injury diagnosis and your physiotherapist can refer you if a MRI is considered necessary.

Okay, so I’ve done my ACL. What next?

The path back from an ACL injury can be a long and frustrating one and it all starts with surgery.

The most common surgery performed is a hamstring graft, which involves taking a slice of one of the hamstrings and using it to remodel a new ACL. The surgery is performed via keyhole and scarring is minimal.

After surgery, rehabilitation is necessary. Rehabilitation will be guided by both your surgeon and your physiotherapist and it will take anywhere between 8 to 12 months before you are fully fit to play again.

The most important part of your rehabilitation is to allow enough time to establish good motor control of your muscles to minimise the risk of the ACL being injured again.
The take home message about ACL injuries is that they will take a long time to get back to where you were when you injured your knee, but if you are diligent with your rehabilitation and are guided well by your physiotherapist, you will be back on the court and as good as new for next season.

Sports Focus Physiotherapy locations
Castle Hill (02) 8850 0797
Liverpool (02) 9601 8411
Mt Pritchard (02) 8786 0666
Northbridge (02) 9958 8986
Willoughby (02) 9967 0013
Wynyard (02) 9262 4147

Don’t forget SNV members receive a discount at Sports Focus Physiotherapy, read about it here.