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Anterior Cruciate Ligament Injury (ACL) Description

Anterior Cruciate Ligament Injury (ACL)


About half of all injuries to the anterior cruciate ligament occur along with damage to other structures in the knee, such as articular cartilage, meniscus, or other ligaments.


The anterior cruciate ligament can be injured in several ways:

  • Changing direction rapidly
  • Stopping suddenly
  • Slowing down while running
  • Landing from a jump incorrectly
  • Direct contact or collision, such as a football tackle

Several studies have shown that female athletes have a higher incidence of ACL injury than male athletes in certain sports. It has been proposed that this is due to differences in physical conditioning, muscular strength, and neuromuscular control. Other suggested causes include differences in pelvis and lower extremity (leg) alignment, increased ligament looseness, and the effects of estrogen on ligament properties.


When you injure your anterior cruciate ligament, you might hear a “popping” noise and you may feel your knee give out from under you. Other typical symptoms include:

  • Pain with swelling. Within 24 hours, your knee will swell. If ignored, the swelling and pain may resolve on its own. However, if you attempt to return to sports, your knee will probably be unstable and you risk causing further damage to the cushioning cartilage (meniscus) of your knee.
  • Knee instability
  • Loss of full range of motion
  • Tenderness along the joint line
  • Discomfort while walking


Dr Slattery will take a detailed history of your injury, the symptoms you have had since, as well as your activity level and occupational demands.  He will then perform a thorough physical examination of your knee to evaluate its stability, and the presence of other associated injuries.  Specific tests for ACL rupture are:

  • Lachmann Test
  • Anterior Drawer Test
  • Pivot Shift Test

It is also critical to evaluate the knee for its range of motion, swelling, alignment and for the presence of other ligament or meniscal injuries.


ACL injuries can be diagnosed both clinically (by your doctor) and with the help of imaging tests:

  • X Rays: these can show fractures and the underlying alignment of your bones, which may need to be addressed.  In children they also critically show the growth plates which need to be considered when doing surgical reconstruction.
  • MRI Scans: these show an ACL rupture, and are very useful for assessing other injuries such as Meniscal Tears (up to 60%), Meniscal Avulsions, or Cartilage Damage.
  • CT Scans: these can be used if there has been a prior ACL reconstruction to look at the position of the graft, and the tunnels
ACL Injury
Above: Typical ACL Injury – Landing and twisting on a planted foot
David Slattery
Above: X Ray showing a ‘Segond’ Fracture – indicating an ACL injury
Above: MRI Showing an ACL Rupture
MRI Bone Oedema
Above: MRI Showing bone bruising associated with an ACL injury
To book an appointment please contact Dr Slattery’s rooms on
03 5752 5020 mobile
We aim to see all fractures within 24hrs