ACL Injuries

Everything you need to know

ACL injuries: Everything you need to know:

The ACL (anterior cruciate ligament) is located in the knee and is one of the most common ligament injuries of the knee. ACL ruptures have a high prevalence in people participating in high-risk sports, like soccer, rugby, and basketball.


  • Anterior cruciate ligament – attaches the tibia and the femur in the centre of your knee; it’s located deep inside the knee and in front of the posterior cruciate ligament. It limits rotation and forward motion of the tibia.
  • Posterior cruciate ligament – is the strongest ligament and attaches the tibia and the femur; it’s also deep inside the knee behind the anterior cruciate ligament. It limits the backwards motion of the knee.
  • Medial Collateral Ligament (tibial collateral ligament) – attaches the medial side of the femur to the medial side of the tibia and limits sideways motion of your knee.
  • Lateral Collateral Ligament (fibular collateral ligament) – attaches the lateral side of the femur to the lateral side of the fibula and limits sideways motion of your knee.
  • Patellar ligament – attaches the kneecap to the tibia

Signs and symptoms:

  • You will hear an audible ‘pop’ or ‘crack’ in the knee
  • Most complete tears of the ACL are extremely painful, mainly in the 1st few minutes after injury.
  • Initially you will be unable to carry on with your activity.
  • Pain will limit further activity with complete ACL tears
  • Swelling
  • Instability
  • Restricted movement – loss of extension
  • Widespread mild tenderness
  • Joint tenderness on the side of the knee

Grade or severity of injury:

  • Grade I Sprain:
    • The fibers of the ligament are stretched but there is no tear.
    • Some tenderness and swelling
    • No instability
    • No increased laxity
  • Grade II Sprain:
    • The fibers of the ligament are partially torn
    • Some tenderness and moderate swelling
    • Some loss of function is present
    • Some instability in the knee
  • Grade III Sprain:
    • The fibers of the ligament are completely torn (ruptured)
    • Tenderness, but not a lot of pain
    • There may be a little swelling or a lot of swelling
    • The ligament cannot control knee movements
    • Significant instability
    • There is also rotational instability

Causes of ACL injuries:

ACL injuries usually occur with non-contact mechanisms of injury, such as pivoting, sidestepping or quick acceleration-deceleration movements. Female athletes are more prone to ACL injuries, because of female specific muscular strength, body alignment, physical condition, and increased ligament laxity.

Surgical vs non-surgical management:

With non -surgical management, progressive rehabilitation and physiotherapy is advised to return to full functioning. Non-surgical management will be encouraged in the following cases:

  • Isolated ACL injuries
  • Partial tear of ACL ligament
  • No instability
  • People who do not participate in high-risk sports

Surgical management may be necessary in certain cases. During surgery the ACL ligament will be replaced with a graft made out of a tendon. Surgical management will be encouraged in the following cases:

  • Combined injuries (ACL injury combined with another structural injury of the knee)
  • Complete ACL ruptures
  • Complete instability
  • Athletes needing to return to high-risk sport as soon as possible


Physiotherapy plays an important role in the rehabilitation of ACL injuries. Pre-operative as well as post-operative therapy are crucial to ensure full recovery and return to sport.

Pre-operative rehabilitation:

Pre-operative rehabilitation consists of strength and conditioning of the knee to ensure quick recovery post-operatively.

Post-operative rehabilitation:

Post-operative rehabilitation will start immediately post-surgery. Rehabilitation will continue for a few months to return to full function.

The goals of rehabilitation immediately post-ACL reconstruction will consist of reducing swelling, improving range of motion in the knee and maintain the strength of the muscles surrounding the knee. Rehabilitation will continue when the patient starts with full weight bearing to improve the walking pattern and start with functional strengthening.

Sport specific strength will follow upon completion of functional strengthening and will be combined with balance and control exercises. Plyometrics and agility drills will also form part of the patient’s final phase of rehabilitation to prepare the athlete to return to sport.

Written by Elzanne Myburgh May 2020