ACL Injury

At the moment of injuring an anterior cruciate ligament (ACL), people commonly feel or hear a ‘pop’ in their knee – like a thick elastic band giving way. This is typically followed by rapid knee swelling within two hours of the incident.

What you might be feeling

After these initial symptoms, ACL injuries can cause broad knee tenderness, reduced knee movement and a feeling of knee instability or ‘giving way’. Depending on damage to other structures, there may also be pain medially and laterally and/or a feeling of ‘locking’ with knee movement.

What’s really going on inside

A torn ACL is a significant injury, especially for sports players. The ACL is a band of fibrous tissue connecting the thigh bone (femur) to the shin bone (tibia). The ACL’s primary functions are to limit twisting (rotational) forces through the leg and to prevent forward movement of the tibia on the femur. ACL injuries occur frequently in sports involving pivoting and sudden deceleration such as, football, basketball, netball, soccer, gymnastics and downhill skiing.

The majority of ACL tears occur in non-contact situations when a person lands from a jump, pivots or decelerates suddenly. ACL tears can also occur in contact sports when the knee is forced to rotate, the shin is forced backwards or incorrect binding release while skiing.

Acute management advice

The priority immediately after an ACL injury should be to control knee swelling and seek advice from a Physiotherapist or Sports Doctor. This can be achieved by following these principles in the first 72 hours:

  • Rest: restrict occasions of walking and standing to essential tasks
  • Ice: apply to the knee, focusing on areas of pain
  • Compression: using an elastic bandage or compression garment
  • Elevation: using cushion or pillow for support and comfort
  • Referral: to a Physiotherapist or Sports Doctor for ongoing care

How a Physiotherapist can help

If your physiotherapist is the first person to see you after an ACL injury they will take a thorough history of what happened and then assess your knee. Manual assessment of the knee is often hindered by the large amount of swelling that occurs after an ACL injury. As such, the most accurate assessments are conducted immediately after a suspected ACL injury (prior swelling accumulation) or once swelling has subsided. Based on your injury history and the best possible assessment of the ACL and other structures, your physiotherapist should be able to diagnose what damage has been done.

If your physiotherapist suspects an ACL rupture they may refer you for further assessment and investigation by your General Practitioner, a Sports Doctor or to an Orthopaedic Surgeon. A referral for an MRI will often be done to look inside the knee and determine the extent of the damage.

Whether surgery is undertaken or not, there is excellent evidence to show that physiotherapist-guided rehabilitation is vital to maximizing recovery. The optimal management of an ACL rupture is debated; consequently, a decision on whether to follow surgical or non-surgical management is usually made based on a number of factors:

  • The age of the patient
  • Instability: at rest and during movement
  • A concurrent meniscus tear
  • Associated injuries (commonly medial cruciate ligament sprain)
  • The patient’s desire to return to sports involving jumping and pivoting
  • The patient’s occupation (e.g. fireman, policeman)
  • Adherence with a comprehensive rehabilitation program after surgery. A decision is made between the Orthopaedic Surgeon and the patient and reflects what will be best for the patient’s needs.

The time taken to return to sport and daily activities varies. For the general population, it usually takes around 9–12 months to return to sports that require changes of direction. In some cases, the prognosis is more optimistic, with recovery being much shorter (6–9 months). Most patients start to feel a lot better after 10–14 days; often reporting that they get better and better with each day, once pain starts to subside. However, feelings of knee instability are likely to persist if rehabilitation is not undertaken. The necessary rehabilitation is extensive and essential to restore the knee to full function post injury/surgery. Your physiotherapist will guide you throughout your rehabilitation, providing appropriate treatment/exercise progression and understanding of the healing process and treatment options.

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