What is an ACL Injury?
The Anterior Cruciate Ligament (ACL) is one of the main stabilising ligaments in the knee. It prevents the knee from giving way during twisting, pivoting, or sudden stopping movements.
ACL injuries most commonly occur during:
- Football, rugby, skiing, and basketball
- Sudden changes in direction
- Awkward landings or collisions
A complete ACL tear will not heal on its own and often causes long-term instability if left untreated.
Common Symptoms of ACL Tears
You may benefit from ACL reconstruction if you experience:
- Ongoing pain or instability despite physiotherapy
- A popping sensation at the time of injury
- Rapid Knee swelling within hours of injury
- Repeated “giving way” during activity
- Inability to return to sport or confidence in your knee
ACL Reconstruction
ACL reconstruction is a minimally invasive arthroscopic procedure that replaces the torn ligament with a tendon graft (usually your hamstring or Quads tendon).
Small keyhole incisions are used to:
- Remove the damaged ACL
- Prepare the knee joint
- Secure a new graft in the correct anatomical position
This restores knee stability and allows patients to safely return to activity.
The procedure typically takes around 1 hour, but this can be longer if additional meniscal repairs are needed or the addition of a lateral extra-articular tenodesis (LET) is recommended. The role of this LET will be discussed with you at your pre-operative consultation, but is typically for patients at higher risk of re-rupture.
Some patients may require a knee brace if any meniscal repair surgery was required.
Who Is ACL Reconstruction Suitable For?
ACL reconstruction is commonly recommended for:
- Active individuals wishing to return to sport
- Patients with knee instability affecting daily life
- Those with associated meniscal or cartilage damage
Not all ACL injuries require surgery — a personalised assessment is essential.
It is recommended to complete a full prehabilitation program before any surgery is undertaken.
Recovery & Rehabilitation Timeline
The physiotherapy rehabilitation program plays a crucial role in the recovery process. Please refer to the Melbourne ACL Rehabilitation Guide which provides a structured overview of the rehabilitation process following ACL reconstruction. [ Post-Op Rehabilitation ]
First 6 weeks
- Swelling control
- Restoration of knee extension and movement
- Gradual return to normal walking
6–12 weeks
- Strength and balance training
- Return to daily activities
3–6 months
- Progressive strengthening
- Balance and neuromuscular training
- Controlled straight-line activities only
9–12 months
- Sport-specific rehabilitation
- Gradual return to pivoting sports
- Return to sport only after meeting strict functional & strength criteria
Most patients return to sport around 12 months, depending on progress and goals. This gradual approach allows the new ligament to heal without excessive load as it undergoes ligamentisation over the 12 months following surgery. It may take some patients longer to progress to being ready for sport.
Return to Play decisions are based on:
- Strength symmetry
- Functional testing
- Psychological readiness
- Time-based graft maturation
Frequently Asked Questions?
Will I need surgery immediately?
Not always. Some patients benefit from a trial of physiotherapy before deciding. Surgery carried. out too early is associated with the risk of arthrofibrosis (knee stiffness) – so it is best to wait until all swelling is out of the knee and you have completed a pre-habilitation program to restore muscle around the injured knee. Unfortunately if you have a significant meniscal injury that is blocking your knee movement your surgery may need to be carried out sooner than this.
How long before I can drive?
Usually 2–4 weeks, depending on which knee and your progress and if you have required additional surgery such as meniscal repair. If you have been placed in a brace following meniscal repair it may be better to avoid driving until after the brace is removed (typically 6-8 weeks).
Will I need a knee brace?
A brace will only be required if additional surgery around the knee or additional injuries are present. Bracing is commonly used after meniscal repair or to protect a co-lateral ligament injury. This is most commonly a hinged knee brace secured to the leg with velcro straps.