What does the ACL do?
The ACL is one of two cruciate ligaments inside the knee. It prevents the tibia from sliding forward on the femur and provides rotational stability — critical for twisting and pivoting activities such as rugby, netball, football, skiing and basketball.
Mechanism of injury
The ACL is most often torn during a non-contact pivoting injury — a sudden change of direction with the foot planted, or landing awkwardly from a jump. It can also be torn from direct contact.
Symptoms
- An audible "pop" at the time of injury
- Immediate pain and rapid swelling within hours
- A feeling of the knee giving way
- Difficulty bearing weight and continuing the activity
- Ongoing instability — particularly when twisting or changing direction
Diagnosis
Diagnosis is usually clinical and confirmed with an MRI scan. MRI also identifies associated damage to the menisci, cartilage and other ligaments — important when planning treatment.
Non-surgical treatment
Not every ACL tear requires surgical reconstruction. A structured rehabilitation programme over at least three months — focused on regaining range of motion, quadriceps strengthening and proprioception — allows many patients to return to lower-demand activities. Bracing is sometimes helpful.
Surgical treatment
ACL reconstruction is recommended for:
- Patients wishing to return to twisting or pivoting sports
- Heavy manual work involving twisting or unstable surfaces
- Ongoing functional instability despite rehabilitation
- Associated meniscal or cartilage damage requiring repair