An ACL injury, thus, causes limitations in movement and interrupts your stability. An ACL injury is also a common injury that one can incur and is often accompanied by other forms of knee injuries such as meniscus injuries.  

ACL injury is commonly regarded as a “sprain” and can manifest as:

• Partial tear: ligament becomes loose, however, these forms of tear are rare. 
• Complete tear: ligament is torn or ruptured in half or completely pulled away from the bone.

The extent of the injury is graded by different levels of sprain:

• Grade 1: mild damage in the form of a stretch but still capable of maintaining joint stability. 
• Grade 2: ligament is loose, ability to maintain joint stability is affected, and often referred to as a partial tear. 
• Grade 3: complete tear or rupture and knee joint is completely unstable.

These include:

• A sudden change of direction that places strain on the ligament
• Abruptly stopping when moving in a fast motion
• Incorrectly landing causing an upward force on the ligament 
• Direct and heavy contact at the knee 

• A loud “pop” or “snap” when an injury occurs 
• Swollen knees
• Pain that forces you to compensate by using the uninjured leg for support 
• Difficulty conducting any form of movement (walking, running)
• Generally feeling unstable and the sensation of your leg “giving away” or buckling

Pain has been reported between mild and excruciating, the levels varying by the degree of sprain that one has incurred. Even amongst those with a high tolerance for pain, an ACL injury still provides high levels of discomfort. 

• Athletes: ACL injuries are common among athletes of football, rugby, and basketball. 
• Gender: women athletes are more prone to ACL injuries potentially attributed to the anatomical difference of the lower extremities, looseness of ligaments, and other physical conditioning.

• Physical examination and medical history: inform your orthopaedist of the potential activities that may have led to an injury such as trauma, exercise, or sports. Physically the area of injury will be examined and several motion tests will be conducted to review the injury. 

• Imaging tests: magnetic resonance imaging (MRI) or dynamic ultrasonography would be required to examine if surrounding areas of the ACL are impacted given the likelihood of ACL injury being accompanied by other forms of injury. An x-ray if a fracture is suspected.
• Diagnostic arthroscopy: arthroscopy, a minimally invasive procedure would be conducted where a small camera is inserted into the knee joint to visualise the structures inside if a diagnosis cannot be made from other tests or if surrounding damage of the knee is predicted.
  

• Rest: you would be advised to observe complete rest to relieve pain and reduce swelling.
• Medications: non-steroidal anti-inflammatory drugs (NSAIDs) and painkillers are commonly prescribed as the first course of treatment to reduce inflammation and manage pain.  
• Injections: corticosteroid injections may be administered to reduce inflammation and provide immediate relief. 
• Brace: to reduce movement of the joint and allow the ligament to heal.
• Crutches: to limit placing weight on the affected knee.
• Physiotherapy: upon discontinuation of the use of the brace, an active range of motion exercise would be administered via physiotherapy to regain mobility and strengthen muscle.
• Surgery: knee arthroscopy surgery would be administered if deemed necessary to restore the structure of ligament damage.