Whether you’re a competitive athlete, weekend warrior, or simply active in your daily life, an anterior cruciate ligament (ACL) injury can be a painful setback. The ACL is one of the most important stabilizing ligaments in the knee, and injuries can significantly impact movement, strength, and confidence. Understanding how ACL injuries happen, how they are treated, and what you can do to help prevent them can keep you active and moving forward.
At Center for Sports Medicine & Orthopaedics, our team specializes in the diagnosis, treatment, and rehabilitation of sports-related injuries, helping patients return to the activities they love.
What Is the ACL?
The anterior cruciate ligament (ACL) is one of four major ligaments in the knee. It runs through the center of the knee joint, connecting the thigh bone (femur) to the shin bone (tibia). The ACL’s primary job is to keep the shin bone from sliding too far forward and to provide rotational stability during movements like pivoting, cutting, and jumping.
Because the ACL is essential for controlling knee motion, injuries to this ligament can make the knee feel unstable and may limit participation in sports and everyday activities.
How Do ACL Injuries Occur?
ACL injuries can occur through both contact and non-contact mechanisms.
A contact injury may happen when a direct blow forces the knee into an abnormal position, such as a collision during football or other contact sports.
However, most ACL tears actually occur without contact. These injuries commonly happen when an athlete:
- Quickly changes direction or pivots
- Stops suddenly while running
- Lands awkwardly from a jump
- Hyperextends the knee
Research has shown that approximately 70% of ACL injuries occur through non-contact mechanisms, making proper movement mechanics and training especially important.
Why Are Some Athletes at Higher Risk?
Several factors can contribute to an increased risk of ACL injury.
External factors may include:
- Poor body control during landing or deceleration
- Certain playing surfaces
- Footwear and shoe-surface interaction
- Contact with another player or unexpected changes in movement
Internal factors may include:
- Differences in anatomy
- Muscle strength and flexibility
- Hormonal influences
- Neuromuscular control, or how effectively the muscles coordinate to stabilize the knee
Female athletes, especially those participating in sports that involve frequent jumping and cutting such as soccer and basketball, have been shown to experience ACL injuries at higher rates than their male counterparts.
Signs and Symptoms of an ACL Tear
Many people who tear their ACL describe hearing or feeling a noticeable “pop” at the moment of injury. Other common symptoms include:
- A feeling that the knee gave out or shifted
- Immediate pain and inability to continue activity
- Rapid swelling within the first several hours
- Difficulty walking or putting weight on the knee
- Reduced range of motion
- A feeling of instability when turning or pivoting
If you experience these symptoms after a knee injury, it is important to be evaluated by an orthopaedic specialist.
How Is an ACL Tear Diagnosed?
An orthopaedic physician can often diagnose an ACL injury through a detailed medical history and physical examination of the knee. Because swelling and pain can sometimes make the examination difficult, additional imaging may be needed.
An MRI is commonly used to confirm the diagnosis and identify associated injuries, such as damage to cartilage or the meniscus.
Do All ACL Tears Require Surgery?
One of the most common questions after an ACL injury is: “Will I need surgery?”
The answer depends on several factors, including:
- Your age and activity level
- Your goals for returning to sports or physical activities
- The degree of knee instability
- The presence of additional injuries, such as cartilage or meniscus damage
Younger, highly active patients who wish to return to sports that involve cutting and pivoting often benefit from ACL reconstruction surgery. Others who participate in lower-impact activities may be able to successfully manage their injury with physical therapy and strengthening.
Regardless of whether surgery is needed, rehabilitation plays a critical role in recovery. Early treatment focuses on restoring motion, followed by strengthening the muscles surrounding the knee and improving balance and coordination.
How Is ACL Surgery Performed?
Modern ACL surgery typically involves ACL reconstruction, rather than simply stitching the torn ligament back together.
During reconstruction, a surgeon creates a new ligament using tissue from another tendon in the patient’s body (an autograft) or from a donor (an allograft). The graft is positioned through small tunnels created in the thigh bone and shin bone and secured to function as a new ACL.
Over time, this graft incorporates into the body and functions as a new living ligament.
What Is Recovery Like After ACL Reconstruction?
Recovery from ACL surgery requires patience and dedication to rehabilitation.
Most patients begin physical therapy soon after surgery to restore movement, rebuild strength, and regain proper knee mechanics. The timeline for returning to work varies depending on job demands. Desk workers may return within a few weeks, while individuals with physically demanding jobs may require several months.
Return to sports is based on strength, stability, balance, and functional testing—not just the amount of time since surgery.
The success rate of ACL reconstruction is high, and most patients can return to an active lifestyle with proper surgical treatment and rehabilitation.
Can ACL Injuries Be Prevented?
While not every ACL injury can be avoided, prevention programs can significantly reduce the risk of injury.
Effective ACL prevention focuses on improving how the body controls movement and may include:
- Plyometric training to improve jumping and landing mechanics
- Balance exercises to improve stability and body awareness
- Strength training for the hips, quadriceps, hamstrings, and core
- Training to avoid excessive inward collapse of the knee during movement
Learning proper movement techniques and maintaining strength and flexibility can help athletes perform safely and reduce the likelihood of injury.
Don’t Let a Knee Injury Keep You on the Sidelines
An ACL injury can be frustrating, but with an accurate diagnosis, individualized treatment plan, and dedicated rehabilitation, many patients successfully return to the sports and activities they enjoy.
If you have experienced a knee injury or are concerned about instability, the specialists at the Center for Sports Medicine & Orthopaedics can help you understand your options and create a personalized path to recovery. Learn more about our knee specialists.