Anterior Cruciate Ligament (ACL) Injury

The ACL (anterior cruciate ligament) is one of the most commonly injured ligaments in the body. Anterior cruciate ligament injuries are characterized by pain, instability, and weakness in the knee joint. Full ACL tears frequently require surgical reconstruction.

ACL Anatomy

The knee joint is one of the largest and most complex joints in the human body. Bringing together the thigh bone (femur), shin bone (tibia), and kneecap (patella), it supports the body’s weight and enables essential movements like walking, running, sitting, and standing.

Inside the joint, four primary ligaments (strong bands of tissue) connect the bones together and help to stabilize the knee. These are the MCL (medial collateral ligament), LCL (lateral collateral ligament), PCL (posterior cruciate ligament), and ACL (anterior cruciate ligament):

Collateral Ligaments

The collateral ligaments are found at the sides of the knee – the MCL on the inner side and the LCL on the outer side. They help to stabilize the joint by preventing excessive side-to-side movement.

Cruciate Ligaments

The PCL runs from the back of the tibia to the back of the femur, and the ACL runs from the front of the tibia to the back of the femur. These ligaments cross in the center of the knee, forming an X shape (thus the name cruciate). They help to stabilize the joint by controlling its forward and backward movement.

Symptoms Of ACL Tears

When the ACL is injured, patients usually feel immediate pain and experience swelling for the first 24 hours. This initial pain and swelling may resolve on its own if ignored. However, instability in the knee is often persistent and can cause other post-traumatic conditions over time, like damage to the meniscus or arthritis.

Indications that an ACL injury may have occurred include:

• A popping sound or sensation at the time of injury
• Intense pain
• Rapid swelling of the knee joint
• Loss of the full range of motion
• Difficulty walking
• Instability in the knee joint (often described as a feeling of “giving way” when bearing weight)

An injured ACL ligament is considered a “sprain” and graded using a severity scale from 1 to 3. On this scale, a Grade 1 Sprain represents a mildly damaged ACL while a Grade 3 Sprain represents a complete ACL tear.

Risk Factors

ACL tears are relatively common, and anyone can experience this type of injury. That being said, the following groups of people may be at higher risk of experiencing an ACL injury:

• Athletes – especially those in sports where quick direction changes are required, such as soccer, basketball, football, gymnastics, and downhill skiing
• Individuals who don’t use proper technique when performing movements such as landing from jumps or lifting heavy loads
• Females – possibly due to differences in anatomy, strength, and hormones
• Individuals who are poorly conditioned, wear improper footwear, or use faulty sports equipment
• Patients who have previously experienced an ACL injury

Possible Complications

Timely diagnosis and proper treatment of ACL injuries greatly reduce the likelihood that complications will arise. Nevertheless, some of the possible complications associated with ACL tears and reconstruction surgery can include:

• Post-traumatic osteoarthritis in the injured knee joint (can develop with or without surgical intervention)
• Stiffness, loss of range of motion, or muscle atrophy – especially if rehabilitation is delayed or incomplete
• Muscle weakness in the hamstring, particularly if a hamstring tendon autograft is used for ACL reconstruction
• Graft failure after surgery

Prevention

ACL injury prevention focuses on improving strength, balance, and movement technique. Key recommendations include:

• Always warm up properly before engaging in sports or other strenuous physical activities.
• Wear appropriate footwear for the activity you are doing.
• Work on stabilizing the knee joint by strengthening the quadriceps, hamstrings, hips, and core.
• Practice balance, coordination, and agility exercises to improve control during sudden movements.
• Apply proper technique when lifting heavy loads or landing from jumps.
• Gradually increase the complexity and intensity of physical training to avoid overloading the knee joint.

Schedule An Appointment

Living with an anterior cruciate ligament injury? To receive cutting-edge care and a personalized treatment plan, schedule an appointment with one of our world-class specialists at Modern Orthopaedics of New Jersey today! We look forward to working with you.