ACL Injury & Tear: Symptoms, Recovery, and Beyond

The anterior cruciate ligament (ACL) is a small but crucial structure in the knee joint. Despite its size, an ACL injury can have significant consequences for an individual’s mobility and overall quality of life. In this comprehensive guide, we will delve deeper into the world of ACL injuries, exploring topics such as ACL physiotherapy, the anatomy and function of the ACL, types of ACL injuries, ACL injury treatments, their clinical significance, risk factors, symptoms, diagnosis, treatment options, prevention strategies, and the impact of ACL tears on athletes’ careers.

Understanding the ACL: Anatomy and Function

What is an ACL?

The ACL, or anterior cruciate ligament, is one of the four major ligaments in the human knee joint. It is situated deep within the knee and serves as a critical stabilizer, connecting the thigh bone (femur) to the shinbone (tibia). Despite its relatively small size, the ACL plays a pivotal role in knee stability and overall joint function.

Function of the ACL

The ACL has several essential functions:

  1. Stability: One of the primary roles of the ACL is to provide stability to the knee joint. It acts as a safeguard against the tibia moving excessively forward to the femur.
  2. Control: The ACL assists in controlling the range of motion within the knee joint, particularly during activities that involve cutting, pivoting, and rapid changes in direction.
  3. Protection: Beyond its stabilizing role, the ACL also helps protect other structures within the knee, such as the menisci and articular cartilage, from excessive stress and potential injury.

Types of ACL Injuries

Not all ACL injuries are the same, and they can vary in severity. We often categorize ACL injuries into three main types:

  1. Grade I Sprain: This is considered a mild ACL injury, where only a few of the ligament fibers are affected. In Grade I sprains, the knee joint remains relatively stable, and surgery is rarely required for recovery.
  2. Grade II Sprain: A Grade II ACL injury is of moderate severity, involving damage to a more significant number of ligament fibers. While the knee may feel somewhat unstable, surgery is not always necessary.
  3. Grade III Sprain (Complete Tear): The most severe form of ACL injury, a Grade III sprain, involves a complete tear of the ACL into two separate pieces. This type of injury renders the knee highly unstable, and surgery is often recommended to regain stability and function.

Clinical Significance of ACL Injuries

An ACL injury is not a minor concern; it can have profound consequences for an individual’s knee health and overall well-being. Some of the clinical significance of ACL injuries include:

  • Instability: Individuals with a torn ACL often experience instability in their knee, leading to a feeling of wobbliness and unpredictability during various activities.
  • Meniscus Tears: The increased instability in the knee can result in tears to the meniscus, the wedge-shaped cartilage that cushions the joint.
  • Early-Onset Arthritis: Over time, untreated or inadequately treated ACL injuries can contribute to the development of arthritis in the knee joint, leading to pain and decreased function.

Risk Factors for ACL Injuries

ACL injuries are not limited to a specific demographic; they can affect individuals from all walks of life. However, certain risk factors can increase the likelihood of experiencing an ACL injury:

  1. Sports Participation: Athletes involved in sports that require sudden stops, rapid changes in direction, jumping, or pivoting are at a higher risk of ACL injuries. Sports such as basketball, soccer, football, skiing, and tennis are prime examples.
  2. Gender: It is worth noting that females are more prone to ACL injuries than males. This discrepancy is believed to be partly due to differences in biomechanics and hormonal influences.
  3. Previous Injury: A history of ACL injury in one knee increases the risk of injuring the other knee. Individuals who have already experienced an ACL tear should be especially cautious.
  4. Environmental Factors: Playing conditions, footwear choices, and the type of training surfaces can all influence the risk of ACL injuries. For example, playing on a wet or uneven field can increase the risk.

What Does an ACL Tear Feel Like?

The symptoms of an ACL tear can vary, but they often include:

  • A sudden and audible “pop” or “snap” at the time of the injury.
  • Severe pain and swelling in the knee that typically develops within a few hours.
  • An unstable feeling in the knee, as if it might give way when bearing weight.
  • Walking or placing any weight on the injured leg becomes an arduous task.

How Common are ACL Injuries?

ACL injuries are relatively common, particularly among athletes. According to data from the American Academy of Orthopedic Surgeons, there are approximately 200,000 ACL tears in the United States annually. These injuries occur across a spectrum of sports, making them a widespread concern.

What Causes ACL Tears?

ACL tears can occur due to various reasons and mechanisms:

  • Sudden Stops or Changes in Direction: Many ACL injuries happen when an individual abruptly stops or changes direction while running or moving.
  • Improper Landing: Landing awkwardly from a jump, especially with the knee extended, can put significant stress on the ACL.
  • Direct Impact: A direct blow to the knee, such as in a car accident or sports collision, can cause an ACL injury.
  • Overuse and Repetitive Stress: In some cases, ACL injuries can develop over time due to repetitive stress and strain on the ligament, particularly in sports that involve repetitive cutting and pivoting motions.

How are ACL Tears Diagnosed?

To diagnose an ACL tear, healthcare providers employ a combination of methods:

  • Physical Examination: The doctor will assess the knee’s stability, looking for signs of swelling, tenderness, and limitations in range of motion.
  • Medical Imaging: An MRI (Magnetic Resonance Imaging) scan is often used to obtain detailed images of the knee’s internal structures. This imaging modality is instrumental in providing a definitive diagnosis of ACL tears.

Can an ACL Tear Heal on Its Own?

While some minor ACL injuries, typically Grade I sprains, may heal with conservative treatment and rest, most complete ACL tears (Grade III sprains) do not heal on their own. Without intervention, a torn ACL can lead to ongoing instability and a higher risk of secondary injuries.

ACL Tear Surgery

For most individuals with a complete ACL tear, surgical intervention is recommended. ACL reconstruction surgery involves replacing the damaged ligament with a graft, which can be harvested from the patient’s own body (autograft) or obtained from a donor (allograft). This surgical method is usually carried out arthroscopically, employing tiny incisions and specialized medical equipment.

Rehabilitation After ACL Surgery

Rehabilitation plays a critical role in the recovery process after ACL surgery. The goals of rehabilitation include:

  • Regaining both flexibility and strength within the knee.
  • Improving overall joint stability.
  • Enhancing neuromuscular control and proprioception (awareness of joint position).
  • Gradually returning to sports and physical activities.

Rehabilitation programs are typically tailored to the individual’s specific needs and progress, but they often involve a series of phases, with a focus on gradually increasing the intensity of exercises and activities.

Phases of Physiotherapy for ACL Post-Op Recovery

Recovery from an Anterior Cruciate Ligament (ACL) post-operative surgery is a multi-phased process that typically spans several months. The goal of physiotherapy during ACL post-op recovery is to restore knee function, strength, and stability while minimizing pain and the risk of re-injury. Here are the general phases of physiotherapy for ACL post-op recovery:

  1. Immediate Post-Op Phase (0-2 weeks):
  • Focus on pain management, swelling reduction, and protecting the surgical site using machines like High Powered LASER, Ultrasound, or TENS
  • Begin gentle range of motion (ROM) exercises, including ankle pumps and isometric quadriceps contractions.
  • Assist the patient in regaining the ability to walk with crutches or a brace as necessary.
  • Educate the patient about the importance of following the prescribed medication and icing regimen.
  1. Early Mobilization Phase (2-6 weeks):
  • Continue managing pain and swelling.
  • Gradually increase the range of motion through passive and active-assisted exercises.
  • Initiate closed-chain exercises to improve weight-bearing and proprioception.
  • Begin strengthening exercises for the quadriceps, hamstrings, and calf muscles.
  • Work on improving gait and balance.
  1. Intermediate Phase (6-12 weeks):
  • Focus on restoring full range of motion (0-130 degrees) and normal gait pattern.
  • Progressively increase the intensity of strengthening exercises, incorporating resistance bands, bodyweight exercises, and light weights.
  • Enhance neuromuscular control and proprioception through balance and stability exercises.
  • Begin functional exercises that mimic everyday activities, such as squatting, lunging, and step-ups.
  • Incorporate cardiovascular conditioning exercises like stationary cycling.
  1. Late Recovery Phase (12-24 weeks):
  • Continue to advance strength and endurance training, gradually increasing resistance and intensity.
  • Integrate agility and plyometric exercises to improve functional performance and athletic abilities.
  • Address any remaining deficits in muscle strength and coordination.
  • Assess the readiness for return to sport or physical activities. This phase may vary depending on individual progress and sport-specific requirements.
  • Focus on injury prevention strategies to reduce the risk of future ACL injuries, including proper warm-up and cool-down routines, agility drills, and sport-specific training.
  1. Return to Sport Phase (24+ weeks):
  • Ensure the patient has achieved full strength, stability, and confidence in the injured knee.
  • Implement sport-specific training drills, including cutting, pivoting, and jumping activities.
  • Gradually reintroduce the patient to their specific sport with a structured and monitored program.
  • Emphasize continued strength and conditioning to maintain optimal performance and reduce the risk of re-injury.
  • Finally, declaring that the patient can return to sports again

It’s essential to note that the timeline for each phase can vary depending on the individual’s progress and the surgeon’s recommendations. Close communication between the patient, physical therapist, and surgeon is crucial throughout the ACL post-op recovery process to ensure the best possible outcome and a safe return to physical activities.

How Can I Prevent a Torn ACL?

Preventing ACL injuries is a topic of great importance, particularly for athletes and active individuals. Here are some strategies to help reduce the risk of ACL tears:

  • Strength Training: Engaging in targeted strength training exercises, particularly for the muscles around the knee and hip, can help support the ACL and reduce the risk of injury.
  • Proper Technique: Athletes should receive training in proper landing and cutting techniques to minimize stress on the ACL during sports activities.
  • Equipment: Wearing appropriate footwear and using protective gear, such as knee braces, can provide an added layer of protection against ACL injuries.
  • Warm-up and Cool-down: Ensuring that the body is properly warmed up before engaging in physical activity and that it cools down afterward can help prevent injuries.
  • Balance and Coordination Training: Improving balance and coordination can enhance joint stability and reduce the risk of falls and awkward landings.

Can You Walk if Your ACL is Torn?

While it is possible to walk with a torn ACL, it is not advisable. Walking with a torn ACL can exacerbate the injury, cause further damage to the knee, and lead to complications in the long run. In many cases, individuals with ACL tears use crutches to minimize weight-bearing on the affected leg until they receive appropriate treatment.

When Should I See My Healthcare Provider?

If you suspect that you have an ACL injury or experience symptoms such as a sudden pop in the knee, severe pain, swelling, or instability, it is crucial to consult a healthcare provider promptly. Early diagnosis and treatment can significantly improve the outcome and reduce the risk of long-term complications.

Questions to Ask Your Doctor

When discussing an ACL injury with your healthcare provider, consider asking the following questions:

  1. What is the extent of my ACL injury?
  2. Do I need surgery, or can I pursue non-surgical treatments?
  3. What is the expected recovery timeline for my specific case?
  4. Are there any specific exercises or physical therapy I should do during my recovery?
  5. When can I expect to return to sports or other physical activities, and what steps should I follow to do so safely?

Will an ACL Tear Happen Again?

After a successful ACL reconstruction surgery and rehabilitation, many individuals can return to their previous level of physical activity without re-injuring their ACL. However, it’s essential to continue to take precautions and follow proper training techniques to reduce the risk of future knee problems. Having experienced an ACL injury does make an individual more susceptible to subsequent knee issues, emphasizing the importance of ongoing knee care and maintenance.

Here at Bangkok Physiotherapy Center, we can help reduce the chance of this happening with the right exercises, and prevention techniques and always monitoring your progress through every phase of your exercise regimen.

Is an ACL Tear “Career-Ending” for an Athlete?

The term “career-ending” can be daunting for any athlete facing an ACL tear. While it can be a significant setback, it is not necessarily the end of an athlete’s career. With appropriate treatment, surgery, and rehabilitation, many athletes have successfully returned to their respective sports at a competitive level. However, the road to recovery can be challenging and requires dedication to the rehabilitation process.


In conclusion, an ACL tear is a complex and multifaceted injury that can affect individuals of all ages and activity levels. Understanding the anatomy and function of the ACL, recognizing the risk factors, and being aware of the signs and symptoms of ACL injuries are crucial for early diagnosis and effective treatment. 

Whether you are an athlete or someone seeking to maintain an active lifestyle, the knowledge and awareness about ACL injuries, ACL tear treatment without surgery, ACL injury treatments, and ACL physiotherapy can help you make informed decisions regarding your knee health. If you suspect an ACL injury, don’t delay seeking medical attention, as early intervention can make a significant difference in your long-term knee health and mobility.