ACL Injury and Rehabilitation: What to Expect During Recovery
An anterior cruciate ligament (ACL) injury can affect knee stability, strength, movement, and confidence. Although ACL tears are commonly associated with sports, they can happen to anyone during an activity that places sudden stress on the knee.
Some ACL injuries are managed without surgery, while others require ACL reconstruction. In either situation, physical therapy can help restore function and prepare you for a gradual return to daily activities, exercise, or sports.
What Is the ACL?
The ACL is one of the primary ligaments that help stabilize the knee. Located inside the knee joint, it connects the thighbone to the shinbone and helps control forward movement and rotation of the shinbone.
The ACL plays an especially important role during activities involving running, jumping, pivoting, cutting, or quickly changing direction.
How Do ACL Injuries Happen?
Many ACL injuries occur without direct contact. The ligament may be injured when someone:
- Changes direction or pivots with the foot planted
- Suddenly slows down or stops
- Lands awkwardly from a jump
- Experiences direct contact that forces the knee into an unstable position
Sports involving frequent jumping, landing, pivoting, or changes of direction tend to carry a greater risk of ACL injury.
Female athletes experience ACL injuries at higher rates than male athletes in certain sports. Researchers believe this difference is influenced by multiple factors, which may include anatomy, hormones, biomechanics, neuromuscular control, and sport exposure. No single factor explains every ACL injury.
What Are the Symptoms of an ACL Injury?
Symptoms vary depending on the extent of the injury and whether other structures in the knee were also affected. Possible signs include:
- A popping sound or sensation at the time of injury
- Rapid swelling
- Pain or tenderness
- A feeling that the knee is unstable or giving way
- Reduced range of motion
- Difficulty bearing weight or continuing the activity
Not everyone experiences every symptom. ACL injuries can also occur alongside damage to the meniscus, cartilage, or other knee ligaments.
A medical evaluation is important after a significant knee injury. A healthcare professional may use the injury history, symptoms, physical examination, and imaging when appropriate to determine the cause and extent of the injury.
Are There Different Types of ACL Injuries?
ACL injuries are commonly described by the extent of damage to the ligament:
Grade 1 sprain: The ligament has been stretched but can still help stabilize the knee.
Grade 2 sprain: The ligament has been stretched to the point that it becomes loose. This is often described as a partial tear.
Grade 3 sprain: The ligament has torn completely, resulting in a loss of normal ACL stability.
The grade of the injury does not determine treatment by itself. Knee stability, associated injuries, activity goals, overall health, and recommendations from the healthcare team must also be considered.
Does Every ACL Tear Require Surgery?
No. Some people may be able to manage an ACL injury without surgery, particularly when the knee remains functionally stable and their desired activities do not involve frequent pivoting, cutting, or other high-demand movements.
Nonsurgical care may include physical therapy, activity modification, and, in some cases, bracing. Physical therapy cannot guarantee that a torn ACL will heal or restore the ligament’s original structure. Rehabilitation instead focuses on improving knee motion, strength, balance, movement control, and overall function.
ACL reconstruction may be recommended for people who experience continued instability, want to return to high-demand pivoting sports, or have additional injuries within the knee. This decision should be made with an orthopedic provider based on the injury and the individual’s needs and goals.
Can Physical Therapy Help Before ACL Surgery?
Physical therapy before ACL reconstruction is often called prehabilitation, or prehab.
Depending on the injury and the surgeon’s recommendations, prehabilitation may focus on:
- Reducing swelling
- Restoring knee motion
- Improving quadriceps activation
- Maintaining or rebuilding lower-body strength
- Improving walking and movement
- Preparing the patient for postoperative rehabilitation
The appropriate timing and goals of prehabilitation depend on the condition and surgical plan.
What Does ACL Rehabilitation Involve?
ACL rehabilitation is individualized. The plan will depend on whether surgery was performed, the extent of the injury, other injuries within the knee, healing requirements, symptoms, goals, and response to treatment.
Following ACL reconstruction, the physical therapist will also consider instructions and precautions from the surgeon.
Early Recovery
Early rehabilitation commonly focuses on managing swelling, restoring knee motion, activating the quadriceps, and gradually improving walking. Regaining full knee extension is often an important early goal.
EStrength and Movement
As recovery progresses, treatment focuses on rebuilding strength throughout the lower body. Exercises may address the quadriceps, hamstrings, hips, calves, and core.
Rehabilitation may also work to improve:
Early rehabilitation commonly focuses on managing swelling, restoring knee
- Balance and stability
- Movement control
- Muscular endurance
- Mobility
- Ability to complete daily activities
Exercises and resistance are gradually advanced based on the person’s healing, abilities, and response.
motion, activating the quadriceps, and gradually improving walking. Regaining full knee extension is often an important early goal.
Running, Jumping, and Sport-Specific Movement
Running, jumping, landing, and agility exercises should not be introduced based on time alone. Before progressing, a physical therapist may consider knee motion, swelling, pain, strength, movement control, and the ability to perform foundational exercises.
Higher-level rehabilitation may include:
- A gradual running progression
- Jumping and landing exercises
- Acceleration and deceleration
- Changes of direction
- Agility drills
- Sport-specific movement
- Conditioning for practice or competition
Not every patient needs the same activities. Rehabilitation should reflect the demands of the sport, job, exercise routine, or recreational activity the person wants to resume.
How Is Readiness to Return to Sports Evaluated?
Returning to sports is a progression rather than one moment of clearance. An athlete may advance from rehabilitation exercises to individual drills, modified practice, full practice, and eventually unrestricted participation.
Time matters because the injured ligament or surgical graft needs time to heal. However, time alone does not show whether an athlete is prepared for the demands of a sport.
Depending on the injury, sport, and available clinic resources, a physical therapist may evaluate:
- Pain and swelling
- Knee range of motion and stability
- Quadriceps and hamstring strength
- Balance and single-leg control
- Jumping and landing mechanics
- Running and change-of-direction ability
- Endurance and activity tolerance
- Sport-specific movements
- Confidence and psychological readiness
No single test can guarantee that another injury will not occur. Return-to-sport decisions should consider several factors and involve communication among the patient, physical therapist, physician or surgeon when applicable, athletic trainer, and other members of the healthcare team.
How Long Does ACL Rehabilitation Take?
There is no single timeline that applies to everyone. Recovery can be influenced by:
- The severity of the ACL injury
- Whether surgery was performed
- Other injuries within the knee
- Healing and postoperative precautions
- Strength and function before the injury or surgery
- Rehabilitation progress
- The demands of the desired activity or sport
Returning to daily activities generally requires less strength, power, and movement control than returning to a sport involving sprinting, jumping, cutting, or contact. The physical therapist and medical team will help determine when the patient is ready for each stage of recovery.
Can ACL Injuries Be Prevented?
No program can prevent every ACL injury. However, research supports neuromuscular training programs as a way to reduce the risk of some noncontact ACL injuries.
These programs may combine:
- Strength training
- Balance and coordination exercises
- Jumping and landing practice
- Agility and change-of-direction training
- Education about movement technique
An injury risk-reduction program should be appropriate for the athlete’s age, sport, ability, and training demands.
Take the Next Step in Your Recovery
ACL recovery involves more than waiting for pain to improve. Rehabilitation should rebuild the mobility, strength, control, endurance, and confidence required for the activities that matter to you.
At Optimum Therapies, physical therapy is personalized to your injury, abilities, and goals. Whether you are managing an ACL injury without surgery, preparing for ACL reconstruction, or working toward a return to sports, your physical therapist can guide you through an individualized rehabilitation progression.
Learn more about Sports & Fitness Rehabilitation at Optimum Therapies.
Preparing for or recovering from ACL reconstruction? Learn more about Pre- & Post-Surgical Rehabilitation.
Contact our team to find an Optimum Therapies clinic near you.
References
- American Academy of Orthopaedic Surgeons: Anterior Cruciate Ligament Injuries
- American Academy of Orthopaedic Surgeons: Management of Anterior Cruciate Ligament Injuries Clinical Practice Guideline
- British Journal of Sports Medicine: Clinical Practice Guideline on Rehabilitation After ACL Reconstruction
- Orthopaedic Journal of Sports Medicine: Return to Sport After ACL Injury Consensus Statement
Content reviewed by Drew Strope, PT, DPT at Optimum Therapies.