Knee injuries are among the most common in sports like football, basketball, soccer, and skiing. Sometimes all it takes is a sudden pivot, a quick cut, or an awkward landing to sprain your ACL. In more severe cases, that same movement can cause a full tear.
In our previous guide to ACL injuries, we covered the different types of tears, treatment options, and the full recovery process. In this article, we’re focusing on the mildest type of ACL injury: a Grade 1 ACL sprain.
A sprained ACL usually heals much faster than a torn ligament, but recovery still follows a specific healing process.
So how long does an ACL sprain take to heal? And how can you tell the difference between a sprain and a tear? Let’s walk through the ACL sprain healing process, what to expect during recovery, and how physical therapy helps you get back to your sport safely.
What is an ACL Sprain?
The ACL, or anterior cruciate ligament, is one of the main ligaments that keeps your knee stable. It connects your femur (thigh bone) to your tibia (shin bone) and helps control forward movement and rotation.
An ACL sprain happens when that ligament stretches beyond its normal range. In a Grade 1 sprain, the ligament stays intact, but some of its fibers become overstretched. The knee can still do its job, although it needs time to heal.
ACL sprains often happen during the same movements that cause more serious knee ligament injuries. A sudden change of direction in football or basketball, a quick stop while sprinting, or an awkward landing can all place enough stress on the ACL to cause a sprain.
What about the symptoms of an ACL strain? Most athletes notice mild swelling, stiffness, and discomfort around the knee. The joint usually remains stable, and many people can still walk and bend the knee, although those movements may feel sore or limited.
But, a tear is a different story.
ACL Sprain vs ACL Tear
How can you tell the difference between an ACL sprain and a tear? The answer depends on how much the ligament has been damaged.
A Grade 1 ACL sprain means the ligament has been overstretched but remains intact. Grades 2 and 3 involve a partial or complete tear, which usually leads to greater instability and a longer ACL rehabilitation timeline.
While every injury is different, here’s a quick comparison:
| Knee Injury | Common Symptoms | Typical Recovery |
| ACL sprain (Grade 1) | Mild swelling, stiffness, discomfort. Knee generally feels stable. | Usually 3 to 6 weeks with physiotherapy for ACL sprain. |
| Partial ACL tear (Grade 2) | More swelling, pain, and noticeable instability. Pivoting and changing direction become difficult. | Several months, depending on the severity and treatment plan. |
| Complete ACL tear (Grade 3) | Significant instability, swelling, and loss of knee function. Many athletes report hearing or feeling a “pop” at the time of injury. | Around 9 to 12 months after reconstruction surgery, or several months with non-operative rehabilitation in selected cases. |
If you think you’ve injured your ACL, avoid returning to play until you’ve been evaluated. An early assessment helps identify the severity of the injury and guides the right treatment from the start.
If your physician confirms a Grade 1 ACL sprain, the next step is helping the ligament heal while restoring your strength, mobility, and knee stability. That’s exactly what we’ll cover next.
Treatment Options & Recovery Process
The main treatment for a Grade 1 ACL sprain is conservative care, with physical therapy leading the recovery process. The goal is simple: help the ligament heal, restore normal knee movement, and rebuild the strength and stability you need to return to your sport.
Right after the injury, the priority is controlling pain and swelling. The RICE method is a great place to start:
- Rest: Avoid running, jumping, pivoting, and other movements that stress the knee.
- Ice: Apply ice for 15 to 20 minutes several times a day during the first couple of days.
- Compression: A compression sleeve or elastic wrap can help manage swelling.
- Elevation: Keep your leg elevated whenever possible to reduce fluid buildup.
In some cases, you may need a knee brace or a knee compression sleeve.
Once the initial swelling starts to settle, physical therapy becomes the most important part of the ACL sprain healing process. Your therapist will gradually restore range of motion, activate the muscles around the knee, and improve balance and control before returning you to sports.
ACL Sprain Stretches and Exercises
Early rehabilitation focuses on restoring comfortable movement without placing excessive stress on the healing ligament.
These are some of the best exercises that our physical therapy team recommends:
Heel Slides:
- Lie on your back with your injured leg straight.
- Slowly slide your heel toward your body until you feel a gentle stretch in the knee.
- Pause, then slide your leg back to the starting position.
Quad Sets:
- Place a rolled towel or foam roller under your knee while lying on your back.
- Tighten your quadriceps by pressing the back of your knee into the towel.
- Hold for 30 seconds, then relax.
Even though there’s very little movement, this exercise helps reactivate the muscles that support the knee.
Hamstring Stretch:
- Loop a strap around your foot while lying on your back.
- Keeping your knee straight, gently pull your leg upward until you feel a stretch along the back of your thigh.
- Hold for about 30 seconds before lowering your leg slowly.
Straight Leg Raises:
- Lie on your back with your injured leg straight and your opposite knee bent for support.
- Tighten your thigh muscles, then slowly lift your straight leg several inches off the floor.
- Lower your leg in a controlled move.
Clamshells:
- Lie on your side with your knees bent and your feet together.
- Keeping your hips stacked and your feet touching, slowly lift your top knee, then lower it with control.
The movement should come from your hip, not your lower back.
Clamshells strengthen the glutes, which help improve knee stability during walking, running, and cutting movements. We cover this exercise in more detail in our Clamshell Exercise Guide
Other Exercises For ACL Sprain Recovery:
As your knee gets stronger, we’ll begin introducing more challenging exercises to improve stability, strength, and movement control. These may include:
- Terminal knee extensions
- Calf raises
- Step-ups
- Side-lying leg lifts with a resistance band
- Single-leg balance exercises or balance board drills
- Mini squats
- Hip abduction with a resistance band
Physiotherapy & Rehab Timeline
But enough about the exercises. Let’s talk about recovery.
How long does an ACL sprain take to heal? For a Grade 1 injury, many athletes recover in about 3 to 6 weeks. The exact timeline depends on the severity of the sprain, how well the knee responds to rehabilitation, and how closely you follow your treatment plan.
Rather than rushing back to sport, physical therapists look for steady progress. Your pain should improve, your range of motion should return, and your knee should feel stable before you move on to more demanding activities.
An ACL sprain is not a tear, but you still need to slow things down and give the ligament time to heal.
Here’s what a typical ACL sprain rehabilitation timeline looks like:
- Week 1: Reduce pain and swelling while restoring gentle knee movement. RICE, heel slides, quad sets.
- Week 2: Improve range of motion and begin rebuilding strength. Straight leg raises, gentle hamstring stretches, continued quad activation.
- Week 3: Restore balance, stability, and functional strength. Step-ups, mini squats, calf raises, single-leg balance drills.
- Weeks 4-6: Return to functional movement and gradually resume sport-specific training once strength and knee stability have returned. Progression to higher-level strengthening, balance, and sport-specific exercises.
Just remember that this timeline is only a guide. Recovery depends on the severity of the injury, your medical history, and how your knee responds to rehabilitation. Some athletes move through each phase more quickly, while others need extra time before their knee is ready for running, cutting, or jumping again.
Your physical therapist will use your strength, balance, and knee stability, rather than the calendar alone, to decide when you’re ready for the next stage.
Healing an ACL Sprain the Right Way
A Grade 1 ACL sprain usually responds very well to physical therapy rehabilitation. The key is giving the ligament enough time to heal while rebuilding your strength, mobility, and knee stability.
It’s important that athletes start with an accurate diagnosis, follow your physical therapist‘s recommendations, and progress through each stage of rehabilitation without rushing back to sport. A few extra days of recovery can make a big difference in preventing setbacks and helping you return with confidence.
At Performance One, we’ve been helping Utah athletes recover from injuries for more than two decades. Whether you’re dealing with an ACL sprain, a complete tear, or you’re looking to prevent your next injury, our team is here to guide you every step of the way.
Become a P1 member, and recovery doesn’t stop when the pain goes away. You’ll have physical therapists, coaches, and trainers working together to help you recover and perform at your best. Because, as we say here at Performance One, we train to be the ONE.
