Ever twisted your leg the wrong way and felt that awful jolt of pain in your knee? If so, you might have had a knee sprain—an injury that sounds minor but can seriously slow you down. Whether it happens during sports, a misstep on the stairs, or even just walking awkwardly, a knee sprain needs the right care to heal properly and avoid long-term damage.
What Is a Sprained Knee?
A sprained knee occurs when one or more of the knee’s ligaments—strong bands of tissue that connect your bones—get stretched or torn due to an awkward twist, fall, or collision. There are four key ligaments that can be injured in a knee sprain: your ACL (anterior cruciate ligament), your PCL (posterior cruciate ligament), your MCL, (medial collateral ligament), and your LCL (lateral collateral ligament). According to the American Academy of Orthopedic Surgeons, the most common knee sprains are ACL sprains, accounting for as many as 200,0000 incidents per year in the United States.
Medical professionals classify knee sprains into three grades based on the degree of ligament damage. Understanding these grades can help guide treatment, predict healing time, and determine whether surgery or rehabilitation is needed.
Grade 1 Sprain: Mild
In a Grade 1 sprain, the ligaments in the knee are stretched but remain intact. There may be microscopic tears, but there’s no instability in the knee joint. Mild sprained knee symptoms can include mild tenderness and swelling, but a full range of motion is preserved even if there’s slight stiffness.
Grade 2 Sprain: Moderate
A Grade 2 sprain involves a partial tear of the ligament fibers. You’ll experience moderate pain and swelling as well as bruising around the knee. You can expect some loss of knee function as well as some instability. Most people with a Grade 2 sprain report a noticeable weakness in the knee and some degree of loss of function and/or mild joint knee instability.
Grade 3 Sprain: Severe
In a Grade 3 knee sprain, there’s a complete tear of one of the major knee ligaments. It’s usually accompanied by severe pain at the time of the injury, though the pain may lessen a bit after. Severe sprained knee symptoms include significant swelling, bruising around the knee joint, and marked joint instability. Your knee may “give out” under body weight.
It’s typical in a Grade 3 sprain to lose significant knee function. You may not be able to fully straighten or bend the knee and may be unable to bear weight or walk without support. Sometimes you may even hear a popping sound during the injury which usually indicates a tear in your ACL. Grade 3 sprains often mimic fractures in terms of pain and mobility loss, so an MRI or X-ray is usually required for an accurate diagnosis.
How to Heal a Sprained Knee
Many doctors recommend a simple, yet effective four-step process for healing sprained knees called the R.I.C.E method.
Rest. Avoid putting weight on the injured knee for the first 24 to 72 hours. Use crutches if needed.
Ice. Apply ice packs for 15 to 20 minutes every two to three hours to reduce inflammation.
Compression. Wrap your knee using a compression bandage, or wear a brace to support the joint and limit swelling
Elevation. Raise your injured leg above the level of your heart when sitting or lying down. That will help reduce fluid buildup.
The new RICE protocol
“The Rice protocol has recently been updated,” says Charles Berk, MD, a family physician in New York. “The new acronym is POLICE, which stands for protect, optimal loading, ice, compression, and elevation.” Instead of the old “R” for rest, the new protocol calls for early controlled movement to stimulate healing, prevent stiffness, and regain strength and function sooner. “We recommend gentle range-of-motion exercises and gradual weight bearing using crutches or a brace,” adds Dr. Berk.
How Long Does a Sprained Knee Take to Heal?
Healing times depends on the grade of the sprain. A mild sprained knee can heal quickly. More severe injuries can take months. Typical healing times are one to two weeks for a Grade 1 (mild) sprain and involve rest and light rehab. Grade 2 (moderate) sprains may take between three and six weeks to heal properly and may require more intensive rehab therapy. Grade 3 (severe) sprains can take several months for complete healing and may require surgery and a full regimen of physical therapy.
When is it time to see a doctor?
Most sprained knees improve with self-care, but you should see a healthcare professional if your knee can’t bear weight, there’s severe swelling or bruising, your knee keeps “giving out,” you hear a popping sound and feel instant pain or if symptoms don’t improve by themselves after a few days.
The importance of physical therapy
Once the pain and swelling go down, it’s crucial not to let the knee stiffen up again. Your ligaments need time to fully regain their strength. That’s why physical therapy (PT) plays a key role in the healing process. A guided PT program, whether done with a professional or at home with proper instruction, greatly increases your chances of a safe and complete recovery. Many people decide to skip PT, especially after a mild or moderate sprain. That’s a good way to develop chronic knee instability and increase your chances of re-spraining it again. A targeted rehab plan gradually reintroduces movement, strength, and coordination to your injured knee.
A good rehab program for a knee sprain should include:
- Quad sets and straight leg raises
- Heel slides to regain flexibility
- Balance and stability training
- Strength training for quads, hamstring
Quad sets: Sit or lie down with your leg straight. Tighten your thigh muscle by pressing the knee down toward the floor. Hold for five to 10 seconds. Repeat 10 to 15 times.
Straight leg raises: Lie flat on the floor and keep your injured leg straight. Lift it about 12 inches off the floor. Hold for a few seconds, then lower slowly. Repeat 10 to 15 times, two to three times a day.
Heel slides: This exercise will help you regain knee flexibility without overloading the joint. Lie on your back with your legs straight. Slowly slide the heel of your injured leg toward your buttocks, bending the knee. Slowly slide it back down to straight. Do 10 to 15 per set, two to three times per day
Balance and stability training: Balance training is essential after a knee sprain, especially if the ACL, MCL, or LCL was involved. Ligament injuries often disrupt proprioception, your body’s sense of joint position. That’s why balance training is essential after a knee sprain—especially if the ACL, MCL, or LCL was involved. Stand on one leg, holding onto a chair or table for support initially. Keep the standing knee slightly bent and hold for up to 30 seconds. Progress to doing it without support.
Tandem Walking (heel-to-toe walking in a straight line): This exercise improves coordination, balance, and gait control. Find a flat, open space, like a hallway or gym. Walk heel-to-toe in a straight line by placing the heel of your front foot directly in front of the toes of your back foot. Keep your eyes forward and your arms relaxed at your sides. Take about 10 to 15 steps, then turn around and repeat. Try to do three to five walks each session, one to two times per day.
It’s best to do these exercises barefoot or in flat, supportive shoes. Start slowly and build up only as you can tolerate it. Discontinue if pain, swelling, or joint instability increases.
A sprained knee may seem like a simple setback, but without proper care, it can turn into a long-term problem. Whether you’re facing a mild strain or a complete ligament tear, the key to recovery lies in understanding your sprained knee symptoms, following the right treatment plan, and sticking with your rehab. From rest and ice to targeted exercises and balance training, every step matters. And remember: how long a sprained knee takes to heal depends not just on the severity of the injury—but on the quality of your recovery. Listen to your body, work with your healthcare provider, and take rehab seriously. That’s how you turn a painful injury into a strong comeback.
