An anterior cruciate ligament (ACL) injury can be as complicated as the name sounds. It involves the ligament in the middle of the knee which prevents the shin bone from sliding out in front of the thigh bone. An ACL injury is caused by overstretching or tearing the ligament, either partially or completely.1
An injury to the ACL affects the very stability of your knee, resulting in a loss of leg strength and a restriction in the knee's range of motion. Severe tears or ruptures will often require surgery and extensive rehabilitation to fully restore your mobility.1
At-Home Rehabilitation for ACL Injuries
If faced with an ACL injury, there are a number of exercises you can do at home to better retain strength and movement without causing further injury to the ACL. These can be done prior to surgery if needed, or in conjunction with ongoing physical therapy.
The aim is to avoid compression of the knee or any exercise that may be weight-bearing. Instead, you would focus on strengthening muscles surrounding the knee—the quadriceps ("quads") and hamstrings ("hams") —while gradually extending your range of motion so that your knee doesn't "freeze."2
By doing these at home (ideally with the input of your doctor or physical therapist), you can be better prepared for surgery if needed, or to reap the full benefits of a structured rehabilitation program.
ACL Rehab Exercises for When Your Knee Is Still Fragile
Here are three of the best (and safest) exercises to treat an ACL injury when first starting out:3
Heel slides involve the extension of the knee without bearing any weight. Start by sitting on the floor with your legs outstretched. Slowly bend the injured knee while sliding your heel across the floor toward you. Slowly slide the foot back into the starting position and repeat 10 times.
Isometric contractions of the quads are also done seated. For this, you would need to sit on the floor with your injured leg extended and your other leg bent. Now slowly contract the quadriceps of the injured knee without moving the leg and hold for 10 seconds. Relax. Repeat 10 times.
Prone knee flexion involves lying on your stomach with your legs straight. Now bend your injured knee and bring your heel toward your buttocks. Hold five seconds. Relax. Repeat 10 times.
When first starting, forget the adage "no pain, no gain." While you will likely experience discomfort when exercising the quads and hams, back away from any movement that causes outright pain. Pushing too hard can make matters worse and result in lengthier recovery time.
ACL Rehab Exercises When the Swelling Subsides
As the swelling of your knee begins to subside, you should gradually be able to stand squarely on both feet without favoring the uninjured leg. When you are fully able to do this, you can start adding the following exercises:4
Passive knee extensions require two chairs of equal height. Place the chairs facing each other at a distance slightly shorter than the length of your leg. Sit in one chair and place your heel on the seat of the other. Relax your leg and allow your knee to straighten. Rest in this position one to two minutes several times a day to gradually stretch out the hamstrings.
Heel raises are done while standing. Start by placing one hand on the back of a chair for balance. Now slowly lift the heel of your injured leg up, standing on your tiptoes. Stay there for five to 10 seconds. Slowly lower your heels. Repeat 10 times.
Half squats are done standing while holding a sturdy table with both hands. Placing your feet a shoulder’s width apart, slowly bend your knees and lower your hips into a half squat. Hold for 10 seconds and then slowly return to a standing position. Repeat 10 times.
Knee extensions require either a TheraBand or a length of an exercise band. To begin, loop one end of Theraband around the leg of the table and the other around the ankle of your injured leg. (Alternately, tie both ends of the exercise band around the table leg and insert the ankle of your injured leg into the looped end.) Facing the table, slowly bend your knee about 45 degrees against the resistance of the tubing. Hold for a few seconds and slowly return to a standing position. Repeat 10 times.
Standing on one leg is a great way to build and evaluate your strength and balance. Do so by lifting the uninjured leg and standing unassisted on the injured leg for 10 seconds. This exercise may not be so easy at first, but, with time and patience, you should able to do so while a few weeks.