Reconstruction of the anterior cruciate ligament (ACL) is a surgery designed to restore knee movement and strength after your ligament has been torn. The torn ligament must be removed and replaced with another ligament from your body or with tissue from a cadaver.
The knee is a hinge joint where the femur (thighbone) meets the tibia (shinbone). This important joint is held together by four ligaments (fibrous tissues) that connect the bones to one another:
- anterior cruciate ligament (ACL)
- medial collateral ligament (MCL)
- lateral collateral ligament (LCL)
- posterior cruciate ligament (PCL)
Your ACL runs diagonally between the femur and the tibia. It keeps the tibia from slipping in front of the femur and provides stability to the knee when it rotates from side to side.
An ACL tear is one of the most common knee injuries, especially among people who participate in high-impact sports like basketball, football, soccer, skiing, and hockey.
The majority of those injuries—70 percent—occur without impact to another player, according to the American Academy of Orthopaedic Surgeons (AAOS). They most often occur when an athlete twists or pivots during play.
There are about 200,000 ACL injuries every year in the United States. According to the AAOS, about half of those injured undergo ACL reconstructive surgery (AAOS).
Research from the Boston Children’s Hospital found that injecting a gel mixed with platelet-rich blood plasma into the knee helped torn ligaments repair themselves. Though the testing was performed on dogs, the preliminary findings suggest that ACL reconstructive surgery may not be necessary to repair torn ligaments in the future (Boston Children’s Hospital).
Until then, ACL reconstructive surgery remains the gold standard for repairing this common knee injury. The AAOS reports that about 9 out of 10 ACL reconstruction surgeries yield excellent results and full knee stability.
ACL reconstructive surgery is done to repair a torn ACL and regain stability and movement in the knee. While not all cases of a torn ligament require surgery, very active people or those in persistent pain may opt for surgery.
ACL reconstruction is often recommended if:
- you are young and active
- you suffer from persistent knee pain
- your injury causes your knee to buckle during routine activities, such as walking
- you are an athlete who wants to remain active
You will have several appointments with your doctor and/or surgeon prior to your surgery. You will discuss your treatment options, undergo several knee examinations, and make a decision about which type of anesthesia to use during surgery. During these meetings, it’s important to ask any questions you may have.
Discuss with your doctor where the tendon that will be surgically implanted in your knee will come from. Typical sources for these tendons include:
- patellar tendon: the tendon that attaches the bottom of your kneecap (patella) to your tibia
- hamstring: the tendon that connects the long muscles in the back of your leg to the back of your knee
- quadriceps: a tendon from the front of the thigh. This type of graft is typically reserved for taller or heavier patients, or for people who have had previous unsuccessful grafts.
- cadaver: tissue from a dead body. This procedure is called an “allograft.”
While all cadavers are carefully screened for disease prior to surgery, some people have concerns about using dead tissue. Discuss any concerns you have with your doctor.
Your doctor will give you complete instructions for the day of your surgery. Instructions may include fasting for 12 hours prior to surgery and refraining from using aspirin or blood-thinning medications.
Make sure to arrange to have someone come with you for your surgery. It’s helpful to have someone there to listen to post-operative instructions and to drive you home.
You will change into a hospital gown and be wheeled into the operating room on a gurney. An IV will be placed into your arm so doctors can administer medications, anesthesia, or sedatives for the procedure.
Once the sample tissue is selected, it is either surgically removed from your body or prepared from a cadaver. The tendon is then outfitted with “bone plugs,” or anchor points, to graft the tendon into the knee.
During surgery, your surgeon will make a small incision in the front of the knee so that an arthroscope (a thin tube outfitted with a fiberoptic camera and surgical tools) can be inserted. This allows the surgeon to see inside your knee during the procedure.
The first thing the surgeon will do is remove your torn ACL and clean the area. Then, small holes will be drilled into your tibia and femur so that the bone plugs can be attached with posts, screws, staples, or washers.
Following the attachment of the new ligament, the surgeon will test your knee’s range of motion and tension to ensure that the graft is secure. Then, the opening will be closed with stitches, the wound dressed, and the knee stabilized with a brace.
Patients typically go home on the day of their surgery.
Because ACL reconstruction is a surgical procedure, it carries certain risks, including:
- bleeding and blood clots
- continued knee pain
- disease transmission if the graft comes from a cadaver
- knee stiffness or weakness
- loss of range of motion
- improper healing if the graft is rejected by your immune system
Young children with ACL tears run the risk of growth-plate injuries. Growth plates at the ends of long bones in the arms and legs allow the bones to grow. Growth-plate injuries can result in shortened bones.
Doctors evaluate these risks when deciding if surgery should wait until the child is older and the growth plates have formed into solid bone.
Rehabilitation is key to the success of ACL reconstruction.
Immediately after surgery, you’ll be advised to take pain medications, keep your incision clean and dry, and rest. You’ll most likely have a follow-up appointment with your doctor or surgeon within a few weeks of surgery.
Here’s what to expect following ACL surgery:
- some pain
- restricted activity for several months
- walking with crutches for up to six weeks
- wearing a knee brace for at least one week
You can expect to regain range of motion in your knee within a few weeks of surgery. Athletes typically return to their sports within 6 to 12 months.
Once the surgery has been deemed successful and the incision wound has healed, a physical therapy regimen can begin. The success of such therapy varies from person to person.