(Anterior Cruciate Ligament Tears)
One of the most common knee injuries is an anterior cruciate ligament sprain or tear. ACL injuries are typically the result of an acute injury, and often occur during sports activities. About half of all injuries to the ACL occur with damage to other structures of the knee, such as articular cartilage, meniscus, or other ligaments.
The ACL is located in the middle of the knee joint and connects the femur (thigh bone) and tibia (shin bone). The ACL limits forward motion of the tibia off the femur and works in conjunction with the posterior cruciate ligament (PCL) to control the back and forth motion of the knee.
Causes of ACL Injuries:
The anterior cruciate ligament can be injured in a variety of ways:
- Changing direction quickly
- Sudden stopping
- Landing from a jump incorrectly
- Direct impact to the knee while the foot is firmly planted on the ground
- Slowing down while running
Research shows that female athletes have a higher rate of ACL tears than male athletes in certain sports. This is the result of biomechanics, physical conditioning, muscle strength, anatomical differences in the pelvis and lower extremities, and the effect of estrogen on ligaments.
Typical symptoms of ACL injuries include:
- Popping noise at the time of injury
- Instability of the knee joint
- Pain with swelling
- Discomfort when walking
- Tenderness along the joint line
While X-rays cannot identify soft tissues, they may be needed to rule out damage to the bones, such as a fracture. Advanced imaging tests, such as a CT scan or MRI, will show images of soft tissue (muscles, ligaments, tendons) within the knee joint, and may be used to further diagnosis the extent of the tear.
Your physician will assess any damage to the ACL by conducting a physical exam. During the physical exam, your physician will perform a series of movements to test the integrity of the ligament. The Lachman test and Anterior Drawer test are common tests used to diagnosis ACL tears.
Treatment options for ACL tears vary based on whether or not the ligament is sprained or torn. Injured ligaments that are considered “sprained” are graded as follows:
- Grade 1 Sprain: refers to mild damage where the ligament has been slightly stretched, but the knee joint remains stable
- Grade 2 Sprain: refers to stretching of the ACL to the point that it is loose. This is often called a partially torn ligament. These injuries are rare as most ACL injuries are completely torn, or almost completely torn
- Grade 3 Sprain: refers to a complete tear of the ACL. The ligament has been split and the knee joint is unstable
Surgery for anterior cruciate ligament tears involves reconstructing or repairing the ligament. ACLs are reconstructed by grafting a piece of tendon onto the knee where the ACL was torn. The new tendon is fixed to the bone with biodegradable screws or buttons. There are two types of grafts used in ACL reconstruction:
- Autograph reconstruction means harvesting tissue from your own body to replace the torn ACL. Tendons such as the patellar tendon (tendon of the kneecap) and hamstring tendon are taken and used to repair the torn ACL.
- Allograft reconstruction means harvesting tissue from human donors rather than your own body.
ACL surgery is performed arthroscopically by making small incision into the knee joint. The ACL graft is anchored to the upper and lower leg bones, and hardware is used to secure the graft. During ACL surgery, the surgeon may repair other injured parts of the knee, such as meniscus, cartilage, or other ligaments.
For several days following surgery your knee will be swollen, you may feel numbness around the incisions, and your ankle and shin may be bruised or swollen. Most of the swelling and bruising will go away in a few days, and you should start seeing improvement in the knee. During this time, you will not be able to bear weight on the affected leg, so plan on using crutches and limiting your mobility.Shortly after surgery, you will begin the rehabilitation process. You will be given exercises that must be performed daily to support your recovery. Physical therapy will help you regain a full range of motion, strengthen the leg, and restore your mobility. Two to three months after surgery, you should be able to begin more low-impact activities such as cycling and swimming. Three to six months after surgery, your body is almost ready to return to some athletic activities. Bracing is typically required, even for low-impact activities. After six months, if the damaged tissues have fully healed, you can return to normal athletic activity. Recovery is different for each patient, so it’s important to communicate with your physicians and physical therapist regarding restrictions and progress.
Restrictions following surgery
Patients should not drive while taking pain medication following surgery. If surgery was performed on your left knee, you will be able to resume driving once you feel your reaction times are back to normal (usually around a week). If surgery was performed on your right knee, you should allow 4 to 6 weeks before driving.A leg immobilizer will be worn at all times for at least the first week. If meniscus repair is performed, the immobilizer will be worn for 4 to 6 weeks.Crutches should be used for balance and support at all times for the first 2 weeks. If meniscal repair is performed, crutches will be used for 4 weeks.