ACL, or anterior cruciate ligament, injuries are one of the most common injuries among athletes. Depending on the severity of the sprain or tear, a patient may require surgery to regain full mobility of the knee.

ACL illustrationPhoto Source: OrthoInfo

The knee joint is made up of three bones (femur, tibia, and patella) and these bones are connected by four main ligaments. The first two, the medial and lateral collateral ligament are on the sides of the knee and control the sideways movement. The second two, the anterior and posterior cruciate ligament, are inside the knee joint and create an “X”. The cruciate ligaments control the back and forth motion of the knee. Not only does the ACL control these motions, but the ACL keeps the tibia from sliding in front of the femur and provides stability for the knee.[1]

Most ACL injuries occur during strenuous sports that require jumping, sudden stops, or changes in direction. Common causes of ACL injury are:
1. Landing incorrectly when jumping
2. Suddenly stopping and changing direction
3. Direct contact or collision to the knee joint
4. Planting your foot and quickly changing direction (pivoting)

ACL injuries are categorized by different sprain levels from 1-3, with 3 being the most severe. Grade 1 sprains have minor damage to the ACL with some stretching of the ligament but the ligament is still able to hold the knee in place. A grade 3 sprain is often called an ACL tear. In this instance, the ACL is split in two and the knee joint is unstable. Surprisingly, most ACL sprains are complete tears of the ligament, partial tears are not common.[2]

Women & ACL Tears
ACL tears are more common in women. Studies show that women have a strength imbalance in the thigh: the quadriceps tend to be stronger than the hamstrings. The hamstrings hold the tibia in place and prevent it from moving too far forward. If the tibia moves too far forward strain is placed on the ACL. Researchers have also found that when jumping, women are more likely to land in a position that puts strain on the knee joint.[3]

It is recommend that women strengthen the muscles in the leg lower torso, and hips to prevent ACL injury. Practicing correct jumping and landing techniques may also prevent ACL injury.

An ACL injury most often includes a popping noise when the injury occurs. A patient may feel as though the knee is “going out from under them.” These two symptoms are most common with ACL injury and signs that something is wrong. Within 24 hours, the joint will swell and be painful. The swelling may resolve on its own but returning to sports or fitness too early can further agitate the joint. Additional symptoms include difficulty walking, tenderness, and loss of full range of motion.[4]

Most ACL injuries can be diagnosed with a physical exam, comparing the injured knee to the non-injured knee. An X-Ray or MRI may be used to further diagnose the ACL injury. X-ray is used to see if the injury is associated with a broken bone while MRI allows the physician to see damage to the soft tissues and ligaments. Right after the ACL injury, the RICE method is recommended: rest, ice, compression, elevation.

Nonsurgical treatment for ACL injury is most common if the stability of the knee is not fully compromised and if the patient is elderly and can live a low-activity lifestyle. In nonsurgical treatment, physical therapy is the most important aspect of rehabilitation. The therapist will show the patient exercises aimed at strengthening the muscles around the knee that will help restore the knee joint to full range of motion. A brace or crutches may also be used to further stabilize the joint.

Surgical treatment is recommended for athletes who want to continue with a high-activity level, if the patient is young and active, if more than one ligament is damaged, or if the joint is buckling during everyday activities. Most ACL injuries cannot be sutured back together and therefore require a graft. The graft is usually a tendon taken from elsewhere in the body. After surgery, the patient returns to physical therapy to continue building strength and stability within and around the joint. Regrowth from the graft takes time; recovery to full range of motion and activity level can take six to 12 months.

There is no number one way to prevent ACL injury and prior to starting any prevention routine a physician or physical therapist should be consulted. Many prevention plans include strengthening the legs muscles. When strength training, special focus is paid to the hamstrings to ensure strength balance along the entire leg. Strength training will also include strengthening the hips, core, and lower abdomen. Keeping all of these areas strong helps stabilize the leg muscles and joints. A physical therapist will also work with a patient to teach proper techniques for jumping, landing, pivoting, and cutting. And of course, it is important to have gear that properly fits when performing any type of exercise.


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