A Publication of WTVP

In a recent issue, I discussed meniscal tears, which can affect both athletes and non-athletes and sometimes occur in combination with other injuries, such as torn anterior cruciate ligaments (ACL). This article will continue the discussion with an overview of ACL injuries.

What is the ACL?

The anterior cruciate ligament is an important stabilizer of the knee, and one of the four primary ligaments around the knee joint. It runs from the femur (thigh bone) to the tibia (shin bone) through the center of the knee. ACL injuries are some of the most prevalent problems involving the knee joint.
ACL tears most commonly occur in sports-related injuries, where hyperextension (forceful over-straightening) or pivoting of the knee occurs. Skiing, football, tennis and soccer are examples of sports that may strain the ACL. An ACL injury can also be the result of trauma—being struck on the outer side of the knee, or as a result of a motor vehicle accident in which the knee is forced under the dashboard. Repeated trauma, coupled with wear and tear, can also cause small tears in the ligament that can exacerbate the ACL over time.

“Trick knee” and other symptoms

Many people report hearing a “popping” sound when this injury occurs. They also feel as if their knee has “given out.” Other symptoms may include immediate and significant swelling, the inability to bend or fully straighten the knee, and extreme stiffness of the joint. The term “trick knee,” where the knee may lock up for no apparent reason, is often associated with this type of injury. Pain may be moderate to severe.

To diagnose the condition, your physician will first perform a thorough knee examination to determine the laxity (looseness), strength and pain points within the joint. In addition, he may order X-rays and an MRI to evaluate the ACL and to look for other injuries of the ligaments.

Degree of injury

There are three levels of ACL injuries: Grades 1, 2 and 3. A Grade 1 injury involves the ligament being stretched but not torn. Grade 2 is partial tearing of the ligament. For Grade 1 and 2 injuries, initial treatment follows the RICE rule:

In addition, your doctor may suggest you wear a knee brace and take nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen to relieve pain and swelling. He or she may also recommend physical therapy to rehabilitate the injury.

A Grade 3 injury is a complete tearing of the ACL, with a greater degree of knee instability. ACL injuries that require surgery are either Grade 3, or Grade 1 or 2 tears that have not responded to treatment over time.

Surgical treatment

Surgery for an ACL injury involves repairing or reconstructing the anterior cruciate ligament. With a repair, the existing damaged ligament is sutured if the tear is in the middle. If the ligament has detached from the bone, the bony fragment is reattached. Surgical reconstruction requires taking a portion of a tendon from another part of the body or from within the knee itself to replace the ACL.

Many surgeons use arthroscopic surgery rather than open surgery primarily because the procedure uses a smaller incision, has fewer risks and rehabilitation is often faster. Arthroscopic ACL surgery involves making two to three incisions around the knee. An arthroscope—a thin, flexible fiberoptic scope—is inserted into one of the incisions, and a camera at the end transmits pictures of the knee to a TV monitor.

The surgeon drills small holes into the upper and lower leg bones to form tunnels through which replacement tissues, or grafts, will be anchored. He secures the graft with screws or staples and closes the incision. A tube may be inserted into the wound to drain fluid. Also during ACL surgery, the surgeon may repair other parts of the knee, such as ligaments, cartilage and broken bones.

Getting back on your feet

Rehabilitation is key after ACL surgery in order to rebuild your strength and get range of motion back in your knee. While in the hospital, you may start partial weight-bearing exercises to re-establish knee joint mobility. You may be required to wear a brace or use crutches for the first six weeks.
You will begin a physical therapy program starting with range-of-motion and resistive exercises, then move to power, aerobic and muscular endurance, flexibility, and coordination drills. A patient usually returns to normal activities within a few weeks of surgery, and sports between six and 12 months after surgery.


Though ACL injuries can happen without warning, there are measures you can take to lessen your risk:

For reasons that are still unclear, women are particularly susceptible to ACL injuries. However, both male and female athletes need to take precautions to reduce the incidents of this sidelining knee injury. iBi