The ACL (anterior cruciate ligament) is the main support structure of the knee joint. It prevents forward translation of the tibia relative to the femur. The ACL is the most common injured ligament in the knee. Injuries to the ACL are typically caused my traumatic events such as collisions in athletics, accidents or severe falls. Patients with ACL injuries often complain of a "pop" sound from inside the joint, immediate, intense pain and a feeling of the knee giving out. Due to strength, size and hormonal factors, females are at increased risk for ACL injuries.
An MRI of the injured knee can assist in diagnosing ACL tears and damage to other ligaments and soft tissues of the joint.
ACL injuries are classified according to a grading system:
Grade I: Stretch or sprain of ACL fibers. Pain and swelling is present
Treatment: Rest, ice and anti-inflammatories
Grade II: Partial tearing of the ACL
Treatment: May require surgery depending on the nature of the tear and patient specific needs
Grade III: Complete tear of the ACL
Treatment: Surgery is almost always recommended for athletes, active individuals and patients who have chronic knee instability
An arthroscopic technique is commonly used to repair or replace torn ligaments of the knee. Arthroscopic knee surgery incorporates the use of small poke-hole incisions (portals) around the joint, and the use of a specialized camera (arthroscope) among other specified arthroscopic surgical instruments. The goal of arthroscopic surgery is to repair and restore the joint to optimal strength, while maintaining range of motion. Due to the minimally invasive nature of the arthroscopic technique, damage to surrounding muscles, ligaments, tendons, nerves and blood vessels is significantly reduced. Risk of infection, post-operative pain and rehabilitation are also decreased compared to the traditional open-technique. ACL surgery involves the removal of damaged ligament fragments and replacement of the ligament with either the patient's own soft tissue or tissue from a cadaver; known as an autograft or an allograft respectively. ACL surgery may either be performed as an outpatient, or inpatient procedure with an overnight hospital stay.
After an ACL reconstruction, patients can expect to bear weight as tolerated without a brace as long as there were no other injuries to the knee requiring additional surgical intervention. They may use crutches for the initial days of recovery to regain stability during ambulation. The patient will also use a continuous passive motion machine daily to prevent stiffness postoperatively.
All knee arthroscopy patients can expect to be involved in physical therapy after surgery to strengthen and condition their knee and return to sports in peak condition.