Media-savvy consumers of health information are likely to know something about anterior cruciate ligament (ACL) knee injuries and reconstruction, but new advances in the field - including innovative surgical techniques designed to more exactly reproduce the anatomy and function of the ACL - point toward making these procedures even more effective.
The ACL is part of a complex of ligaments that help stabilize and support the knee joint.
The ACL is frequently injured in athletic individuals, particularly those pursuing “pivoting” sports, such as soccer, lacrosse, football, basketball, field hockey, and skiing. Some patients report hearing a “popping” sound at the moment that the tear occurs. Pain, swelling, and a feeling of instability in the knee may occur within the immediate period after the injury; however, in some cases, the initial symptoms may be mild.
Without an intact ACL, there is instability of the knee, resulting in a sudden sense of shifting or buckling; the injured person cannot jump and land on the knee, accelerate and then change directions, or rapidly pivot on the knee.
Sagittal MR image demonstrates intact anterior cruciate ligament.
Sagittal MR image demonstrates a complete tear of the ACL.
People of all ages, physical abilities, and conditioning can tear their anterior cruciate ligaments. In recent years, many investigators have noted the high incidence of ACL injuries among women. A number of theories - none of them confirmed - have been proposed, including greater laxity (looseness) in the ligaments, anatomical differences, and hormonal fluctuations.
ACL injuries are also increasingly common in children, for whom treatment, including non-operative measures, proves more difficult. Owing to concern for preserving normal growth, treatment for children has traditionally been non-operative. However, more recently developed techniques have made surgical repair an option at some institutions, such as HSS.
When the tear to the ACL is the only injury present, and if the patient’s lifestyle does not require the performance of the movements described, non-surgical treatment is a viable option. Immediately after the injury, the patient is advised to stay off the leg and elevate it, apply ice, and to take medication such as ibuprofen to reduce pain and inflammation.
A course of physical therapy is prescribed to strengthen surrounding muscles, and a brace may be fitted for use during activities that would place special stress on the knee. Many people with a torn ACL treated with conservative measures continue to lead an active lifestyle that includes the use of most equipment found at the gym or health club, swimming, jogging, and skiing (up to an intermediate level).
However, long-term outcome for patients who are treated non-surgically varies, and the role of bracing is unclear. Those who return to unrestricted activity are likely to experience some instability.
It has been well documented that the conservative (non-operative) treatment of an ACL tear in those individuals who desire to return to pivoting sports after injury often leads to cartilage damage in the knee. Recurrent instability can result in damage to the meniscus (the pad of cartilage that cushions the bones that meet at the knee joint) and the articular cartilage on the surface of the joint. Possible consequences of this damage include an increase in pain and swelling in the knee, and an increased risk of ultimately developing osteoarthritis, an irreversible condition.
For this reason, surgical reconstruction of the torn ACL is the treatment of choice for most active individuals, particularly young athletes, in whom the effects of early cartilage damage can be life-altering.
ACL reconstruction has become a commonly performed procedure. Today, the majority of ACL surgeries are performed using arthroscopic techniques (“Endoscopic ACL Reconstruction”), in which a combination of fiber optics, small incisions, and small instruments are used.
The current, widely accepted procedure uses a tendon graft placed in the knee using an arthroscopic method, avoiding large and painful incisions into the knee. The graft - usually a tendon - may be drawn from many sources, including the patient’s own hamstring tendon, patellar tendon, the quadriceps tendon, or an allograft (human donor tissue). The type of graft used is determined on a case-by-case basis.
ACL surgery is generally scheduled between two and six weeks after the injury occurs in order to allow inflammation in the area to subside. If surgery is performed too early, patients may develop arthrofibrosis, a profound scar tissue response. Orthopedic surgeons gauge the appropriate timing of surgery based on the presence of other injuries (which may require more prompt attention), physical appearance of the knee, and the patient’s level of pain, degree of range of motion, and quality of muscle control.
At Hospital for Special Surgery (HSS), ACL surgery is most commonly performed using epidural anesthesia —the same type of regional anesthesia that many women receive during childbirth. Patients may be awake or have light sedation and sleep during their surgery. General anesthesia is also available. An overnight stay in the hospital is usually not necessary.
Following surgery, the patient enters a rehabilitation program to regain strength, stability, and range of motion to the knee. Recovery time varies, with a period from about six to nine months representing the average. Assessment of recovery is based on restoration of strength, range of motion, and proprioception (the awareness of the position of one’s body). The degree of pain associated with ACL recovery also varies and can be addressed successfully with medication.
The pioneering work in understanding and treating ACL injury started at HSS more than 30 years ago. According to Dr. Scott Rodeo, one of the HSS surgeon researchers who continue to study ACL injury and repair, studies evaluating existing techniques show very good outcomes when surgery is performed by experienced knee surgeons. However, there are recent innovations which are expected to result in even better long-term stability of the knee.
Dr. Answorth Allen advocates a technical variation that permits better placement of the graft and the use of a “double bundle” repair. Dr David Altchek has completed a study of an “anatomic footprint” technique, based on laboratory and clinical data, which allows the surgeon to arthroscopically place the ACL graft in the exact center of the original position of the patient’s own ACL. These variations in surgical technique are advanced to more precisely reproduce the anatomy and function of the native ACL, and provide patients anterior/posterior as well as rotational stability of the knee and durable long-term function in high demand activity.
Working with a dedicated team of experienced nurses, along with specialists in rehabilitation and pain management, the orthopedic surgeons at HSS are well-prepared to respond to the clinical needs of a wide range of patients with ACL tears, including those with multiple injuries and/or pre-existing disease.
Orthopedic surgeons at HSS perform more than 850 ACL reconstructions annually and have considerable experience with pediatric patients.
For more information on treatment of ACL injuries at HSS, please visit the Physician Referral Service or call 1.877.606.1555.
Summary by Nancy Novick