One of the most common injuries to the knee is a sprain or a tear of the anterior cruciate ligament or commonly known as the ACL. These injuries are particularly common in high demand sporting activities such as football, basketball and skiing. Each time we hear of a professional football player requiring ligament surgery to the knee, it is likely that he is going for ACL reconstruction surgery!
Anatomy
Ligaments are strong bands of tissue that connects one bone to another in a joint. The anterior cruciate ligament (ACL) is one of the four ligaments in the knee that provides stabilization for the knee joint. It is found in the middle of the knee. It interacts with the posterior cruciate ligament, or the PCL, to form a “X” when viewed from the side, giving them the “cruciate” name. The ACL is responsible for providing stability by preventing the tibia (shin bone) from sliding out in front of the femur (thigh bone). It also provides rotational stability to the knee.
Causes of ACL Injury
Most ACL injuries occur due to sports or fitness activities. The ligament gets stretched and tears when the foot is firmly planted and the knee locks and twists or pivots at the same time. This commonly occurs in ball sports or gymnastics, where a sudden change in direction stresses and damages the ligament. Injuries to the ACL due to direct trauma is less common.
Current literature and research studies have shown that female athletes have a higher incidence of ACL injures when compared to their male counterparts. It has been proposed that this is due to differences in physical conditioning, muscle strength and neuromuscular control.
About half of all injuries to the ACL have associated damage to other structures in the knee. The more common once are injuries to the meniscus, cartilage and other ligaments.
Symptoms of a Torn ACL
Patient often describes that they hear and/ or feel a loud “pop” and you might feel the knee giving way. Other common symptoms include:
- Pain
- Swelling. Swelling in the knee usually progresses rapidly within the first 24hours.
- Pain along the joint lines and inability to continue with activity.
- Reduction in range of motion.
- Difficulty walking or getting up after the fall.
- Sensation of instability or of the knee “giving way”. This is experienced if the injury is left untreated. The ability to participate in sports is significantly reduced due to instability.
ACL Injury Diagnosis
Physical Examination
During your first visit with the doctor, a thorough history will be taken and examination of the knee will be performed. The doctor will be looking for painful areas and swelling in the knee. He may also check your knee for range of motion and do stability tests. It is common to compare the findings with the uninjured knee. Most ligament injuries to the knee can be detected with a thorough physical examination!
Imaging Tests
X-rays of the knee may be done to check for broken bones as the symptoms of fractures may mimic a torn ACL. In patients with an ACL tear, the X-rays are often normal.
MRI
MRI is the investigation of choice to image the knee looking for ligament injury. It will also pick up associated injuries such as injuries to the meniscus. In addition to defining the injury, it can help the orthopaedic surgeon decide on the best treatment options. However, MRI does not replace physical examination and many knee injuries do not require an MRI to confirm the diagnosis.
Treatment for ACL injury
Treatment planning for ACL tear depends upon on the presence of other associated injuries as well as the patient’s individual needs. A sporty and athletic is more likely to require surgery to be able to safely return to sports at a pre-injury level. The less active or older patient might be able to lead a quieter lifestyle without surgery.
Non-Surgical Treatment
The torn ACL does not heal without surgery. Non-surgical treatment may be appropriate for patients who are less active or in older patients. Treatment often involves a period of physiotherapy after the pain and swelling in the acute phase of injury has improved. Specific exercises aimed at strengthening the knee and to restore function will be needed to maximize the recovery of the injured knee. The doctor may also recommend a brace to protect the knee from instability. This will allow the affected individuals to participate in low level exercise and recreational activities.
Surgical Treatment
Surgical repair is recommended for those who wish to return to active sports. This is generally not an emergency and is undertaken after understanding all treatment options. Surgical treatment often needed in the following situations:
- In an active or sporty person, who wishes to return to the same level of play prior to sustaining the injury
- Having sustained associated injuries to the knee as a result. This includes injuries to other ligaments and meniscus tears.
- The injury results in the knee feeling unstable and/ or continues to “give way” despite conservative treatment.
ACL tear, during knee arthroscopy
Same knee, after ACL reconstruction
The ACL cannot heal and therefore cannot be sutured (stitched) back together. To fix the torn ligament and restore stability to the knee, a reconstructive procedure is performed. This is the current “Gold Standard” treatment for ACL tears. The injured and torn ligament is surgically removed and replaced with a tissue graft. This tissue graft acts as a scaffold for a new ligament to grow onto. The surgery is done via minimally invasive technique. The benefits of less invasive surgery techniques include less pain after surgery, less blood loss and faster recovery time.
Grafts are usually taken from the hamstring tendons at the back of the thigh or the patella tendon, which runs between the knee cap and the shin bone. An alternative would be to use cadaveric grafts, which are tissue grafts from donors. The use of such grafts is increasingly common. Each of these graft choices have its unique pros and cons. It is important to discuss with the doctor to determine which is the best option for you.
After Surgery Rehabilitation
Rehabilitation after surgery is an important process that cannot be stressed enough. The recovery and ligament regrowth takes time. It is common to require at least 6-12 months of rehabilitation before you can return to sporting activities. Physical therapy focuses on returning range of motion to the knee. This is followed by strengthening the individual muscle groups, coordination training across different muscle groups and dynamic functional training to return the athlete back to his or her sport.
