Injury of ligaments of the knee is not uncommon, especially in athletes. There are around 200,000 anterior cruciate ligament tears every year and near half of them are treated surgically. Lately, there has been a significant increase in the surgical treatment of ACL tears, even without surgery. 
The anterior cruciate ligament (ACL) is located inside the knee joint and it connects the femur and tibia. It is surrounded by joint fluid and it gets all nutrients from a small artery located in the knee area. The main role of the ACL is to provide stability to the knee and to prevent excessive forward movement of the lower leg.
Mechanism Of Injury
The most common mechanism of an ACL tear injury is deceleration, cutting or jumping. 
Patients typically complain of a popping sound followed by strong pain and an inability to continue activity or sport. In most cases, the knee joint fills with blood and swells within a few hours. There are a number of orthopedic tests which are used to confirm the ACL tear. The most sensitive among them is the Lachman test. But the pivot shift test, Anterior drawer test, Martens test, Losee test can also be used to confirm the diagnosis.  MRI can be used to confirm the diagnosis and provide further details about the injury.
There are a lot of factors which affect the healing process of a torn ligament. The most important factors include which ligament is injured, local factors such as the presence of edema, inflammation, hemorrhage, associated injuries, the age of the patient, and activity level prior the surgery.
Every healing process consists of four main stages:
- Hemorrhage is the first stage after the injury. It occurs right after ligament injury, and the blood which flows out of injured blood vessels creates hematoma.
- The inflammatory phase is the second phase of the healing process. In this stage, inflammatory cells will appear near the hematoma and replace it with granulation tissue (repair tissue). At the end of this phase, granulation tissue is replaced with collagen fibers.
- The third phase is the reparative phase. During this phase of recovery, the body will create new blood vessels at the injured site and the regenerative tissue will continue to grow and get stronger.
- The last phase of ligament healing is remodeling and it can last for years. It allows ligaments to heal to achieve almost the same condition they were in before the injury.
ACL Injury Treatment Options
For an ACL tear injury, there are two main treatment options:
- Nonoperative management
More aggressive orthopedic surgeons will probably recommend surgery for every ACL tear. They will not take into consideration important factors like the patient’s age, activity level prior to surgery, cost of surgery, or the patient’s willingness to get surgery.
The average cost of ACL repair depends on a lot of factors (the type of surgery-autograft, allograft, facility fee, surgeon’s fee, anesthesiologist fee, drugs, instruments, etc.). Generally speaking, the cost varies between $4,600 and $5700.  In the USA, around three billion dollars are spent on ACL surgeries every year.
Surgery is not the only solution for an ACL tear and it is not the best ACL treatment option for every patient. A patient who doesn't want to have a surgery and who is willing to change their lifestyle should be treated using non-surgical methods. Also, every patient should be allowed to go through an aggressive rehabilitation protocol prior to any surgery. Surgery should be reserved only for patients with knee instability even after physical therapy. 
Evidence-Based Medicine And ACL Tear Treatment
A study by Daniel et al researched the quality of life of patients who suffer from an ACL tear. Over 60 percent of them were able to continue normal life activities without surgery. It is very important to use an aggressive rehabilitation protocol to give your knee the stability it needs. 
According to Clancy et al, conservative treatment of ACL tear injuries can provide reasonably good results when compared with ACL reconstruction. 
Another study by Kessler et al concluded that there is no significant long-term difference in the level of physical activity between conservative and surgically treated patients. Conservative treatment can be used as an initial treatment option for ACL tear injuries. 
Conservative treatment might be the best ACL treatment option for older patients with lower activity levels or younger patients who aren’t athletes. In one study, over 97 percent of examined patients with ACL tear injuries were satisfied with the outcome of conservative treatment. They were able to continue daily life activities without any issues.  Conservative treatment can provide excellent results in patients with partial ACL tears. 
When To Consider Conservative Treatment For ACL Tear Injuries:
- Every Grade I and Grade II ACL tear injury
- Grade III ACL tear injury before considering a surgery
- Older patients
- Patients with a lower level of activities
- Partial ACL tear
- Younger non-athlete patients
- Contraindications for anesthesia
For patients with ACL tears, surgery should not be the only option. A lot of ACL injuries can be treated conservatively with great success. Conservative treatment can provide the required knee stability and allow the ACL tear injury time to heal on its own.
The most important part of the recovery period is patient education. The patient should be aware that healed or replaced ACL doesn’t mean the ability to immediately return to the same activity level as prior to the injury. Rather, patients should adjust their activity levels and slowly build up the activities to the pre-treatment level.