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ACL Tear

What is the ACL?

The anterior cruciate ligament (ACL) is housed within the knee. The knee joint is the connection between the femur (thigh bone) and the tibia (shin bone). These bones are held together with four rope-like structures called ligaments – the ACL, PCL, MCL, and LCL. The MCL and LCL run up the sides of the knee while the ACL and PCL are deep in the center of the joint. These ligaments work together to allow the knee to move in a controlled fashion, making it possible activities such as running, jumping, and playing sports.

What does the ACL do?

The ACL is important for a variety of knee movements, especially those seen with higher level activities such as running, jumping, and playing sports. Patients with an ACL tear often feel a sense of instability or apprehension (and sometimes even buckling or giving way of the knee) when trying to move side-to-side, walk on uneven ground, or change direction.

Causes and Symptoms

Often times, a tear occurs while changing directions rapidly (think juking a would-be tackler in football), landing awkwardly from a jump, or a collision. It has also been shown that females have a much higher rate of injury than males, due to a variety of anatomical differences.

In many cases when the initial injury occurs, patients often feel and/or hear a “pop” in their knee followed by the knee giving out or buckling. Pain and swelling after injury is common, as well as loss of range of motion and tenderness around the joint. Injuries of this nature should not be ignored or “toughed out” as doing so can cause further damage to the knee.

It is important to understand that each patient is different and the symptoms listed above do not always mean you have a ligament injury. A diagnosis should be made by an orthopedic surgeon to make sure the injury is treated appropriately.


Diagnosis is based on the patient history, physical exam, and imaging (such as X-rays and/or MRI). An ACL tear can often be diagnosed on physical exam, using the Lachman test. The Lachman test evaluates how “loose” the ACL is. Additional exam findings include swelling, decreased range of motion, and joint line tenderness.

In most cases of an ACL injury, the X-rays of the knee will appear normal. If there is a concern about a ligament or other soft tissue injury, an MRI is usually performed. An MRI can evaluate the severity of an ACL tear as well as look for other knee injuries such as a cartilage or meniscus tear.

ACL injuries have different degrees of injury called “grades.” These grades are determined by the amount of damage to the ligament.

  • A grade one injury is the most mild of the three. In grade one injuries the ligament has been stretched but is not torn and can still perform its basic functions to keep the knee stable.
  • Grade two injuries have stretched the ligament even further, causing it to become loose. At this point, the ligament is unable to keep your knee stable. This grade may also be referred to as a partial tear. Partial tears are rare injuries. In most cases, the ACL is either stretched slightly or torn completely (grade three).
  • Grade three injuries are the most common of the three. The ligament has been completely or almost completely torn into two pieces. The knee is extremely unstable and surgery is usually required to repair the damage.

Non-Surgical Treatment

Surgery is not required in all patients with a torn ACL. Lower grade injuries are often amenable to non-operative management. In addition, patients who are older and/or have a lower activity level may be able to avoid surgery, even with complete tears. Non-operative treatment often includes a period of rest followed by a course of physical therapy. This allows the patient to build strength in the muscles surrounding the knee joint, allowing for normal knee function with certain activities.

Surgical Treatment

Surgery is usually recommended for younger and more active individuals with grade two and three injuries.

The result of repairing a torn ACL is quite unpredictable. As a result, the standard surgical treatment for an ACL tear is to replace, or reconstruct, the ligament. Reconstructing the ACL is done with a piece of tissue called a graft. The graft can come from a donor/cadaver (allograft) or from the patient’s own body (autograft). Each graft option has potential benefits and risks. Before surgery, your surgeon will have a discussion with you about the different graft options in order to determine the best graft option for you and your lifestyle.

ACL reconstruction is usually performed through several small incisions around the knee and with the use of an arthroscopy (a special camera to look in the knee joint). Surgery is usually 1-2 hours in length and is usually performed as an outpatient procedure in an ambulatory surgery center (ASC).


There are potential complications with any surgical procedure. With ACL surgery, some of the potential complications include knee stiffness, re-tear of the ACL, and infection. In order to minimize the risk of these complications, your surgeon will give you antibiotics during the procedure (to minimize risk of infection) and you will begin formal physical therapy within 1-2 weeks of surgery (to minimize the risk of stiffness and/or re-tear). Fortunately, these complications are rare, but when they do occur, additional surgery can sometimes be required.


ACL surgery is usually 1-2 hours in length and is usually performed as an outpatient procedure in an ambulatory surgery center (ASC). Following surgery, patients are given specific instructions in order to ensure the best possible outcome. This includes a small prescription of pain medications and specific instructions regarding activity and wound care. Your surgeon may also have you use crutches and a knee brace for a period of time following surgery. In most cases, patients will also start in formal physical therapy to help rehabilitate the knee. Typically, patients are able to return to sports between nine and 12 months following surgery.


Overall, the outcomes of ACL reconstruction surgery are very good. With the appropriate physical therapy and rehabilitation, patients can expect to return to their normal pre-injury activity level.

Unrestricted return to sports such as skiing, soccer, football, and basketball usually occurs between 9 and 12 months following surgery.

Why Choose ROC?

Your best chance at having an excellent outcome is to have things done right the first time. It’s absolutely imperative to make the diagnosis, have the appropriate treatment, and rehabilitate the knee, all in a timely manner. At Reno Orthopedic Center, we have fellowship-trained sports medicine surgeons who focus on treating knee injuries. Our sports medicine team has the training, experience, and expertise to treat your knee injury and get you back to the activities you enjoy.