What are the symptoms of an ACL tear?
An ACL tear most often occurs during sporting activities when an athlete suddenly pivots causing excessive rotational forces on the ligament. Other mechanisms that can cause an ACL tear include severe trauma and work injuries. Individuals who experience ACL tears usually describe a feeling of the joint giving out, or buckling--patients also often say they hear a "pop."
Signs you may have sustained an ACL tear:
- Sudden giving way of the knee
- Hearing a 'pop' at the time of injury
- Sudden swelling of the knee joint
- Pain in the knee when walking
Patients who think they have an ACL tear should be evaluated by their doctor. An ACL tear may be difficult to diagnose immediately after the injury because of associated pain and swelling. There may also be muscle spasm that contributes to making the knee difficult to examine. Therefore, it may not be possible to conclusively determine the presence of an ACL tear soon after the injury. If an ACL tear is suspected, you will return for follow-up evaluation with your orthopedic surgeon.
How does my doctor make the diagnosis of an ACL tear?
The presence of an ACL tear is suspected whenever a patient has an injury to their knee. In the orthopedists office, knee instability can be assessed by specific maneuvers performed by your physician. These maneuvers test the function of the ligament to determine if an ACL tear is present. The most commonly used tests to determine the presence of an ACL tear include:
- Lachman Test
The Lachman test is performed to evaluate abnormal forward movement of the tibia (shin bone). By pulling the shin bone forward, your surgeon can feel for an ACL tear. If there is an ACL tear, the shin bone will move too far forward. - Pivot Shift Maneuver
The pivot shift is difficult to perform in the office, it is usually more helpful in the operating room with a patient under anesthesia. The pivot shift maneuver detects abnormal motion of the knee joint when there is an ACL tear present.
A complete examination of the knee is also necessary to determine if other injuries may have occurred that could be causing your symptoms.
Your physician will also evaluate x-rays of the knee to assess for any possible fractures, and a MRI may be ordered to evaluate for ligament or cartilage damage. However, MRI studies may not be needed to diagnose an ACL tear. In fact, the physical examination and history are just as good as a MRI in diagnosing an ACL tear! Many patients are concerned when their doctor does not order a MRI. While the MRI may be necessary in some cases, it is not necessary to diagnose most ACL tears.
Will I need an operation for an ACL tear?
The decision as to whether or not to operate on an ACL tear is dependent on several factors. Some patients who experience ACL tears are able to resume normal daily activities without surgical reconstruction of this ligament. There are some important factors to consider in making the decision as to whether or not operative treatment of an ACL tear is needed. These factors include the age of the patient, the activity level of the patient (both recreational and occupational), the expectations of the patient, the ability and willingness of the patient to participate in post-operative rehabilitation, the degree of instability of the joint, and any other associated injuries to the knee (e.g. other ligamentous or meniscal problems).
If you are unsure as to whether or not you need surgery for an ACL tear, read through the information on making a decision about ACL reconstruction.
For more information on the ACL reconstruction surgery, read on...
