The diagnosis of a torn anterior cruciate ligament is based on the:
history
physical examination
arthrometry and,
diagnostic aids or imaging.
The History
- Twisting injury to knee with pop.
- Pain and immediate swelling.
- The giving way of the knee with pivoting.
- The patient demonstrates the '2 fist ' sign, indicating the sensation of the knee coming apart.
The Physical Examination
There are four types of physical examinations that can be preferred to make the diagnososis of an ACL tear. They are as follows:
The Lachman Test (the main clinical examination test)
Pivot Shift Test
The pivot shift test is the test that reproduces the feeling of the instability that the patient complains about.
Range of Motion
The knee is examined for range of motion. An operation should not be performed until the patient has a full range of motion.
Swelling
Usually when the anterior cruciate is torn, it bleeds and fills the knee with blood. In fact, in 75% of cases of blood in the knee, a tear anterior cruciate is responsible.
The Arthrometry
The KT-1000 is used to get a objective measurement of the a-p displacement of the knee. A significant tear is diagnosed when there is 7 mm side to side difference in the measurement.
The Diagnostic Aids or Imaging
Plain X-Rays
The plain x-ray can not diagnose the tear of the anterior cruciate but is used to rule out associated fractures, and degenerative changes in the knee.
MRI
The MRI can image the tear of the tear of the anterior cruciate, but is unable to distinquish the degree of tear.
