Humans are able to move around and perform many physical movements thanks to the lower limbs. The lower limbs consist of muscle, bone, nerve and blood supply that works in a system. When one of these structures fails to work properly, such as after an injury, it can lead to problems in movement or difficulty using the limbs. Regular health screening can help identify risk and what can be done to avoid limb issues. In this article, we will be learning about the differences between the two tests, the McMurray test and the Apley compression test. These tests often are used to detect certain injury to the limb.
Before going through the differences, do you know that these two tests are actually checking or evaluating the same thing? These two tests are used to detect meniscus injury. What exactly is meniscus? Meniscus are rubbery disks that help cushion the knee joint. It sits between the lower leg bone (tibia) and the thigh bone (femur). In general, meniscus acts as a shock absorber. Meniscus tears usually take place when there is a sudden twist of the knee while bearing weight on it such as in athletes and those playing sports. For example, twisting the knee while the foot is planted on the ground when playing volleyball.
This test is done while the patient is lying down on their back. Practitioner will bend the knee to 90 degrees perpendicular to the rest of the body. Then, the practitioner will rotate the bent knee toward the body (internal rotation) and away from the body (external rotation). Lastly, the practitioner straightens the leg.
The principle of McMurray’s test is to apply mild stress to the meniscus in different positions. Such movements are similar to the kind of force applied to the knee in daily routine.
McMurray test is said positive when there is presence of pain and joint making sound such as popping, clicking and snaps. A painful click on the inward rotation means there is tear to the lateral meniscus (meniscus on the outside of the knee) whereas a painful click on the outward rotation means there is tear to the medial meniscus (meniscus on the inside of the knee).
Apley Compression Test
To understand how Apley compression test is performed, best to know the Apley distraction test first. This test is done while the patient is lying down on stomach (prone position). Practitioner will lean the knee back of the thigh and hold the leg in place. The knee is then bent to 90 degrees (perpendicular to the rest of the leg). Knee is pulled up lightly. Then, the practitioner rotates the lower leg away from the centre of the body and back toward the centre of the body. In the Apley compression test, the lower leg is pressed down lightly instead of pulled up.
The principle of these tests is to apply mild stress to the meniscus such as when applied to the knee in daily life activities.
Both Apley distraction and compression test is typically known as Apley test. The test is said to be positive when there is pain or restriction during rotation of leg. If pain is experienced to the medial aspect (internal rotation) of the knee, this means that there is tear in medial meniscus whereas pain experienced to the lateral aspect (external rotation) of the knee means there is tear in lateral meniscus.
McMurray test and Apley test are done when there is suspicion of meniscus tear. Symptoms of meniscus tear include popping sensation when injury occurs, swelling or stiffness, pain especially when twisting or rotating the knee, difficulty to fully straighten the knee and locking of the knee. Most people can still walk on the injured knee for over 2 to 3 days before the knee is presented with symptoms.
These two tests are performed on both sides of the legs, typically with the healthy legs or legs with no symptoms. This is done to evaluate how severe the injury is and to make a fair comparison. Although the two tests do help in identifying if there is injury to the meniscus, since symptoms can resemble other knee injuries, doctors typically run imaging tests to help confirm diagnosis. Meniscal tears are best viewed using MRI.
It can be concluded that although there are differences in the way the McMurray test and Apley test is performed, both aim in looking for signs of meniscal tear. When these two tests are performed on the same setting, it increases the confidence for identifying meniscal tear.These tests may cause discomfort especially to the injured knee but in general it is a safe test and can be done in a doctor’s office. The tests should not be causing intense pain. Imaging tests are usually needed after a knee injury, at least one such as x-ray. When there is great suspicion of the meniscal tear, further imaging tests such as MRI is done to help identify which part of the meniscus is affected.