What is a Labral Tear?
The labrum is a lip or rim of fibrous cartilage attached to the edge of the acetabulum (hip socket). The exact function of the labrum is still being investigated but it does appear to act as a suction seal for the hip joint and helps spread the lubricating fluid evenly between the ball and socket.
The labrum maybe damaged with certain twisting movements of the hip that bring the neck of the femur (the part of the thigh bone attached to the ball of the hip joint) in to contact with the labrum. The labrum can be torn from its attachment to the edge of the socket. Very often there is a subtle abnormality of the bony anatomy around the hip in patients with labral tears that also needs to be addressed at surgery (see Femoroacetabular impingement below).
A labrum tear can produce mechanical symptoms such as clicking and catching in the hip as well as pain that is frequently felt in the groin. The pain can be during activities such as walking or jogging but can also be felt at rest especially after a lot of activity or while sitting with the hip flexed such as while resting in a low chair. The labrum probably does have some healing potential and it is usual to rehabilitate the hip with physiotherapy for three to six months to see if symptoms abate.
Labrum tears are more commonly seen in young athletes who participate in sports requiring a large range of hip motion. Examples of this would be soccer, hockey, dancing and martial arts. Labral tears are also seen in people with arthritis. Hip pain in the presence of arthritis and a labral tear is not well treated with hip arthroscopy. Also, in the presence of arthritis of the hip there is almost always a labral tear.
The history is usually one of a twisting injury followed by persistent groin pain that will not settle. Some times, an athlete such as a squash player or a soccer player will have a history of recurrent groin strains that fail to settle.
Examination often reveals a reduction in internal rotation and pain when the hip is flexed up, internally rotated and brought across the body. Greater loss of motion in all directions often signifies the onset of more significant arthritis.
A weight bearing X-ray is very useful and will always be required in the work up of patients with groin pain. It will show the bony anatomy of the hip joint and predisposing anatomical factors that can lead to labral tears. Crucially it will best indicate if arthritis is present as a major cause of the groin pain.
An MR arthrogram is the best test to show a labral tear however it is not always needed prior to surgery. It should also never be done before getting X-rays. An MRI scan uses strong magnets rather than radiation and shows the soft tissues such as cartilage and muscle very clearly. An MR arthrogram is an MRI scan taken after the injection of a contrast dye into the hip joint prior to the scan.
The contrast agent is nontoxic and is excreted in the urine a short time after but can make the hip ache a little more over the next 24-48 hours. The contrast fluid fills the gap between the edge of the socket and the torn labrum, thus outlining the tear.
The MR arthrogram may also show some of the bony abnormalities that can cause femoroacetabular impingement and are thought to contribute to labral tears. However, it is also sometimes necessary to obtain a CT scan which is the most accurate way to show any bony predisposing factors.
If a period of rest followed by rehabilitation and alteration of aggravating activities does not result in improvement in symptoms then surgery can be considered. Arthroscopic surgery is performed as a daycare procedure. The edge of any labral tear is cleaned up and the edge of the bony socket is likewise prepared using small shavers and burs. Small anchors are inserted into the edge of the hip socket and a strong suture is placed around or through the labrum securing it back to the bone.
Importantly, it is rare that an isolated labral tear is the main problem and cause of the pain. The surgeon must treat the cam and/or pincer impingement to treat the pain and prevent recurrence of the labral tear. This is done by reshaping the abnormal bony anatomy to a more normal shape using the arthroscopic instruments.