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Sports Medicine & Shoulder Surgery Patient Guides
Patient
Guide to Labrum Tears in the Shoulder
Edward G. McFarland,
M.D. - 410-583-2850
Steve A. Petersen, M.D. - 410-847-3517
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What
is the labrum? The labrum is a type of cartilage found in the shoulder joint. The shoulder is a ball and socket joint where the arm meets the body (Figure 1). The arm bone (humerus) forms a ball at the shoulder which meets the socket which is part of the shoulder blade. These two bones are connected by ligaments which are tough tissues forming tethers that hold the bones in relationship to each other. There are two kinds of cartilage in the joint. The first type is the white cartilage on the ends of the bones (called articular cartilage) which allows the bones to glide and move on each other. When this type of cartilage starts to wear out (a process called arthritis), the joint becomes painful and stiff (see Patient Guide to Shoulder Replacements). The labrum is a second kind of cartilage in the shoulder which is distinctly different from the articular cartilage. This cartilage is more fibrous or rigid than the cartilage on the ends of the ball and socket. Also, this cartilage is also found only around the socket where it is attached. |
What
is the function of the labrum?
The labrum has basically two functions. The first is too deepen the socket
so that the ball stays in place. The best analogy is to picture the shoulder
joint as a beach ball on a dinner plate. The ball of the humerus ( the “beach
ball”) is much larger than the flat socket ( the “dinner plate”).
One thing that keeps the ball in the socket are the ligaments; these are the
tethers that go from bone to bone which hold the bones together. The other
way the ball is kept in the socket is the labrum (Figure 2).
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The
labrum is a thick tissue or type of cartilage that
is attached to the rim of the socket and essentially
forms a bumper which deepens the socket and helps keep
the ball in place. In individuals where the labrum
is too small or is torn due to an injury, the ball
may slide part of the way out of the socket (called
a “subluxation”) or all the way out of
the socket (called a “dislocation”) ( See
Patient Guide to Shoulder Instability. The labrum goes
all the way around the socket and in most areas is
firmly attached to the bone of the socket. In some
areas it is not firmly attached and only recently have
specialists determined which parts are normal and which
parts reflect tearing of the labrum. The second function of the labrum is as an attachment of other structures or tissues around the joint. For example, the ligaments that help hold the joint together attach to the labrum in certain key locations. If there is an injury to the shoulder that tears the ligaments, sometimes the labrum is pulled off of the rim of the bone as well (Figure III). |
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This
injury usually involves a subluxation or dislocation
of the shoulder and is usually due to trauma. The ball
of the shoulder can dislocate toward the front of the
shoulder (an anterior dislocation) or it can go out
the back of the shoulder (called a posterior dislocation).
In either case the labrum can be torn off of the bone.
Usually when this happens the labrum does not heal
back in the right location. Whether the joint continues
to be unstable depends upon many factors. The other structure that attaches to the labrum is the tendon of the biceps muscle (Figure 4a). The biceps muscle is the muscle on the front of the arm which gets firm with bending the elbow. While this muscle is quite large, it turns into a small tendon about the size of a pencil which attaches inside the shoulder joint. At the other end of the muscle is a large tendon which attaches beyond the elbow in the forearm. The portion which attaches in the shoulder actually goes through a small hole in the rotator cuff tendons designed specifically for that tendon. Once inside the joint the tendon attached in part to the bone near the socket and in part to the labrum at the top of the joint. This tendon can get torn where it attaches to the bone, where it attaches to the labrum or at both locations (Figure 4b). |
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A labrum tear can take several forms, and it is very easy to confuse these types. As a result, it is important that you discuss with your physician exactly what type of tear he/she is talking about. The first type of tear is one where the labrum is torn completely off of the bone (Figure 3). This is usually associated with an injury to the shoulder where the shoulder has subluxated or dislocated. Sometimes this type of tear occurs and the individual does not appreciate that the shoulder has slid out of the socket.
The second type of labrum tear is tearing within the substance of the labrum itself. The edge of the labrum over time may get frayed so that the edge is not smooth. This type of tearing is quite common and rarely causes symptoms. It is seen frequently in the shoulder as people get more mature (over forty years of age). Sometimes the labrum may have a large tear where a portion of the labrum gets into the joint and causes clicking and catching as the ball moves around in the socket. This type of tear is very rare, and most labrum tears do not cause these symptoms.
A third type of labrum tear is in the area where the biceps tendon attaches to the upper end of the socket. The socket can be divided into four regions: anterior (or front), posterior (or back), the upperend near your head (or superior), and the lower end (or inferior) which is toward the elbow (Figure 5).
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The biceps tendon attaches at the superior end where it blends in with the labrum. The labrum runs from there around the joint, both in an anterior and in a posterior direction. Due to injury in this area where the biceps tendon attaches, the labrum also can get injured. The injury in this area can be mild or it can be severe. Because the injury typically involves the biceps tendon and the labrum, because it is at the superior end of the socket and because it can effect the labrum attachments anterior and posterior to where the biceps attaches in this region, the acronym or abbreviation for this injury is a SLAP lesion. This stands for an injury which is Superior Labrum Anterior and Posterior. There have been several grading systems or classification systems of this injury. In a lesser injury the labrum is only partially detached in this area. In a more severe injury the whole labrum is pulled off of the bone along with the biceps tendon. The most common classification divides SLAP lesions into four types (Figure 6). |
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How
is a diagnosis of a labrum tear made?
Because this cartilage is deep in the shoulder, it is very difficult to make
the diagnosis of a torn labrum upon physical examination. There are several
tests that the physician can perform which may indicate a torn labrum, but
these tests are not always accurate. The other problem is that labrum tears
take different forms as described above, and certain tests will detect one
kind of tear but not another. Some physicians feel very confident that they
can make the diagnosis of a labral tear upon physical examination, but this
is controversial. There are not many scientific studies that show that physical
examination is reliable for making the diagnosis of a labral tear. As a result
of this uncertainty, other studies can be done to confirm the diagnosis if
it is suspected.
The best tests available to make the diagnosis of a labral tear are magnetic
resonance imaging or a test called a CT-arthrogram ( the latter is a CAT scan
preceded by an arthrogram where dye is injected into the shoulder). Both of
these tests are relatively good at defining a labrum tear due to a subluxation
or dislocation, but they are only around 80-85% accurate. For that reason,
some physicians believe that are not always needed if the diagnosis of subluxation
or dislocation can be made by history and physical examination. Neither of
those tests is currently very good at making the diagnosis of a SLAP lesion.
This area is very complex and it is difficult to reliably get good pictures
of this area with MRI.
However, if the MRI definitely shows a tear then frequently it will be present.
The problem is that the MRI may miss smaller tears and cannot reliably make
the diagnosis in larger tears of the labrum.
The best way to make the diagnosis of labrum tearing is with arthroscopy of
the shoulder. Unfortunately this is an operative procedure and requires some
form of anesthesia. Making the diagnosis also takes some experience on the
part of the surgeon, since the anatomy of the inside of the shoulder can be
quite complex. The relationship between labrum tears and symptoms has not been
totally figured out, so it is not clearly known which ones should be repaired
and which ones can be left alone.
What is the treatment for labrum tears?
The treatment depends upon which kind of tear there is in the labrum. Tears
that are due to instability of the shoulder, either subluxation or dislocations,
require that the labrum be reattached to the rim of the socket. This can be
done with an incision on the front of the shoulder, or it can be done with
arthroscopic techniques through smaller incisions. There are advantages and
disadvantages of each approach (see Patient Guide to Shoulder Instability).
At this institution we favor an open operation with an incision until arthroscopic
techniques become more perfected.
If the labrum is frayed, usually no treatment is necessary since it doesn’t
usually cause symptoms. However, if there is a large tear of the labrum, the
torn part should either be cut out and trimmed, or it should be repaired. Which
treatment is used depends upon where the tear is located and how big it is.
This type of tear requiring repair without instability of the shoulder is rare.
Tears of the labrum near the biceps tendon attachment (SLAP lesions) may be
just trimmed or may need to be reattached to the top of the socket. The best
way to do this is with arthroscopic surgery since this area is difficult to
reach with an open operation through a large incision. Using the arthroscope
and small incisions for other instruments, the labrum can be re-attached to
the rim of the socket using either sutures or tacks.
What is the recovery from labrum surgery?
The recovery depends upon many factors, such as where the tear was located,
how severe it was and how good the surgical repair was. It is believed that
it takes at least four to six weeks for the labrum to re-attach itself to the
rim of the bone, and probably another four to six weeks to get strong. Once
the labrum has healed to the rim of the bone, it should see stress very gradually
so that it can gather strength. It is important not to re-injure it while it
is healing.
How much motion and strengthening of the arm is allowed after surgery also
depends upon many factors, and it is up to the surgeon to let you know your
limitations and how fast to progress. Because of the variability in the injury
and the type of repair done, it is difficult to predict how soon someone can
to return to activities and to sports after the repair. The type of sport also
is important, since contact sports have a greater chance of injuring the labrum
repair. However, a vast majority of patients have full function of the shoulder
after labrum repair, and most patients can return to their previous level of
sports with no or few restrictions.
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